Android 实现图片的圆角

将一个Activity的背景图设置为圆角，即将Activity的LinerLayout的背景设置为圆角：

配置文件 main.xml：

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

</LinearLayout>

 

Java代码：

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
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.LinearLayout;

/**
 * 将Activity的背景图设置为圆角图
 */
public class AndroidTestActivity 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.yexuan);
  BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
  Bitmap bitmap = bitmapDrawable.getBitmap();
  BitmapDrawable bdRound = new BitmapDrawable(toRoundCorner(bitmap, 30));
  layout.setBackgroundDrawable(bdRound);
  // ImageView imageView = (ImageView) findViewById(R.id.imgShow);
  // imageView.setImageBitmap(MyActivity.getRoundedCornerBitmap(bitmap));
  // imageView.setImageBitmap(MyActivity.toRoundCorner(bitmap, 20));
 }

 /**
  * 获取圆角位图的方法
  * @param bitmap 需要转化成圆角的位图
  * @param pixels 圆角的度数，数值越大，圆角越大
  * @return 处理后的圆角位图
  */
 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;
 }

}