src/images/SkImageDecoder.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 "SkImageDecoder.h"
#include "SkBitmap.h"
#include "SkImagePriv.h"
#include "SkPixelRef.h"
#include "SkStream.h"
#include "SkTemplates.h"
#include "SkCanvas.h"

SkImageDecoder::SkImageDecoder()
    : fPeeker(nullptr)
    , fAllocator(nullptr)
    , fSampleSize(1)
    , fDefaultPref(kUnknown_SkColorType)
    , fPreserveSrcDepth(false)
    , fDitherImage(true)
    , fSkipWritingZeroes(false)
    , fPreferQualityOverSpeed(false)
    , fRequireUnpremultipliedColors(false) {
}

SkImageDecoder::~SkImageDecoder() {
    SkSafeUnref(fPeeker);
    SkSafeUnref(fAllocator);
}

void SkImageDecoder::copyFieldsToOther(SkImageDecoder* other) {
    if (nullptr == other) {
        return;
    }
    other->setPeeker(fPeeker);
    other->setAllocator(fAllocator);
    other->setSampleSize(fSampleSize);
    other->setPreserveSrcDepth(fPreserveSrcDepth);
    other->setDitherImage(fDitherImage);
    other->setSkipWritingZeroes(fSkipWritingZeroes);
    other->setPreferQualityOverSpeed(fPreferQualityOverSpeed);
    other->setRequireUnpremultipliedColors(fRequireUnpremultipliedColors);
}

SkImageDecoder::Format SkImageDecoder::getFormat() const {
    return kUnknown_Format;
}

const char* SkImageDecoder::getFormatName() const {
    return GetFormatName(this->getFormat());
}

const char* SkImageDecoder::GetFormatName(Format format) {
    switch (format) {
        case kUnknown_Format:
            return "Unknown Format";
        case kBMP_Format:
            return "BMP";
        case kGIF_Format:
            return "GIF";
        case kICO_Format:
            return "ICO";
        case kPKM_Format:
            return "PKM";
        case kKTX_Format:
            return "KTX";
        case kASTC_Format:
            return "ASTC";
        case kJPEG_Format:
            return "JPEG";
        case kPNG_Format:
            return "PNG";
        case kWBMP_Format:
            return "WBMP";
        case kWEBP_Format:
            return "WEBP";
        default:
            SkDEBUGFAIL("Invalid format type!");
    }
    return "Unknown Format";
}

SkPngChunkReader* SkImageDecoder::setPeeker(SkPngChunkReader* peeker) {
    SkRefCnt_SafeAssign(fPeeker, peeker);
    return peeker;
}

SkBitmap::Allocator* SkImageDecoder::setAllocator(SkBitmap::Allocator* alloc) {
    SkRefCnt_SafeAssign(fAllocator, alloc);
    return alloc;
}

void SkImageDecoder::setSampleSize(int size) {
    if (size < 1) {
        size = 1;
    }
    fSampleSize = size;
}

bool SkImageDecoder::allocPixelRef(SkBitmap* bitmap,
                                   SkColorTable* ctable) const {
    return bitmap->tryAllocPixels(fAllocator, ctable);
}

///////////////////////////////////////////////////////////////////////////////

SkColorType SkImageDecoder::getPrefColorType(SrcDepth srcDepth, bool srcHasAlpha) const {
    SkColorType ct = fDefaultPref;
    if (fPreserveSrcDepth) {
        switch (srcDepth) {
            case kIndex_SrcDepth:
                ct = kIndex_8_SkColorType;
                break;
            case k8BitGray_SrcDepth:
                ct = kN32_SkColorType;
                break;
            case k32Bit_SrcDepth:
                ct = kN32_SkColorType;
                break;
        }
    }
    return ct;
}

SkImageDecoder::Result SkImageDecoder::decode(SkStream* stream, SkBitmap* bm, SkColorType pref,
                                              Mode mode) {
    // we reset this to false before calling onDecode
    fShouldCancelDecode = false;
    // assign this, for use by getPrefColorType(), in case fUsePrefTable is false
    fDefaultPref = pref;

    // pass a temporary bitmap, so that if we return false, we are assured of
    // leaving the caller's bitmap untouched.
    SkBitmap tmp;
    const Result result = this->onDecode(stream, &tmp, mode);
    if (kFailure != result) {
        bm->swap(tmp);
    }
    return result;
}

///////////////////////////////////////////////////////////////////////////////

bool SkImageDecoder::DecodeFile(const char file[], SkBitmap* bm, SkColorType pref,  Mode mode,
                                Format* format) {
    SkASSERT(file);
    SkASSERT(bm);

    SkAutoTDelete<SkStreamRewindable> stream(SkStream::NewFromFile(file));
    if (stream.get()) {
        if (SkImageDecoder::DecodeStream(stream, bm, pref, mode, format)) {
            if (SkPixelRef* pr = bm->pixelRef()) {
                pr->setURI(file);
            }
            return true;
        }
    }
    return false;
}

bool SkImageDecoder::DecodeMemory(const void* buffer, size_t size, SkBitmap* bm, SkColorType pref,
                                  Mode mode, Format* format) {
    if (0 == size) {
        return false;
    }
    SkASSERT(buffer);

    SkMemoryStream  stream(buffer, size);
    return SkImageDecoder::DecodeStream(&stream, bm, pref, mode, format);
}

bool SkImageDecoder::DecodeStream(SkStreamRewindable* stream, SkBitmap* bm, SkColorType pref,
                                  Mode mode, Format* format) {
    SkASSERT(stream);
    SkASSERT(bm);

    bool success = false;
    SkImageDecoder* codec = SkImageDecoder::Factory(stream);

    if (codec) {
        success = codec->decode(stream, bm, pref, mode) != kFailure;
        if (success && format) {
            *format = codec->getFormat();
            if (kUnknown_Format == *format) {
                if (stream->rewind()) {
                    *format = GetStreamFormat(stream);
                }
            }
        }
        delete codec;
    }
    return success;
}

bool SkImageDecoder::decodeYUV8Planes(SkStream* stream, SkISize componentSizes[3], void* planes[3],
                                      size_t rowBytes[3], SkYUVColorSpace* colorSpace) {
    // we reset this to false before calling onDecodeYUV8Planes
    fShouldCancelDecode = false;

    return this->onDecodeYUV8Planes(stream, componentSizes, planes, rowBytes, colorSpace);
}