android画图------字节数组转化为图片

在这个例程当中，主要讲了将一个图片压缩成字节流，然后转化成数组在变成图片的故事。
首先图片压缩成流在转变成图片的方法还是值得学习的：
private static Bitmap codec(Bitmap src, Bitmap.CompressFormat format,
int quality) {
ByteArrayOutputStream os = new ByteArrayOutputStream();
src.compress(format, quality, os);

byte[] array = os.toByteArray();
return BitmapFactory.decodeByteArray(array, 0, array.length);
}

初始化图片：
mBitmaps = new Bitmap[6];
// these three are initialized with colors[]
mBitmaps[0] = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT,
Bitmap.Config.ARGB_8888);
mBitmaps[1] = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT, Bitmap.Config.RGB_565);
mBitmaps[2] = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT,
Bitmap.Config.ARGB_4444);

// these three will have their colors set later
mBitmaps[3] = Bitmap.createBitmap(WIDTH, HEIGHT,
Bitmap.Config.ARGB_8888);
mBitmaps[4] = Bitmap.createBitmap(WIDTH, HEIGHT,
Bitmap.Config.RGB_565); mBitmaps[5] = Bitmap.createBitmap(WIDTH, HEIGHT,
Bitmap.Config.ARGB_4444);
for (int i = 3; i <= 5; i++) {
mBitmaps[i].setPixels(colors, 0, STRIDE, 0, 0, WIDTH, HEIGHT);
}

for (int i = 0; i < mBitmaps.length; i++) {
mJPEG[i] = codec(mBitmaps[i], Bitmap.CompressFormat.JPEG, 80);
mPNG[i] = codec(mBitmaps[i], Bitmap.CompressFormat.PNG, 0);

最后将图片绘画在屏幕上
@Override protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);

for (int i = 0; i < mBitmaps.length; i++) {
canvas.drawBitmap(mBitmaps[i], 0, 0, null);
canvas.drawBitmap(mJPEG[i], 80, 0, null);
canvas.drawBitmap(mPNG[i], 160, 0, null);
canvas.translate(0, mBitmaps[i].getHeight());
}

// draw the color array directly, w/o craeting a bitmap object
canvas.drawBitmap(mColors, 0, STRIDE, 0, 0, WIDTH, HEIGHT,
true, null);
canvas.translate(0, HEIGHT);
canvas.drawBitmap(mColors, 0, STRIDE, 0, 0, WIDTH, HEIGHT,
false, mPaint);
}
上面的绘制有三种情况绘制jpeg 绘制png 直接绘制原数组。
mBitmaps[i].setPixels(colors, 0, STRIDE, 0, 0, WIDTH, HEIGHT);
也可以通过上面的方式来改变颜色

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