Monday, July 30, 2012

Reduce Bitmap size using BitmapFactory.Options.inSampleSize

In the post "Load ImageView with JPG file in SD Card", the ImageView is loaded with bitmap in full-size. It cost too much resources for a mobile device, and easy to make the app closed unexpectly.

We can generate a shrinked bitmap using BitmapFactory.Optionswith inSampleSize; such that to reduce the needed resources greatly.

package com.AndroidLoadImageView;

import android.os.Bundle;
import android.widget.ImageView;

public class AndroidLoadImageViewActivity extends Activity {
 String imagefile ="/sdcard/IMG_9331.JPG";
    /** Called when the activity is first created. */
    public void onCreate(Bundle savedInstanceState) {
        ImageView image = (ImageView)findViewById(;
        //Bitmap bm = BitmapFactory.decodeFile(imagefile);
        Bitmap bm = ShrinkBitmap(imagefile, 300, 300);
 Bitmap ShrinkBitmap(String file, int width, int height){
     BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
        bmpFactoryOptions.inJustDecodeBounds = true;
        Bitmap bitmap = BitmapFactory.decodeFile(file, bmpFactoryOptions);
        int heightRatio = (int)Math.ceil(bmpFactoryOptions.outHeight/(float)height);
        int widthRatio = (int)Math.ceil(bmpFactoryOptions.outWidth/(float)width);
        if (heightRatio > 1 || widthRatio > 1)
         if (heightRatio > widthRatio)
          bmpFactoryOptions.inSampleSize = heightRatio;
         } else {
          bmpFactoryOptions.inSampleSize = widthRatio; 
        bmpFactoryOptions.inJustDecodeBounds = false;
        bitmap = BitmapFactory.decodeFile(file, bmpFactoryOptions);
     return bitmap;

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