Android:使用Canvas合并Bit地图

• 关键点

canvas.drawBitmap(bitmap, srcRect, dstRect, null);

将bitmap的srcRect区域绘制到canvas的dstRect区域

• Demo

main.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/rl_root"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="@android:color/background_dark"    android:orientation="horizontal" >    <ImageView        android:id="@+id/iv_bmp1"        android:layout_width="80dp"        android:layout_height="100dp"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:layout_alignParentTop="true"        android:layout_marginLeft="20dp"        android:layout_marginStart="20dp"        android:layout_marginTop="20dp"        android:contentDescription="@null"        android:src="@drawable/baby" />    <ImageView        android:id="@+id/iv_bmp2"        android:layout_width="80dp"        android:layout_height="100dp"        android:layout_alignParentEnd="true"        android:layout_alignParentRight="true"        android:layout_alignParentTop="true"        android:layout_marginEnd="20dp"        android:layout_marginRight="20dp"        android:layout_marginTop="20dp"        android:contentDescription="@null"        android:src="@drawable/baby2" />    <Button        android:id="@+id/btn_merge"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/iv_bmp1"        android:layout_centerHorizontal="true"        android:layout_marginTop="20dp"        android:text="Merge" />    <ImageView        android:id="@+id/iv_bmp_merge"        android:layout_width="160dp"        android:layout_height="100dp"        android:layout_below="@id/btn_merge"        android:layout_centerHorizontal="true"        android:layout_marginTop="20dp"        android:contentDescription="@null" /></RelativeLayout>

目的就是将ivBmp1和ivBmp2上的图片，合并之后，显示在iv_bmp_merger上

• MainActivity.java

package net.mobctrl.mergebitmap;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Rect;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.os.Handler;import android.os.Handler.Callback;import android.os.Message;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;/** *  * @author Zheng Haibo * @web http://www.mobctrl.net * */public class MainActivity extends Activity {    private ImageView ivBmp1;    private ImageView ivBmp2;    private ImageView ivBmpMerge;    private Button mergeBtn;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        initUi();    }    private void initUi() {        ivBmp1 = (ImageView) findViewById(R.id.iv_bmp1);        ivBmp2 = (ImageView) findViewById(R.id.iv_bmp2);        ivBmpMerge = (ImageView) findViewById(R.id.iv_bmp_merge);        mergeBtn = (Button) findViewById(R.id.btn_merge);        mergeBtn.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                showMergeBitmap();            }        });    }    private Handler handler = new Handler(new Callback() {        @Override        public boolean handleMessage(Message msg) {            Bitmap bitmap = (Bitmap) msg.obj;            ivBmpMerge.setImageBitmap(bitmap);            return false;        }    });    /**     * 显示合并的图     */    protected void showMergeBitmap() {        new Thread(new Runnable() {            @Override            public void run() {                Bitmap bitmap = mergeBitmap();                Message messge = handler.obtainMessage();                messge.obj = bitmap;                handler.sendMessage(messge);            }        }).start();    }    /*     * 使用Canvas合并Bitmap     */    private Bitmap mergeBitmap() {        // 获取ImageView上得Bitmap图片        Bitmap bmp1 = ((BitmapDrawable) ivBmp1.getDrawable()).getBitmap();        Bitmap bmp2 = ((BitmapDrawable) ivBmp2.getDrawable()).getBitmap();        // 创建空得背景bitmap        // 生成画布图像        Bitmap resultBitmap = Bitmap.createBitmap(ivBmpMerge.getWidth(),                ivBmpMerge.getHeight(), Bitmap.Config.RGB_565);        Canvas canvas = new Canvas(resultBitmap);// 使用空白图片生成canvas        // 将bmp1绘制在画布上        Rect srcRect = new Rect(0, 0, bmp1.getWidth(), bmp1.getHeight());// 截取bmp1中的矩形区域        Rect dstRect = new Rect(0, 0, ivBmpMerge.getWidth() / 2,                ivBmpMerge.getHeight());// bmp1在目标画布中的位置        canvas.drawBitmap(bmp1, srcRect, dstRect, null);        // 将bmp2绘制在画布上        srcRect = new Rect(0, 0, bmp2.getWidth(), bmp2.getHeight());// 截取bmp1中的矩形区域        dstRect = new Rect(ivBmpMerge.getWidth() / 2, 0, ivBmpMerge.getWidth(),                ivBmpMerge.getHeight());// bmp2在目标画布中的位置        canvas.drawBitmap(bmp2, srcRect, dstRect, null);        // 将bmp1,bmp2合并显示        return resultBitmap;    }}

• 运行效果
  
  点击merge之后