Introduce Animated Logo to Chrome on Android

third_party/gif_player/src/jp/tomorrowkey/android/gifplayer/BaseGifImage.java

+/*
+ * Copyright (C) 2015 The Gifplayer Authors. 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
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 jp.tomorrowkey.android.gifplayer;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+
+/**
+ * A base wrapper for GIF image data.
+ */
+public class BaseGifImage {
+    private final byte[] mData;
+    private final int mOffset;
+    private int mWidth;
+    private int mHeight;
+
+    private static final byte[] sColorTableBuffer = new byte[256 * 3];
+
+    int mHeaderSize;
+    boolean mGlobalColorTableUsed;
+    boolean mError;
+    int[] mGlobalColorTable = new int[256];
+    int mGlobalColorTableSize;
+    int mBackgroundColor;
+    int mBackgroundIndex;
+
+    public BaseGifImage(byte[] data) {
+        this(data, 0);
+    }
+
+    /**
+     * Unlike the desktop JVM, ByteBuffers created with allocateDirect() can (and since froyo, do)
+     * provide a backing array, enabling zero-copy interop with native code. However, they are
+     * aligned on a byte boundary, meaning that they often have an arrayOffset as well - in those
+     * cases, we can avoid allocating large byte arrays and a copy.
+     */
+    public BaseGifImage(ByteBuffer data) {
+        this(bufferToArray(data), bufferToOffset(data));
+    }
+
+    private static int bufferToOffset(ByteBuffer buffer) {
+        return buffer.hasArray() ? buffer.arrayOffset() : 0;
+    }
+
+    private static byte[] bufferToArray(ByteBuffer buffer) {
+        if (buffer.hasArray()) {
+            return buffer.array();
+        } else {
+            int position = buffer.position();
+            try {
+                byte[] newData = new byte[buffer.capacity()];
+                buffer.get(newData);
+                return newData;
+            } finally {
+                buffer.position(position);
+            }
+        }
+    }
+
+    public BaseGifImage(byte[] data, int offset) {
+        mData = data;
+        mOffset = offset;
+
+        GifHeaderStream stream = new GifHeaderStream(data);
+        stream.skip(offset);
+        try {
+            readHeader(stream);
+            mHeaderSize = stream.getPosition();
+        } catch (IOException e) {
+            mError = true;
+        }
+
+        try {
+            stream.close();
+        } catch (IOException e) {
+            // Ignore
+        }
+    }
+
+    public byte[] getData() {
+        return mData;
+    }
+
+    public int getDataOffset() {
+        return mOffset;
+    }
+
+    public int getWidth() {
+        return mWidth;
+    }
+
+    public int getHeight() {
+        return mHeight;
+    }
+
+    /**
+     * Returns an estimate of the size of the object in bytes.
+     */
+    public int getSizeEstimate() {
+        return mData.length + mGlobalColorTable.length * 4;
+    }
+
+    /**
+     * Reads GIF file header information.
+     */
+    private void readHeader(InputStream stream) throws IOException {
+        boolean valid = stream.read() == 'G';
+        valid = valid && stream.read() == 'I';
+        valid = valid && stream.read() == 'F';
+        if (!valid) {
+            mError = true;
+            return;
+        }
+
+        // Skip the next three letter, which represent the variation of the GIF standard.
+        stream.skip(3);
+
+        readLogicalScreenDescriptor(stream);
+
+        if (mGlobalColorTableUsed && !mError) {
+            readColorTable(stream, mGlobalColorTable, mGlobalColorTableSize);
+            mBackgroundColor = mGlobalColorTable[mBackgroundIndex];
+        }
+    }
+
+    /**
+     * Reads Logical Screen Descriptor
+     */
+    private void readLogicalScreenDescriptor(InputStream stream) throws IOException {
+        // logical screen size
+        mWidth = readShort(stream);
+        mHeight = readShort(stream);
+        // packed fields
+        int packed = stream.read();
+        mGlobalColorTableUsed = (packed & 0x80) != 0; // 1 : global color table flag
+        // 2-4 : color resolution - ignore
+        // 5 : gct sort flag - ignore
+        mGlobalColorTableSize = 2 << (packed & 7); // 6-8 : gct size
+        mBackgroundIndex = stream.read();
+        stream.skip(1); // pixel aspect ratio - ignore
+    }
+
+    /**
+     * Reads color table as 256 RGB integer values
+     *
+     * @param ncolors int number of colors to read
+     */
+    static boolean readColorTable(InputStream stream, int[] colorTable, int ncolors)
+            throws IOException {
+        synchronized (sColorTableBuffer) {
+            int nbytes = 3 * ncolors;
+            int n = stream.read(sColorTableBuffer, 0, nbytes);
+            if (n < nbytes) {
+                return false;
+            } else {
+                int i = 0;
+                int j = 0;
+                while (i < ncolors) {
+                    int r = sColorTableBuffer[j++] & 0xff;
+                    int g = sColorTableBuffer[j++] & 0xff;
+                    int b = sColorTableBuffer[j++] & 0xff;
+                    colorTable[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
+                }
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Reads next 16-bit value, LSB first
+     */
+    private int readShort(InputStream stream) throws IOException {
+        // read 16-bit value, LSB first
+        return stream.read() | (stream.read() << 8);
+    }
+
+    private final class GifHeaderStream extends ByteArrayInputStream {
+
+        private GifHeaderStream(byte[] buf) {
+            super(buf);
+        }
+
+        public int getPosition() {
+            return pos;
+        }
+    }
+}