src/images/SkImageDecoder.cpp

/* libs/graphics/images/SkImageDecoder.cpp
**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License"); 
** you may not use this file except in compliance with the License. 
** You may obtain a copy of the License at 
**
**     http://www.apache.org/licenses/LICENSE-2.0 
**
** Unless required by applicable law or agreed to in writing, software 
** distributed under the License is distributed on an "AS IS" BASIS, 
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
** See the License for the specific language governing permissions and 
** limitations under the License.
*/

#include "SkImageDecoder.h"
#include "SkBitmap.h"
#include "SkPixelRef.h"
#include "SkStream.h"
#include "SkTemplates.h"

static SkBitmap::Config gDeviceConfig = SkBitmap::kNo_Config;

SkBitmap::Config SkImageDecoder::GetDeviceConfig()
{
    return gDeviceConfig;
}

void SkImageDecoder::SetDeviceConfig(SkBitmap::Config config)
{
    gDeviceConfig = config;
}

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

SkImageDecoder::SkImageDecoder()
    : fPeeker(NULL), fChooser(NULL), fAllocator(NULL), fSampleSize(1),
      fDitherImage(true) {
}

SkImageDecoder::~SkImageDecoder() {
    fPeeker->safeUnref();
    fChooser->safeUnref();
    fAllocator->safeUnref();
}

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

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

SkImageDecoder::Chooser* SkImageDecoder::setChooser(Chooser* chooser) {
    SkRefCnt_SafeAssign(fChooser, chooser);
    return chooser;
}

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::chooseFromOneChoice(SkBitmap::Config config, int width,
                                         int height) const {
    Chooser* chooser = fChooser;

    if (NULL == chooser) {    // no chooser, we just say YES to decoding :)
        return true;
    }
    chooser->begin(1);
    chooser->inspect(0, config, width, height);
    return chooser->choose() == 0;
}

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

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

bool SkImageDecoder::decode(SkStream* stream, SkBitmap* bm,
                            SkBitmap::Config pref, Mode mode) {
    SkBitmap    tmp;

    // we reset this to false before calling onDecode
    fShouldCancelDecode = false;

    // pass a temporary bitmap, so that if we return false, we are assured of
    // leaving the caller's bitmap untouched.
    if (this->onDecode(stream, &tmp, pref, mode)) {
        /*  We operate on a tmp bitmap until we know we succeed. This way
         we're sure we don't change the caller's bitmap and then later
         return false. Returning false must mean that their parameter
         is unchanged.
         */
        bm->swap(tmp);
        return true;
    }
    return false;
}

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

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

    SkFILEStream    stream(file);
    if (stream.isValid()) {
        if (SkImageDecoder::DecodeStream(&stream, bm, pref, mode)) {
            bm->pixelRef()->setURI(file);
        }
        return true;
    }
    return false;
}

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

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

bool SkImageDecoder::DecodeStream(SkStream* stream, SkBitmap* bm,
                                  SkBitmap::Config pref, Mode mode) {
    SkASSERT(stream);
    SkASSERT(bm);

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

    if (NULL != codec) {
        success = codec->decode(stream, bm, pref, mode);
        delete codec;
    }
    return success;
}