/*
* Copyright (C) 2015 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package
import android.annotation.TargetApi;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Point;
import
import android.os.AsyncTask;
import android.os.Build;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import
import
import
/**
* An AsyncTask to fetch an image over HTTP and scale it to the desired size. Clients need to extend
* this and implement their own {@code onPostExecute(Bitmap bitmap)} method. It provides a uniform
* treatment of ThreadPool across various versions of Android.
*/
public abstract class FetchBitmapTask extends AsyncTask<Uri, Void, Bitmap> {
private final int mPreferredWidth;
private final int mPreferredHeight;
private final boolean mAllowedToScale;
/**
* Constructs a new FetchBitmapTask that will do in-sampling and scaling, if needed.
*
* @param preferredWidth The preferred image width.
* @param preferredHeight The preferred image height.
* @param allowedToScale If {@code true}, the resulting bitmap will be scaled to match the
* preferred dimensions while keeping the aspect ratio. Otherwise, no additional scaling will
* be performed.
*/
public FetchBitmapTask(int preferredWidth, int preferredHeight, boolean allowedToScale) {
mPreferredWidth = preferredWidth;
mPreferredHeight = preferredHeight;
mAllowedToScale = allowedToScale;
}
/**
* Constructs a new FetchBitmapTask that will do in-sampling but no scaling.
*
* @param preferredWidth The preferred image width.
* @param preferredHeight The preferred image height.
*
* @see FetchBitmapTask#FetchBitmapTask(int, int, boolean)
*/
public FetchBitmapTask(int preferredWidth, int preferredHeight) {
this(preferredWidth, preferredHeight, false);
}
/**
* Constructs a new FetchBitmapTask. No scaling or in-sampling will be performed if you use this
* constructor.
*
* @see FetchBitmapTask#FetchBitmapTask(int, int)
* @see FetchBitmapTask#FetchBitmapTask(int, int, boolean)
*/
public FetchBitmapTask() {
this(0, 0);
}
@Override
protected Bitmap doInBackground(Uri... uris) {
if (uris.length != 1 || uris[0] == null) {
return null;
}
Bitmap bitmap = null;
URL url;
try {
url = new URL(uris[0].toString());
} catch (MalformedURLException e) {
return null;
}
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = false;
options.inSampleSize = 1;
if ((mPreferredWidth > 0) && (mPreferredHeight > 0)) {
// This is done to do appropriate resampling when the image is too large for the
// desired target size; instead of downloading the original image and resizing that
// (which can run into OOM exception), we find an appropriate in-sample-size and
// only adjust the options to download the resized version.
Point originalSize = calculateOriginalDimensions(url);
if (originalSize.x > 0 && originalSize.y > 0) {
options.inSampleSize = calculateInSampleSize(originalSize.x, originalSize.y,
mPreferredWidth, mPreferredHeight);
}
}
HttpURLConnection urlConnection = null;
InputStream stream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setDoInput(true);
if (urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
stream = new BufferedInputStream(urlConnection.getInputStream());
bitmap = BitmapFactory.decodeStream(stream, null, options);
if ((mPreferredWidth > 0) && (mPreferredHeight > 0) && mAllowedToScale) {
bitmap = scaleBitmap(bitmap);
}
}
} catch (IOException e) { /* ignore */
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (stream != null) {
try {
stream.close();
} catch (IOException e) { /* ignore */
}
}
}
return bitmap;
}
/**
* Executes the task.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void execute(Uri uri) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, uri);
} else {
execute(new Uri[] {uri});
}
}
/*
* Scales the bitmap to the preferred width and height.
*
* @param bitmap The bitmap to scale.
* @return The scaled bitmap.
*/
private Bitmap scaleBitmap(Bitmap bitmap) {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
// Calculate deltas.
int dw = width - mPreferredWidth;
int dh = height - mPreferredHeight;
if ((dw == 0) && (dh == 0)) {
return bitmap;
}
float scaleWidth = (float) mPreferredWidth / width;
float scaleHeight = (float) mPreferredHeight / height;
float scaleFactor = Math.min(scaleHeight, scaleWidth);
int finalWidth = (int) ((width * scaleFactor) + 0.5f);
int finalHeight = (int) ((height * scaleFactor) + 0.5f);
return Bitmap.createScaledBitmap(bitmap, finalWidth, finalHeight, false);
}
/**
* Returns the original size of the image.
*/
private Point calculateOriginalDimensions(URL url) {
int inSampleSize = 0;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
options.inSampleSize = inSampleSize;
HttpURLConnection connection = null;
InputStream stream = null;
try {
connection = (HttpURLConnection) url.openConnection();
stream = connection.getInputStream();
BitmapFactory.decodeStream(stream, null, options);
return new Point(options.outWidth, options.outHeight);
} catch (IOException e) {
/* ignore */
} finally {
if (connection != null) {
connection.disconnect();
}
if (stream != null) {
try {
stream.close();
} catch (IOException e) { /* ignore */
}
}
}
return new Point(0, 0);
}
/**
* Find the appropriate in-sample-size (as an inverse power of 2) to help reduce the size of
* downloaded image.
*/
private int calculateInSampleSize(int originalWidth, int originalHeight,
int reqWidth, int reqHeight) {
// Raw height and width of image
int inSampleSize = 1;
if (originalHeight > reqHeight || originalWidth > reqWidth) {
final int halfHeight = originalHeight / 2;
final int halfWidth = originalWidth / 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;
}
}