Android Open Source - BrokenDisplay Bitmap Worker Task

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Back to project page BrokenDisplay.

License

The source code is released under:

Apache License

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Java Source Code

package com.foolish.brokendisplay.picturedialog;
/*from w w  w  . j  av  a  2s.c  om*/
import java.lang.ref.WeakReference;

import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.widget.ImageView;

class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
  private final WeakReference<ImageView> imageViewReference;
  private int data = 0;
  private Context context;

  public BitmapWorkerTask(ImageView imageView, Context context) {
    // Use a WeakReference to ensure the ImageView can be garbage
    // collected
    imageViewReference = new WeakReference<ImageView>(imageView);
    this.context=context;
  }

  // Decode image in background.
  @Override
  protected Bitmap doInBackground(Integer... params) {
    data = params[0];
    return decodeSampledBitmapFromResource(context.getResources(), data,
        100, 100);
  }

  // Once complete, see if ImageView is still around and set bitmap.
  @Override
  protected void onPostExecute(Bitmap bitmap) {
    if (imageViewReference != null && bitmap != null) {
      final ImageView imageView = imageViewReference.get();
      if (imageView != null) {
        imageView.setImageBitmap(bitmap);
      }
    }
  }

  public static Bitmap decodeSampledBitmapFromResource(Resources res,
      int resId, int reqWidth, int reqHeight) {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(res, resId, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth,
        reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeResource(res, resId, options);
  }

  public static 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) {

      final int halfHeight = height / 2;
      final int halfWidth = width / 2;

      // Calculate the largest inSampleSize value that is a power of 2 and
      // keeps both
      // height and width larger than the requested height and width.
      while ((halfHeight / inSampleSize) > reqHeight
          && (halfWidth / inSampleSize) > reqWidth) {
        inSampleSize *= 2;
      }
    }

    return inSampleSize;
  }
}

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