Refactor SkBitmapRegionDecoderInterface for Android

tools/SkBitmapRegionCodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapRegionCodec.h"
 #include "SkAndroidCodec.h"
 #include "SkCodecPriv.h"
 #include "SkCodecTools.h"
 
 SkBitmapRegionCodec::SkBitmapRegionCodec(SkAndroidCodec* codec)
     : INHERITED(codec->getInfo().width(), codec->getInfo().height())
     , fCodec(codec)
 {}
 
-/*
- * Three differences from the Android version:
- *     Returns a skia bitmap instead of an Android bitmap.
- *     Android version attempts to reuse a recycled bitmap.
- *     Removed the options object and used parameters for color type and sample size.
- */
-// FIXME: Should this function should take in SkIRect?
-SkBitmap* SkBitmapRegionCodec::decodeRegion(int inputX, int inputY, int inputWidth, int inputHeight,
-        int sampleSize, SkColorType dstColorType) {
+bool SkBitmapRegionCodec::decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* allocator,
+        const SkIRect& desiredSubset, int sampleSize, SkColorType dstColorType,
+        bool requireUnpremul) {
 
     // Fix the input sampleSize if necessary.
     if (sampleSize < 1) {
         sampleSize = 1;
     }
 
     // The size of the output bitmap is determined by the size of the
     // requested subset, not by the size of the intersection of the subset
     // and the image dimensions.
     // If inputX is negative, we will need to place decoded pixels into the
     // output bitmap starting at a left offset.  Call this outX.
     // If outX is non-zero, subsetX must be zero.
     // If inputY is negative, we will need to place decoded pixels into the
     // output bitmap starting at a top offset.  Call this outY.
     // If outY is non-zero, subsetY must be zero.
     int outX;
     int outY;
-    SkIRect subset = SkIRect::MakeXYWH(inputX, inputY, inputWidth, inputHeight);
+    SkIRect subset = desiredSubset;
     SubsetType type = adjust_subset_rect(fCodec->getInfo().dimensions(), &subset, &outX, &outY);
     if (SubsetType::kOutside_SubsetType == type) {
-        return nullptr;
+        return false;
     }
 
     // Ask the codec for a scaled subset
     if (!fCodec->getSupportedSubset(&subset)) {
         SkCodecPrintf("Error: Could not get subset.\n");
-        return nullptr;
+        return false;
     }
     SkISize scaledSize = fCodec->getSampledSubsetDimensions(sampleSize, subset);
 
     // Create the image info for the decode
     SkAlphaType dstAlphaType = fCodec->getInfo().alphaType();
-    if (kUnpremul_SkAlphaType == dstAlphaType) {
-        dstAlphaType = kPremul_SkAlphaType;
+    if (kOpaque_SkAlphaType != dstAlphaType) {
+        dstAlphaType = requireUnpremul ? kUnpremul_SkAlphaType : kPremul_SkAlphaType;
     }
     SkImageInfo decodeInfo = SkImageInfo::Make(scaledSize.width(), scaledSize.height(),
             dstColorType, dstAlphaType);
 
     // Construct a color table for the decode if necessary
     SkAutoTUnref<SkColorTable> colorTable(nullptr);
     SkPMColor* colorPtr = nullptr;
     int* colorCountPtr = nullptr;
     int maxColors = 256;
     SkPMColor colors[256];
     if (kIndex_8_SkColorType == dstColorType) {
         // TODO (msarett): This performs a copy that is unnecessary since
         //                 we have not yet initialized the color table.
         //                 And then we need to use a const cast to get
         //                 a pointer to the color table that we can
         //                 modify during the decode.  We could alternatively
         //                 perform the decode before creating the bitmap and
         //                 the color table.  We still would need to copy the
         //                 colors into the color table after the decode.
         colorTable.reset(new SkColorTable(colors, maxColors));
         colorPtr = const_cast<SkPMColor*>(colorTable->readColors());
         colorCountPtr = &maxColors;
     }
 
     // Initialize the destination bitmap
-    SkAutoTDelete<SkBitmap> bitmap(new SkBitmap());
     int scaledOutX = 0;
     int scaledOutY = 0;
     int scaledOutWidth = scaledSize.width();
     int scaledOutHeight = scaledSize.height();
     if (SubsetType::kPartiallyInside_SubsetType == type) {
         scaledOutX = outX / sampleSize;
         scaledOutY = outY / sampleSize;
         // We need to be safe here because getSupportedSubset() may have modified the subset.
-        const int extraX = SkTMax(0, inputWidth - outX - subset.width());
-        const int extraY = SkTMax(0, inputHeight - outY - subset.height());
+        const int extraX = SkTMax(0, desiredSubset.width() - outX - subset.width());
+        const int extraY = SkTMax(0, desiredSubset.height() - outY - subset.height());
         const int scaledExtraX = extraX / sampleSize;
         const int scaledExtraY = extraY / sampleSize;
         scaledOutWidth += scaledOutX + scaledExtraX;
         scaledOutHeight += scaledOutY + scaledExtraY;
     }
     SkImageInfo outInfo = decodeInfo.makeWH(scaledOutWidth, scaledOutHeight);
-    if (!bitmap->tryAllocPixels(outInfo, nullptr, colorTable.get())) {
+    bitmap->setInfo(outInfo, outInfo.minRowBytes());
+    if (!bitmap->tryAllocPixels(allocator, colorTable.get())) {
         SkCodecPrintf("Error: Could not allocate pixels.\n");
-        return nullptr;
+        return false;
     }
 
     // Zero the bitmap if the region is not completely within the image.
     // TODO (msarett): Can we make this faster by implementing it to only
     //                 zero parts of the image that we won't overwrite with
     //                 pixels?
     // TODO (msarett): This could be skipped if memory is zero initialized.
     //                 This would matter if this code is moved to Android and
     //                 uses Android bitmaps.
     if (SubsetType::kPartiallyInside_SubsetType == type) {
         void* pixels = bitmap->getPixels();
         size_t bytes = outInfo.getSafeSize(bitmap->rowBytes());
         memset(pixels, 0, bytes);
     }
 
     // Decode into the destination bitmap
     SkAndroidCodec::AndroidOptions options;
     options.fSampleSize = sampleSize;
     options.fSubset = &subset;
     options.fColorPtr = colorPtr;
     options.fColorCount = colorCountPtr;
     void* dst = bitmap->getAddr(scaledOutX, scaledOutY);
     size_t rowBytes = bitmap->rowBytes();
     SkCodec::Result result = fCodec->getAndroidPixels(decodeInfo, dst, rowBytes, &options);
     if (SkCodec::kSuccess != result && SkCodec::kIncompleteInput != result) {
         SkCodecPrintf("Error: Could not get pixels.\n");
-        return nullptr;
+        return false;
     }
 
-    return bitmap.detach();
+    return true;
 }
 
 bool SkBitmapRegionCodec::conversionSupported(SkColorType colorType) {
     // FIXME: Call virtual function when it lands.
     SkImageInfo info = SkImageInfo::Make(0, 0, colorType, fCodec->getInfo().alphaType(),
             fCodec->getInfo().profileType());
     return conversion_possible(info, fCodec->getInfo());
 }