Redefine the meaning of sample counts in GPU backend.

Old: 0  -> nonMSAA
     1+ -> MSAA

New:
     0  -> error/unsupported
     1  -> nonMSAA
     2+ -> MSAA

We still allow 0 to mean nonMSAA in three sets of public APIs for backwards compatibility:

1) SkSurface factories
2) GrBackendRenderTarget constructors
3) GrCaps::getSampleCnt()'s requestedCount parameter

However, we immediately clamp to 1 and treat 0 as invalid/non-renderable internally.

This also changes the behavior when using a large sample count. We now fail in that case rather than using the largest sample available sample count. GrCaps::getSampleCount() will return 0 in this case.


Bug: skia:
Change-Id: Ida22c6b22c1365e563c9046b611e88bf5eb3ff33
Reviewed-on: https://skia-review.googlesource.com/101560
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

37 files changed, 205 insertions, 116 deletions

diff --git a/src/gpu/GrBackendSurface.cpp b/src/gpu/GrBackendSurface.cpp
index 406cb228ea..16fa793d25 100644
--- a/src/gpu/GrBackendSurface.cpp
+++ b/src/gpu/GrBackendSurface.cpp
@@ -106,7 +106,7 @@ GrBackendRenderTarget::GrBackendRenderTarget(int width,
                                              const GrVkImageInfo& vkInfo)
         : fWidth(width)
         , fHeight(height)
-        , fSampleCnt(sampleCnt)
+        , fSampleCnt(SkTMax(1, sampleCnt))
         , fStencilBits(stencilBits)
         , fConfig(GrVkFormatToPixelConfig(vkInfo.fFormat))
         , fBackend(kVulkan_GrBackend)
@@ -121,7 +121,7 @@ GrBackendRenderTarget::GrBackendRenderTarget(int width,
                                              const GrGLFramebufferInfo& glInfo)
         : fWidth(width)
         , fHeight(height)
-        , fSampleCnt(sampleCnt)
+        , fSampleCnt(SkTMax(1, sampleCnt))
         , fStencilBits(stencilBits)
         , fConfig(config)
         , fBackend(kOpenGL_GrBackend)
@@ -134,7 +134,7 @@ GrBackendRenderTarget::GrBackendRenderTarget(int width,
                                              const GrGLFramebufferInfo& glInfo)
         : fWidth(width)
         , fHeight(height)
-        , fSampleCnt(sampleCnt)
+        , fSampleCnt(SkTMax(1, sampleCnt))
         , fStencilBits(stencilBits)
         , fConfig(GrGLSizedFormatToPixelConfig(glInfo.fFormat))
         , fBackend(kOpenGL_GrBackend)
diff --git a/src/gpu/GrBackendTextureImageGenerator.cpp b/src/gpu/GrBackendTextureImageGenerator.cpp
index ae27912b32..af28409cfe 100644
--- a/src/gpu/GrBackendTextureImageGenerator.cpp
+++ b/src/gpu/GrBackendTextureImageGenerator.cpp
@@ -186,8 +186,8 @@ sk_sp<GrTextureProxy> GrBackendTextureImageGenerator::onGenerateTexture(
         GrMipMapped mipMapped = willNeedMipMaps ? GrMipMapped::kYes : GrMipMapped::kNo;
 
         sk_sp<GrRenderTargetContext> rtContext(context->makeDeferredRenderTargetContext(
-                SkBackingFit::kExact, info.width(), info.height(), proxy->config(), nullptr,
-                0, mipMapped, proxy->origin(), nullptr, SkBudgeted::kYes));
+                SkBackingFit::kExact, info.width(), info.height(), proxy->config(), nullptr, 1,
+                mipMapped, proxy->origin(), nullptr, SkBudgeted::kYes));
 
         if (!rtContext) {
             return nullptr;
diff --git a/src/gpu/GrBlurUtils.cpp b/src/gpu/GrBlurUtils.cpp
index b79a38a884..b6e3092d5a 100644
--- a/src/gpu/GrBlurUtils.cpp
+++ b/src/gpu/GrBlurUtils.cpp
@@ -110,7 +110,7 @@ static sk_sp<GrTextureProxy> create_mask_GPU(GrContext* context,
                                              int sampleCnt) {
     if (GrAA::kNo == aa) {
         // Don't need MSAA if mask isn't AA
-        sampleCnt = 0;
+        sampleCnt = 1;
     }
 
     sk_sp<GrRenderTargetContext> rtContext(context->makeDeferredRenderTargetContextWithFallback(
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index b427e70beb..baa5232032 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -862,6 +862,7 @@ sk_sp<GrRenderTargetContext> GrContextPriv::makeBackendTextureRenderTargetContex
                                                                    sk_sp<SkColorSpace> colorSpace,
                                                                    const SkSurfaceProps* props) {
     ASSERT_SINGLE_OWNER_PRIV
+    SkASSERT(sampleCnt > 0);
 
     sk_sp<GrTextureProxy> proxy(this->proxyProvider()->createWrappedTextureProxy(tex, origin,
                                                                                  sampleCnt));
@@ -898,7 +899,7 @@ sk_sp<GrRenderTargetContext> GrContextPriv::makeBackendTextureAsRenderTargetRend
                                                      sk_sp<SkColorSpace> colorSpace,
                                                      const SkSurfaceProps* props) {
     ASSERT_SINGLE_OWNER_PRIV
-
+    SkASSERT(sampleCnt > 0);
     sk_sp<GrSurfaceProxy> proxy(this->proxyProvider()->createWrappedRenderTargetProxy(tex, origin,
                                                                                       sampleCnt));
     if (!proxy) {
@@ -949,7 +950,8 @@ sk_sp<GrRenderTargetContext> GrContext::makeDeferredRenderTargetContextWithFallb
                                                                  GrSurfaceOrigin origin,
                                                                  const SkSurfaceProps* surfaceProps,
                                                                  SkBudgeted budgeted) {
-    if (!this->caps()->isConfigRenderable(config, sampleCnt > 0)) {
+    SkASSERT(sampleCnt > 0);
+    if (!this->caps()->isConfigRenderable(config, sampleCnt > 1)) {
         config = GrPixelConfigFallback(config);
     }
 
@@ -968,6 +970,7 @@ sk_sp<GrRenderTargetContext> GrContext::makeDeferredRenderTargetContext(
                                                         GrSurfaceOrigin origin,
                                                         const SkSurfaceProps* surfaceProps,
                                                         SkBudgeted budgeted) {
+    SkASSERT(sampleCnt > 0);
     if (this->abandoned()) {
         return nullptr;
     }
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index eb005d110a..bea6a601e6 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -94,12 +94,16 @@ static bool check_texture_creation_params(const GrCaps& caps, const GrSurfaceDes
     }
 
     *isRT = SkToBool(desc.fFlags & kRenderTarget_GrSurfaceFlag);
-    if (*isRT && !caps.isConfigRenderable(desc.fConfig, desc.fSampleCnt > 0)) {
+    if (*isRT && !caps.isConfigRenderable(desc.fConfig, desc.fSampleCnt > 1)) {
+        return false;
+    }
+
+    if (desc.fSampleCnt < 1) {
         return false;
     }
 
     // We currently do not support multisampled textures
-    if (!*isRT && desc.fSampleCnt > 0) {
+    if (!*isRT && desc.fSampleCnt > 1) {
         return false;
     }
 
@@ -131,9 +135,14 @@ sk_sp<GrTexture> GrGpu::createTexture(const GrSurfaceDesc& origDesc, SkBudgeted
         return nullptr;
     }
 
-    desc.fSampleCnt = caps->getSampleCount(desc.fSampleCnt, desc.fConfig);
+    if (isRT) {
+        desc.fSampleCnt = caps->getSampleCount(desc.fSampleCnt, desc.fConfig);
+        if (!desc.fSampleCnt) {
+            return nullptr;
+        }
+    }
     // Attempt to catch un- or wrongly initialized sample counts.
-    SkASSERT(desc.fSampleCnt >= 0 && desc.fSampleCnt <= 64);
+    SkASSERT(desc.fSampleCnt > 0 && desc.fSampleCnt <= 64);
 
     if (mipLevelCount && (desc.fFlags & kPerformInitialClear_GrSurfaceFlag)) {
         return nullptr;
@@ -179,8 +188,11 @@ sk_sp<GrTexture> GrGpu::wrapBackendTexture(const GrBackendTexture& backendTex,
 sk_sp<GrTexture> GrGpu::wrapRenderableBackendTexture(const GrBackendTexture& backendTex,
                                                      int sampleCnt, GrWrapOwnership ownership) {
     this->handleDirtyContext();
+    if (sampleCnt < 1) {
+        return nullptr;
+    }
     if (!this->caps()->isConfigTexturable(backendTex.config()) ||
-        !this->caps()->isConfigRenderable(backendTex.config(), sampleCnt > 0)) {
+        !this->caps()->isConfigRenderable(backendTex.config(), sampleCnt > 1)) {
         return nullptr;
     }
 
@@ -197,7 +209,7 @@ sk_sp<GrTexture> GrGpu::wrapRenderableBackendTexture(const GrBackendTexture& bac
 }
 
 sk_sp<GrRenderTarget> GrGpu::wrapBackendRenderTarget(const GrBackendRenderTarget& backendRT) {
-    if (!this->caps()->isConfigRenderable(backendRT.config(), backendRT.sampleCnt() > 0)) {
+    if (!this->caps()->isConfigRenderable(backendRT.config(), backendRT.sampleCnt() > 1)) {
         return nullptr;
     }
     this->handleDirtyContext();
@@ -207,7 +219,7 @@ sk_sp<GrRenderTarget> GrGpu::wrapBackendRenderTarget(const GrBackendRenderTarget
 sk_sp<GrRenderTarget> GrGpu::wrapBackendTextureAsRenderTarget(const GrBackendTexture& tex,
                                                               int sampleCnt) {
     this->handleDirtyContext();
-    if (!this->caps()->isConfigRenderable(tex.config(), sampleCnt > 0)) {
+    if (!this->caps()->isConfigRenderable(tex.config(), sampleCnt > 1)) {
         return nullptr;
     }
     int maxSize = this->caps()->maxTextureSize();
diff --git a/src/gpu/GrProxyProvider.cpp b/src/gpu/GrProxyProvider.cpp
index ec05243d18..193b321190 100644
--- a/src/gpu/GrProxyProvider.cpp
+++ b/src/gpu/GrProxyProvider.cpp
@@ -322,12 +322,16 @@ sk_sp<GrTextureProxy> GrProxyProvider::createProxy(const GrSurfaceDesc& desc,
     }
 
     bool willBeRT = SkToBool(desc.fFlags & kRenderTarget_GrSurfaceFlag);
-    if (willBeRT && !caps->isConfigRenderable(desc.fConfig, desc.fSampleCnt > 0)) {
+    if (willBeRT && !caps->isConfigRenderable(desc.fConfig, desc.fSampleCnt > 1)) {
         return nullptr;
     }
 
     // We currently do not support multisampled textures
-    if (!willBeRT && desc.fSampleCnt > 0) {
+    if (!willBeRT && desc.fSampleCnt > 1) {
+        return nullptr;
+    }
+
+    if (willBeRT && !caps->getSampleCount(desc.fSampleCnt, desc.fConfig)) {
         return nullptr;
     }
 
@@ -505,7 +509,7 @@ sk_sp<GrTextureProxy> GrProxyProvider::createFullyLazyProxy(LazyInstantiateCallb
     desc.fWidth = -1;
     desc.fHeight = -1;
     desc.fConfig = config;
-    desc.fSampleCnt = 0;
+    desc.fSampleCnt = 1;
 
     return this->createLazyProxy(std::move(callback), desc, GrMipMapped::kNo,
                                  SkBackingFit::kApprox, SkBudgeted::kYes);
diff --git a/src/gpu/GrRenderTarget.cpp b/src/gpu/GrRenderTarget.cpp
index 3090219751..36fa4ddf1b 100644
--- a/src/gpu/GrRenderTarget.cpp
+++ b/src/gpu/GrRenderTarget.cpp
@@ -27,7 +27,7 @@ GrRenderTarget::GrRenderTarget(GrGpu* gpu, const GrSurfaceDesc& desc,
         , fMultisampleSpecsID(0)
         , fFlags(flags) {
     SkASSERT(desc.fFlags & kRenderTarget_GrSurfaceFlag);
-    SkASSERT(!(fFlags & GrRenderTargetFlags::kMixedSampled) || fSampleCnt > 0);
+    SkASSERT(!(fFlags & GrRenderTargetFlags::kMixedSampled) || fSampleCnt > 1);
     SkASSERT(!(fFlags & GrRenderTargetFlags::kWindowRectsSupport) ||
              gpu->caps()->maxWindowRectangles() > 0);
     fResolveRect = SkRectPriv::MakeILargestInverted();
diff --git a/src/gpu/GrRenderTargetProxy.cpp b/src/gpu/GrRenderTargetProxy.cpp
index 9eb37a0b2f..841d4b18fd 100644
--- a/src/gpu/GrRenderTargetProxy.cpp
+++ b/src/gpu/GrRenderTargetProxy.cpp
@@ -26,7 +26,7 @@ GrRenderTargetProxy::GrRenderTargetProxy(const GrCaps& caps, const GrSurfaceDesc
         , fRenderTargetFlags(GrRenderTargetFlags::kNone) {
     // Since we know the newly created render target will be internal, we are able to precompute
     // what the flags will ultimately end up being.
-    if (caps.usesMixedSamples() && fSampleCnt > 0) {
+    if (caps.usesMixedSamples() && fSampleCnt > 1) {
         fRenderTargetFlags |= GrRenderTargetFlags::kMixedSampled;
     }
     if (caps.maxWindowRectangles() > 0) {
@@ -97,7 +97,11 @@ sk_sp<GrSurface> GrRenderTargetProxy::createSurface(GrResourceProvider* resource
 }
 
 size_t GrRenderTargetProxy::onUninstantiatedGpuMemorySize() const {
-    int colorSamplesPerPixel = this->numColorSamples() + 1;
+    int colorSamplesPerPixel = this->numColorSamples();
+    if (colorSamplesPerPixel > 1) {
+        // Add one for the resolve buffer.
+        ++colorSamplesPerPixel;
+    }
 
     // TODO: do we have enough information to improve this worst case estimate?
     return GrSurface::ComputeSize(this->config(), this->width(), this->height(),
diff --git a/src/gpu/GrResourceProvider.cpp b/src/gpu/GrResourceProvider.cpp
index 9cf4e6c3e7..011ad6f5a9 100644
--- a/src/gpu/GrResourceProvider.cpp
+++ b/src/gpu/GrResourceProvider.cpp
@@ -47,6 +47,10 @@ GrResourceProvider::GrResourceProvider(GrGpu* gpu, GrResourceCache* cache, GrSin
 }
 
 bool validate_desc(const GrSurfaceDesc& desc, const GrCaps& caps, int levelCount = 0) {
+    if (desc.fSampleCnt < 1) {
+        return false;
+    }
+
     if (desc.fWidth <= 0 || desc.fHeight <= 0) {
         return false;
     }
@@ -54,11 +58,11 @@ bool validate_desc(const GrSurfaceDesc& desc, const GrCaps& caps, int levelCount
         return false;
     }
     if (desc.fFlags & kRenderTarget_GrSurfaceFlag) {
-        if (!caps.isConfigRenderable(desc.fConfig, desc.fSampleCnt > 0)) {
+        if (!caps.isConfigRenderable(desc.fConfig, desc.fSampleCnt > 1)) {
             return false;
         }
     } else {
-        if (desc.fSampleCnt) {
+        if (desc.fSampleCnt > 1) {
             return false;
         }
     }
@@ -156,7 +160,6 @@ sk_sp<GrTexture> GrResourceProvider::createTexture(const GrSurfaceDesc& desc,
 sk_sp<GrTexture> GrResourceProvider::createTexture(const GrSurfaceDesc& desc, SkBudgeted budgeted,
                                                    uint32_t flags) {
     ASSERT_SINGLE_OWNER
-
     if (this->isAbandoned()) {
         return nullptr;
     }
diff --git a/src/gpu/GrResourceProvider.h b/src/gpu/GrResourceProvider.h
index bf7f28e93d..18df8597bd 100644
--- a/src/gpu/GrResourceProvider.h
+++ b/src/gpu/GrResourceProvider.h
@@ -88,7 +88,7 @@ public:
                                         GrWrapOwnership = kBorrow_GrWrapOwnership);
 
     /**
-     * This makes the backend texture be renderable. If sampleCnt is > 0 and the underlying API
+     * This makes the backend texture be renderable. If sampleCnt is > 1 and the underlying API
      * uses separate MSAA render buffers then a MSAA render buffer is created that resolves
      * to the texture.
      */
diff --git a/src/gpu/GrSurface.cpp b/src/gpu/GrSurface.cpp
index ec503d7066..b35683c548 100644
--- a/src/gpu/GrSurface.cpp
+++ b/src/gpu/GrSurface.cpp
@@ -29,8 +29,9 @@ size_t GrSurface::WorstCaseSize(const GrSurfaceDesc& desc, bool useNextPow2) {
     bool isRenderTarget = SkToBool(desc.fFlags & kRenderTarget_GrSurfaceFlag);
     if (isRenderTarget) {
         // We own one color value for each MSAA sample.
-        int colorValuesPerPixel = SkTMax(1, desc.fSampleCnt);
-        if (desc.fSampleCnt) {
+        SkASSERT(desc.fSampleCnt >= 1);
+        int colorValuesPerPixel = desc.fSampleCnt;
+        if (desc.fSampleCnt > 1) {
             // Worse case, we own the resolve buffer so that is one more sample per pixel.
             colorValuesPerPixel += 1;
         }
diff --git a/src/gpu/GrSurfaceProxy.cpp b/src/gpu/GrSurfaceProxy.cpp
index 64c47b56b1..4020758259 100644
--- a/src/gpu/GrSurfaceProxy.cpp
+++ b/src/gpu/GrSurfaceProxy.cpp
@@ -26,7 +26,7 @@ static bool is_valid_fully_lazy(const GrSurfaceDesc& desc, SkBackingFit fit) {
     return desc.fWidth <= 0 &&
            desc.fHeight <= 0 &&
            desc.fConfig != kUnknown_GrPixelConfig &&
-           desc.fSampleCnt == 0 &&
+           desc.fSampleCnt == 1 &&
            SkBackingFit::kApprox == fit;
 }
 
@@ -190,7 +190,7 @@ bool GrSurfaceProxy::instantiateImpl(GrResourceProvider* resourceProvider, int s
 void GrSurfaceProxy::computeScratchKey(GrScratchKey* key) const {
     SkASSERT(LazyState::kFully != this->lazyInstantiationState());
     const GrRenderTargetProxy* rtp = this->asRenderTargetProxy();
-    int sampleCount = 0;
+    int sampleCount = 1;
     if (rtp) {
         sampleCount = rtp->numStencilSamples();
     }
diff --git a/src/gpu/GrTexture.cpp b/src/gpu/GrTexture.cpp
index b4cefb0174..dd0631775f 100644
--- a/src/gpu/GrTexture.cpp
+++ b/src/gpu/GrTexture.cpp
@@ -78,7 +78,7 @@ bool GrTexture::StealBackendTexture(sk_sp<GrTexture>&& texture,
 
 void GrTexture::computeScratchKey(GrScratchKey* key) const {
     const GrRenderTarget* rt = this->asRenderTarget();
-    int sampleCount = 0;
+    int sampleCount = 1;
     if (rt) {
         sampleCount = rt->numStencilSamples();
     }
@@ -92,8 +92,10 @@ void GrTexturePriv::ComputeScratchKey(GrPixelConfig config, int width, int heigh
                                       GrMipMapped mipMapped, GrScratchKey* key) {
     static const GrScratchKey::ResourceType kType = GrScratchKey::GenerateResourceType();
     uint32_t flags = isRenderTarget;
-
-    SkASSERT(0 == sampleCnt || isRenderTarget);
+    SkASSERT(width > 0);
+    SkASSERT(height > 0);
+    SkASSERT(sampleCnt > 0);
+    SkASSERT(1 == sampleCnt || isRenderTarget);
 
     // make sure desc.fConfig fits in 5 bits
     SkASSERT(sk_float_log2(kLast_GrPixelConfig) <= 5);
diff --git a/src/gpu/GrTextureProducer.cpp b/src/gpu/GrTextureProducer.cpp
index 9593cb6873..9b344cb831 100644
--- a/src/gpu/GrTextureProducer.cpp
+++ b/src/gpu/GrTextureProducer.cpp
@@ -25,8 +25,8 @@ sk_sp<GrTextureProxy> GrTextureProducer::CopyOnGpu(GrContext* context,
     GrMipMapped mipMapped = dstWillRequireMipMaps ? GrMipMapped::kYes : GrMipMapped::kNo;
 
     sk_sp<GrRenderTargetContext> copyRTC = context->makeDeferredRenderTargetContextWithFallback(
-        SkBackingFit::kExact, dstRect.width(), dstRect.height(), inputProxy->config(), nullptr,
-        0, mipMapped, inputProxy->origin());
+            SkBackingFit::kExact, dstRect.width(), dstRect.height(), inputProxy->config(), nullptr,
+            1, mipMapped, inputProxy->origin());
     if (!copyRTC) {
         return nullptr;
     }
diff --git a/src/gpu/GrTextureProxy.cpp b/src/gpu/GrTextureProxy.cpp
index 8e6afbf0a7..54d0769a63 100644
--- a/src/gpu/GrTextureProxy.cpp
+++ b/src/gpu/GrTextureProxy.cpp
@@ -64,7 +64,7 @@ bool GrTextureProxy::instantiate(GrResourceProvider* resourceProvider) {
     if (LazyState::kNot != this->lazyInstantiationState()) {
         return false;
     }
-    if (!this->instantiateImpl(resourceProvider, 0, /* needsStencil = */ false,
+    if (!this->instantiateImpl(resourceProvider, 1, /* needsStencil = */ false,
                                kNone_GrSurfaceFlags, fMipMapped, fMipColorMode,
                                fUniqueKey.isValid() ? &fUniqueKey : nullptr)) {
         return false;
@@ -76,7 +76,7 @@ bool GrTextureProxy::instantiate(GrResourceProvider* resourceProvider) {
 }
 
 sk_sp<GrSurface> GrTextureProxy::createSurface(GrResourceProvider* resourceProvider) const {
-    sk_sp<GrSurface> surface= this->createSurfaceImpl(resourceProvider, 0,
+    sk_sp<GrSurface> surface= this->createSurfaceImpl(resourceProvider, 1,
                                                       /* needsStencil = */ false,
                                                       kNone_GrSurfaceFlags,
                                                       fMipMapped, fMipColorMode);
diff --git a/src/gpu/GrTextureRenderTargetProxy.cpp b/src/gpu/GrTextureRenderTargetProxy.cpp
index da8e48307d..843524c062 100644
--- a/src/gpu/GrTextureRenderTargetProxy.cpp
+++ b/src/gpu/GrTextureRenderTargetProxy.cpp
@@ -53,7 +53,11 @@ GrTextureRenderTargetProxy::GrTextureRenderTargetProxy(sk_sp<GrSurface> surf,
 }
 
 size_t GrTextureRenderTargetProxy::onUninstantiatedGpuMemorySize() const {
-    int colorSamplesPerPixel = this->numColorSamples() + 1;
+    int colorSamplesPerPixel = this->numColorSamples();
+    if (colorSamplesPerPixel > 1) {
+        // Add one to account for the resolve buffer.
+        ++colorSamplesPerPixel += 1;
+    }
 
     // TODO: do we have enough information to improve this worst case estimate?
     return GrSurface::ComputeSize(this->config(), this->width(), this->height(),
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 976339b96f..a702d06395 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -47,7 +47,7 @@ GrSurfaceDesc GrImageInfoToSurfaceDesc(const SkImageInfo& info, const GrCaps& ca
     desc.fWidth = info.width();
     desc.fHeight = info.height();
     desc.fConfig = SkImageInfo2GrPixelConfig(info, caps);
-    desc.fSampleCnt = 0;
+    desc.fSampleCnt = 1;
     return desc;
 }
 
@@ -169,7 +169,7 @@ sk_sp<GrTextureProxy> GrCopyBaseMipMapToTextureProxy(GrContext* ctx, GrTexturePr
     desc.fWidth = baseProxy->width();
     desc.fHeight = baseProxy->height();
     desc.fConfig = baseProxy->config();
-    desc.fSampleCnt = 0;
+    desc.fSampleCnt = 1;
 
     sk_sp<GrTextureProxy> proxy = proxyProvider->createMipMapProxy(desc, SkBudgeted::kYes);
     if (!proxy) {
diff --git a/src/gpu/ddl/GrDDLGpu.h b/src/gpu/ddl/GrDDLGpu.h
index 16deab0353..e1f463f073 100644
--- a/src/gpu/ddl/GrDDLGpu.h
+++ b/src/gpu/ddl/GrDDLGpu.h
@@ -46,7 +46,7 @@ public:
     void onQueryMultisampleSpecs(GrRenderTarget* rt, GrSurfaceOrigin, const GrStencilSettings&,
                                  int* effectiveSampleCnt, SamplePattern*) override {
         SkASSERT(0);
-        *effectiveSampleCnt = 0; // ??
+        *effectiveSampleCnt = 1;  // ??
     }
 
     GrGpuRTCommandBuffer* createCommandBuffer(
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 3b90676be1..93a7e614fd 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -1958,6 +1958,8 @@ void GrGLCaps::initConfigTable(const GrContextOptions& contextOptions,
 
     for (int i = 0; i < kGrPixelConfigCnt; ++i) {
         if (ConfigInfo::kRenderableWithMSAA_Flag & fConfigTable[i].fFlags) {
+            // We assume that MSAA rendering is supported only if we support non-MSAA rendering.
+            SkASSERT(ConfigInfo::kRenderable_Flag & fConfigTable[i].fFlags);
             if ((kGL_GrGLStandard == ctxInfo.standard() &&
                  (ctxInfo.version() >= GR_GL_VER(4,2) ||
                   ctxInfo.hasExtension("GL_ARB_internalformat_query"))) ||
@@ -1970,10 +1972,15 @@ void GrGLCaps::initConfigTable(const GrContextOptions& contextOptions,
                     int* temp = new int[count];
                     GR_GL_GetInternalformativ(gli, GR_GL_RENDERBUFFER, format, GR_GL_SAMPLES, count,
                                               temp);
+                    // GL has a concept of MSAA rasterization with a single sample but we do not.
+                    if (count && temp[count - 1] == 1) {
+                        --count;
+                        SkASSERT(!count || temp[count -1] > 1);
+                    }
                     fConfigTable[i].fColorSampleCounts.setCount(count+1);
-                    // We initialize our supported values with 0 (no msaa) and reverse the order
+                    // We initialize our supported values with 1 (no msaa) and reverse the order
                     // returned by GL so that the array is ascending.
-                    fConfigTable[i].fColorSampleCounts[0] = 0;
+                    fConfigTable[i].fColorSampleCounts[0] = 1;
                     for (int j = 0; j < count; ++j) {
                         fConfigTable[i].fColorSampleCounts[j+1] = temp[count - j - 1];
                     }
@@ -1982,14 +1989,16 @@ void GrGLCaps::initConfigTable(const GrContextOptions& contextOptions,
             } else {
                 // Fake out the table using some semi-standard counts up to the max allowed sample
                 // count.
-                int maxSampleCnt = 0;
+                int maxSampleCnt = 1;
                 if (GrGLCaps::kES_IMG_MsToTexture_MSFBOType == fMSFBOType) {
                     GR_GL_GetIntegerv(gli, GR_GL_MAX_SAMPLES_IMG, &maxSampleCnt);
                 } else if (GrGLCaps::kNone_MSFBOType != fMSFBOType) {
                     GR_GL_GetIntegerv(gli, GR_GL_MAX_SAMPLES, &maxSampleCnt);
                 }
+                // Chrome has a mock GL implementation that returns 0.
+                maxSampleCnt = SkTMax(1, maxSampleCnt);
 
-                static constexpr int kDefaultSamples[] = {0, 1, 2, 4, 8};
+                static constexpr int kDefaultSamples[] = {1, 2, 4, 8};
                 int count = SK_ARRAY_COUNT(kDefaultSamples);
                 for (; count > 0; --count) {
                     if (kDefaultSamples[count - 1] <= maxSampleCnt) {
@@ -2000,6 +2009,9 @@ void GrGLCaps::initConfigTable(const GrContextOptions& contextOptions,
                     fConfigTable[i].fColorSampleCounts.append(count, kDefaultSamples);
                 }
             }
+        } else if (ConfigInfo::kRenderable_Flag & fConfigTable[i].fFlags) {
+            fConfigTable[i].fColorSampleCounts.setCount(1);
+            fConfigTable[i].fColorSampleCounts[0] = 1;
         }
     }
 
@@ -2457,17 +2469,22 @@ void GrGLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {
 }
 
 int GrGLCaps::getSampleCount(int requestedCount, GrPixelConfig config) const {
+    requestedCount = SkTMax(1, requestedCount);
     int count = fConfigTable[config].fColorSampleCounts.count();
-    if (!count || !this->isConfigRenderable(config, true)) {
+    if (!count || !this->isConfigRenderable(config, requestedCount > 1)) {
         return 0;
     }
 
+    if (1 == requestedCount) {
+        return fConfigTable[config].fColorSampleCounts[0] == 1 ? 1 : 0;
+    }
+
     for (int i = 0; i < count; ++i) {
         if (fConfigTable[config].fColorSampleCounts[i] >= requestedCount) {
             return fConfigTable[config].fColorSampleCounts[i];
         }
     }
-    return fConfigTable[config].fColorSampleCounts[count-1];
+    return 0;
 }
 
 bool validate_sized_format(GrGLenum format, SkColorType ct, GrPixelConfig* config,
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index ae31495b06..e117488647 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -545,7 +545,7 @@ sk_sp<GrTexture> GrGLGpu::onWrapBackendTexture(const GrBackendTexture& backendTe
     surfDesc.fWidth = backendTex.width();
     surfDesc.fHeight = backendTex.height();
     surfDesc.fConfig = backendTex.config();
-    surfDesc.fSampleCnt = 0;
+    surfDesc.fSampleCnt = 1;
 
     GrMipMapsStatus mipMapsStatus = backendTex.hasMipMaps() ? GrMipMapsStatus::kValid
                                                             : GrMipMapsStatus::kNotAllocated;
@@ -582,6 +582,9 @@ sk_sp<GrTexture> GrGLGpu::onWrapRenderableBackendTexture(const GrBackendTexture&
     surfDesc.fHeight = backendTex.height();
     surfDesc.fConfig = backendTex.config();
     surfDesc.fSampleCnt = this->caps()->getSampleCount(sampleCnt, backendTex.config());
+    if (surfDesc.fSampleCnt < 1) {
+        return nullptr;
+    }
 
     GrGLRenderTarget::IDDesc rtIDDesc;
     if (!this->createRenderTargetObjects(surfDesc, idDesc.fInfo, &rtIDDesc)) {
@@ -686,7 +689,7 @@ bool GrGLGpu::onGetWritePixelsInfo(GrSurface* dstSurface, GrSurfaceOrigin dstOri
     }
 
     // If the dst is MSAA, we have to draw, or we'll just be writing to the resolve target.
-    if (dstSurface->asRenderTarget() && dstSurface->asRenderTarget()->numColorSamples() > 0) {
+    if (dstSurface->asRenderTarget() && dstSurface->asRenderTarget()->numColorSamples() > 1) {
         ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
     }
 
@@ -704,7 +707,7 @@ bool GrGLGpu::onGetWritePixelsInfo(GrSurface* dstSurface, GrSurfaceOrigin dstOri
     tempDrawInfo->fTempSurfaceDesc.fConfig = srcConfig;
     tempDrawInfo->fTempSurfaceDesc.fWidth = width;
     tempDrawInfo->fTempSurfaceDesc.fHeight = height;
-    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 0;
+    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 1;
     tempDrawInfo->fTempSurfaceDesc.fOrigin = kTopLeft_GrSurfaceOrigin; // no CPU y-flip for TL.
 
     bool configsAreRBSwaps = GrPixelConfigSwapRAndB(srcConfig) == dstSurface->config();
@@ -1277,13 +1280,13 @@ bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc,
     idDesc->fTexFBOID = 0;
     SkASSERT((GrGLCaps::kMixedSamples_MSFBOType == this->glCaps().msFBOType()) ==
              this->caps()->usesMixedSamples());
-    idDesc->fIsMixedSampled = desc.fSampleCnt > 0 && this->caps()->usesMixedSamples();
+    idDesc->fIsMixedSampled = desc.fSampleCnt > 1 && this->caps()->usesMixedSamples();
 
     GrGLenum status;
 
     GrGLenum colorRenderbufferFormat = 0; // suppress warning
 
-    if (desc.fSampleCnt > 0 && GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType()) {
+    if (desc.fSampleCnt > 1 && GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType()) {
         goto FAILED;
     }
 
@@ -1296,7 +1299,7 @@ bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc,
     // the texture bound to the other. The exception is the IMG multisample extension. With this
     // extension the texture is multisampled when rendered to and then auto-resolves it when it is
     // rendered from.
-    if (desc.fSampleCnt > 0 && this->glCaps().usesMSAARenderBuffers()) {
+    if (desc.fSampleCnt > 1 && this->glCaps().usesMSAARenderBuffers()) {
         GL_CALL(GenFramebuffers(1, &idDesc->fRTFBOID));
         GL_CALL(GenRenderbuffers(1, &idDesc->fMSColorRenderbufferID));
         if (!idDesc->fRTFBOID ||
@@ -1313,7 +1316,7 @@ bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc,
     // below here we may bind the FBO
     fHWBoundRenderTargetUniqueID.makeInvalid();
     if (idDesc->fRTFBOID != idDesc->fTexFBOID) {
-        SkASSERT(desc.fSampleCnt > 0);
+        SkASSERT(desc.fSampleCnt > 1);
         GL_CALL(BindRenderbuffer(GR_GL_RENDERBUFFER, idDesc->fMSColorRenderbufferID));
         if (!renderbuffer_storage_msaa(*fGLContext,
                                        desc.fSampleCnt,
@@ -1338,7 +1341,7 @@ bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc,
     fStats.incRenderTargetBinds();
     GL_CALL(BindFramebuffer(GR_GL_FRAMEBUFFER, idDesc->fTexFBOID));
 
-    if (this->glCaps().usesImplicitMSAAResolve() && desc.fSampleCnt > 0) {
+    if (this->glCaps().usesImplicitMSAAResolve() && desc.fSampleCnt > 1) {
         GL_CALL(FramebufferTexture2DMultisample(GR_GL_FRAMEBUFFER,
                                                 GR_GL_COLOR_ATTACHMENT0,
                                                 texInfo.fTarget,
@@ -1415,7 +1418,7 @@ sk_sp<GrTexture> GrGLGpu::onCreateTexture(const GrSurfaceDesc& desc,
                                           const GrMipLevel texels[],
                                           int mipLevelCount) {
     // We fail if the MSAA was requested and is not available.
-    if (GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType() && desc.fSampleCnt) {
+    if (GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType() && desc.fSampleCnt > 1) {
         //SkDebugf("MSAA RT requested but not supported on this platform.");
         return return_null_texture();
     }
@@ -1694,7 +1697,7 @@ GrStencilAttachment* GrGLGpu::createStencilAttachmentForRenderTarget(const GrRen
     CLEAR_ERROR_BEFORE_ALLOC(this->glInterface());
     // we do this "if" so that we don't call the multisample
     // version on a GL that doesn't have an MSAA extension.
-    if (samples > 0) {
+    if (samples > 1) {
         SkAssertResult(renderbuffer_storage_msaa(*fGLContext,
                                                  samples,
                                                  sFmt.fInternalFormat,
@@ -2194,7 +2197,7 @@ bool GrGLGpu::onGetReadPixelsInfo(GrSurface* srcSurface, GrSurfaceOrigin srcOrig
     tempDrawInfo->fTempSurfaceDesc.fFlags = kRenderTarget_GrSurfaceFlag;
     tempDrawInfo->fTempSurfaceDesc.fWidth = width;
     tempDrawInfo->fTempSurfaceDesc.fHeight = height;
-    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 0;
+    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 1;
     tempDrawInfo->fTempSurfaceDesc.fOrigin = kTopLeft_GrSurfaceOrigin; // no CPU y-flip for TL.
     tempDrawInfo->fTempSurfaceFit = this->glCaps().partialFBOReadIsSlow() ? SkBackingFit::kExact
                                                                           : SkBackingFit::kApprox;
@@ -3334,8 +3337,8 @@ static inline bool can_blit_framebuffer_for_copy_surface(
         }
     }
     if (GrGLCaps::kResolveMustBeFull_BlitFrambufferFlag & blitFramebufferFlags) {
-        if (srcRT && srcRT->numColorSamples()) {
-            if (dstRT && !dstRT->numColorSamples()) {
+        if (srcRT && srcRT->numColorSamples() > 1) {
+            if (dstRT && 1 == dstRT->numColorSamples()) {
                 return false;
             }
             if (SkRect::Make(srcRect) != srcRT->getBoundsRect()) {
@@ -3344,7 +3347,7 @@ static inline bool can_blit_framebuffer_for_copy_surface(
         }
     }
     if (GrGLCaps::kNoMSAADst_BlitFramebufferFlag & blitFramebufferFlags) {
-        if (dstRT && dstRT->numColorSamples() > 0) {
+        if (dstRT && dstRT->numColorSamples() > 1) {
             return false;
         }
     }
@@ -3354,12 +3357,12 @@ static inline bool can_blit_framebuffer_for_copy_surface(
         }
     } else if (GrGLCaps::kNoFormatConversionForMSAASrc_BlitFramebufferFlag & blitFramebufferFlags) {
         const GrRenderTarget* srcRT = src->asRenderTarget();
-        if (srcRT && srcRT->numColorSamples() && dst->config() != src->config()) {
+        if (srcRT && srcRT->numColorSamples() > 1 && dst->config() != src->config()) {
             return false;
         }
     }
     if (GrGLCaps::kRectsMustMatchForMSAASrc_BlitFramebufferFlag & blitFramebufferFlags) {
-        if (srcRT && srcRT->numColorSamples()) {
+        if (srcRT && srcRT->numColorSamples() > 1) {
             if (dstPoint.fX != srcRect.fLeft || dstPoint.fY != srcRect.fTop) {
                 return false;
             }
@@ -3376,7 +3379,7 @@ static bool rt_has_msaa_render_buffer(const GrGLRenderTarget* rt, const GrGLCaps
     // 1) It's multisampled
     // 2) We're using an extension with separate MSAA renderbuffers
     // 3) It's not FBO 0, which is special and always auto-resolves
-    return rt->numColorSamples() > 0 && glCaps.usesMSAARenderBuffers() && rt->renderFBOID() != 0;
+    return rt->numColorSamples() > 1 && glCaps.usesMSAARenderBuffers() && rt->renderFBOID() != 0;
 }
 
 static inline bool can_copy_texsubimage(const GrSurface* dst, GrSurfaceOrigin dstOrigin,
diff --git a/src/gpu/gl/GrGLRenderTarget.cpp b/src/gpu/gl/GrGLRenderTarget.cpp
index 443128d4d4..6f3714c504 100644
--- a/src/gpu/gl/GrGLRenderTarget.cpp
+++ b/src/gpu/gl/GrGLRenderTarget.cpp
@@ -224,7 +224,7 @@ int GrGLRenderTarget::msaaSamples() const {
     if (fTexFBOID == kUnresolvableFBOID || fTexFBOID != fRTFBOID) {
         // If the render target's FBO is external (fTexFBOID == kUnresolvableFBOID), or if we own
         // the render target's FBO (fTexFBOID == fRTFBOID) then we use the provided sample count.
-        return SkTMax(1, this->numStencilSamples());
+        return this->numStencilSamples();
     }
 
     // When fTexFBOID == fRTFBOID, we either are not using MSAA, or MSAA is auto resolving, so use
diff --git a/src/gpu/gl/GrGLStencilAttachment.cpp b/src/gpu/gl/GrGLStencilAttachment.cpp
index aa813ed50e..5c07a7d383 100644
--- a/src/gpu/gl/GrGLStencilAttachment.cpp
+++ b/src/gpu/gl/GrGLStencilAttachment.cpp
@@ -14,7 +14,7 @@ size_t GrGLStencilAttachment::onGpuMemorySize() const {
     uint64_t size = this->width();
     size *= this->height();
     size *= fFormat.fTotalBits;
-    size *= SkTMax(1,this->numSamples());
+    size *= this->numSamples();
     return static_cast<size_t>(size / 8);
 }
 
diff --git a/src/gpu/mock/GrMockCaps.h b/src/gpu/mock/GrMockCaps.h
index edec5563c4..399517b0f5 100644
--- a/src/gpu/mock/GrMockCaps.h
+++ b/src/gpu/mock/GrMockCaps.h
@@ -33,8 +33,8 @@ public:
 
         this->applyOptionsOverrides(contextOptions);
     }
-    int getSampleCount(int /*requestCount*/, GrPixelConfig /*config*/) const override {
-        return 0;
+    int getSampleCount(int requestCount, GrPixelConfig /*config*/) const override {
+        return (requestCount > 0 && requestCount <= 16) ? GrNextPow2(requestCount) : 0;
     }
     bool isConfigTexturable(GrPixelConfig config) const override {
         return fOptions.fConfigOptions[config].fTexturable;
diff --git a/src/gpu/mock/GrMockTexture.h b/src/gpu/mock/GrMockTexture.h
index 9b6501a3c4..b5cc4a27c0 100644
--- a/src/gpu/mock/GrMockTexture.h
+++ b/src/gpu/mock/GrMockTexture.h
@@ -90,8 +90,11 @@ private:
     }
 
     size_t onGpuMemorySize() const override {
-        // The plus 1 is to account for the resolve texture.
-        int numColorSamples = this->numColorSamples() + 1;
+        int numColorSamples = this->numColorSamples();
+        if (numColorSamples > 1) {
+            // Add one to account for the resolve buffer.
+            ++numColorSamples;
+        }
         return GrSurface::ComputeSize(this->config(), this->width(), this->height(),
                                       numColorSamples,
                                       this->texturePriv().mipMapped());
diff --git a/src/gpu/vk/GrVkCaps.cpp b/src/gpu/vk/GrVkCaps.cpp
index 0ae7c00995..e9f239c294 100644
--- a/src/gpu/vk/GrVkCaps.cpp
+++ b/src/gpu/vk/GrVkCaps.cpp
@@ -346,7 +346,7 @@ void GrVkCaps::ConfigInfo::initSampleCounts(const GrVkInterface* interface,
                                                                  &properties));
     VkSampleCountFlags flags = properties.sampleCounts;
     if (flags & VK_SAMPLE_COUNT_1_BIT) {
-        fColorSampleCounts.push(0);
+        fColorSampleCounts.push(1);
     }
     if (kImagination_VkVendor == physProps.vendorID) {
         // MSAA does not work on imagination
@@ -386,18 +386,39 @@ void GrVkCaps::ConfigInfo::init(const GrVkInterface* interface,
     }
 }
 
+bool GrVkCaps::isConfigRenderable(GrPixelConfig config, bool withMSAA) const {
+    if (!SkToBool(ConfigInfo::kRenderable_Flag & fConfigTable[config].fOptimalFlags)) {
+        return false;
+    }
+    if (withMSAA && fConfigTable[config].fColorSampleCounts.count() < 2) {
+        // We expect any renderable config to support non-MSAA rendering.
+        SkASSERT(1 == fConfigTable[config].fColorSampleCounts.count());
+        SkASSERT(1 == fConfigTable[config].fColorSampleCounts[0]);
+        return false;
+    }
+    return true;
+}
+
 int GrVkCaps::getSampleCount(int requestedCount, GrPixelConfig config) const {
+    requestedCount = SkTMax(1, requestedCount);
     int count = fConfigTable[config].fColorSampleCounts.count();
-    if (!count || !this->isConfigRenderable(config, true)) {
+
+    if (!count || !this->isConfigRenderable(config, requestedCount > 1)) {
         return 0;
     }
 
+    if (1 == requestedCount) {
+        SkASSERT(fConfigTable[config].fColorSampleCounts.count() &&
+                 fConfigTable[config].fColorSampleCounts[0] == 1);
+        return 1;
+    }
+
     for (int i = 0; i < count; ++i) {
         if (fConfigTable[config].fColorSampleCounts[i] >= requestedCount) {
             return fConfigTable[config].fColorSampleCounts[i];
         }
     }
-    return fConfigTable[config].fColorSampleCounts[count-1];
+    return 0;
 }
 
 bool validate_image_info(const GrVkImageInfo* imageInfo, SkColorType ct, GrPixelConfig* config) {
diff --git a/src/gpu/vk/GrVkCaps.h b/src/gpu/vk/GrVkCaps.h
index d63c2ba9b5..4468d89697 100644
--- a/src/gpu/vk/GrVkCaps.h
+++ b/src/gpu/vk/GrVkCaps.h
@@ -35,9 +35,7 @@ public:
         return SkToBool(ConfigInfo::kTextureable_Flag & fConfigTable[config].fOptimalFlags);
     }
 
-    bool isConfigRenderable(GrPixelConfig config, bool withMSAA) const override {
-        return SkToBool(ConfigInfo::kRenderable_Flag & fConfigTable[config].fOptimalFlags);
-    }
+    bool isConfigRenderable(GrPixelConfig config, bool withMSAA) const override;
 
     bool isConfigCopyable(GrPixelConfig config) const override {
         return true;
diff --git a/src/gpu/vk/GrVkGpu.cpp b/src/gpu/vk/GrVkGpu.cpp
index f7e3d47dd9..4550dfe1ed 100644
--- a/src/gpu/vk/GrVkGpu.cpp
+++ b/src/gpu/vk/GrVkGpu.cpp
@@ -352,7 +352,7 @@ bool GrVkGpu::onGetWritePixelsInfo(GrSurface* dstSurface, GrSurfaceOrigin dstOri
     tempDrawInfo->fTempSurfaceDesc.fConfig = srcConfig;
     tempDrawInfo->fTempSurfaceDesc.fWidth = width;
     tempDrawInfo->fTempSurfaceDesc.fHeight = height;
-    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 0;
+    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 1;
     tempDrawInfo->fTempSurfaceDesc.fOrigin = kTopLeft_GrSurfaceOrigin;
 
     if (dstSurface->config() == srcConfig) {
@@ -914,7 +914,7 @@ sk_sp<GrTexture> GrVkGpu::onWrapBackendTexture(const GrBackendTexture& backendTe
     surfDesc.fWidth = backendTex.width();
     surfDesc.fHeight = backendTex.height();
     surfDesc.fConfig = backendTex.config();
-    surfDesc.fSampleCnt = 0;
+    surfDesc.fSampleCnt = 1;
 
     return GrVkTexture::MakeWrappedTexture(this, surfDesc, ownership, backendTex.getVkImageInfo());
 }
@@ -943,7 +943,7 @@ sk_sp<GrRenderTarget> GrVkGpu::onWrapBackendRenderTarget(const GrBackendRenderTa
     // general this is not an issue since swapchain images in vulkan are never multisampled. Thus if
     // you want a multisampled RT it is best to wrap the swapchain images and then let Skia handle
     // creating and owning the MSAA images.
-    if (backendRT.sampleCnt()) {
+    if (backendRT.sampleCnt() > 1) {
         return nullptr;
     }
 
@@ -961,7 +961,7 @@ sk_sp<GrRenderTarget> GrVkGpu::onWrapBackendRenderTarget(const GrBackendRenderTa
     desc.fWidth = backendRT.width();
     desc.fHeight = backendRT.height();
     desc.fConfig = backendRT.config();
-    desc.fSampleCnt = 0;
+    desc.fSampleCnt = 1;
 
     sk_sp<GrVkRenderTarget> tgt = GrVkRenderTarget::MakeWrappedRenderTarget(this, desc, info);
     if (tgt && backendRT.stencilBits()) {
@@ -990,6 +990,9 @@ sk_sp<GrRenderTarget> GrVkGpu::onWrapBackendTextureAsRenderTarget(const GrBacken
     desc.fHeight = tex.height();
     desc.fConfig = tex.config();
     desc.fSampleCnt = this->caps()->getSampleCount(sampleCnt, tex.config());
+    if (!desc.fSampleCnt) {
+        return nullptr;
+    }
 
     sk_sp<GrVkRenderTarget> tgt = GrVkRenderTarget::MakeWrappedRenderTarget(this, desc, info);
     return tgt;
@@ -1796,7 +1799,7 @@ inline bool can_copy_as_resolve(const GrSurface* dst, GrSurfaceOrigin dstOrigin,
                                 const GrSurface* src, GrSurfaceOrigin srcOrigin,
                                 const GrVkGpu* gpu) {
     // Our src must be a multisampled render target
-    if (!src->asRenderTarget() || src->asRenderTarget()->numColorSamples() <= 1) {
+    if (!src->asRenderTarget() || 1 == src->asRenderTarget()->numColorSamples()) {
         return false;
     }
 
@@ -1894,7 +1897,7 @@ bool GrVkGpu::onGetReadPixelsInfo(GrSurface* srcSurface, GrSurfaceOrigin srcOrig
     tempDrawInfo->fTempSurfaceDesc.fFlags = kRenderTarget_GrSurfaceFlag;
     tempDrawInfo->fTempSurfaceDesc.fWidth = width;
     tempDrawInfo->fTempSurfaceDesc.fHeight = height;
-    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 0;
+    tempDrawInfo->fTempSurfaceDesc.fSampleCnt = 1;
     tempDrawInfo->fTempSurfaceDesc.fOrigin = kTopLeft_GrSurfaceOrigin; // no CPU y-flip for TL.
     tempDrawInfo->fTempSurfaceFit = SkBackingFit::kApprox;
 
diff --git a/src/gpu/vk/GrVkRenderTarget.cpp b/src/gpu/vk/GrVkRenderTarget.cpp
index c5a8628cc4..2a745ed51c 100644
--- a/src/gpu/vk/GrVkRenderTarget.cpp
+++ b/src/gpu/vk/GrVkRenderTarget.cpp
@@ -39,7 +39,7 @@ GrVkRenderTarget::GrVkRenderTarget(GrVkGpu* gpu,
     , fResolveAttachmentView(resolveAttachmentView)
     , fFramebuffer(nullptr)
     , fCachedSimpleRenderPass(nullptr) {
-    SkASSERT(desc.fSampleCnt);
+    SkASSERT(desc.fSampleCnt > 1);
     this->createFramebuffer(gpu);
     this->registerWithCache(budgeted);
 }
@@ -62,7 +62,7 @@ GrVkRenderTarget::GrVkRenderTarget(GrVkGpu* gpu,
     , fResolveAttachmentView(resolveAttachmentView)
     , fFramebuffer(nullptr)
     , fCachedSimpleRenderPass(nullptr) {
-    SkASSERT(desc.fSampleCnt);
+    SkASSERT(desc.fSampleCnt > 1);
     this->createFramebuffer(gpu);
 }
 
@@ -82,7 +82,7 @@ GrVkRenderTarget::GrVkRenderTarget(GrVkGpu* gpu,
     , fResolveAttachmentView(nullptr)
     , fFramebuffer(nullptr)
     , fCachedSimpleRenderPass(nullptr) {
-    SkASSERT(!desc.fSampleCnt);
+    SkASSERT(1 == desc.fSampleCnt);
     this->createFramebuffer(gpu);
     this->registerWithCache(budgeted);
 }
@@ -102,7 +102,7 @@ GrVkRenderTarget::GrVkRenderTarget(GrVkGpu* gpu,
     , fResolveAttachmentView(nullptr)
     , fFramebuffer(nullptr)
     , fCachedSimpleRenderPass(nullptr) {
-    SkASSERT(!desc.fSampleCnt);
+    SkASSERT(1 == desc.fSampleCnt);
     this->createFramebuffer(gpu);
 }
 
@@ -121,7 +121,7 @@ GrVkRenderTarget::Create(GrVkGpu* gpu,
     // create msaa surface if necessary
     GrVkImageInfo msInfo;
     const GrVkImageView* resolveAttachmentView = nullptr;
-    if (desc.fSampleCnt) {
+    if (desc.fSampleCnt > 1) {
         GrVkImage::ImageDesc msImageDesc;
         msImageDesc.fImageType = VK_IMAGE_TYPE_2D;
         msImageDesc.fFormat = pixelFormat;
@@ -158,7 +158,7 @@ GrVkRenderTarget::Create(GrVkGpu* gpu,
     const GrVkImageView* colorAttachmentView = GrVkImageView::Create(gpu, colorImage, pixelFormat,
                                                                      GrVkImageView::kColor_Type, 1);
     if (!colorAttachmentView) {
-        if (desc.fSampleCnt) {
+        if (desc.fSampleCnt > 1) {
             resolveAttachmentView->unref(gpu);
             GrVkImage::DestroyImageInfo(gpu, &msInfo);
         }
@@ -166,7 +166,7 @@ GrVkRenderTarget::Create(GrVkGpu* gpu,
     }
 
     GrVkRenderTarget* texRT;
-    if (desc.fSampleCnt) {
+    if (desc.fSampleCnt > 1) {
         texRT = new GrVkRenderTarget(gpu, budgeted, desc, info, msInfo,
                                      colorAttachmentView, resolveAttachmentView, ownership);
     } else {
@@ -237,11 +237,10 @@ void GrVkRenderTarget::createFramebuffer(GrVkGpu* gpu) {
 void GrVkRenderTarget::getAttachmentsDescriptor(
                                            GrVkRenderPass::AttachmentsDescriptor* desc,
                                            GrVkRenderPass::AttachmentFlags* attachmentFlags) const {
-    int colorSamples = this->numColorSamples();
     VkFormat colorFormat;
     GrPixelConfigToVkFormat(this->config(), &colorFormat);
     desc->fColor.fFormat = colorFormat;
-    desc->fColor.fSamples = colorSamples ? colorSamples : 1;
+    desc->fColor.fSamples = this->numColorSamples();
     *attachmentFlags = GrVkRenderPass::kColor_AttachmentFlag;
     uint32_t attachmentCount = 1;
 
@@ -249,7 +248,7 @@ void GrVkRenderTarget::getAttachmentsDescriptor(
     if (stencil) {
         const GrVkStencilAttachment* vkStencil = static_cast<const GrVkStencilAttachment*>(stencil);
         desc->fStencil.fFormat = vkStencil->vkFormat();
-        desc->fStencil.fSamples = vkStencil->numSamples() ? vkStencil->numSamples() : 1;
+        desc->fStencil.fSamples = vkStencil->numSamples();
         // Currently in vulkan stencil and color attachments must all have same number of samples
         SkASSERT(desc->fColor.fSamples == desc->fStencil.fSamples);
         *attachmentFlags |= GrVkRenderPass::kStencil_AttachmentFlag;
diff --git a/src/gpu/vk/GrVkRenderTarget.h b/src/gpu/vk/GrVkRenderTarget.h
index eb297a8a1d..bea90a759b 100644
--- a/src/gpu/vk/GrVkRenderTarget.h
+++ b/src/gpu/vk/GrVkRenderTarget.h
@@ -99,8 +99,11 @@ protected:
 
     // This accounts for the texture's memory and any MSAA renderbuffer's memory.
     size_t onGpuMemorySize() const override {
-        // The plus 1 is to account for the resolve texture or if not using msaa the RT itself
-        int numColorSamples = this->numColorSamples() + 1;
+        int numColorSamples = this->numColorSamples();
+        if (numColorSamples > 1) {
+            // Add one to account for the resolved  VkImage.
+            numColorSamples += 1;
+        }
         return GrSurface::ComputeSize(this->config(), this->width(), this->height(),
                                       numColorSamples, GrMipMapped::kNo);
     }
diff --git a/src/gpu/vk/GrVkStencilAttachment.cpp b/src/gpu/vk/GrVkStencilAttachment.cpp
index 5348885a6b..139c00f3b2 100644
--- a/src/gpu/vk/GrVkStencilAttachment.cpp
+++ b/src/gpu/vk/GrVkStencilAttachment.cpp
@@ -72,7 +72,7 @@ size_t GrVkStencilAttachment::onGpuMemorySize() const {
     uint64_t size = this->width();
     size *= this->height();
     size *= fFormat.fTotalBits;
-    size *= SkTMax(1,this->numSamples());
+    size *= this->numSamples();
     return static_cast<size_t>(size / 8);
 }
 
diff --git a/src/gpu/vk/GrVkTextureRenderTarget.cpp b/src/gpu/vk/GrVkTextureRenderTarget.cpp
index 9a211e208a..ee31f2364a 100644
--- a/src/gpu/vk/GrVkTextureRenderTarget.cpp
+++ b/src/gpu/vk/GrVkTextureRenderTarget.cpp
@@ -106,7 +106,7 @@ sk_sp<GrVkTextureRenderTarget> GrVkTextureRenderTarget::Make(GrVkGpu* gpu,
     // create msaa surface if necessary
     GrVkImageInfo msInfo;
     const GrVkImageView* resolveAttachmentView = nullptr;
-    if (desc.fSampleCnt) {
+    if (desc.fSampleCnt > 1) {
         GrVkImage::ImageDesc msImageDesc;
         msImageDesc.fImageType = VK_IMAGE_TYPE_2D;
         msImageDesc.fFormat = pixelFormat;
@@ -145,7 +145,7 @@ sk_sp<GrVkTextureRenderTarget> GrVkTextureRenderTarget::Make(GrVkGpu* gpu,
     const GrVkImageView* colorAttachmentView = GrVkImageView::Create(gpu, colorImage, pixelFormat,
                                                                      GrVkImageView::kColor_Type, 1);
     if (!colorAttachmentView) {
-        if (desc.fSampleCnt) {
+        if (desc.fSampleCnt > 1) {
             resolveAttachmentView->unref(gpu);
             GrVkImage::DestroyImageInfo(gpu, &msInfo);
         }
@@ -154,7 +154,7 @@ sk_sp<GrVkTextureRenderTarget> GrVkTextureRenderTarget::Make(GrVkGpu* gpu,
     }
 
     sk_sp<GrVkTextureRenderTarget> texRT;
-    if (desc.fSampleCnt) {
+    if (desc.fSampleCnt > 1) {
         if (!isWrapped) {
             texRT = sk_sp<GrVkTextureRenderTarget>(new GrVkTextureRenderTarget(
                                                       gpu, budgeted, desc,
@@ -232,7 +232,7 @@ GrVkTextureRenderTarget::MakeWrappedTextureRenderTarget(GrVkGpu* gpu,
 bool GrVkTextureRenderTarget::updateForMipmap(GrVkGpu* gpu, const GrVkImageInfo& newInfo) {
     VkFormat pixelFormat;
     GrPixelConfigToVkFormat(this->config(), &pixelFormat);
-    if (this->numStencilSamples()) {
+    if (this->numStencilSamples() > 1) {
         const GrVkImageView* resolveAttachmentView =
                 GrVkImageView::Create(gpu,
                                       newInfo.fImage,
@@ -262,8 +262,11 @@ bool GrVkTextureRenderTarget::updateForMipmap(GrVkGpu* gpu, const GrVkImageInfo&
 }
 
 size_t GrVkTextureRenderTarget::onGpuMemorySize() const {
-    // The plus 1 is to account for the resolve texture.
-    int numColorSamples = this->numColorSamples() + 1;
+    int numColorSamples = this->numColorSamples();
+    if (numColorSamples > 1) {
+        // Add one to account for the resolve VkImage.
+        ++numColorSamples;
+    }
     return GrSurface::ComputeSize(this->config(), this->width(), this->height(),
                                   numColorSamples,  // TODO: this still correct?
                                   this->texturePriv().mipMapped());
diff --git a/src/gpu/vk/GrVkUtil.cpp b/src/gpu/vk/GrVkUtil.cpp
index cb0046e58c..12db4c111e 100644
--- a/src/gpu/vk/GrVkUtil.cpp
+++ b/src/gpu/vk/GrVkUtil.cpp
@@ -263,8 +263,8 @@ bool GrVkFormatIsSRGB(VkFormat format, VkFormat* linearFormat) {
 }
 
 bool GrSampleCountToVkSampleCount(uint32_t samples, VkSampleCountFlagBits* vkSamples) {
+    SkASSERT(samples >= 1);
     switch (samples) {
-        case 0: // fall through
         case 1:
             *vkSamples = VK_SAMPLE_COUNT_1_BIT;
             return true;
diff --git a/src/image/SkImage_Gpu.cpp b/src/image/SkImage_Gpu.cpp
index c00c50d000..a136c7b49c 100644
--- a/src/image/SkImage_Gpu.cpp
+++ b/src/image/SkImage_Gpu.cpp
@@ -438,13 +438,8 @@ static sk_sp<SkImage> make_from_yuv_textures_copy(GrContext* ctx, SkYUVColorSpac
 
     // Needs to be a render target in order to draw to it for the yuv->rgb conversion.
     sk_sp<GrRenderTargetContext> renderTargetContext(ctx->makeDeferredRenderTargetContext(
-                                                                         SkBackingFit::kExact,
-                                                                         width, height,
-                                                                         kRGBA_8888_GrPixelConfig,
-                                                                         std::move(imageColorSpace),
-                                                                         0,
-                                                                         GrMipMapped::kNo,
-                                                                         origin));
+            SkBackingFit::kExact, width, height, kRGBA_8888_GrPixelConfig,
+            std::move(imageColorSpace), 1, GrMipMapped::kNo, origin));
     if (!renderTargetContext) {
         return nullptr;
     }
diff --git a/src/image/SkSurface.cpp b/src/image/SkSurface.cpp
index 0a684cce60..ef6d809957 100644
--- a/src/image/SkSurface.cpp
+++ b/src/image/SkSurface.cpp
@@ -247,8 +247,8 @@ sk_sp<SkSurface> SkSurface::MakeNull(int width, int height) {
 
 #if !SK_SUPPORT_GPU
 
-sk_sp<SkSurface> SkSurface::MakeRenderTarget(GrContext*, SkBudgeted, const SkImageInfo&,
-                                             int, GrSurfaceOrigin, const SkSurfaceProps*, bool) {
+sk_sp<SkSurface> SkSurface::MakeRenderTarget(GrContext*, SkBudgeted, const SkImageInfo&, int,
+                                             GrSurfaceOrigin, const SkSurfaceProps*, bool) {
     return nullptr;
 }
 
diff --git a/src/image/SkSurface_Gpu.cpp b/src/image/SkSurface_Gpu.cpp
index 9f7ec3b7f5..e811c3a72f 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -256,7 +256,7 @@ sk_sp<SkSurface> SkSurface::MakeRenderTarget(GrContext* ctx, SkBudgeted budgeted
     if (!SkSurface_Gpu::Valid(info)) {
         return nullptr;
     }
-
+    sampleCount = SkTMax(1, sampleCount);
     GrMipMapped mipMapped = shouldCreateWithMips ? GrMipMapped::kYes : GrMipMapped::kNo;
 
     if (!ctx->caps()->mipMapSupport()) {
@@ -299,6 +299,7 @@ sk_sp<SkSurface> SkSurface::MakeFromBackendTexture(GrContext* context, const GrB
     if (!SkSurface_Gpu::Valid(context, tex.config(), colorSpace.get())) {
         return nullptr;
     }
+    sampleCnt = SkTMax(1, sampleCnt);
 
     sk_sp<GrRenderTargetContext> rtc(context->contextPriv().makeBackendTextureRenderTargetContext(
                                                                     tex,
@@ -333,7 +334,7 @@ bool validate_backend_texture(GrContext* ctx, const GrBackendTexture& tex, GrPix
         return false;
     }
 
-    if (!ctx->caps()->isConfigRenderable(*config, sampleCnt > 0)) {
+    if (!ctx->caps()->isConfigRenderable(*config, sampleCnt > 1)) {
         return false;
     }
 
@@ -355,6 +356,7 @@ sk_sp<SkSurface> SkSurface::MakeFromBackendTexture(GrContext* context, const GrB
     if (!context) {
         return nullptr;
     }
+    sampleCnt = SkTMax(1, sampleCnt);
     GrBackendTexture texCopy = tex;
     if (!validate_backend_texture(context, texCopy, &texCopy.fConfig,
                                   sampleCnt, colorType, colorSpace, true)) {
@@ -445,6 +447,7 @@ sk_sp<SkSurface> SkSurface::MakeFromBackendTextureAsRenderTarget(GrContext* cont
     if (!SkSurface_Gpu::Valid(context, tex.config(), colorSpace.get())) {
         return nullptr;
     }
+    sampleCnt = SkTMax(1, sampleCnt);
 
     sk_sp<GrRenderTargetContext> rtc(
         context->contextPriv().makeBackendTextureAsRenderTargetRenderTargetContext(
@@ -475,6 +478,7 @@ sk_sp<SkSurface> SkSurface::MakeFromBackendTextureAsRenderTarget(GrContext* cont
     if (!context) {
         return nullptr;
     }
+    sampleCnt = SkTMax(1, sampleCnt);
     GrBackendTexture texCopy = tex;
     if (!validate_backend_texture(context, texCopy, &texCopy.fConfig,
                                   sampleCnt, colorType, colorSpace, false)) {
diff --git a/src/utils/win/SkWGL.h b/src/utils/win/SkWGL.h
index c6c9479abe..cd19f2eeba 100644
--- a/src/utils/win/SkWGL.h
+++ b/src/utils/win/SkWGL.h
@@ -83,7 +83,8 @@ public:
      * priority are:
      *     * Choose formats with the smallest sample count that is >=
      *       desiredSampleCount (or the largest sample count if all formats have
-     *       fewer samples than desiredSampleCount.)
+     *       fewer samples than desiredSampleCount.) If desiredSampleCount is 1 then
+     *       all msaa formats are excluded from consideration.
      *     * Choose formats with the fewest color samples when coverage sampling
      *       is available.
      *     * If the above rules leave multiple formats, choose the one that
@@ -130,8 +131,9 @@ enum SkWGLContextRequest {
 /**
  * Helper to create an OpenGL context for a DC using WGL. Configs with a sample count >= to
  * msaaSampleCount are preferred but if none is available then a context with a lower sample count
- * (including non-MSAA) will be created. If preferCoreProfile is true but a core profile cannot be
- * created then a compatible profile context will be created.
+ * (including non-MSAA) will be created. If msaaSampleCount is 1 then this will fail if a non-msaa
+ * context cannot be created. If preferCoreProfile is true but a core profile cannot be created
+ * then a compatible profile context will be created.
  */
 HGLRC SkCreateWGLContext(HDC dc, int msaaSampleCount, bool deepColor, SkWGLContextRequest context,
                          HGLRC shareContext = nullptr);
diff --git a/src/utils/win/SkWGL_win.cpp b/src/utils/win/SkWGL_win.cpp
index b7c89944e0..441d7a4ebb 100644
--- a/src/utils/win/SkWGL_win.cpp
+++ b/src/utils/win/SkWGL_win.cpp
@@ -126,6 +126,7 @@ int SkWGLExtensions::selectFormat(const int formats[],
                                   int formatCount,
                                   HDC dc,
                                   int desiredSampleCount) const {
+    SkASSERT(desiredSampleCount >= 1);
     if (formatCount <= 0) {
         return -1;
     }
@@ -146,7 +147,7 @@ int SkWGLExtensions::selectFormat(const int formats[],
                                      &kQueryAttr,
                                      &numSamples);
         rankedFormats[i].fFormat =  formats[i];
-        rankedFormats[i].fSampleCnt = numSamples;
+        rankedFormats[i].fSampleCnt = SkTMax(1, numSamples);
         rankedFormats[i].fChoosePixelFormatRank = i;
     }
     SkTQSort(rankedFormats.begin(),
@@ -159,6 +160,10 @@ int SkWGLExtensions::selectFormat(const int formats[],
     if (idx < 0) {
         idx = ~idx;
     }
+    // If the caller asked for non-MSAA fail if the closest format has MSAA.
+    if (desiredSampleCount == 1 && rankedFormats[idx].fSampleCnt != 1) {
+        return -1;
+    }
     return rankedFormats[idx].fFormat;
 }