实现Android图片圆角

这里介绍一个主要的方法，也是从网上找的，在此整理出来。。。以备不时之需

public static Bitmap toRoundCorner(Bitmap bitmap, int pixels) {  
          
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);  
        Canvas canvas = new Canvas(output);  
  
        final int color = 0xff424242;  
        final Paint paint = new Paint();  
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());  
        final RectF rectF = new RectF(rect);  
        final float roundPx = pixels;  
  
        paint.setAntiAlias(true);  
        canvas.drawARGB(0, 0, 0, 0);  
        paint.setColor(color);  
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);  
  
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));  
        canvas.drawBitmap(bitmap, rect, rect, paint);  
  
        return output;  
    }

当我们需要圆角的时候，调用这个方法，第一个参数是传入需要转化成圆角的图片，第二个参数是圆角的度数，数值越大，圆角越大

下面兴趣个例子，我有一个LinearLayout，我想把它的背景图片设置成圆角

布局文件main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    >
</LinearLayout>

package com.test.demo;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class MyActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

//        Drawable drawable = getResources().getDrawable(R.drawable.bg);
//        BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
//        Bitmap bitmap = bitmapDrawable.getBitmap();
        
        LinearLayout layout = (LinearLayout) findViewById(R.id.layout);
        Drawable drawable = getResources().getDrawable(R.drawable.bg);
        BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
        Bitmap bitmap = bitmapDrawable.getBitmap();
        
        BitmapDrawable bbb = new BitmapDrawable(toRoundCorner(bitmap, 30));
        layout.setBackgroundDrawable(bbb);
        //ImageView imageView = (ImageView) findViewById(R.id.imgShow);
        //imageView.setImageBitmap(MyActivity.getRoundedCornerBitmap(bitmap));
        //imageView.setImageBitmap(MyActivity.toRoundCorner(bitmap, 20));
    }
    public static Bitmap toRoundCorner(Bitmap bitmap, int pixels) {  
          
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);  
        Canvas canvas = new Canvas(output);  
  
        final int color = 0xff424242;  
        final Paint paint = new Paint();  
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());  
        final RectF rectF = new RectF(rect);  
        final float roundPx = pixels;  
  
        paint.setAntiAlias(true);  
        canvas.drawARGB(0, 0, 0, 0);  
        paint.setColor(color);  
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);  
  
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));  
        canvas.drawBitmap(bitmap, rect, rect, paint);  
  
        return output;  
    }
}

当然对ImageView设置图片也可以，不仅是background属性
上面那个类中注释的代码就是