Fix: adding elements didn't cause remeasure.

Fixes: 135668890

When a new element was added through composition, the
containing layout didn't remeasure and relayout that child.
This CL asks the parent to remeasure and relayout when
a child is added or removed.

Test: new test

Change-Id: Ida8f71f9f6a159be79767c04b96ffc1d2c42b3fe

5 files changed, 79 insertions, 16 deletions

diff --git a/ui/framework/src/androidTest/java/androidx/ui/core/test/AndroidLayoutDrawTest.kt b/ui/framework/src/androidTest/java/androidx/ui/core/test/AndroidLayoutDrawTest.kt
index 52cf3dc761a..3d4ff9abfbe 100644
--- a/ui/framework/src/androidTest/java/androidx/ui/core/test/AndroidLayoutDrawTest.kt
+++ b/ui/framework/src/androidTest/java/androidx/ui/core/test/AndroidLayoutDrawTest.kt
@@ -665,6 +665,51 @@ class AndroidLayoutDrawTest {
         }
     }
 
+    // When a new child is added, the parent must be remeasured because we don't know
+    // if it affects the size and the child's measure() must be called as well.
+    @SdkSuppress(minSdkVersion = Build.VERSION_CODES.O)
+    @Test
+    fun testRelayoutOnNewChild() {
+        val drawChild = DoDraw()
+
+        val outerColor = Color(0xFF000080.toInt())
+        val innerColor = Color(0xFFFFFFFF.toInt())
+        runOnUiThread {
+            activity.setContent {
+                CraneWrapper {
+                    AtLeastSize(size = 30.ipx) {
+                        Draw { canvas, parentSize ->
+                            drawLatch.countDown()
+                            val paint = Paint()
+                            paint.color = outerColor
+                            canvas.drawRect(parentSize.toRect(), paint)
+                        }
+                        if (drawChild.value) {
+                            Padding(size = 20.ipx) {
+                                AtLeastSize(size = 20.ipx) {
+                                    Draw { canvas, parentSize ->
+                                        drawLatch.countDown()
+                                        val paint = Paint()
+                                        paint.color = innerColor
+                                        canvas.drawRect(parentSize.toRect(), paint)
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        // The padded area doesn't draw
+        validateSquareColors(outerColor = outerColor, innerColor = outerColor, size = 10)
+
+        drawLatch = CountDownLatch(1)
+        runOnUiThread { drawChild.value = true }
+
+        validateSquareColors(outerColor = outerColor, innerColor = innerColor, size = 20)
+    }
+
     // We only need this because IR compiler doesn't like converting lambdas to Runnables
     private fun runOnUiThread(block: () -> Unit) {
         val runnable: Runnable = object : Runnable {
@@ -1044,4 +1089,7 @@ class SquareModel(
 )
 
 @Model
-class OffsetModel(var offset: IntPx)
\ No newline at end of file
+class OffsetModel(var offset: IntPx)
+
+@Model
+class DoDraw(var value: Boolean = false)
diff --git a/ui/platform/api/1.0.0-alpha01.txt b/ui/platform/api/1.0.0-alpha01.txt
index 579dd35cc91..24d3185a20c 100644
--- a/ui/platform/api/1.0.0-alpha01.txt
+++ b/ui/platform/api/1.0.0-alpha01.txt
@@ -21,7 +21,6 @@ package androidx.ui.core {
     method public void onSizeChange(androidx.ui.core.LayoutNode layoutNode);
     method public void onStartLayout(androidx.ui.core.LayoutNode layoutNode);
     method public void onStartMeasure(androidx.ui.core.LayoutNode layoutNode);
-    method public void requestRelayout(androidx.ui.core.LayoutNode layoutNode);
     method public void sendEvent(android.view.MotionEvent event);
     method public void setCommitUnsubscribe(kotlin.jvm.functions.Function0<kotlin.Unit>? p);
     method public void setConstraints(androidx.ui.core.Constraints p);
diff --git a/ui/platform/api/current.txt b/ui/platform/api/current.txt
index 579dd35cc91..24d3185a20c 100644
--- a/ui/platform/api/current.txt
+++ b/ui/platform/api/current.txt
@@ -21,7 +21,6 @@ package androidx.ui.core {
     method public void onSizeChange(androidx.ui.core.LayoutNode layoutNode);
     method public void onStartLayout(androidx.ui.core.LayoutNode layoutNode);
     method public void onStartMeasure(androidx.ui.core.LayoutNode layoutNode);
-    method public void requestRelayout(androidx.ui.core.LayoutNode layoutNode);
     method public void sendEvent(android.view.MotionEvent event);
     method public void setCommitUnsubscribe(kotlin.jvm.functions.Function0<kotlin.Unit>? p);
     method public void setConstraints(androidx.ui.core.Constraints p);
diff --git a/ui/platform/src/main/java/androidx/ui/core/AndroidOwner.kt b/ui/platform/src/main/java/androidx/ui/core/AndroidOwner.kt
index d042f491d72..1ffe8c11daf 100644
--- a/ui/platform/src/main/java/androidx/ui/core/AndroidOwner.kt
+++ b/ui/platform/src/main/java/androidx/ui/core/AndroidOwner.kt
@@ -198,11 +198,20 @@ class AndroidCraneView constructor(context: Context)
 
     override fun onRequestMeasure(layoutNode: LayoutNode) {
         // find root of layout request:
+        if (layoutNode.needsRemeasure) {
+            // don't need to do anything because it already needs to be remeasured
+            return
+        }
         layoutNode.needsRemeasure = true
 
         var layout = layoutNode
-        while (layout.parentLayoutNode != null && layout.affectsParentSize) {
+        while (layout.parentLayoutNode != null && layout.parentLayoutNode != root &&
+            layout.affectsParentSize) {
             layout = layout.parentLayoutNode!!
+            if (layout.needsRemeasure) {
+                // don't need to do anything else since the parent already needs measuring
+                return
+            }
             layout.needsRemeasure = true
         }
 
@@ -214,8 +223,8 @@ class AndroidCraneView constructor(context: Context)
         }
     }
 
-    fun requestRelayout(layoutNode: LayoutNode) {
-        if (layoutNode == root) {
+    private fun requestRelayout(layoutNode: LayoutNode) {
+        if (layoutNode == root || constraints.isZero) {
             requestLayout()
         } else if (relayoutNodes.isEmpty()) {
             Choreographer.getInstance().postFrameCallback {
@@ -259,13 +268,11 @@ class AndroidCraneView constructor(context: Context)
                 relayoutNodes.sortedBy { it.depth }.forEach { layoutNode ->
                     if (layoutNode.needsRemeasure) {
                         val parent = layoutNode.parentLayoutNode
-                        if (parent != null) {
+                        if (parent != null && parent.layout != null) {
                             // This should call measure and layout on the child
-                            val parentLayout = parent.layout
-                            if (parentLayout != null) {
-                                parent.needsRelayout = true
-                                parentLayout.callLayout()
-                            }
+                            val parentLayout = parent.layout!!
+                            parent.needsRelayout = true
+                            parentLayout.callLayout()
                         } else {
                             layoutNode.layout?.callMeasure(layoutNode.constraints)
                             layoutNode.layout?.callLayout()
diff --git a/ui/platform/src/main/java/androidx/ui/core/ComponentNodes.kt b/ui/platform/src/main/java/androidx/ui/core/ComponentNodes.kt
index 04e4607ba29..72ba120ab28 100644
--- a/ui/platform/src/main/java/androidx/ui/core/ComponentNodes.kt
+++ b/ui/platform/src/main/java/androidx/ui/core/ComponentNodes.kt
@@ -394,7 +394,7 @@ class LayoutNode : ComponentNode() {
     /**
      * `true` when the parent's size depends on this LayoutNode's size
      */
-    var affectsParentSize: Boolean = false
+    var affectsParentSize: Boolean = true
 
     /**
      * `true` when called between [startMeasure] and [endMeasure]
@@ -405,14 +405,14 @@ class LayoutNode : ComponentNode() {
      * `true` when the layout has been dirtied by [requestRemeasure]. `false` after
      * the measurement has been complete ([resize] has been called).
      */
-    var needsRemeasure = true
+    var needsRemeasure = false
         internal set
 
     /**
      * `true` when the layout has been measured or dirtied because the layout
      * lambda accessed a model that has been dirtied.
      */
-    var needsRelayout = true
+    var needsRelayout = false
         internal set
 
     override val parentLayoutNode: LayoutNode?
@@ -421,6 +421,16 @@ class LayoutNode : ComponentNode() {
     override val containingLayoutNode: LayoutNode?
         get() = this
 
+    override fun attach(owner: Owner) {
+        super.attach(owner)
+        requestRemeasure()
+    }
+
+    override fun detach() {
+        parentLayoutNode?.requestRemeasure()
+        super.detach()
+    }
+
     fun moveTo(x: IntPx, y: IntPx) {
         visible = true
         if (x != this.x || y != this.y) {
@@ -432,7 +442,6 @@ class LayoutNode : ComponentNode() {
 
     fun resize(width: IntPx, height: IntPx) {
         val parent = parentLayoutNode
-        needsRemeasure = false // we must have just finished measurement
         if (parent != null && parent.isInMeasure) {
             affectsParentSize = true
         }
@@ -461,6 +470,7 @@ class LayoutNode : ComponentNode() {
     fun endMeasure() {
         owner?.onEndMeasure(this)
         isInMeasure = false
+        needsRemeasure = false
         needsRelayout = true
     }