Android 实现图片的圆角

/**
 * 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;
}

下面就测试一下这个方法，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：

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 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));
	}

	/**
	 * 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;
	}

}

转载于：http://blog.csdn.net/akon_vm/article/details/7418210