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 18 matching lines @@
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 //  Only valid if...
 //      1. src == dst format
 //      2. paint has no modifiers (i.e. alpha, colorfilter, etc.)
 //      3. xfermode needs no blending: e.g. kSrc_Mode or kSrcOver_Mode + opaque src
 //
-class SkSpriteBlitter_memcpy : public SkSpriteBlitter {
+class SkSpriteBlitter_Src_SrcOver : public SkSpriteBlitter {
 public:
     static bool Supports(const SkPixmap& dst, const SkPixmap& src, const SkPaint& paint) {
         if (dst.colorType() != src.colorType()) {
             return false;
         }
         if (dst.info().profileType() != src.info().profileType()) {
             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;
         }
         if (SkXfermode::kSrc_Mode == mode) {
             return true;
         }
         if (SkXfermode::kSrcOver_Mode == mode && src.isOpaque()) {
             return true;
         }
-        return false;
+
+        // At this point memcpy can't be used. The following check for using SrcOver.
+
+        if (dst.colorType() != kN32_SkColorType
+            || dst.info().profileType() != kSRGB_SkColorProfileType) {
+            return false;
+        }
+
+        return SkXfermode::kSrcOver_Mode == mode;
     }
 
-    SkSpriteBlitter_memcpy(const SkPixmap& src)  : INHERITED(src) {}
+    SkSpriteBlitter_Src_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(mode == SkXfermode::kSrcOver_Mode || mode == SkXfermode::kSrc_Mode);
+
+        if (mode == SkXfermode::kSrcOver_Mode && !fSource.isOpaque()) {
+            fUseMemcpy = false;
+        }
     }
 
     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);
 
-        char* dst = (char*)fDst.writable_addr(x, y);
-        const char* src = (const char*)fSource.addr(x - fLeft, y - fTop);
-        const size_t dstRB = fDst.rowBytes();
-        const size_t srcRB = fSource.rowBytes();
-        const size_t bytesToCopy = width << fSource.shiftPerPixel();
+        if (fUseMemcpy) {
+            char* dst = (char*)fDst.writable_addr(x, y);
+            const char* src = (const char*)fSource.addr(x - fLeft, y - fTop);
+            const size_t dstRB = fDst.rowBytes();
+            const size_t srcRB = fSource.rowBytes();
+            const size_t bytesToCopy = width << fSource.shiftPerPixel();
 
-        while (--height >= 0) {
-            memcpy(dst, src, bytesToCopy);
-            dst += dstRB;
-            src += srcRB;
+            while (height --> 0) {
+                memcpy(dst, src, bytesToCopy);
+                dst += dstRB;
+                src += srcRB;
+            }
+        } else {
+            uint32_t* dst       = fDst.writable_addr32(x, y);
+            const uint32_t* src = fSource.addr32(x - fLeft, y - fTop);
+            const int dstStride = fDst.rowBytesAsPixels();
+            const int srcStride = fSource.rowBytesAsPixels();
+
+            while (height --> 0) {
+                SkOpts::srcover_srgb_srgb(dst, src, width, width);
+                dst += dstStride;
+                src += srcStride;
+            }
         }
     }
 
+private:
     typedef SkSpriteBlitter INHERITED;
+
+    bool fUseMemcpy {true};
 };
 
-
 // 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);
+    if (SkSpriteBlitter_Src_SrcOver::Supports(dst, source, paint)) {
+        blitter = allocator->createT<SkSpriteBlitter_Src_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;
 }