package com.android.volley.toolbox;import com.android.volley.DefaultRetryPolicy;
import com.android.volley.NetworkResponse;
import com.android.volley.ParseError;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyLog;import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.widget.ImageView.ScaleType;/*** A canned request for getting an image at a given URL and calling* back with a decoded Bitmap.*/
public class ImageRequest extends Request<Bitmap> {/** Socket timeout in milliseconds for image requests */private static final int IMAGE_TIMEOUT_MS = 1000;/** Default number of retries for image requests */private static final int IMAGE_MAX_RETRIES = 2;/** Default backoff multiplier for image requests */private static final float IMAGE_BACKOFF_MULT = 2f;private final Response.Listener<Bitmap> mListener;private final Config mDecodeConfig;private final int mMaxWidth;private final int mMaxHeight;private ScaleType mScaleType;/** Decoding lock so that we don't decode more than one image at a time (to avoid OOM's) */private static final Object sDecodeLock = new Object();/*** Creates a new image request, decoding to a maximum specified width and* height. If both width and height are zero, the image will be decoded to* its natural size. If one of the two is nonzero, that dimension will be* clamped and the other one will be set to preserve the image's aspect* ratio. If both width and height are nonzero, the image will be decoded to* be fit in the rectangle of dimensions width x height while keeping its* aspect ratio.** [[@param](http://my.oschina.net/u/2303379)](http://my.oschina.net/u/2303379) url URL of the image* [[@param](http://my.oschina.net/u/2303379)](http://my.oschina.net/u/2303379) listener Listener to receive the decoded bitmap* [[@param](http://my.oschina.net/u/2303379)](http://my.oschina.net/u/2303379) maxWidth Maximum width to decode this bitmap to, or zero for none* [[@param](http://my.oschina.net/u/2303379)](http://my.oschina.net/u/2303379) maxHeight Maximum height to decode this bitmap to, or zero for* none* [[@param](http://my.oschina.net/u/2303379)](http://my.oschina.net/u/2303379) scaleType The ImageViews ScaleType used to calculate the needed image size.* @param decodeConfig Format to decode the bitmap to* @param errorListener Error listener, or null to ignore errors*/public ImageRequest(String url, Response.Listener<Bitmap> listener, int maxWidth, int maxHeight,ScaleType scaleType, Config decodeConfig, Response.ErrorListener errorListener) {super(Method.GET, url, errorListener); setRetryPolicy(new DefaultRetryPolicy(IMAGE_TIMEOUT_MS, IMAGE_MAX_RETRIES, IMAGE_BACKOFF_MULT));mListener = listener;mDecodeConfig = decodeConfig;mMaxWidth = maxWidth;mMaxHeight = maxHeight;mScaleType = scaleType;}/*** For API compatibility with the pre-ScaleType variant of the constructor. Equivalent to* the normal constructor with {@code ScaleType.CENTER_INSIDE}.*/@Deprecatedpublic ImageRequest(String url, Response.Listener<Bitmap> listener, int maxWidth, int maxHeight,Config decodeConfig, Response.ErrorListener errorListener) {this(url, listener, maxWidth, maxHeight,ScaleType.CENTER_INSIDE, decodeConfig, errorListener);}@Overridepublic Priority getPriority() {return Priority.LOW;}/*** Scales one side of a rectangle to fit aspect ratio.** @param maxPrimary Maximum size of the primary dimension (i.e. width for* max width), or zero to maintain aspect ratio with secondary* dimension* @param maxSecondary Maximum size of the secondary dimension, or zero to* maintain aspect ratio with primary dimension* @param actualPrimary Actual size of the primary dimension* @param actualSecondary Actual size of the secondary dimension* @param scaleType The ScaleType used to calculate the needed image size.*/private static int getResizedDimension(int maxPrimary, int maxSecondary, int actualPrimary,int actualSecondary, ScaleType scaleType) {// If no dominant value at all, just return the actual.if ((maxPrimary == 0) && (maxSecondary == 0)) {return actualPrimary;}// If ScaleType.FIT_XY fill the whole rectangle, ignore ratio.if (scaleType == ScaleType.FIT_XY) {if (maxPrimary == 0) {return actualPrimary;}return maxPrimary;}// If primary is unspecified, scale primary to match secondary's scaling ratio.if (maxPrimary == 0) {double ratio = (double) maxSecondary / (double) actualSecondary;return (int) (actualPrimary * ratio);}if (maxSecondary == 0) {return maxPrimary;}double ratio = (double) actualSecondary / (double) actualPrimary;int resized = maxPrimary;// If ScaleType.CENTER_CROP fill the whole rectangle, preserve aspect ratio.if (scaleType == ScaleType.CENTER_CROP) {if ((resized * ratio) < maxSecondary) {resized = (int) (maxSecondary / ratio);}return resized;}if ((resized * ratio) > maxSecondary) {resized = (int) (maxSecondary / ratio);}return resized;}@Overrideprotected Response<Bitmap> parseNetworkResponse(NetworkResponse response) {// Serialize all decode on a global lock to reduce concurrent heap usage.synchronized (sDecodeLock) {try {return doParse(response);} catch (OutOfMemoryError e) {VolleyLog.e("Caught OOM for %d byte image, url=%s", response.data.length, getUrl());return Response.error(new ParseError(e));}}}/*** The real guts of parseNetworkResponse. Broken out for readability.*/private Response<Bitmap> doParse(NetworkResponse response) {byte[] data = response.data;BitmapFactory.Options decodeOptions = new BitmapFactory.Options();Bitmap bitmap = null;if (mMaxWidth == 0 && mMaxHeight == 0) {decodeOptions.inPreferredConfig = mDecodeConfig;bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);} else {// If we have to resize this image, first get the natural bounds.decodeOptions.inJustDecodeBounds = true;BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);int actualWidth = decodeOptions.outWidth;int actualHeight = decodeOptions.outHeight;// Then compute the dimensions we would ideally like to decode to.int desiredWidth = getResizedDimension(mMaxWidth, mMaxHeight,actualWidth, actualHeight, mScaleType);int desiredHeight = getResizedDimension(mMaxHeight, mMaxWidth,actualHeight, actualWidth, mScaleType);// Decode to the nearest power of two scaling factor.decodeOptions.inJustDecodeBounds = false;// TODO(ficus): Do we need this or is it okay since API 8 doesn't support it?// decodeOptions.inPreferQualityOverSpeed = PREFER_QUALITY_OVER_SPEED;decodeOptions.inSampleSize =findBestSampleSize(actualWidth, actualHeight, desiredWidth, desiredHeight);Bitmap tempBitmap =BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);// If necessary, scale down to the maximal acceptable size.if (tempBitmap != null && (tempBitmap.getWidth() > desiredWidth ||tempBitmap.getHeight() > desiredHeight)) {bitmap = Bitmap.createScaledBitmap(tempBitmap,desiredWidth, desiredHeight, true);tempBitmap.recycle();} else {bitmap = tempBitmap;}}if (bitmap == null) {return Response.error(new ParseError(response));} else {return Response.success(bitmap, HttpHeaderParser.parseCacheHeaders(response));}}@Overrideprotected void deliverResponse(Bitmap response) {mListener.onResponse(response);}/*** Returns the largest power-of-two divisor for use in downscaling a bitmap* that will not result in the scaling past the desired dimensions.** @param actualWidth Actual width of the bitmap* @param actualHeight Actual height of the bitmap* @param desiredWidth Desired width of the bitmap* @param desiredHeight Desired height of the bitmap*/// Visible for testing.static int findBestSampleSize(int actualWidth, int actualHeight, int desiredWidth, int desiredHeight) {double wr = (double) actualWidth / desiredWidth;double hr = (double) actualHeight / desiredHeight;double ratio = Math.min(wr, hr);float n = 1.0f;while ((n * 2) <= ratio) {n *= 2;}return (int) n;}
}
