Combine bitmap, half/half

This example demonstrate how to combin two bitmap, half from a bitmap, another from the mirror bitmap of the same source.

package com.example.androiddrawbitmap;

import java.io.FileNotFoundException;

import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

 Button btnLoadImage;
 TextView textSource;
 ImageView imageResult;

 final int RQS_IMAGE1 = 1;

 Uri source;
 Bitmap bitmapMaster;
 Canvas canvasMaster;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  btnLoadImage = (Button) findViewById(R.id.loadimage);
  textSource = (TextView) findViewById(R.id.sourceuri);
  imageResult = (ImageView) findViewById(R.id.result);

  btnLoadImage.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {
    Intent intent = new Intent(
      Intent.ACTION_PICK,
      android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(intent, RQS_IMAGE1);
   }
  });

 }

 @Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);

  Bitmap tempBitmap;

  if (resultCode == RESULT_OK) {
   switch (requestCode) {
   case RQS_IMAGE1:
    source = data.getData();

    try {
     tempBitmap = BitmapFactory
       .decodeStream(getContentResolver().openInputStream(
         source));

     //create a mirror bitmap
     Matrix matrixMirror = new Matrix();
     matrixMirror.preScale(-1.0f, 1.0f);
     Bitmap bitmapMirror = Bitmap.createBitmap(tempBitmap, 0, 0,
       tempBitmap.getWidth(), tempBitmap.getHeight(),
       matrixMirror, false);

     //define half/half area
     Rect rect1Half = new Rect(0, 0, tempBitmap.getWidth() / 2,
       tempBitmap.getHeight());
     Rect rect2Half = new Rect((tempBitmap.getWidth() / 2) + 1,
       0, tempBitmap.getWidth(), tempBitmap.getHeight());

     Config config = tempBitmap.getConfig();
     if (config == null) {
      config = Bitmap.Config.ARGB_8888;
     }

     //craete the master bitmap
     bitmapMaster = Bitmap.createBitmap(
       tempBitmap.getWidth(), tempBitmap.getHeight(), config);
     canvasMaster = new Canvas(bitmapMaster);

     //merge bitmap half/half
     canvasMaster.drawBitmap(tempBitmap, rect1Half, rect1Half,
       null);
     canvasMaster.drawBitmap(bitmapMirror, rect2Half, rect2Half,
       null);

     imageResult.setImageBitmap(bitmapMaster);

    } catch (FileNotFoundException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    break;
   }
  }
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/loadimage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Load Image 1" />

    <TextView
        android:id="@+id/sourceuri"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    
    <ImageView
            android:id="@+id/result"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:adjustViewBounds="true"
            android:background="@android:color/background_dark"
            android:scaleType="centerInside" />

</LinearLayout>

Download the files.

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more: Something about processing images in Android