Android 将一张图片变为圆形图片

前度时间做的一个项目中有这样的需求，把网络请求下来的图片变为圆形图片显示在客服端。开始想了很久，都没找到好的解决方案，最后还是通过Bitmap.createBitmap方法解决的。具体实现如下：

将图片转换为圆形图片，输入需要一个Bitmap的对象

/**
* 转换图片成圆形
*
* @param bitmap
*            传入Bitmap对象
* @return
*/
public static Bitmap toRoundBitmap(Bitmap bitmap) {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
float roundPx;
float left, top, right, bottom, dst_left, dst_top, dst_right, dst_bottom;
if (width <= height) {
roundPx = width / 2;
left = 0;
top = 0;
right = width;
bottom = width;
height = width;
dst_left = 0;
dst_top = 0;
dst_right = width;
dst_bottom = width;
} else {
roundPx = height / 2;
float clip = (width - height) / 2;
left = clip;
right = width - clip;
top = 0;
bottom = height;
width = height;
dst_left = 0;
dst_top = 0;
dst_right = height;
dst_bottom = height;
}

Bitmap output = Bitmap.createBitmap(width, height, Config.ARGB_8888);
Canvas canvas = new Canvas(output);

final int color = 0xff424242;
final Paint paint = new Paint();
final Rect src = new Rect((int) left, (int) top, (int) right,
(int) bottom);
final Rect dst = new Rect((int) dst_left, (int) dst_top,
(int) dst_right, (int) dst_bottom);
new RectF(dst);

paint.setAntiAlias(true);// 设置画笔无锯齿

canvas.drawARGB(0, 0, 0, 0); // 填充整个Canvas
paint.setColor(color);
canvas.drawCircle(roundPx, roundPx, roundPx, paint);

paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));// 设置两张图片相交时的模式,参考http://trylovecatch.iteye.com/blog/1189452
canvas.drawBitmap(bitmap, src, dst, paint); // 以Mode.SRC_IN模式合并bitmap和已经draw了的Circle

return output;
}

将drawable中的图片转为Bitmap对象

/**
* drawable2Bitmap
*
* @param bitmap
*            传入Drawable对象
* @return
*/

@SuppressWarnings("deprecation")
public static Bitmap drawable2Bitmap(int a ,Context context) {
Resources resources = context.getResources();
Drawable drawable = resources.getDrawable(a);
if (drawable instanceof BitmapDrawable) {
return ((BitmapDrawable) drawable).getBitmap();
} else if (drawable instanceof NinePatchDrawable) {
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);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight());
drawable.draw(canvas);
return bitmap;
} else {
return null;
}
}

图片旋转

/**

* rotateImage

*

* @param id

* 传入derawable id

* @return bitmap

*/

public Bitmap rotateImage(int id,Context context,float rotate){
Bitmap bitmap = ((BitmapDrawable) context.getResources().getDrawable(id)).getBitmap();
Matrix matrix = new Matrix();
matrix.setRotate(rotate);
bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
return bitmap;
}