Add SkCanvas::writePixels that takes info+pixels directly

src/core/SkBitmapDevice.cpp

Index: src/core/SkBitmapDevice.cpp
diff --git a/src/core/SkBitmapDevice.cpp b/src/core/SkBitmapDevice.cpp
index 7ed8058c6a371b0f7e69221a8d786fe3f6927c27..098f0fc96ce95b9c12710cfb2f938a7e0e55cc40 100644
--- a/src/core/SkBitmapDevice.cpp
+++ b/src/core/SkBitmapDevice.cpp
@@ -199,6 +199,7 @@ bool SkBitmapDevice::onReadPixels(const SkBitmap& bitmap,
     return true;
 }
 
+#ifdef SK_SUPPORT_LEGACY_WRITEPIXELSCONFIG
 void SkBitmapDevice::writePixels(const SkBitmap& bitmap,
                                  int x, int y,
                                  SkCanvas::Config8888 config8888) {
@@ -265,6 +266,96 @@ void SkBitmapDevice::writePixels(const SkBitmap& bitmap,
     draw.fMatrix = &SkMatrix::I();
     this->drawSprite(draw, *sprite, x, y, paint);
 }
+#endif
+
+static void rect_memcpy(void* dst, size_t dstRB, const void* src, size_t srcRB, size_t bytesPerRow,
+                        int rowCount) {
+    SkASSERT(bytesPerRow <= srcRB);
+    SkASSERT(bytesPerRow <= dstRB);
+    for (int i = 0; i < rowCount; ++i) {
+        memcpy(dst, src, bytesPerRow);
+        dst = (char*)dst + dstRB;
+        src = (const char*)src + srcRB;
+    }
+}
+
+static bool info2config8888(const SkImageInfo& info, SkCanvas::Config8888* config) {
+    bool pre;
+    switch (info.alphaType()) {
+        case kPremul_SkAlphaType:
+        case kOpaque_SkAlphaType:
+            pre = true;
+            break;
+        case kUnpremul_SkAlphaType:
+            pre = false;
+            break;
+        default:
+            return false;
+    }
+    switch (info.colorType()) {
+        case kRGBA_8888_SkColorType:
+            *config = pre ? SkCanvas::kRGBA_Premul_Config8888 : SkCanvas::kRGBA_Unpremul_Config8888;
+            return true;
+        case kBGRA_8888_SkColorType:
+            *config = pre ? SkCanvas::kBGRA_Premul_Config8888 : SkCanvas::kBGRA_Unpremul_Config8888;
+            return true;
+        default:
+            return false;
+    }
+}
+
+// TODO: make this guy real, and not rely on legacy config8888 utility
+#include "SkConfig8888.h"
+static bool write_pixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
+                         const SkImageInfo& srcInfo, const void* srcPixels, size_t srcRowBytes) {
+    if (srcInfo.dimensions() != dstInfo.dimensions()) {
+        return false;
+    }
+    if (4 == srcInfo.bytesPerPixel() && 4 == dstInfo.bytesPerPixel()) {
+        SkCanvas::Config8888 srcConfig, dstConfig;
+        if (!info2config8888(srcInfo, &srcConfig) || !info2config8888(dstInfo, &dstConfig)) {
+            return false;
+        }
+        SkConvertConfig8888Pixels((uint32_t*)dstPixels, dstRowBytes, dstConfig,
+                                  (const uint32_t*)srcPixels, srcRowBytes, srcConfig,
+                                  srcInfo.width(), srcInfo.height());
+        return true;
+    }
+    if (srcInfo.colorType() == dstInfo.colorType()) {
+        switch (srcInfo.colorType()) {
+            case kRGB_565_SkColorType:
+            case kAlpha_8_SkColorType:
+                break;
+            case kARGB_4444_SkColorType:
+                if (srcInfo.alphaType() != dstInfo.alphaType()) {
+                    return false;
+                }
+                break;
+            default:
+                return false;
+        }
+        rect_memcpy(dstPixels, dstRowBytes, srcPixels, srcRowBytes,
+                    srcInfo.width() * srcInfo.bytesPerPixel(), srcInfo.height());
+    }
+    // TODO: add support for more conversions as needed
+    return false;
+}
+
+bool SkBitmapDevice::onWritePixels(const SkImageInfo& srcInfo, const void* srcPixels,
+                                   size_t srcRowBytes, int x, int y) {
+    SkImageInfo dstInfo = fBitmap.info();
+    dstInfo.fWidth = srcInfo.width();
+    dstInfo.fHeight = srcInfo.height();
+
+    void* dstPixels = fBitmap.getAddr(x, y);
+    size_t dstRowBytes = fBitmap.rowBytes();
+
+    if (write_pixels(dstInfo, dstPixels, dstRowBytes, srcInfo, srcPixels, srcRowBytes)) {
+        fBitmap.notifyPixelsChanged();
+        return true;
+    }
+    return false;
+}
 
 ///////////////////////////////////////////////////////////////////////////////