Fine tune scaled down bitmap to exact size

Last post genarate a scaled down bitmaps, approximate but not exact size. In order to fine tune bitmap to exact size, we can re-create another bitmap from this scaled bitmap using Bitmap.createScaledBitmap() method with expected width and height.

Modify MainActivity.java from Last post to fine tune bitmap after scaled.

package com.test.androidimageprocessing;

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.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.example.androidimageprocessing.R;

public class MainActivity extends Activity {

 Button btnLoadImage1, btnLoadImage2;
 TextView textSource1, textSource2;
 Button btnProcessing;
 ImageView imageResult;
 Spinner spinnerMode;

 final int RQS_IMAGE1 = 1;
 final int RQS_IMAGE2 = 2;

 Uri source1, source2;

 String[] arrayModeName = { "ADD", "CLEAR", "DARKEN", "DST", "DST_ATOP",
   "DST_IN", "DST_OUT", "DST_OVER", "LIGHTEN", "MULTIPLY", "OVERLAY",
   "SCREEN", "SRC", "SRC_ATOP", "SRC_IN", "SRC_OUT", "SRC_OVER", "XOR" };

 /*
  * To use Mode.ADD and Mode.OVERLAY, android:minSdkVersion have to be set
  * "11" or higher.
  */
 PorterDuff.Mode[] arrayMode = { Mode.ADD, Mode.CLEAR, Mode.DARKEN,
   Mode.DST, Mode.DST_ATOP, Mode.DST_IN, Mode.DST_OUT, Mode.DST_OVER,
   Mode.LIGHTEN, Mode.MULTIPLY, Mode.OVERLAY, Mode.SCREEN, Mode.SRC,
   Mode.SRC_ATOP, Mode.SRC_IN, Mode.SRC_OUT, Mode.SRC_OVER, Mode.XOR };

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);

  setContentView(R.layout.activity_main);
  btnLoadImage1 = (Button) findViewById(R.id.loadimage1);
  btnLoadImage2 = (Button) findViewById(R.id.loadimage2);
  textSource1 = (TextView) findViewById(R.id.sourceuri1);
  textSource2 = (TextView) findViewById(R.id.sourceuri2);
  btnProcessing = (Button) findViewById(R.id.processing);
  imageResult = (ImageView) findViewById(R.id.result);

  spinnerMode = (Spinner) findViewById(R.id.mode);
  ArrayAdapter<String> adapter = new ArrayAdapter<String>(
    MainActivity.this, android.R.layout.simple_spinner_item,
    arrayModeName);
  adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
  spinnerMode.setAdapter(adapter);

  btnLoadImage1.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);
   }
  });

  btnLoadImage2.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_IMAGE2);
   }
  });

  btnProcessing.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View v) {

    if (source1 != null && source2 != null) {
     Bitmap processedBitmap = ProcessingBitmap();
     if (processedBitmap != null) {
      imageResult.setImageBitmap(processedBitmap);
      Toast.makeText(getApplicationContext(), "Done",
        Toast.LENGTH_LONG).show();
     } else {
      Toast.makeText(getApplicationContext(),
        "Something wrong in processing!",
        Toast.LENGTH_LONG).show();
     }
    } else {
     Toast.makeText(getApplicationContext(),
       "Select both image!", Toast.LENGTH_LONG).show();
    }

   }
  });
 }

 @Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  if (resultCode == RESULT_OK) {
   switch (requestCode) {
   case RQS_IMAGE1:
    source1 = data.getData();
    textSource1.setText(source1.toString());
    break;
   case RQS_IMAGE2:
    source2 = data.getData();
    textSource2.setText(source2.toString());
    break;
   }
  }
 }

 private Bitmap ProcessingBitmap() {
  Bitmap bm1 = null;
  Bitmap bm2 = null;
  Bitmap newBitmap = null;

  try {
   /*
    * bm1 = BitmapFactory.decodeStream(getContentResolver()
    * .openInputStream(source1)); 
    * bm2 = BitmapFactory.decodeStream(getContentResolver()
    * .openInputStream(source2));
    */

   bm1 = loadScaledBitmap(source1);
   Toast.makeText(getApplicationContext(),
     "bm1: " + bm1.getWidth() + " x " + bm1.getHeight(),
     Toast.LENGTH_LONG).show();

   bm2 = loadScaledBitmap(source2);
   Toast.makeText(getApplicationContext(),
     "bm2: " + bm2.getWidth() + " x " + bm2.getHeight(),
     Toast.LENGTH_LONG).show();

   int w;
   if (bm1.getWidth() >= bm2.getWidth()) {
    w = bm1.getWidth();
   } else {
    w = bm2.getWidth();
   }

   int h;
   if (bm1.getHeight() >= bm2.getHeight()) {
    h = bm1.getHeight();
   } else {
    h = bm2.getHeight();
   }

   Config config = bm1.getConfig();
   if (config == null) {
    config = Bitmap.Config.ARGB_8888;
   }

   newBitmap = Bitmap.createBitmap(w, h, config);
   Canvas newCanvas = new Canvas(newBitmap);

   newCanvas.drawBitmap(bm1, 0, 0, null);

   Paint paint = new Paint();

   int selectedPos = spinnerMode.getSelectedItemPosition();
   PorterDuff.Mode selectedMode = arrayMode[selectedPos];

   paint.setXfermode(new PorterDuffXfermode(selectedMode));
   newCanvas.drawBitmap(bm2, 0, 0, paint);

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

  return newBitmap;
 }

 private Bitmap loadScaledBitmap(Uri src) throws FileNotFoundException {

  // required max width/height
  final int REQ_WIDTH = 1024;
  final int REQ_HEIGHT = 1024;

  Bitmap bm = null;

  // First decode with inJustDecodeBounds=true to check dimensions
  final BitmapFactory.Options options = new BitmapFactory.Options();
  options.inJustDecodeBounds = true;
  BitmapFactory.decodeStream(getContentResolver().openInputStream(src),
    null, options);

  // Calculate inSampleSize
  options.inSampleSize = calculateInSampleSize(options, REQ_WIDTH,
    REQ_HEIGHT);

  // Decode bitmap with inSampleSize set
  options.inJustDecodeBounds = false;
  bm = BitmapFactory.decodeStream(
    getContentResolver().openInputStream(src), null, options);
  
  /*
   * Up to here, bm will be scaled down, but not exactly expected size!
   * 
   * To fine tune the size, re-create another bitmap from this scaled bitmap
   * using Bitmap.createScaledBitmap() method with expected width and height.
   */
  final int LONGEST_LENGTH = 1024;
  int dstWidth, dstHeight;
  
  if(options.outWidth >= options.outHeight){
   //Landscape orientation
   dstWidth = LONGEST_LENGTH;
   dstHeight = LONGEST_LENGTH * options.outHeight/options.outWidth;
  }else{
   //portrait orientation
   dstHeight = LONGEST_LENGTH;
   dstWidth = LONGEST_LENGTH * options.outWidth/options.outHeight;
  }
  
  //To save memory, re-use bm
  bm = Bitmap.createScaledBitmap(bm, dstWidth, dstHeight, false);

  return bm;
 }

 private int calculateInSampleSize(BitmapFactory.Options options,
   int reqWidth, int reqHeight) {
  // Raw height and width of image
  final int height = options.outHeight;
  final int width = options.outWidth;
  int inSampleSize = 1;

  if (height > reqHeight || width > reqWidth) {

   // Calculate ratios of height and width to requested height and
   // width
   final int heightRatio = Math.round((float) height
     / (float) reqHeight);
   final int widthRatio = Math.round((float) width / (float) reqWidth);

   // Choose the smallest ratio as inSampleSize value, this will
   // guarantee
   // a final image with both dimensions larger than or equal to the
   // requested height and width.
   inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
  }

  Toast.makeText(getApplicationContext(),
    "inSampleSize: " + inSampleSize, Toast.LENGTH_LONG).show();

  return inSampleSize;
 }

}

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more: Something about processing images in Android