Reduce instantiations.

Author: Yuncong Zhang

Runtime/ui/painting/codec_gif.cs

@@ -26,6 +26,8 @@ public class FrameData {
         volatile Texture2D _texture;
         volatile FrameData _frameData;
         volatile Image _image;
+        volatile GifDecoder _decoder;
+        volatile MemoryStream _stream;
         IEnumerator _coroutine;
 
         public GifCodec(byte[] bytes) {
@@ -38,59 +40,51 @@ public GifCodec(byte[] bytes) {
             this._frameIndex = 0;
             this._bytes = bytes;
             this._coroutine = this._startDecoding();
-            this._init();
-            this._texture = new Texture2D(this._width, this._height, TextureFormat.BGRA32, false);
-            this._texture.hideFlags = HideFlags.HideAndDontSave;
-            this._image = new Image(this._texture);
+            this._decoder = new GifDecoder();
+            this._stream = new MemoryStream(this._bytes);
+            this._frameData = new FrameData() {
+                frameInfo = new FrameInfo()
+            };
         }
 
-        void _init() {
-            var bytesStream = new MemoryStream(this._bytes);
+        IEnumerator _startDecoding() {
+            this._stream.Seek(0, SeekOrigin.Begin);
 
-            var gifDecoder = new GifDecoder();
-            if (gifDecoder.read(bytesStream) != GifDecoder.STATUS_OK) {
+            if (this._decoder.read(this._stream) != GifDecoder.STATUS_OK) {
                 throw new Exception("Failed to decode gif.");
             }
 
-            this._width = gifDecoder.frameWidth;
-            this._height = gifDecoder.frameHeight;
-        }
-
-        IEnumerator _startDecoding() {
-            var bytesStream = new MemoryStream(this._bytes);
+            this._width = this._decoder.frameWidth;
+            this._height = this._decoder.frameHeight;
 
-            var gifDecoder = new GifDecoder();
-            if (gifDecoder.read(bytesStream) != GifDecoder.STATUS_OK) {
-                throw new Exception("Failed to decode gif.");
+            if (this._texture == null) {
+                this._texture = new Texture2D(this._width, this._height, TextureFormat.BGRA32, false);
+                this._texture.hideFlags = HideFlags.HideAndDontSave;
+                this._image = new Image(this._texture);
+                this._frameData.frameInfo.image = this._image;
             }
-
-            this._width = gifDecoder.frameWidth;
-            this._height = gifDecoder.frameHeight;
+            this._frameData.gifFrame = this._decoder.currentFrame;
+            D.assert(this._frameData.gifFrame != null);
 
             int i = 0;
             while (true) {
-                if (gifDecoder.nextFrame() != GifDecoder.STATUS_OK) {
+                if (this._decoder.nextFrame() != GifDecoder.STATUS_OK) {
                     throw new Exception("Failed to decode gif.");
                 }
 
-                if (gifDecoder.done) {
+                if (this._decoder.done) {
                     break;
                 }
 
-                var frameData = new FrameData {
-                    gifFrame = gifDecoder.currentFrame
-                };
-
-                this._frameData = frameData;
 
                 i++;
 
                 yield return null;
             }
 
-            D.assert(gifDecoder.frameCount == i);
-            this._frameCount = gifDecoder.frameCount;
-            this._repetitionCount = gifDecoder.loopCount;
+            D.assert(this._decoder.frameCount == i);
+            this._frameCount = this._decoder.frameCount;
+            this._repetitionCount = this._decoder.loopCount;
             this._isDone = true;
         }
 
@@ -120,10 +114,7 @@ public FrameInfo getNextFrame() {
             this._nextFrame();
             this._texture.LoadRawTextureData(this._frameData.gifFrame.bytes);
             this._texture.Apply();
-            this._frameData.frameInfo = new FrameInfo() {
-                image = this._image,
-                duration = TimeSpan.FromMilliseconds(this._frameData.gifFrame.delay)
-            };
+            this._frameData.frameInfo.duration = TimeSpan.FromMilliseconds(this._frameData.gifFrame.delay);
             return this._frameData.frameInfo;
         }