一起学android之设置资源图片为圆角图片 （28）

public class MainActivity extends Activity {
private ImageView imageView1;
private ImageView imageView2;
Bitmap mBitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.image);
initView();

}

private void initView(){
imageView1=(ImageView)findViewById(R.id.imageView1);
imageView2=(ImageView)findViewById(R.id.imageView2);
//读取资源图片
mBitmap=readBitMap();
//对资源图片进行缩放
Bitmap bitmap=zoomBitmap(mBitmap, mBitmap.getWidth()/2, mBitmap.getHeight()/2);
//设置圆角图片
imageView2.setImageBitmap(setRoundedCorner(bitmap,20f));
}

/**
* 读取资源图片
* @return
*/
private Bitmap readBitMap(){
BitmapFactory.Options opt=new BitmapFactory.Options();
/*
* 设置让解码器以最佳方式解码
*/
opt.inPreferredConfig=Bitmap.Config.RGB_565;
//下面两个字段需要组合使用
opt.inPurgeable=true;
opt.inInputShareable=true;
/*
* 获取资源图片
*/
InputStream is=this.getResources().openRawResource(R.drawable.mei);
return BitmapFactory.decodeStream(is, null, opt);
}

/**
* 缩放图片
* @param bitmap
* @param w
* @param h
* @return
*/
public  Bitmap zoomBitmap(Bitmap bitmap, int w, int h) {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
Matrix matrix = new Matrix();
float scaleWidht = ((float) w / width);
float scaleHeight = ((float) h / height);
/*
* 通过Matrix类的postScale方法进行缩放
*/
matrix.postScale(scaleWidht, scaleHeight);
Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
return newbmp;
}

/**
* 设置图片为圆角
* @param bitmap
* @param roundPx  圆角角度
* @return
*/
public  Bitmap setRoundedCorner(Bitmap bitmap, float roundPx) {
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);

final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
/*
* 椭圆形
*/
final RectF rectF = new RectF(rect);
/*
* 去锯齿
*/
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);

/*
* 绘制圆角矩形
*/
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
/*
* 设置两个图形相交
*/
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);

return output;
}

}