Refactor SkBitmapRegionDecoderInterface for Android

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 9a61b020e8f7eb4a5f330b0cc38ccc4581dcdb57..4e072ebeaf976587e9e95c8da53eeb6f08064db1 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -108,15 +108,18 @@ Error BRDSrc::draw(SkCanvas* canvas) const {
             break;
     }
 
+    // Construct a color table for the decode if necessary
+    SkAutoTUnref<SkColorTable> colorTable(nullptr);
+    if (kIndex_8_SkColorType == colorType) {
+        SkPMColor colors[256];
+        colorTable.reset(new SkColorTable(colors, 256));
+    }
+
     SkAutoTDelete<SkBitmapRegionDecoderInterface> brd(create_brd(fPath, fStrategy));
     if (nullptr == brd.get()) {
         return Error::Nonfatal(SkStringPrintf("Could not create brd for %s.", fPath.c_str()));
     }
 
-    if (!brd->conversionSupported(colorType)) {
-        return Error::Nonfatal("Cannot convert to color type.\n");
-    }
-
     const uint32_t width = brd->width();
     const uint32_t height = brd->height();
     // Visually inspecting very small output images is not necessary.
@@ -125,12 +128,25 @@ Error BRDSrc::draw(SkCanvas* canvas) const {
     }
     switch (fMode) {
         case kFullImage_Mode: {
-            SkAutoTDelete<SkBitmap> bitmap(brd->decodeRegion(0, 0, width, height, fSampleSize,
-                    colorType));
-            if (nullptr == bitmap.get() || colorType != bitmap->colorType()) {
+            SkImageInfo info;
+            SkIRect subset = SkIRect::MakeXYWH(0, 0, width, height);
+            if (!brd->prepareRegion(subset, fSampleSize, colorType, false, &info)) {
+                return Error::Nonfatal("Cannot set up for subset decode.\n");
+            }
+
+            SkBitmap bitmap;
+            if (SkBitmapRegionDecoderInterface::kOriginal_Strategy != fStrategy) {
+                if (!bitmap.tryAllocPixels(info, nullptr, colorTable)) {
+                    return "Could not allocate pixels.";
+                }
+            }
+            if (!brd->decodeRegion(bitmap)) {
+                return "Failed to decode subset";
+            }
+            if (colorType != bitmap.colorType()) {
                 return Error::Nonfatal("Cannot convert to color type.\n");
             }
-            canvas->drawBitmap(*bitmap, 0, 0);
+            canvas->drawBitmap(bitmap, 0, 0);
             return "";
         }
         case kDivisor_Mode: {
@@ -178,13 +194,28 @@ Error BRDSrc::draw(SkCanvas* canvas) const {
                     const int decodeTop = top - unscaledBorder;
                     const uint32_t decodeWidth = subsetWidth + unscaledBorder * 2;
                     const uint32_t decodeHeight = subsetHeight + unscaledBorder * 2;
-                    SkAutoTDelete<SkBitmap> bitmap(brd->decodeRegion(decodeLeft,
-                            decodeTop, decodeWidth, decodeHeight, fSampleSize, colorType));
-                    if (nullptr == bitmap.get() || colorType != bitmap->colorType()) {
+
+                    SkImageInfo info;
+                    SkIRect subset = SkIRect::MakeXYWH(decodeLeft, decodeTop, decodeWidth,
+                            decodeHeight);
+                    if (!brd->prepareRegion(subset, fSampleSize, colorType, false, &info)) {
+                        return Error::Nonfatal("Cannot set up for subset decode.\n");
+                    }
+
+                    SkBitmap bitmap;
+                    if (SkBitmapRegionDecoderInterface::kOriginal_Strategy != fStrategy) {
+                        if (!bitmap.tryAllocPixels(info, nullptr, colorTable)) {
+                            return "Could not allocate pixels.";
+                        }
+                    }
+                    if (!brd->decodeRegion(bitmap)) {
+                        return "Failed to decode subset";
+                    }
+                    if (colorType != bitmap.colorType()) {
                         return Error::Nonfatal("Cannot convert to color type.\n");
                     }
 
-                    canvas->drawBitmapRect(*bitmap,
+                    canvas->drawBitmapRect(bitmap,
                             SkRect::MakeXYWH((SkScalar) scaledBorder, (SkScalar) scaledBorder,
                                     (SkScalar) (subsetWidth / fSampleSize),
                                     (SkScalar) (subsetHeight / fSampleSize)),