Srcover for sprite blitters.

src/core/SkBlitter_Sprite.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
+#include "SkOpts.h"
 #include "SkSmallAllocator.h"
 #include "SkSpriteBlitter.h"
 
 SkSpriteBlitter::SkSpriteBlitter(const SkPixmap& source) : fSource(source) {}
 
 void SkSpriteBlitter::setup(const SkPixmap& dst, int left, int top, const SkPaint& paint) {
     fDst = dst;
     fLeft = left;
     fTop = top;
     fPaint = &paint;
@@ skipping 74 matching lines @@
         while (--height >= 0) {
             memcpy(dst, src, bytesToCopy);
             dst += dstRB;
             src += srcRB;
         }
     }
 
     typedef SkSpriteBlitter INHERITED;
 };
 
+class SkSpriteBlitter_SrcOver : public SkSpriteBlitter {
+public:
+    static bool Supports(const SkPixmap& dst, const SkPixmap& src, const SkPaint& paint) {
+        if (dst.colorType() != src.colorType() || dst.colorType() != kN32_SkColorType) {
+            return false;
+        }
+        if (dst.info().profileType() != src.info().profileType()

[msarett, 2016/05/20 15:46:58]

Can you check the gDefaultProfileIsSRGB flag directly here?  Instead of relying
on SkCodec to check it for you?

I'd like to remove that logic from SkCodec.

+            || dst.info().profileType() != kSRGB_SkColorProfileType) {
+            return false;
+        }
+        if (paint.getMaskFilter() || paint.getColorFilter() || paint.getImageFilter()) {
+            return false;
+        }
+        if (0xFF != paint.getAlpha()) {
+            return false;
+        }
+        SkXfermode::Mode mode;
+        if (!SkXfermode::AsMode(paint.getXfermode(), &mode)) {
+            return false;
+        }
+        return SkXfermode::kSrcOver_Mode == mode;
+    }
+
+    SkSpriteBlitter_SrcOver(const SkPixmap& src)  : INHERITED(src) {}
+
+    void setup(const SkPixmap& dst, int left, int top, const SkPaint& paint) override {
+        SkASSERT(Supports(dst, fSource, paint));
+        this->INHERITED::setup(dst, left, top, paint);
+        SkXfermode::Mode mode;
+        if (!SkXfermode::AsMode(paint.getXfermode(), &mode)) {
+            SkFAIL("Should never happen.");
+        }
+        SkASSERT(SkXfermode::kSrcOver_Mode == mode);
+    }
+
+    void blitRect(int x, int y, int width, int height) override {
+        SkASSERT(fDst.colorType() == fSource.colorType());
+        SkASSERT(fDst.info().profileType() == fSource.info().profileType());
+        SkASSERT(width > 0 && height > 0);
+
+        uint32_t* dst = fDst.writable_addr32(x, y);
+        const uint32_t* src = fSource.addr32(x - fLeft, y - fTop);
+        const int dstRB = fDst.rowBytesAsPixels();
+        const int srcRB = fSource.rowBytesAsPixels();
+
+        while (height --> 0) {
+            SkOpts::srcover_srgb_srgb(dst, src, width, width);
+            dst += dstRB;
+            src += srcRB;
+        }
+    }
+
+    typedef SkSpriteBlitter INHERITED;
+};
 
 // returning null means the caller will call SkBlitter::Choose() and
 // have wrapped the source bitmap inside a shader
 SkBlitter* SkBlitter::ChooseSprite(const SkPixmap& dst, const SkPaint& paint,
         const SkPixmap& source, int left, int top, SkTBlitterAllocator* allocator) {
     /*  We currently ignore antialiasing and filtertype, meaning we will take our
         special blitters regardless of these settings. Ignoring filtertype seems fine
         since by definition there is no scale in the matrix. Ignoring antialiasing is
         a bit of a hack, since we "could" pass in the fractional left/top for the bitmap,
         and respect that by blending the edges of the bitmap against the device. To support
         this we could either add more special blitters here, or detect antialiasing in the
         paint and return null if it is set, forcing the client to take the slow shader case
         (which does respect soft edges).
     */
     SkASSERT(allocator != nullptr);
 
-    SkSpriteBlitter* blitter;
+    SkSpriteBlitter* blitter = nullptr;
 
     if (SkSpriteBlitter_memcpy::Supports(dst, source, paint)) {
         blitter = allocator->createT<SkSpriteBlitter_memcpy>(source);
+    } else if (SkSpriteBlitter_SrcOver::Supports(dst, source, paint)) {
+        blitter = allocator->createT<SkSpriteBlitter_SrcOver>(source);
     } else {
         switch (dst.colorType()) {
             case kRGB_565_SkColorType:
                 blitter = SkSpriteBlitter::ChooseD16(source, paint, allocator);
                 break;
             case kN32_SkColorType:
                 if (dst.info().isSRGB()) {
                     blitter = SkSpriteBlitter::ChooseS32(source, paint, allocator);
                 } else {
                     blitter = SkSpriteBlitter::ChooseL32(source, paint, allocator);
                 }
                 break;
             case kRGBA_F16_SkColorType:
                 blitter = SkSpriteBlitter::ChooseF16(source, paint, allocator);
                 break;
             default:
-                blitter = nullptr;
                 break;
         }
     }
 
     if (blitter) {
         blitter->setup(dst, left, top, paint);
     }
     return blitter;
 }