1 files changed, 65 insertions, 0 deletions
diff --git a/image/decoders/GIF2.h b/image/decoders/GIF2.h
new file mode 100644
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+++ b/image/decoders/GIF2.h
@@ -0,0 +1,65 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_image_decoders_GIF2_H
+#define mozilla_image_decoders_GIF2_H
+
+#define MAX_LZW_BITS          12
+#define MAX_BITS            4097 // 2^MAX_LZW_BITS+1
+#define MAX_COLORS           256
+#define MIN_HOLD_SIZE        256
+
+enum { GIF_TRAILER                     = 0x3B }; // ';'
+enum { GIF_IMAGE_SEPARATOR             = 0x2C }; // ','
+enum { GIF_EXTENSION_INTRODUCER        = 0x21 }; // '!'
+enum { GIF_GRAPHIC_CONTROL_LABEL       = 0xF9 };
+enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF };
+
+// A GIF decoder's state
+typedef struct gif_struct {
+    // LZW decoder state machine
+    uint8_t* stackp;            // Current stack pointer
+    int datasize;
+    int codesize;
+    int codemask;
+    int avail;                  // Index of next available slot in dictionary
+    int oldcode;
+    uint8_t firstchar;
+    int bits;                   // Number of unread bits in "datum"
+    int32_t datum;              // 32-bit input buffer
+
+    // Output state machine
+    int64_t pixels_remaining;  // Pixels remaining to be output.
+
+    // Parameters for image frame currently being decoded
+    int tpixel;                 // Index of transparent pixel
+    int32_t disposal_method;    // Restore to background, leave in place, etc.
+    uint32_t* local_colormap;   // Per-image colormap
+    int local_colormap_size;    // Size of local colormap array.
+    uint32_t delay_time;        // Display time, in milliseconds,
+                                // for this image in a multi-image GIF
+
+    // Global (multi-image) state
+    int version;                // Either 89 for GIF89 or 87 for GIF87
+    int32_t screen_width;       // Logical screen width & height
+    int32_t screen_height;
+    uint8_t global_colormap_depth; // Depth of global colormap array
+    uint16_t global_colormap_count; // Number of colors in global colormap
+    int images_decoded;         // Counts images for multi-part GIFs
+    int loop_count;             // Netscape specific extension block to control
+                                // the number of animation loops a GIF
+                                // renders.
+
+    bool is_transparent;        // TRUE, if tpixel is valid
+
+    uint16_t  prefix[MAX_BITS];            // LZW decoding tables
+    uint32_t  global_colormap[MAX_COLORS]; // Default colormap if local not
+                                           //   supplied
+    uint8_t   suffix[MAX_BITS];            // LZW decoding tables
+    uint8_t   stack[MAX_BITS];             // Base of LZW decoder stack
+
+} gif_struct;
+
+#endif // mozilla_image_decoders_GIF2_H