plumb y through to SkJumper

There'll still be a little more refactoring after this, but this is the
main thing we want to do.

This makes y available in a general-purpose register in pipeline stages,
just like x.  Stages that need y (seed_shader and dither) can just use
it rather than pulling it off a context pointer.  seed_shader loses its
context pointer, and dither's gets simpler.

Change-Id: Ic2d1e13b03fb45b73e308b38aafbb3a14c29cf7f
Reviewed-on: https://skia-review.googlesource.com/18383
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 7 insertions, 9 deletions

diff --git a/src/core/SkConvertPixels.cpp b/src/core/SkConvertPixels.cpp
index 2ada61f14e..b3a6a06974 100644
--- a/src/core/SkConvertPixels.cpp
+++ b/src/core/SkConvertPixels.cpp
@@ -359,17 +359,16 @@ static void convert_with_pipeline(const SkImageInfo& dstInfo, void* dstRow, size
     SkASSERT(premulState == dat || kOpaque_SkAlphaType == srcInfo.alphaType());
 
     // We'll dither if we're decreasing precision below 32-bit.
-    int y;
-    SkJumper_DitherCtx dither = {&y, 0.0f};
+    float dither_rate = 0.0f;
     if (srcInfo.bytesPerPixel() > dstInfo.bytesPerPixel()) {
         switch (dstInfo.colorType()) {
-            case   kRGB_565_SkColorType: dither.rate = 1/63.0f; break;
-            case kARGB_4444_SkColorType: dither.rate = 1/15.0f; break;
-            default:                     dither.rate =    0.0f; break;
+            case   kRGB_565_SkColorType: dither_rate = 1/63.0f; break;
+            case kARGB_4444_SkColorType: dither_rate = 1/15.0f; break;
+            default:                     dither_rate =    0.0f; break;
         }
     }
-    if (dither.rate > 0) {
-        pipeline.append(SkRasterPipeline::dither, &dither);
+    if (dither_rate > 0) {
+        pipeline.append(SkRasterPipeline::dither, &dither_rate);
     }
 
     switch (dstInfo.colorType()) {
@@ -395,8 +394,7 @@ static void convert_with_pipeline(const SkImageInfo& dstInfo, void* dstRow, size
     }
 
     auto run = pipeline.compile();
-    // This y is declared above when handling dither (which needs to know y).
-    for (y = 0; y < srcInfo.height(); ++y) {
+    for (int y = 0; y < srcInfo.height(); ++y) {
         run(0,y, srcInfo.width());
         // The pipeline has pointers to srcRow and dstRow, so we just need to update them in the
         // loop to move between rows of src/dst.