Android实现自定义圆形、圆角和椭圆ImageView（使用Xfermode图形渲染方法）

/**
     * 测量view的大小
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // TODO Auto-generated method stub
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        //如果类型是圆形，则强制设置view的宽高一致，取宽高的较小值 
        if(mType == TYPE_CIRCLE){
            int width = Math.min(getMeasuredWidth(),getMeasuredHeight());
            setMeasuredDimension(width, width);
        }
    }

/**
     * 绘制不同的图形Bitmap
     */
    private Bitmap getDrawBitmap(){
        Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(),  
                Bitmap.Config.ARGB_8888);  
        Canvas canvas = new Canvas(bitmap);  
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);  
        paint.setColor(Color.BLACK);  
  
        if(mType == TYPE_CIRCLE)
        {//绘制圆形 
            canvas.drawCircle(getWidth() / 2, getWidth() / 2, getWidth() / 2,  
                    paint); 
        }else if(mType == TYPE_ROUND)  
        {//绘制圆角矩形
            canvas.drawRoundRect(new RectF(0, 0, getWidth(), getHeight()),  
                    mRoundBorderRadius, mRoundBorderRadius, paint);  
        }else if(mType == TYPE_OVAL ){
         //绘制椭圆
            canvas.drawOval(new RectF(0, 0, getWidth(), getHeight()), mPaint);
        }
  
        return bitmap;  
    }

/**
     * 绘制view的内容
     */
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        //从缓存中取出bitmap
        Bitmap bmp = (mBufferBitmap == null ? null:mBufferBitmap.get());
        if(bmp == null || bmp.isRecycled()){
            //如果没有缓存存在的情况
            //获取drawable
            Drawable drawable = getDrawable();
            //获取drawable的宽高
            int dwidth = drawable.getIntrinsicWidth();
            int dheight = drawable.getIntrinsicHeight();
            Log.v("czm","dwidth="+dwidth+",width="+getWidth());
            if(null != drawable){
                bmp = Bitmap.createBitmap(getWidth(), getHeight(),  
                        Config.ARGB_8888); 
                float scale = 1.0f;
                //创建画布
                Canvas drawCanvas = new Canvas(bmp);
                //按照bitmap的宽高，以及view的宽高，计算缩放比例；因为设置的src宽高
                //比例可能和imageview的宽高比例不同，这里我们不希望图片失真；  
                
                if(mType == TYPE_CIRCLE)  
                {//如果是圆形  
                    scale = getWidth() * 1.0F / Math.min(dwidth, dheight);  
                }else if (mType == TYPE_ROUND || mType == TYPE_OVAL)  
                {//如果是圆角矩形或椭圆 
                    // 如果图片的宽或者高与view的宽高不匹配，计算出需要缩放的比例；
                    //缩放后的图片的宽高，一定要大于我们view的宽高；所以我们这里取大值；  
                    scale = Math.max(getWidth() * 1.0f / dwidth, getHeight()  
                            * 1.0f / dheight);  
                }
                Log.v("czm","scale="+scale);
                //根据缩放比例，设置bounds，即相当于做缩放图片  
                drawable.setBounds(0, 0, (int)(scale * dwidth), (int)(scale * dheight));
                drawable.draw(drawCanvas);
                //获取bitmap，即圆形、圆角或椭圆的bitmap
                if(mMaskBitmap == null || mMaskBitmap.isRecycled()){
                    mMaskBitmap = getDrawBitmap();
                }
                //为paint设置Xfermode 渲染模式
                mPaint.reset();
                mPaint.setFilterBitmap(false);
                mPaint.setXfermode(mXfermode);
                //绘制不同形状
                drawCanvas.drawBitmap(mMaskBitmap, 0, 0,mPaint);
                mPaint.setXfermode(null);
                
                //将准备好的bitmap绘制出来  
                canvas.drawBitmap(bmp, 0, 0, null);  
                //bitmap缓存起来，避免每次调用onDraw，分配内存  
                mBufferBitmap = new WeakReference<Bitmap>(bmp); 
            }
            
        }else{
            //如果缓存还存在的情况
            mPaint.setXfermode(null);  
            canvas.drawBitmap(bmp, 0.0f, 0.0f, mPaint);  
            return; 
        }
    }

/**
     * 因为使用了缓存技术，所以需要在invalidate中做些回收释放资源的处理
     */
    @Override
    public void invalidate() {
        // TODO Auto-generated method stub
        mBufferBitmap = null;
        if(mMaskBitmap != null){
            mMaskBitmap.recycle();
            mMaskBitmap = null;
        }
        super.invalidate();
    }

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
     >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="55dp"
        android:orientation="vertical" >

        <com.czm.myroundimageview.XCRoundImageViewByXfermode
            android:id="@+id/cicleImageView"
            android:layout_width="150dp"
            android:layout_height="150dp"
            android:src="@drawable/img1" />

        <com.czm.myroundimageview.XCRoundImageViewByXfermode
            android:id="@+id/roundRectImageView"
            android:layout_width="125dp"
            android:layout_height="145dp"
            android:layout_marginTop="15dp"
            android:src="@drawable/img2" />

        <com.czm.myroundimageview.XCRoundImageViewByXfermode
            android:id="@+id/ovalImageView"
            android:layout_width="140dp"
            android:layout_height="184dp"
            android:layout_marginTop="15dp"
            android:src="@drawable/img3" />
    </LinearLayout>

</ScrollView>

package com.czm.myroundimageview;

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {

    private XCRoundImageViewByXfermode circleImageView;//圆形图片
    private XCRoundImageViewByXfermode roundRectImageView;//圆角矩形图片
    private XCRoundImageViewByXfermode ovalImageView;//椭圆图片
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initViews();
    }
    /**
     * 初始化Views
     */
    private void initViews(){
        circleImageView = (XCRoundImageViewByXfermode)findViewById(R.id.cicleImageView);
        roundRectImageView = (XCRoundImageViewByXfermode)findViewById(R.id.roundRectImageView);
        ovalImageView = (XCRoundImageViewByXfermode)findViewById(R.id.ovalImageView);
        
        roundRectImageView.setType(XCRoundImageViewByXfermode.TYPE_ROUND);
        roundRectImageView.setRoundBorderRadius(100);
        
        ovalImageView.setType(XCRoundImageViewByXfermode.TYPE_OVAL);
        ovalImageView.setRoundBorderRadius(50);
        
    }

   

}