From b1296f2c97c6fdc1c6a9922dc09c951b5cafdc12 Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Mon, 29 Oct 2018 21:49:54 +0100
Subject: Initial commit

---
 src/Gif.cpp | 189 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 189 insertions(+)
 create mode 100644 src/Gif.cpp

(limited to 'src/Gif.cpp')

diff --git a/src/Gif.cpp b/src/Gif.cpp
new file mode 100644
index 0000000..0c52f7d
--- /dev/null
+++ b/src/Gif.cpp
@@ -0,0 +1,189 @@
+#include "../include/dchat/Gif.hpp"
+#include "../include/FileUtil.hpp"
+
+using namespace std;
+
+namespace dchat
+{
+    static void* bitmapCreate(int width, int height)
+    {
+        return calloc(width * height, 4);
+    }
+    
+    static void bitmapDestroy(void *bitmap)
+    {
+        free(bitmap);
+    }
+    
+    static unsigned char* bitmapGetBuffer(void *bitmap)
+    {
+        return (unsigned char*)bitmap;
+    }
+    
+    static void bitmapSetOpaque(void *bitmap, bool opaque)
+    {
+        
+    }
+    
+    static bool bitmapTestOpaque(void *bitmap)
+    {
+        return false;
+    }
+    
+    static void bitmapModified(void *bitmap)
+    {
+        
+    }
+    
+    static const char* gifResultToString(gif_result code)
+    {
+        switch(code)
+        {
+            case GIF_INSUFFICIENT_FRAME_DATA:
+                return "GIF_INSUFFICIENT_FRAME_DATA";
+            case GIF_FRAME_DATA_ERROR:
+                return "GIF_FRAME_DATA_ERROR";
+            case GIF_INSUFFICIENT_DATA:
+                return "GIF_INSUFFICIENT_DATA";
+            case GIF_DATA_ERROR:
+                return "GIF_DATA_ERROR";
+            case GIF_INSUFFICIENT_MEMORY:
+                return "GIF_INSUFFICIENT_MEMORY";
+            default:
+                return "Unknown gif result code";
+        }
+    }
+    
+    Gif::Gif(const boost::filesystem::path &filepath) : 
+        currentFrame(0),
+        timeElapsedCs(0.0)
+    {
+        try
+        {
+            fileContent = getFileContent(filepath);
+        }
+        catch(FileException &e)
+        {
+            throw GifLoadException(e.what());
+        }
+        
+        try
+        {
+            init();
+        }
+        catch(GifLoadException &e)
+        {
+            delete[] fileContent.data;
+            throw e;
+        }
+    }
+    
+    Gif::Gif(StringView _fileContent) : 
+        fileContent(move(_fileContent)),
+        currentFrame(0),
+        timeElapsedCs(0.0)
+    {
+        try
+        {
+            init();
+        }
+        catch(GifLoadException &e)
+        {
+            delete[] fileContent.data;
+            throw e;
+        }
+    }
+    
+    void Gif::init()
+    {
+        gif_bitmap_callback_vt bitmapCallbacks = 
+        {
+            bitmapCreate,
+            bitmapDestroy,
+            bitmapGetBuffer,
+            bitmapSetOpaque,
+            bitmapTestOpaque,
+            bitmapModified
+        };
+        
+        gif_create(&gif, &bitmapCallbacks);
+        
+        gif_result code;
+        do
+        {
+            code = gif_initialise(&gif, fileContent.size, (unsigned char*)fileContent.data);
+            if(code != GIF_OK && code != GIF_WORKING)
+            {
+                string errMsg = "Failed to initialize gif, reason: ";
+                errMsg += gifResultToString(code);
+                throw GifLoadException(errMsg);
+            }
+        }
+        while(code != GIF_OK);
+        
+        if(!createTexture(gif.width, gif.height))
+            throw GifLoadException("Failed to create texture for gif");
+    }
+    
+    Gif::~Gif()
+    {
+        gif_finalise(&gif);
+        delete[] fileContent.data;
+    }
+    
+    Vec2u Gif::getSize() const
+    {
+        return { gif.width, gif.height };
+    }
+    
+    void Gif::update()
+    {
+        double timeElapsedMilli = (double)frameTimer.getElapsedTimeMillis();
+        // If gif is not redrawn for a while, then we reset timer (gif is paused). This happens when gif is not visible and then appears visible
+        // (because it's visible in window). The reason this is done is to prevent too much time between rendering gif frames, as processing a gif
+        // requires to process all frames between two points in time, if elapsed frame time is too high, then we would require to process several
+        // frames of gif in one application render frame.
+        if(timeElapsedMilli > 1000.0)
+            timeElapsedMilli = 0.0;
+        double frameDeltaCs = timeElapsedMilli * 0.1; // Centisecond
+        frameTimer.restart();
+        timeElapsedCs += frameDeltaCs;
+        
+        unsigned char *image = nullptr;
+        u32 startFrame = currentFrame;
+        while(true)
+        {
+            u32 i = currentFrame % gif.frame_count;
+            gif_result code = gif_decode_frame(&gif, i);
+            if(code != GIF_OK)
+            {
+                printf("Warning: gif_decode_frame: %s\n", gifResultToString(code));
+                break;
+            }
+            
+            gif_frame &frame = gif.frames[i];
+            // frame_delay is in centiseconds
+            unsigned int frameDelay = frame.frame_delay;
+            if(frameDelay == 0)
+                frameDelay = 7;
+            double fFrameDelay = (double)frameDelay;
+            if(timeElapsedCs >= fFrameDelay)
+                timeElapsedCs -= fFrameDelay;
+            else
+                break;
+            
+            image = (unsigned char*)gif.frame_image;
+            ++currentFrame;
+        }
+        
+        if(currentFrame != startFrame)
+        {
+            updateTexture(image);
+        }
+    }
+    
+    bool Gif::isDataGif(const StringView &data)
+    {
+        return data.size >= 6 && (memcmp(data.data, "GIF87a", 6) == 0 || memcmp(data.data, "GIF89a", 6) == 0);
+    }
+}
-- 
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