Android-只有2个圆角的ImageView

本例子是针对将图片两个直角转换为圆角的例子：

1.自定义3个属性 宽高，圆角值：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyPhotoView">
        <attr name="width" format="dimension"></attr>
        <attr name="height" format="dimension"></attr>
        <attr name="radus" format="dimension"></attr>
    </declare-styleable>
</resources>

2.在引用的布局中使用

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:bc="http://schemas.android.com/apk/res/org.lean"
    android:layout_width="match_parent"
    android:layout_height="match_parent"  >
	<org.lean.MyPhotoView
	    android:id="@+id/photo_iv"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:layout_marginTop="20dp"
	    android:layout_marginLeft="60dp"
	    bc:width="160dp"
	    bc:height="240dp"
	    bc:radus="10dp" />
</RelativeLayout>

3.在Java代码中设置两个图层。这里有2个图片 先绘制的叫目标图层，然后设置混合渲染绘制 ，后绘制的图层成为源图层。

SRC_IN 模式在两者相交的地方绘制源图层（同时隐藏目标图层），并且绘制的效果会受到目标图像对应地方透明度的影响；

package org.lean;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.widget.ImageView;

/**
 *	重绘的ImageView
 *
 * @author Lean
 */
public class MyPhotoView extends ImageView{

	private Bitmap mImageBtp;
	private Rect mImageSrcRect ,mImageDesRect;
	private Rect mBtmRect;
	private float mTotalWidth;
	private float mTotalHeight;
	private float mRadus;

	public MyPhotoView(Context context,int with,int height,float radus) {
		super(context);
		mTotalWidth=with;
		mTotalHeight=height;
		mRadus=radus;
	}

	public MyPhotoView(Context context, AttributeSet attrs) {
		super(context, attrs);

		TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.MyPhotoView);
		mTotalWidth = array.getDimensionPixelSize(R.styleable.MyPhotoView_width, 0);
		mTotalHeight = array.getDimensionPixelSize(R.styleable.MyPhotoView_height, 0);
		mRadus = array.getDimensionPixelSize(R.styleable.MyPhotoView_radus, 0);
		array.recycle();
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);
		mImageDesRect=new Rect(0, 0,(int)mTotalWidth, (int)mTotalHeight);
		mBtmRect=new Rect(0, 0,(int)mTotalWidth,(int)(mTotalHeight+mRadus));
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		Paint paint=new Paint(Paint.ANTI_ALIAS_FLAG);
		PorterDuffXfermode xfermode=new PorterDuffXfermode(PorterDuff.Mode.SRC_IN);
		canvas.drawColor(Color.WHITE);
		int saveCount=canvas.saveLayer(0,0, mTotalWidth,mTotalHeight,paint,Canvas.ALL_SAVE_FLAG);
		if (mImageBtp!=null) {
			paint.setColor(Color.WHITE);
			canvas.drawRoundRect(new RectF(mBtmRect), mRadus, mRadus, paint);
			paint.setXfermode(xfermode);
			canvas.drawBitmap(mImageBtp,mImageSrcRect,mImageDesRect,paint);
			paint.setXfermode(null);
		}
		canvas.restoreToCount(saveCount);
	}

	@Override
	public void setImageBitmap(Bitmap bm) {
		super.setImageBitmap(bm);
		mImageBtp=bm;
		reCalculateRect();
	}

	private void reCalculateRect() {
		mImageSrcRect=new Rect(0, 0,mImageBtp.getWidth(),mImageBtp.getHeight());
		invalidate();
	}

	@Override
	public void setImageResource(int resId) {
		super.setImageResource(resId);
		mImageBtp=((BitmapDrawable)getResources().getDrawable(resId)).getBitmap();
		reCalculateRect();
	}

}