michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.favicons.cache;
michael@0: 
michael@0: import android.graphics.Bitmap;
michael@0: 
michael@0: /**
michael@0:  * Objects stored in the Favicon cache - allow for the bitmap to be tagged to indicate if it has
michael@0:  * been scaled. Unscaled bitmaps are not included in the scaled-bitmap cache's size calculation.
michael@0:  */
michael@0: public class FaviconCacheElement implements Comparable<FaviconCacheElement> {
michael@0:     // Was this Favicon computed via scaling another primary Favicon, or is this a primary Favicon?
michael@0:     final boolean isPrimary;
michael@0: 
michael@0:     // The Favicon bitmap.
michael@0:     Bitmap faviconPayload;
michael@0: 
michael@0:     // If set, faviconPayload is absent. Since the underlying ICO may contain multiple primary
michael@0:     // payloads, primary payloads are never truly deleted from the cache, but instead have their
michael@0:     // payload deleted and this flag set on their FaviconCacheElement. That way, the cache always
michael@0:     // has a record of the existence of a primary payload, even if it is no longer in the cache.
michael@0:     // This means that when a request comes in that will be best served using a primary that is in
michael@0:     // the database but no longer cached, we know that it exists and can go get it (Useful when ICO
michael@0:     // support is added).
michael@0:     volatile boolean invalidated;
michael@0: 
michael@0:     final int imageSize;
michael@0: 
michael@0:     // Used for LRU pruning.
michael@0:     final FaviconsForURL backpointer;
michael@0: 
michael@0:     public FaviconCacheElement(Bitmap payload, boolean primary, int size, FaviconsForURL backpointer) {
michael@0:         this.faviconPayload = payload;
michael@0:         this.isPrimary = primary;
michael@0:         this.imageSize = size;
michael@0:         this.backpointer = backpointer;
michael@0:     }
michael@0: 
michael@0:     public FaviconCacheElement(Bitmap faviconPayload, boolean isPrimary, FaviconsForURL backpointer) {
michael@0:         this.faviconPayload = faviconPayload;
michael@0:         this.isPrimary = isPrimary;
michael@0:         this.backpointer = backpointer;
michael@0: 
michael@0:         if (faviconPayload != null) {
michael@0:             imageSize = faviconPayload.getWidth();
michael@0:         } else {
michael@0:             imageSize = 0;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     public int sizeOf() {
michael@0:         if (invalidated) {
michael@0:             return 0;
michael@0:         }
michael@0:         return faviconPayload.getRowBytes() * faviconPayload.getHeight();
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Establish an ordering on FaviconCacheElements based on size and validity. An element is
michael@0:      * considered "greater than" another if it is valid and the other is not, or if it contains a
michael@0:      * larger payload.
michael@0:      *
michael@0:      * @param another The FaviconCacheElement to compare to this one.
michael@0:      * @return -1 if this element is less than the given one, 1 if the other one is larger than this
michael@0:      *         and 0 if both are of equal value.
michael@0:      */
michael@0:     @Override
michael@0:     public int compareTo(FaviconCacheElement another) {
michael@0:         if (invalidated && !another.invalidated) {
michael@0:             return -1;
michael@0:         }
michael@0: 
michael@0:         if (!invalidated && another.invalidated) {
michael@0:             return 1;
michael@0:         }
michael@0: 
michael@0:         if (invalidated) {
michael@0:             return 0;
michael@0:         }
michael@0: 
michael@0:         final int w1 = imageSize;
michael@0:         final int w2 = another.imageSize;
michael@0:         if (w1 > w2) {
michael@0:             return 1;
michael@0:         } else if (w2 > w1) {
michael@0:             return -1;
michael@0:         }
michael@0:         return 0;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Called when this element is evicted from the cache.
michael@0:      *
michael@0:      * If primary, drop the payload and set invalid. If secondary, just unlink from parent node.
michael@0:      */
michael@0:     public void onEvictedFromCache() {
michael@0:         if (isPrimary) {
michael@0:             // So we keep a record of which primaries exist in the database for this URL, we
michael@0:             // don't actually delete the entry for primaries. Instead, we delete their payload
michael@0:             // and flag them as invalid. This way, we can later figure out that what a request
michael@0:             // really want is one of the primaries that have been dropped from the cache, and we
michael@0:             // can go get it.
michael@0:             invalidated = true;
michael@0:             faviconPayload = null;
michael@0:         } else {
michael@0:             // Secondaries don't matter - just delete them.
michael@0:             if (backpointer == null) {
michael@0:                 return;
michael@0:             }
michael@0:             backpointer.favicons.remove(this);
michael@0:         }
michael@0:     }
michael@0: }