Set minimum and default frame delays.

Fixes #205.

5 files changed, 140 insertions, 9 deletions

diff --git a/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/GifHeaderParserTest.java b/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/GifHeaderParserTest.java
index 0cd0a7af..654b8cef 100644
--- a/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/GifHeaderParserTest.java
+++ b/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/GifHeaderParserTest.java
@@ -79,6 +79,72 @@ public class GifHeaderParserTest {
         assertNotNull(header.frames.get(0));
     }
 
+    private static ByteBuffer writeHeaderWithGceAndFrameDelay(short frameDelay) {
+        final int lzwMinCodeSize = 2;
+        ByteBuffer buffer = ByteBuffer.allocate(
+                GifBytesTestUtil.HEADER_LENGTH
+                + GifBytesTestUtil.GRAPHICS_CONTROL_EXTENSION_LENGTH
+                + GifBytesTestUtil.IMAGE_DESCRIPTOR_LENGTH
+                + GifBytesTestUtil.getImageDataSize(lzwMinCodeSize)
+        ).order(ByteOrder.LITTLE_ENDIAN);
+        GifBytesTestUtil.writeHeaderAndLsd(buffer, 1, 1, false, 0);
+        GifBytesTestUtil.writeGraphicsControlExtension(buffer, frameDelay);
+        GifBytesTestUtil.writeImageDescriptor(buffer, 0, 0, 1, 1, false /*hasLct*/, 0);
+        GifBytesTestUtil.writeFakeImageData(buffer, lzwMinCodeSize);
+        return buffer;
+    }
+
+    @Test
+    public void testCanParseFrameDelay() {
+        final short frameDelay = 50;
+        ByteBuffer buffer = writeHeaderWithGceAndFrameDelay(frameDelay);
+
+        parser.setData(buffer.array());
+        GifHeader header = parser.parseHeader();
+        GifFrame frame = header.frames.get(0);
+
+        // Convert delay in 100ths of a second to ms.
+        assertEquals(frameDelay * 10, frame.delay);
+    }
+
+    @Test
+    public void testSetsDefaultFrameDelayIfFrameDelayIsZero() {
+        ByteBuffer buffer = writeHeaderWithGceAndFrameDelay((short) 0);
+
+        parser.setData(buffer.array());
+        GifHeader header = parser.parseHeader();
+        GifFrame frame = header.frames.get(0);
+
+        // Convert delay in 100ths of a second to ms.
+        assertEquals(GifHeaderParser.DEFAULT_FRAME_DELAY * 10, frame.delay);
+    }
+
+    @Test
+    public void testSetsDefaultFrameDelayIfFrameDelayIsLessThanMinimum() {
+        final short frameDelay = GifHeaderParser.MIN_FRAME_DELAY - 1;
+        ByteBuffer buffer = writeHeaderWithGceAndFrameDelay(frameDelay);
+
+        parser.setData(buffer.array());
+        GifHeader header = parser.parseHeader();
+        GifFrame frame = header.frames.get(0);
+
+        // Convert delay in 100ths of a second to ms.
+        assertEquals(GifHeaderParser.DEFAULT_FRAME_DELAY * 10, frame.delay);
+    }
+
+    @Test
+    public void testObeysFrameDelayIfFrameDelayIsAtMinimum() {
+        final short frameDelay = GifHeaderParser.MIN_FRAME_DELAY;
+        ByteBuffer buffer = writeHeaderWithGceAndFrameDelay(frameDelay);
+
+        parser.setData(buffer.array());
+        GifHeader header = parser.parseHeader();
+        GifFrame frame = header.frames.get(0);
+
+        // Convert delay in 100ths of a second to ms.
+        assertEquals(frameDelay * 10, frame.delay);
+    }
+
     @Test
     public void testSetsFrameLocalColorTableToNullIfNoColorTable() {
         final int lzwMinCodeSize = 2;
diff --git a/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtil.java b/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtil.java
index e389deed..b6f3140e 100644
--- a/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtil.java
+++ b/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtil.java
@@ -10,6 +10,8 @@ public class GifBytesTestUtil {
     public static final int HEADER_LENGTH = 13;
     // Length in bytes.
     public static final int IMAGE_DESCRIPTOR_LENGTH = 10;
+    // Length in bytes.
+    public static final int GRAPHICS_CONTROL_EXTENSION_LENGTH = 8;
 
     public static int getColorTableLength(int numColors) {
         return 3 * numColors;
@@ -104,6 +106,29 @@ public class GifBytesTestUtil {
         out.put((byte) 0);
     }
 
+    public static void writeGraphicsControlExtension(ByteBuffer out, int delayTime) {
+        verifyRemaining(out, GRAPHICS_CONTROL_EXTENSION_LENGTH);
+        verifyShortValues(delayTime);
+
+        // Extension inducer (constant).
+        out.put((byte) 0x21);
+        // Graphic control label (constant).
+        out.put((byte) 0xF9);
+        // Block size (constant).
+        out.put((byte) 0x04);
+        // Packed (disposal method, user input, transparent color flag)
+        out.put((byte) 0x00);
+
+        // Frame delay in 100ths of a second.
+        out.putShort((short) delayTime);
+
+        // Transparent color index.
+        out.put((byte) 0x00);
+
+        // Block terminator (constant).
+        out.put((byte) 0x00);
+    }
+
     private static void verifyRemaining(ByteBuffer buffer, int expected) {
         if (buffer.remaining() < expected) {
             throw new IllegalArgumentException("Must have at least " + expected + " bytes to write");
diff --git a/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtilTest.java b/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtilTest.java
index 88106ea6..b393265f 100644
--- a/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtilTest.java
+++ b/third_party/gif_decoder/src/androidTest/java/com/bumptech/glide/gifdecoder/test/GifBytesTestUtilTest.java
@@ -19,7 +19,7 @@ public class GifBytesTestUtilTest {
 
         byte[] expected = new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x00, 0x08, 0x00, 0x10, 0x20, 0x00, 0x00};
 
-        assertArrayEquals(expected, buffer.array());
+        assertEquals(expected, buffer);
     }
 
     @Test
@@ -30,7 +30,7 @@ public class GifBytesTestUtilTest {
         byte[] expected = new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x00, 0x08, 0x00, 0x10, (byte) 0xA4, 0x00,
                 0x00};
 
-        assertArrayEquals(expected, buffer.array());
+        assertEquals(expected, buffer);
     }
 
     @Test
@@ -53,7 +53,7 @@ public class GifBytesTestUtilTest {
                 0x00
         };
 
-        assertArrayEquals(expected, buffer.array());
+        assertEquals(expected, buffer);
     }
 
     @Test
@@ -81,7 +81,7 @@ public class GifBytesTestUtilTest {
                 packedField
         };
 
-        assertArrayEquals(expected, buffer.array());
+        assertEquals(expected, buffer);
     }
 
     @Test
@@ -102,8 +102,7 @@ public class GifBytesTestUtilTest {
         };
 
 
-        assertArrayEquals("expected=" + Arrays.toString(expected) + " received=" + Arrays.toString(buffer.array()),
-                expected, buffer.array());
+        assertEquals(expected, buffer);
     }
 
     @Test
@@ -113,6 +112,37 @@ public class GifBytesTestUtilTest {
 
         byte[] expected = new byte[] { 0x02, 0x01, 0x01, 0x00 };
 
-        assertArrayEquals(expected, buffer.array());
+        assertEquals(expected, buffer);
+    }
+
+    @Test
+    public void testWritesGraphicsControlExtension() {
+        short delay = 20;
+        ByteBuffer buffer = ByteBuffer.allocate(GifBytesTestUtil.GRAPHICS_CONTROL_EXTENSION_LENGTH);
+        byte[] expected = new byte[] {
+                // Extension inducer.
+                0x21,
+                // Graphic control label.
+                (byte) 0xF9,
+                // Block size.
+                0x04,
+                // Packed byte.
+                0x00,
+                // Frame delay.
+                0x00,
+                0x14,
+                // Transparent color index.
+                0x00,
+                // block terminator.
+                0x00
+        };
+
+        GifBytesTestUtil.writeGraphicsControlExtension(buffer, delay);
+        assertEquals(expected, buffer);
+    }
+
+    private static void assertEquals(byte[] expected, ByteBuffer buffer) {
+        assertArrayEquals("expected=" + Arrays.toString(expected) + " received=" + Arrays.toString(buffer.array()),
+                expected, buffer.array());
     }
 }
diff --git a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java
index 92dc3bfc..ac634ca6 100644
--- a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java
+++ b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java
@@ -202,7 +202,7 @@ public class GifDecoder {
     }
 
     /**
-     * Gets display duration for the upcoming frame.
+     * Gets display duration for the upcoming frame in ms.
      */
     public int getNextDelay() {
         if (header.frameCount <= 0 || framePointer < 0) {
diff --git a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java
index 286a5602..126a799c 100644
--- a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java
+++ b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java
@@ -16,6 +16,11 @@ import static com.bumptech.glide.gifdecoder.GifDecoder.STATUS_FORMAT_ERROR;
 public class GifHeaderParser {
     public static final String TAG = "GifHeaderParser";
 
+    // The minimum frame delay in hundredths of a second.
+    static final int MIN_FRAME_DELAY = 3;
+    // The default frame delay in hundredths of a second for GIFs with frame delays less than the minimum.
+    static final int DEFAULT_FRAME_DELAY = 10;
+
     private static final int MAX_BLOCK_SIZE = 256;
     // Raw data read working array.
     private final byte[] block = new byte[MAX_BLOCK_SIZE];
@@ -147,7 +152,12 @@ public class GifHeaderParser {
         }
         header.currentFrame.transparency = (packed & 1) != 0;
         // Delay in milliseconds.
-        header.currentFrame.delay = readShort() * 10;
+        int delayInHundredthsOfASecond = readShort();
+        // TODO: consider allowing -1 to indicate show forever.
+        if (delayInHundredthsOfASecond < MIN_FRAME_DELAY) {
+            delayInHundredthsOfASecond = DEFAULT_FRAME_DELAY;
+        }
+        header.currentFrame.delay = delayInHundredthsOfASecond * 10;
         // Transparent color index
         header.currentFrame.transIndex = read();
         // Block terminator