Pass alphaType to append_gamut_transform() to inform the clamp

BUG=skia:

Change-Id: I1a8aef36043d4091bffae95b0275fa7fa8a35c97
Reviewed-on: https://skia-review.googlesource.com/9441
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>

3 files changed, 15 insertions, 9 deletions

diff --git a/src/core/SkConvertPixels.cpp b/src/core/SkConvertPixels.cpp
index 2d0cf68830..99564e7222 100644
--- a/src/core/SkConvertPixels.cpp
+++ b/src/core/SkConvertPixels.cpp
@@ -320,7 +320,8 @@ static void convert_with_pipeline(const SkImageInfo& dstInfo, void* dstRow, size
 
     float matrix[12];
     if (isColorAware) {
-        append_gamut_transform(&pipeline, matrix, srcInfo.colorSpace(), dstInfo.colorSpace());
+        append_gamut_transform(&pipeline, matrix, srcInfo.colorSpace(), dstInfo.colorSpace(),
+                               premulState);
     }
 
     SkAlphaType dat = dstInfo.alphaType();
diff --git a/src/core/SkPM4fPriv.h b/src/core/SkPM4fPriv.h
index f4142737b5..795ff4cbf8 100644
--- a/src/core/SkPM4fPriv.h
+++ b/src/core/SkPM4fPriv.h
@@ -101,7 +101,8 @@ static inline void analyze_3x4_matrix(const float matrix[12],
 
 // N.B. scratch_matrix_3x4 must live at least as long as p.
 static inline void append_gamut_transform(SkRasterPipeline* p, float scratch_matrix_3x4[12],
-                                          SkColorSpace* src, SkColorSpace* dst) {
+                                          SkColorSpace* src, SkColorSpace* dst,
+                                          SkAlphaType alphaType) {
     if (src == dst) { return; }   // That was easy.
     if (!dst)       { return; }   // Legacy modes intentionally ignore color gamut.
     if (!src)       { return; }   // A null src color space means linear gamma, dst gamut.
@@ -127,17 +128,21 @@ static inline void append_gamut_transform(SkRasterPipeline* p, float scratch_mat
     *ptr++ = m44.get(0,2); *ptr++ = m44.get(1,2); *ptr++ = m44.get(2,2);
     *ptr++ = m44.get(0,3); *ptr++ = m44.get(1,3); *ptr++ = m44.get(2,3);
 
-    bool needs_clamp_0, needs_clamp_a;
-    analyze_3x4_matrix(scratch_matrix_3x4, &needs_clamp_0, &needs_clamp_a);
+    bool needs_clamp_0, needs_clamp_1;
+    analyze_3x4_matrix(scratch_matrix_3x4, &needs_clamp_0, &needs_clamp_1);
 
     p->append(SkRasterPipeline::matrix_3x4, scratch_matrix_3x4);
     if (needs_clamp_0) { p->append(SkRasterPipeline::clamp_0); }
-    if (needs_clamp_a) { p->append(SkRasterPipeline::clamp_a); }
+    if (needs_clamp_1) {
+        (kPremul_SkAlphaType == alphaType) ? p->append(SkRasterPipeline::clamp_a)
+                                           : p->append(SkRasterPipeline::clamp_1);
+    }
 }
 
 static inline void append_gamut_transform(SkRasterPipeline* p, SkArenaAlloc* scratch,
-                                          SkColorSpace* src, SkColorSpace* dst) {
-    append_gamut_transform(p, scratch->makeArrayDefault<float>(12), src, dst);
+                                          SkColorSpace* src, SkColorSpace* dst,
+                                          SkAlphaType alphaType) {
+    append_gamut_transform(p, scratch->makeArrayDefault<float>(12), src, dst, alphaType);
 }
 
 static inline SkColor4f to_colorspace(const SkColor4f& c, SkColorSpace* src, SkColorSpace* dst) {
@@ -149,7 +154,7 @@ static inline SkColor4f to_colorspace(const SkColor4f& c, SkColorSpace* src, SkC
 
         SkRasterPipeline p;
         p.append(SkRasterPipeline::constant_color, color4f_ptr);
-        append_gamut_transform(&p, scratch_matrix_3x4, src, dst);
+        append_gamut_transform(&p, scratch_matrix_3x4, src, dst, kUnpremul_SkAlphaType);
         p.append(SkRasterPipeline::store_f32, &color4f_ptr);
 
         p.run(0,1);
diff --git a/src/image/SkImageShader.cpp b/src/image/SkImageShader.cpp
index 03897239d0..0dbf944948 100644
--- a/src/image/SkImageShader.cpp
+++ b/src/image/SkImageShader.cpp
@@ -385,6 +385,6 @@ bool SkImageShader::onAppendStages(SkRasterPipeline* p, SkColorSpace* dstCS, SkA
         p->append(SkRasterPipeline::clamp_0);
         p->append(SkRasterPipeline::clamp_a);
     }
-    append_gamut_transform(p, alloc, info.colorSpace(), dstCS);
+    append_gamut_transform(p, alloc, info.colorSpace(), dstCS, kPremul_SkAlphaType);
     return true;
 }