Android Bitmap

1、Drawable → Bitmap

public static Bitmap drawableToBitmap(Drawable drawable) {

Bitmap bitmap = Bitmap

.createBitmap(

drawable.getIntrinsicWidth(),

drawable.getIntrinsicHeight(),

drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888

Bitmap.Config.RGB_565);

Canvas canvas = new Canvas(bitmap);

// canvas.setBitmap(bitmap);

drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),

drawable.getIntrinsicHeight());

drawable.draw(canvas);

return bitmap;

}

2、从资源中获取Bitmap

Resources res=getResources();

Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);

3、Bitmap → byte[]

private byte[] Bitmap2Bytes(Bitmap bm){

ByteArrayOutputStream baos = new ByteArrayOutputStream();

bm.compress(Bitmap.CompressFormat.PNG, 100, baos);

return baos.toByteArray();

}

4、byte[] → Bitmap

private Bitmap Bytes2Bimap(byte[] b){

if(b.length!=0){

return BitmapFactory.decodeByteArray(b, 0, b.length);

}

else {

return null;

}

}

5、保存bitmap

static boolean saveBitmap2file(Bitmap bmp,String filename){

CompressFormat format= Bitmap.CompressFormat.JPEG;

int quality = 100;

OutputStream stream = null;

try {

stream = new FileOutputStream(“/sdcard/” + filename);

} catch (FileNotFoundException e) {

// TODO Auto-generated catch block

Generated by Foxit PDF Creator © Foxit Software

http://www.foxitsoftware.com For evaluation only.

e.printStackTrace();

}

return bmp.compress(format, quality, stream);

}

6、将图片按自己的要求缩放

// 图片源

Bitmap bm = BitmapFactory.decodeStream(getResources()

.openRawResource(R.drawable.dog));

// 获得图片的宽高

int width = bm.getWidth();

int height = bm.getHeight();

// 设置想要的大小

int newWidth = 320;

int newHeight = 480;

// 计算缩放比例

float scaleWidth = ((float) newWidth) / width;

float scaleHeight = ((float) newHeight) / height;

// 取得想要缩放的matrix参数

Matrix matrix = new Matrix();

matrix.postScale(scaleWidth, scaleHeight);

// 得到新的图片

Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,

true);

// 放在画布上

canvas.drawBitmap(newbm, 0, 0, paint);

7、File图片转Bitmap

Bitmap bt = BitmapFactory.decodeFile(“/sdcard/myImage/” + “head.jpg”);//图片地址

8、图片转Bitmap

public Bitmap drawableToBitamp(int drawableResource) {//可以取raw里面的资源
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inPreferredConfig = Bitmap.Config.RGB_565;
opt.inPurgeable = true;
opt.inInputShareable = true;
InputStream is = this.getResources().openRawResource(drawableResource);
BitmapFactory.decodeStream(is, null, opt);
return BitmapFactory.decodeStream(is, null, opt);
}

9、android view的内容 映射成bitmap

 rlHeartQrBg.setDrawingCacheEnabled(true);                    rlHeartQrBg.measure(                            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),                            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));                    rlHeartQrBg.layout(0, 0, rlHeartQrBg.getMeasuredWidth(),                            rlHeartQrBg.getMeasuredHeight());                    rlHeartQrBg.buildDrawingCache();                    Bitmap cacheBitmap2 = rlHeartQrBg.getDrawingCache();                    bitmapImg = Bitmap.createBitmap(cacheBitmap2);

原理：创建一个新的Bitmap，然后再根据它来创建一个Canvas，最后调用View的draw方法将View画到Canvas上，这样得到的Bitmap就是我们想要的。

public Bitmap createViewBitmap(View v) {
Bitmap bitmap = Bitmap.createBitmap(v.getWidth(), v.getHeight(),
Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
v.draw(canvas);
return bitmap;
}