rough clamped tracking in SkRasterPipeline

This should make srgb_color_filter draw correctly in software.
Previously the Rec2020 block would overflow.

Change-Id: Ied4516728039e54214886d55bba92662beee9a26
Reviewed-on: https://skia-review.googlesource.com/26562
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/core/SkRasterPipeline.cpp b/src/core/SkRasterPipeline.cpp
index a7b25d7ef9..5484c9f94c 100644
--- a/src/core/SkRasterPipeline.cpp
+++ b/src/core/SkRasterPipeline.cpp
@@ -15,6 +15,7 @@ void SkRasterPipeline::reset() {
     fStages      = nullptr;
     fNumStages   = 0;
     fSlotsNeeded = 1;  // We always need one extra slot for just_return().
+    fClamped     = true;
 }
 
 void SkRasterPipeline::append(StockStage stage, void* ctx) {
@@ -46,6 +47,7 @@ void SkRasterPipeline::extend(const SkRasterPipeline& src) {
     fStages = &stages[src.fNumStages - 1];
     fNumStages   += src.fNumStages;
     fSlotsNeeded += src.fSlotsNeeded - 1;  // Don't double count just_returns().
+    fClamped = fClamped && src.fClamped;
 }
 
 void SkRasterPipeline::dump() const {
@@ -162,3 +164,12 @@ void SkRasterPipeline::append_matrix(SkArenaAlloc* alloc, const SkMatrix& matrix
         }
     }
 }
+
+void SkRasterPipeline::clamp_if_unclamped(SkAlphaType alphaType) {
+    if (!fClamped) {
+        this->append(SkRasterPipeline::clamp_0);
+        this->append(alphaType == kPremul_SkAlphaType ? SkRasterPipeline::clamp_a
+                                                      : SkRasterPipeline::clamp_1);
+        fClamped = true;
+    }
+}