android 指定角的圆角图片处理

package com.lurencun.androidsysteminfomation;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Bitmap.Config;
import android.graphics.PorterDuff.Mode;

/**
* @author :
* @email
* @date   : 2012-11-8
* @desc   :
*/
public class BitmapFillet {

public static final int ALL = 347120;
public static final int TOP = 547120;
public static final int LEFT = 647120;
public static final int RIGHT = 747120;
public static final int BOTTOM = 847120;

/**
*
* 指定图片的切边，对图片进行圆角处理
* @param type 具体参见：{@link BitmapFillet.ALL} , {@link BitmapFillet.TOP} ,
*              {@link BitmapFillet.LEFT} , {@link BitmapFillet.RIGHT} , {@link BitmapFillet.BOTTOM}
* @param bitmap 需要被切圆角的图片
* @param roundPx 要切的像素大小
* @return
*
*/
public static Bitmap fillet(int type,Bitmap bitmap,int roundPx) {
try {
// 其原理就是：先建立一个与图片大小相同的透明的Bitmap画板
// 然后在画板上画出一个想要的形状的区域。
// 最后把源图片帖上。
final int width = bitmap.getWidth();
final int height = bitmap.getHeight();

Bitmap paintingBoard = Bitmap.createBitmap(width,height, Config.ARGB_8888);
Canvas canvas = new Canvas(paintingBoard);
canvas.drawARGB(Color.TRANSPARENT, Color.TRANSPARENT, Color.TRANSPARENT, Color.TRANSPARENT);

final Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);

if( TOP == type ){
clipTop(canvas,paint,roundPx,width,height);
}else if( LEFT == type ){
clipLeft(canvas,paint,roundPx,width,height);
}else if( RIGHT == type ){
clipRight(canvas,paint,roundPx,width,height);
}else if( BOTTOM == type ){
clipBottom(canvas,paint,roundPx,width,height);
}else{
clipAll(canvas,paint,roundPx,width,height);
}

paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
//帖子图
final Rect src = new Rect(0, 0, width, height);
final Rect dst = src;
canvas.drawBitmap(bitmap, src, dst, paint);
return paintingBoard;
} catch (Exception exp) {
return bitmap;
}
}

private static void clipLeft(final Canvas canvas,final Paint paint,int offset,int width,int height){
final Rect block = new Rect(offset,0,width,height);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(0, 0, offset * 2 , height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipRight(final Canvas canvas,final Paint paint,int offset,int width,int height){
final Rect block = new Rect(0, 0, width-offset, height);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(width - offset * 2, 0, width , height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipTop(final Canvas canvas,final Paint paint,int offset,int width,int height){
final Rect block = new Rect(0, offset, width, height);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(0, 0, width , offset * 2);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipBottom(final Canvas canvas,final Paint paint,int offset,int width,int height){
final Rect block = new Rect(0, 0, width, height - offset);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(0, height - offset * 2 , width , height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipAll(final Canvas canvas,final Paint paint,int offset,int width,int height){
final RectF rectF = new RectF(0, 0, width , height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}
}