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.decoders;
michael@0: 
michael@0: import android.graphics.Bitmap;
michael@0: import android.util.Base64;
michael@0: import android.util.Log;
michael@0: 
michael@0: import org.mozilla.gecko.gfx.BitmapUtils;
michael@0: 
michael@0: import java.util.Iterator;
michael@0: import java.util.NoSuchElementException;
michael@0: 
michael@0: /**
michael@0:  * Class providing static utility methods for decoding favicons.
michael@0:  */
michael@0: public class FaviconDecoder {
michael@0:     private static final String LOG_TAG = "GeckoFaviconDecoder";
michael@0: 
michael@0:     static enum ImageMagicNumbers {
michael@0:         // It is irritating that Java bytes are signed...
michael@0:         PNG(new byte[] {(byte) (0x89 & 0xFF), 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a}),
michael@0:         GIF(new byte[] {0x47, 0x49, 0x46, 0x38}),
michael@0:         JPEG(new byte[] {-0x1, -0x28, -0x1, -0x20}),
michael@0:         BMP(new byte[] {0x42, 0x4d}),
michael@0:         WEB(new byte[] {0x57, 0x45, 0x42, 0x50, 0x0a});
michael@0: 
michael@0:         public byte[] value;
michael@0: 
michael@0:         private ImageMagicNumbers(byte[] value) {
michael@0:             this.value = value;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Check for image format magic numbers of formats supported by Android.
michael@0:      * @param buffer Byte buffer to check for magic numbers
michael@0:      * @param offset Offset at which to look for magic numbers.
michael@0:      * @return true if the buffer contains a bitmap decodable by Android (Or at least, a sequence
michael@0:      *         starting with the magic numbers thereof). false otherwise.
michael@0:      */
michael@0:     private static boolean isDecodableByAndroid(byte[] buffer, int offset) {
michael@0:         for (ImageMagicNumbers m : ImageMagicNumbers.values()) {
michael@0:             if (bufferStartsWith(buffer, m.value, offset)) {
michael@0:                 return true;
michael@0:             }
michael@0:         }
michael@0: 
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Utility function to check for the existence of a test byte sequence at a given offset in a
michael@0:      * buffer.
michael@0:      *
michael@0:      * @param buffer Byte buffer to search.
michael@0:      * @param test Byte sequence to search for.
michael@0:      * @param bufferOffset Index in input buffer to expect test sequence.
michael@0:      * @return true if buffer contains the byte sequence given in test at offset bufferOffset, false
michael@0:      *         otherwise.
michael@0:      */
michael@0:     static boolean bufferStartsWith(byte[] buffer, byte[] test, int bufferOffset) {
michael@0:         if (buffer.length < test.length) {
michael@0:             return false;
michael@0:         }
michael@0: 
michael@0:         for (int i = 0; i < test.length; ++i) {
michael@0:             if (buffer[bufferOffset + i] != test[i]) {
michael@0:                 return false;
michael@0:             }
michael@0:         }
michael@0:         return true;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Decode the favicon present in the region of the provided byte[] starting at offset and
michael@0:      * proceeding for length bytes, if any. Returns either the resulting LoadFaviconResult or null if the
michael@0:      * given range does not contain a bitmap we know how to decode.
michael@0:      *
michael@0:      * @param buffer Byte array containing the favicon to decode.
michael@0:      * @param offset The index of the first byte in the array of the region of interest.
michael@0:      * @param length The length of the region in the array to decode.
michael@0:      * @return The decoded version of the bitmap in the described region, or null if none can be
michael@0:      *         decoded.
michael@0:      */
michael@0:     public static LoadFaviconResult decodeFavicon(byte[] buffer, int offset, int length) {
michael@0:         LoadFaviconResult result;
michael@0:         if (isDecodableByAndroid(buffer, offset)) {
michael@0:             result = new LoadFaviconResult();
michael@0:             result.offset = offset;
michael@0:             result.length = length;
michael@0:             result.isICO = false;
michael@0: 
michael@0:             Bitmap decodedImage = BitmapUtils.decodeByteArray(buffer, offset, length);
michael@0:             if (decodedImage == null) {
michael@0:                 // What we got wasn't decodable after all. Probably corrupted image, or we got a muffled OOM.
michael@0:                 return null;
michael@0:             }
michael@0: 
michael@0:             // We assume here that decodeByteArray doesn't hold on to the entire supplied
michael@0:             // buffer -- worst case, each of our buffers will be twice the necessary size.
michael@0:             result.bitmapsDecoded = new SingleBitmapIterator(decodedImage);
michael@0:             result.faviconBytes = buffer;
michael@0: 
michael@0:             return result;
michael@0:         }
michael@0: 
michael@0:         // If it's not decodable by Android, it might be an ICO. Let's try.
michael@0:         ICODecoder decoder = new ICODecoder(buffer, offset, length);
michael@0: 
michael@0:         result = decoder.decode();
michael@0: 
michael@0:         if (result == null) {
michael@0:             return null;
michael@0:         }
michael@0: 
michael@0:         return result;
michael@0:     }
michael@0: 
michael@0:     public static LoadFaviconResult decodeDataURI(String uri) {
michael@0:         if (uri == null) {
michael@0:             Log.w(LOG_TAG, "Can't decode null data: URI.");
michael@0:             return null;
michael@0:         }
michael@0: 
michael@0:         if (!uri.startsWith("data:image/")) {
michael@0:             Log.w(LOG_TAG, "Can't decode non-image data: URI.");
michael@0:             return null;
michael@0:         }
michael@0: 
michael@0:         // Otherwise, let's attack this blindly. Strictly we should be parsing.
michael@0:         int offset = uri.indexOf(',') + 1;
michael@0:         if (offset == 0) {
michael@0:             Log.w(LOG_TAG, "No ',' in data: URI; malformed?");
michael@0:             return null;
michael@0:         }
michael@0: 
michael@0:         try {
michael@0:             String base64 = uri.substring(offset);
michael@0:             byte[] raw = Base64.decode(base64, Base64.DEFAULT);
michael@0:             return decodeFavicon(raw);
michael@0:         } catch (Exception e) {
michael@0:             Log.w(LOG_TAG, "Couldn't decode data: URI.", e);
michael@0:             return null;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     public static LoadFaviconResult decodeFavicon(byte[] buffer) {
michael@0:         return decodeFavicon(buffer, 0, buffer.length);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Returns the smallest bitmap in the icon represented by the provided
michael@0:      * data: URI that's larger than the desired width, or the largest if
michael@0:      * there is no larger icon.
michael@0:      *
michael@0:      * Returns null if no bitmap could be extracted.
michael@0:      *
michael@0:      * Bug 961600: we shouldn't be doing all of this work. The favicon cache
michael@0:      * should be used, and will give us the right size icon.
michael@0:      */
michael@0:     public static Bitmap getMostSuitableBitmapFromDataURI(String iconURI, int desiredWidth) {
michael@0:         LoadFaviconResult result = FaviconDecoder.decodeDataURI(iconURI);
michael@0:         if (result == null) {
michael@0:             // Nothing we can do.
michael@0:             Log.w(LOG_TAG, "Unable to decode icon URI.");
michael@0:             return null;
michael@0:         }
michael@0: 
michael@0:         final Iterator<Bitmap> bitmaps = result.getBitmaps();
michael@0:         if (!bitmaps.hasNext()) {
michael@0:             Log.w(LOG_TAG, "No bitmaps in decoded icon.");
michael@0:             return null;
michael@0:         }
michael@0: 
michael@0:         Bitmap bitmap = bitmaps.next();
michael@0:         if (!bitmaps.hasNext()) {
michael@0:             // We're done! There was only one, so this is as big as it gets.
michael@0:             return bitmap;
michael@0:         }
michael@0: 
michael@0:         // Find a bitmap of the most suitable size.
michael@0:         int currentWidth = bitmap.getWidth();
michael@0:         while ((currentWidth < desiredWidth) &&
michael@0:                bitmaps.hasNext()) {
michael@0:             final Bitmap b = bitmaps.next();
michael@0:             if (b.getWidth() > currentWidth) {
michael@0:                 currentWidth = b.getWidth();
michael@0:                 bitmap = b;
michael@0:             }
michael@0:         }
michael@0: 
michael@0:         return bitmap;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Iterator to hold a single bitmap.
michael@0:      */
michael@0:     static class SingleBitmapIterator implements Iterator<Bitmap> {
michael@0:         private Bitmap bitmap;
michael@0: 
michael@0:         public SingleBitmapIterator(Bitmap b) {
michael@0:             bitmap = b;
michael@0:         }
michael@0: 
michael@0:         /**
michael@0:          * Slightly cheating here - this iterator supports peeking (Handy in a couple of obscure
michael@0:          * places where the runtime type of the Iterator under consideration is known and
michael@0:          * destruction of it is discouraged.
michael@0:          *
michael@0:          * @return The bitmap carried by this SingleBitmapIterator.
michael@0:          */
michael@0:         public Bitmap peek() {
michael@0:             return bitmap;
michael@0:         }
michael@0: 
michael@0:         @Override
michael@0:         public boolean hasNext() {
michael@0:             return bitmap != null;
michael@0:         }
michael@0: 
michael@0:         @Override
michael@0:         public Bitmap next() {
michael@0:             if (bitmap == null) {
michael@0:                 throw new NoSuchElementException("Element already returned from SingleBitmapIterator.");
michael@0:             }
michael@0: 
michael@0:             Bitmap ret = bitmap;
michael@0:             bitmap = null;
michael@0:             return ret;
michael@0:         }
michael@0: 
michael@0:         @Override
michael@0:         public void remove() {
michael@0:             throw new UnsupportedOperationException("remove() not supported on SingleBitmapIterator.");
michael@0:         }
michael@0:     }
michael@0: }