Android编程绘制圆形图片的方法

package com.rong.activity;import com.rong.test.R;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.util.AttributeSet;import android.widget.ImageView;/** * 利用Xfermode制作一个圆形图片 *  * @author 徐荣 * */public class RoundView extends ImageView {  /**   * 画笔   */  private Paint mPaint;  /**   * 原型图   */  private Bitmap src;  /**   * 遮罩层   */  private Bitmap mask;  public RoundView(Context context, AttributeSet attrs) {    super(context, attrs);    // 初始化画笔    mPaint = new Paint();    mPaint.setAntiAlias(true);    // 拿到原型图    src = BitmapFactory.decodeResource(getResources(), R.drawable.ml);  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {    super.onSizeChanged(w, h, oldw, oldh);    // 图片的遮罩，为什么要在这里面初始化遮罩层呢？因为在这个方法里Width()和Height()才被初始化了    mask = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(), Config.ARGB_4444);  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    // 设置画布的颜色为透明    canvas.drawColor(Color.TRANSPARENT);    // 划出你要显示的圆    Canvas cc = new Canvas(mask);    cc.drawCircle(getMeasuredWidth() / 2, getMeasuredHeight() / 2, getMeasuredHeight() / 2, mPaint);    // 这个方法相当于PS新建图层，下面你要做的事就在这个图层上操作    canvas.saveLayer(0, 0, getMeasuredWidth(), getMeasuredHeight(), null, Canvas.ALL_SAVE_FLAG);    // 先绘制遮罩层    canvas.drawBitmap(mask, 0, 0, mPaint);    // 设置混合模式    mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));    // 再绘制src源图    canvas.drawBitmap(src, 0, 0, mPaint);    // 还原混合模式    mPaint.setXfermode(null);    // 还原画布，相当于Ps的合并图层    canvas.restore();  }}

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:background="#ffffff"  android:orientation="vertical" >  <com.rong.activity.RoundView    android:layout_width="160dp"    android:layout_height="160dp"    android:layout_centerInParent="true" /></RelativeLayout>