Revert of Provides multiple implementations of Android's SkBitmapRegionDecoder

src/utils/SkBitmapRegionCanvas.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 "SkBitmapRegionCanvas.h"
-#include "SkCanvas.h"
-#include "SkScanlineDecoder.h"
-
-SkBitmapRegionCanvas::SkBitmapRegionCanvas(SkScanlineDecoder* decoder)
-    : INHERITED(decoder->getInfo().width(), decoder->getInfo().height())
-    , fDecoder(decoder)
-{}
-
-/*
- * Chooses the correct image subset offsets and dimensions for the partial decode.
- */
-static inline void set_subset_region(int inputOffset, int inputDimension,
-        int imageOriginalDimension, int* imageSubsetOffset, int* outOffset,
-        int* imageSubsetDimension) {
-
-    // This must be at least zero, we can't start decoding the image at a negative coordinate.
-    *imageSubsetOffset = SkTMax(0, inputOffset);
-
-    // If inputOffset is less than zero, we decode to an offset location in the output bitmap.
-    *outOffset = *imageSubsetOffset - inputOffset;
-
-    // Use imageSusetOffset to make sure we don't decode pixels past the edge of the image.
-    // Use outOffset to make sure we don't decode pixels past the edge of the region.
-    *imageSubsetDimension = SkTMin(imageOriginalDimension - *imageSubsetOffset,
-            inputDimension - *outOffset);
-}
-
-/*
- * Returns a scaled dimension based on the original dimension and the sample size.
- * TODO: Share this implementation with SkScaledCodec.
- */
-static int get_scaled_dimension(int srcDimension, int sampleSize) {
-    if (sampleSize > srcDimension) {
-        return 1;
-    }
-    return srcDimension / sampleSize;
-}
-
-/*
- * 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.
- */
-SkBitmap* SkBitmapRegionCanvas::decodeRegion(int inputX, int inputY,
-                                             int inputWidth, int inputHeight,
-                                             int sampleSize,
-                                             SkColorType dstColorType) {
-    // Reject color types not supported by this method
-    if (kIndex_8_SkColorType == dstColorType || kGray_8_SkColorType == dstColorType) {
-        SkDebugf("Error: Color type not supported.\n");
-        return nullptr;
-    }
-
-    // The client may not necessarily request a region that is fully within
-    // the image.  We may need to do some calculation to determine what part
-    // of the image to decode.
-
-    // The left offset of the portion of the image we want, where zero
-    // indicates the left edge of the image.
-    int imageSubsetX;
-
-    // The size of the output bitmap is determined by the size of the
-    // requested region, not by the size of the intersection of the region
-    // and the image dimensions.  If inputX is negative, we will need to
-    // place decoded pixels into the output bitmap starting at a left offset.
-    // If this is non-zero, imageSubsetX must be zero.
-    int outX;
-
-    // The width of the portion of the image that we will write to the output
-    // bitmap.  If the region is not fully contained within the image, this
-    // will not be the same as inputWidth.
-    int imageSubsetWidth;
-    set_subset_region(inputX, inputWidth, this->width(), &imageSubsetX, &outX, &imageSubsetWidth);
-
-    // The top offset of the portion of the image we want, where zero
-    // indicates the top edge of the image.
-    int imageSubsetY;
-
-    // The size of the output bitmap is determined by the size of the
-    // requested region, not by the size of the intersection of the region
-    // and the image dimensions.  If inputY is negative, we will need to
-    // place decoded pixels into the output bitmap starting at a top offset.
-    // If this is non-zero, imageSubsetY must be zero.
-    int outY;
-
-    // The height of the portion of the image that we will write to the output
-    // bitmap.  If the region is not fully contained within the image, this
-    // will not be the same as inputHeight.
-    int imageSubsetHeight;
-    set_subset_region(inputY, inputHeight, this->height(), &imageSubsetY, &outY,
-            &imageSubsetHeight);
-
-    if (imageSubsetWidth <= 0 || imageSubsetHeight <= 0) {
-        SkDebugf("Error: Region must intersect part of the image.\n");
-        return nullptr;
-    }
-
-    // Create the image info for the decode
-    SkAlphaType dstAlphaType = fDecoder->getInfo().alphaType();
-    if (kUnpremul_SkAlphaType == dstAlphaType) {
-        dstAlphaType = kPremul_SkAlphaType;
-    }
-    SkImageInfo decodeInfo = SkImageInfo::Make(this->width(), this->height(),
-            dstColorType, dstAlphaType);
-    
-    // Start the scanline decoder
-    SkCodec::Result r = fDecoder->start(decodeInfo);
-    if (SkCodec::kSuccess != r) {
-        SkDebugf("Error: Could not start scanline decoder.\n");
-        return nullptr;
-    }
-
-    // Allocate a bitmap for the unscaled decode
-    SkBitmap tmp;
-    SkImageInfo tmpInfo = decodeInfo.makeWH(this->width(), imageSubsetHeight);
-    if (!tmp.tryAllocPixels(tmpInfo)) {
-        SkDebugf("Error: Could not allocate pixels.\n");
-        return nullptr;
-    }
-
-    // Skip the unneeded rows
-    if (SkCodec::kSuccess != fDecoder->skipScanlines(imageSubsetY)) {
-        SkDebugf("Error: Failed to skip scanlines.\n");
-        return nullptr;
-    }
-
-    // Decode the necessary rows
-    SkCodec::Result result = fDecoder->getScanlines(tmp.getAddr(0, 0), imageSubsetHeight,
-            tmp.rowBytes());
-    switch (result) {
-        case SkCodec::kSuccess:
-        case SkCodec::kIncompleteInput:
-            break;
-        default:
-            SkDebugf("Error: Failed to get scanlines.\n");
-            return nullptr;
-    }
-
-    // Calculate the size of the output
-    const int outWidth = get_scaled_dimension(inputWidth, sampleSize);
-    const int outHeight = get_scaled_dimension(inputHeight, sampleSize);
-
-    // Initialize the destination bitmap
-    SkAutoTDelete<SkBitmap> bitmap(new SkBitmap());
-    SkImageInfo dstInfo = decodeInfo.makeWH(outWidth, outHeight);
-    if (!bitmap->tryAllocPixels(dstInfo)) {
-        SkDebugf("Error: Could not allocate pixels.\n");
-        return nullptr;
-    }
-
-    // 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 (0 != outX || 0 != outY ||
-            inputX + inputWidth > this->width() ||
-            inputY + inputHeight > this->height()) {
-        bitmap->eraseColor(0);
-    }
-
-    // Use a canvas to crop and scale to the destination bitmap
-    SkCanvas canvas(*bitmap);
-    // TODO (msarett): Maybe we can take advantage of the fact that SkRect uses floats?
-    SkRect src = SkRect::MakeXYWH((SkScalar) imageSubsetX, (SkScalar) 0,
-            (SkScalar) imageSubsetWidth, (SkScalar) imageSubsetHeight);
-    SkRect dst = SkRect::MakeXYWH((SkScalar) (outX / sampleSize), (SkScalar) (outY / sampleSize),
-            (SkScalar) get_scaled_dimension(imageSubsetWidth, sampleSize),
-            (SkScalar) get_scaled_dimension(imageSubsetHeight, sampleSize));
-    SkPaint paint;
-    // Overwrite the dst with the src pixels
-    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
-    // TODO (msarett): Test multiple filter qualities.  kNone is the default.
-    canvas.drawBitmapRect(tmp, src, dst, &paint);
-
-    return bitmap.detach();
-}