moz-skia/experimental/FileReaderApp/ReaderView.cpp

75 строки
2.2 KiB
C++

/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "ReaderView.h"
#include "SkGPipe.h"
#include "SkCanvas.h"
#include <stdio.h>
#define FILE_PATH "/Users/yangsu/Code/test/test.a"
ReaderView::ReaderView() {
fBGColor = 0xFFDDDDDD;
fFilePos = 0;
fBufferBitmaps[0].setConfig(SkBitmap::kARGB_8888_Config, 640, 480);
fBufferBitmaps[0].allocPixels(NULL);
fBufferBitmaps[1].setConfig(SkBitmap::kARGB_8888_Config, 640, 480);
fBufferBitmaps[1].allocPixels(NULL);
fFront = 0;
fBack = 1;
}
void ReaderView::draw(SkCanvas* canvas) {
canvas->drawColor(fBGColor);
SkAutoCanvasRestore acr(canvas, true);
//Create a temporary canvas and reader object that draws into the back
//bitmap so that the incremental changes or incomplete reads are not shown
//on screen
SkCanvas bufferCanvas(fBufferBitmaps[fBack]);
SkGPipeReader reader(&bufferCanvas);
//The file specified by FILE_PATH MUST exist
FILE* f = fopen(FILE_PATH, "rb");
SkASSERT(f != NULL);
fseek(f, 0, SEEK_END);
int size = ftell(f) * sizeof(char);
if (size <= fFilePos) {
fFilePos = 0;
}
//Resume from the last read location
fseek(f, fFilePos, SEEK_SET);
int toBeRead = size - fFilePos;
if (size > 0 && toBeRead > 0) {
void* block = sk_malloc_throw(toBeRead);
fread(block, 1, toBeRead, f);
size_t bytesRead;
SkGPipeReader::Status fStatus = reader.playback(block, toBeRead, &bytesRead);
SkASSERT(SkGPipeReader::kError_Status != fStatus);
SkASSERT(toBeRead >= bytesRead);
//if the reader reaches a done verb, a frame is complete.
//Update the file location and swap the front and back bitmaps to show
//the new frame
if (SkGPipeReader::kDone_Status == fStatus) {
fFilePos += bytesRead;
fFront = fFront ^ 0x1;
fBack = fBack ^ 0x1;
}
sk_free(block);
}
fclose(f);
//the front bitmap is always drawn
canvas->drawBitmap(fBufferBitmaps[fFront], 0, 0, NULL);
this->inval(NULL);
}