implement 4f for composeshader

Bug: skia:
Change-Id: I7ad0077345f7589528c89cd84d252539a1df6614
Reviewed-on: https://skia-review.googlesource.com/16703
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>

3 files changed, 37 insertions, 2 deletions

diff --git a/src/core/SkComposeShader.cpp b/src/core/SkComposeShader.cpp
index 9cb16addc6..ee0fe10c77 100644
--- a/src/core/SkComposeShader.cpp
+++ b/src/core/SkComposeShader.cpp
@@ -182,6 +182,36 @@ void SkComposeShader::ComposeShaderContext::shadeSpan(int x, int y, SkPMColor re
     }
 }
 
+void SkComposeShader::ComposeShaderContext::shadeSpan4f(int x, int y, SkPM4f result[], int count) {
+    SkShader::Context* shaderContextA = fShaderContextA;
+    SkShader::Context* shaderContextB = fShaderContextB;
+    SkBlendMode        mode = static_cast<const SkComposeShader&>(fShader).fMode;
+    unsigned           alpha = this->getPaintAlpha();
+    Sk4f               scale(alpha * (1.0f / 255));
+
+    SkPM4f  tmp[TMP_COLOR_COUNT];
+
+    SkXfermodeProc4f xfer = SkXfermode::GetProc4f(mode);
+    do {
+        int n = SkTMin(count, TMP_COLOR_COUNT);
+
+        shaderContextA->shadeSpan4f(x, y, result, n);
+        shaderContextB->shadeSpan4f(x, y, tmp, n);
+        if (255 == alpha) {
+            for (int i = 0; i < n; ++i) {
+                result[i] = xfer(tmp[i], result[i]);
+            }
+        } else {
+            for (int i = 0; i < n; ++i) {
+                (xfer(tmp[i], result[i]).to4f() * scale).store(result + i);
+            }
+        }
+        result += n;
+        x += n;
+        count -= n;
+    } while (count > 0);
+}
+
 #if SK_SUPPORT_GPU
 
 #include "effects/GrConstColorProcessor.h"
diff --git a/src/core/SkComposeShader.h b/src/core/SkComposeShader.h
index be39393923..0204b76ce4 100644
--- a/src/core/SkComposeShader.h
+++ b/src/core/SkComposeShader.h
@@ -48,6 +48,7 @@ public:
                              SkShader::Context* contextA, SkShader::Context* contextB);
 
         void shadeSpan(int x, int y, SkPMColor[], int count) override;
+        void shadeSpan4f(int x, int y, SkPM4f[], int count) override;
 
     private:
         SkShader::Context* fShaderContextA;
diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index 72ffffbe6c..cbb9d26d14 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -1891,10 +1891,14 @@ void SkTriColorShader::TriColorShaderContext::shadeSpan4f(int x, int y, SkPM4f d
     }
 
     Sk4f c  = fM43.map(SkIntToScalar(x) + 0.5, SkIntToScalar(y) + 0.5),
-         dc = Sk4f::Load(&fM43.fMat[0]);
+         dc = Sk4f::Load(&fM43.fMat[0]),
+         zero(0.0f),
+         one(1.0f);
 
     for (int i = 0; i < count; i++) {
-        c.store(dstC[i].fVec);
+        // We don't expect to be wildly out of 0...1, but we pin just because of minor
+        // numerical imprecision.
+        Sk4f::Min(Sk4f::Max(c, zero), Sk4f::Min(c[3], one)).store(dstC + i);
         c += dc;
     }
 }