Android Launcher 之 图标加框 优化显示效果

直接看代码，解释。主要是用到图片处理的

PorterDuff.Mode.SRC_ATOPSRC_ATOP 

 源像素和目标像素相混合让上层图居中显示，达到加框效果

package com.ferris.launchericonutils;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends Activity {
	private ImageView imageView;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		imageView = (ImageView) findViewById(R.id.imageView1);

		// 获得imageview中设置的图片
		Bitmap lay1 = BitmapFactory.decodeResource(getResources(),
				R.drawable.icon_folder);
		Bitmap lay2 = BitmapFactory.decodeResource(getResources(),
				R.drawable.mobileqq);
		// 获得图片的宽，并创建结果bitmap
		int width = lay1.getWidth();

		Bitmap resultBmp = Bitmap.createBitmap(width, width,
				Bitmap.Config.ARGB_8888);

		Paint paint = new Paint();
		Canvas canvas = new Canvas(resultBmp);

		canvas.drawBitmap(lay1, 0, 0, paint);// 画下层

		// 让上层的图标居中显示
		int top = 0;
		if (lay1.getHeight() > lay2.getHeight()) {
			top = (lay1.getHeight() - lay2.getHeight()) / 2;
		}else{
			//这里可以判断图片是否大于框，进而再继续获取大于的多少，进行上层图片的缩放，然后再进行交集，方法就不写了
		}
		int left = 0;
		if (lay1.getWidth() > lay2.getWidth()) {
			left = (lay1.getWidth() - lay2.getWidth()) / 2;
		}else{
			//这里可以判断图片是否大于框，进而再继续获取大于的多少，进行上层图片的缩放，然后再进行交集，方法就不写了
		}
		paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));// 选择交集去上层图片
		canvas.drawBitmap(lay2, left, top, paint);
		imageView.setImageBitmap(resultBmp);

	}

}