[openexr] speed up scanline reading, read all channels in readMulti (#4457)

* [openexr] speed up scanline reading, read all channels in readMulti

Signed-off-by: Peter Hillman <peter@pedro.kiwi>

* [openexr] rearrange channel order in readMulti

Signed-off-by: Peter Hillman <peter@pedro.kiwi>

1 files changed, 26 insertions, 4 deletions

diff --git a/projects/openexr/openexr_scanlines_fuzzer.cc b/projects/openexr/openexr_scanlines_fuzzer.cc
index e41f1f2ad..c4986e826 100644
--- a/projects/openexr/openexr_scanlines_fuzzer.cc
+++ b/projects/openexr/openexr_scanlines_fuzzer.cc
@@ -17,16 +17,19 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <vector>
 
 #include <ImfArray.h>
 #include <ImfInputPart.h>
 #include <ImfMultiPartInputFile.h>
+#include <ImfChannelList.h>
 #include <ImfRgbaFile.h>
 #include <ImfStdIO.h>
 
 using namespace OPENEXR_IMF_INTERNAL_NAMESPACE;
 using IMATH_NAMESPACE::Box2i;
-
+using std::vector;
+using std::max;
 namespace {
 
 static void readSingle(IStream& is) {
@@ -44,7 +47,10 @@ static void readSingle(IStream& is) {
     Array<Rgba> pixels(w);
     in.setFrameBuffer(&pixels[-dx], 1, 0);
 
-    for (int y = dw.min.y; y <= dw.max.y; ++y) in.readPixels(y);
+    // read up to 10,000 scanlines from file
+    int step = max( 1 , (dw.max.y - dw.min.y + 1) / 10000);
+    for (int y = dw.min.y; y <= dw.max.y; y+=step) in.readPixels(y);
+ 
   } catch (...) {
   }
 }
@@ -75,15 +81,31 @@ static void readMulti(IStream& is) {
       {
 	      throw std::logic_error("ignoring - very wide datawindow\n");
       }
-      Array<Rgba> pixels(w);
+ 
       FrameBuffer i;
+      //
+      // read all channels present (later channels will overwrite earlier ones)
+      vector<half> otherChannels(w);
+      const ChannelList& channelList = in->header().channels();
+      for (ChannelList::ConstIterator c = channelList.begin() ; c != channelList.end() ; ++c )
+      {
+	      i.insert(c.name(),Slice(HALF, (char*)&otherChannels[0] , sizeof(half) , 0 ));
+      }     
+
+      // always try to read RGBA even if not present in file
+      Array<Rgba> pixels(w);
       i.insert("R", Slice(HALF, (char *)&(pixels[-dx].r), sizeof(Rgba), 0));
       i.insert("G", Slice(HALF, (char *)&(pixels[-dx].g), sizeof(Rgba), 0));
       i.insert("B", Slice(HALF, (char *)&(pixels[-dx].b), sizeof(Rgba), 0));
       i.insert("A", Slice(HALF, (char *)&(pixels[-dx].a), sizeof(Rgba), 0));
 
+
+
+
       in->setFrameBuffer(i);
-      for (int y = dw.min.y; y <= dw.max.y; ++y) in->readPixels(y);
+      // read up to 10,000 scanlines from file
+      int step = max( 1 , (dw.max.y - dw.min.y + 1) / 10000);
+      for (int y = dw.min.y; y <= dw.max.y; y+=step) in->readPixels(y);
     } catch (...) {
     }