Android图片的合成示例

package com.example.demo;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv=(ImageView) findViewById(R.id.iv);
        //图片合成画布  先画图片A 再去画图片B
    Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.aaaa);
    Bitmap alertBitmap=Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());

    Canvas canvas=new Canvas(alertBitmap);
    Paint paint=new Paint();
    paint.setColor(Color.BLACK);

    canvas.drawBitmap(bitmap, new Matrix(), paint);
    Bitmap ic_launch=BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
    canvas.drawBitmap(ic_launch, new Matrix(), paint);

    iv.setImageBitmap(alertBitmap);

    }

}