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制作一個圓形圖片 *  * @author 徐榮 * */public class RoundView extends ImageView {  /**   * 畫筆   */  private Paint mPaint;  /**   * 原型圖   */  private Bitmap src;  /**   * 遮罩層   */  private Bitmap mask;  public RoundView(Context context, AttributeSet attrs) {    super(context, attrs);    // 初始化畫筆    mPaint = new Paint();    mPaint.setAntiAlias(true);    // 拿到原型圖    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);    // 圖片的遮罩，為什么要在這里面初始化遮罩層呢？因為在這個方法里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);    // 設置畫布的顏色為透明    canvas.drawColor(Color.TRANSPARENT);    // 劃出你要顯示的圓    Canvas cc = new Canvas(mask);    cc.drawCircle(getMeasuredWidth() / 2, getMeasuredHeight() / 2, getMeasuredHeight() / 2, mPaint);    // 這個方法相當于PS新建圖層，下面你要做的事就在這個圖層上操作    canvas.saveLayer(0, 0, getMeasuredWidth(), getMeasuredHeight(), null, Canvas.ALL_SAVE_FLAG);    // 先繪制遮罩層    canvas.drawBitmap(mask, 0, 0, mPaint);    // 設置混合模式    mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));    // 再繪制src源圖    canvas.drawBitmap(src, 0, 0, mPaint);    // 還原混合模式    mPaint.setXfermode(null);    // 還原畫布，相當于Ps的合并圖層    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>