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      1 /*
      2  * Copyright (C) 2013 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.bitmapscaling;
     18 
     19 import android.app.Activity;
     20 import android.graphics.Bitmap;
     21 import android.graphics.BitmapFactory;
     22 import android.os.Bundle;
     23 import android.widget.ImageView;
     24 import android.widget.LinearLayout;
     25 import android.widget.LinearLayout.LayoutParams;
     26 
     27 /**
     28  * This example shows how the use of BitmapOptions affects the resulting size of a loaded
     29  * bitmap. Sub-sampling can speed up load times and reduce the need for large bitmaps
     30  * in memory if your target bitmap size is much smaller, although it's good to understand
     31  * that you can't get specific Bitmap sizes, but rather power-of-two reductions in sizes.
     32  *
     33  * Watch the associated video for this demo on the DevBytes channel of developer.android.com
     34  * or on YouTube at https://www.youtube.com/watch?v=12cB7gnL6po.
     35  */
     36 public class BitmapScaling extends Activity {
     37 
     38     @Override
     39     public void onCreate(Bundle savedInstanceState) {
     40         super.onCreate(savedInstanceState);
     41         setContentView(R.layout.activity_bitmap_scaling);
     42 
     43         LinearLayout container = (LinearLayout) findViewById(R.id.scaledImageContainer);
     44         ImageView originalImageView = (ImageView) findViewById(R.id.originalImageHolder);
     45 
     46         Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
     47                 R.drawable.jellybean_statue);
     48         originalImageView.setImageBitmap(bitmap);
     49 
     50         for (int i = 2; i < 10; ++i) {
     51             addScaledImageView(bitmap, i, container);
     52         }
     53     }
     54 
     55     private void addScaledImageView(Bitmap original, int sampleSize, LinearLayout container) {
     56 
     57         // inSampleSize tells the loader how much to scale the final image, which it does at
     58         // load time by simply reading less pixels for every pixel value in the final bitmap.
     59         // Note that it only scales by powers of two, so a value of two results in a bitmap
     60         // 1/2 the size of the original and a value of four results in a bitmap 1/4 the original
     61         // size. Intermediate values are rounded down, so a value of three results in a bitmap 1/2
     62         // the original size.
     63 
     64         BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
     65         bitmapOptions.inSampleSize = sampleSize;
     66 
     67         Bitmap scaledBitmap = BitmapFactory.decodeResource(getResources(),
     68                 R.drawable.jellybean_statue, bitmapOptions);
     69         ImageView scaledImageView = new ImageView(this);
     70         scaledImageView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
     71                 LayoutParams.WRAP_CONTENT));
     72         scaledImageView.setImageBitmap(scaledBitmap);
     73         container.addView(scaledImageView);
     74     }
     75 }
     76