Add gif-h helper to create screen capture

Press key `I` (shift+`i`) to start a screen capture creating a gif with
the captured screen. Hit `I` again to stop the screen recording.

---

Add gif-h helper header only library

Copied from https://github.com/charlietangora/gif-h

charlietangora/gif-h@3d2657b

Author: NeroBurner

CMakeLists.txt

@@ -286,4 +286,6 @@ if(WITH_PNG)
   target_link_libraries(infinisim PRIVATE png_static)
 endif()
 
+target_include_directories(infinisim PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/gif-h")
+
 install(TARGETS infinisim DESTINATION bin)

README.md

@@ -112,6 +112,7 @@ Using the keyboard the following events can be triggered:
 - `h` ... set heartrate running, and on further presses increase by 10 bpm
 - `H` ... stop heartrate
 - `i` ... take screenshot
+- `I` ... start/stop Gif scren capture
 
 ## Licenses
 

gif-h/LICENSE

@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org>

gif-h/README.md

@@ -0,0 +1,45 @@
+gif-h
+=====
+
+This one-header library offers a simple, very limited way to create animated GIFs directly in code.
+Those looking for particular cleverness are likely to be disappointed; it's pretty much a straight-ahead
+implementation of the GIF format with optional Floyd-Steinberg dithering. (It does at least use delta
+encoding - only the changed portions of each frame are saved.) 
+
+So resulting files are often quite large. The hope is that it will be handy nonetheless as a quick and easily-integrated way for programs to spit out animations.
+
+Only RGBA8 is currently supported as an input format. (The alpha is ignored.) 
+
+Email me : ctangora -at- gmail -dot- com
+
+Usage:
+-------------------
+Create a GifWriter struct. 
+
+Pass the struct to GifBegin() to initialize values and write the file header.
+
+Pass frames of the animation to GifWriteFrame().
+
+Finally, call GifEnd() to close the file handle and free memory.
+
+	#include <vector>
+	#include <cstdint>
+	#include <gif.h>
+	int main()
+	{
+		int width = 100;
+		int height = 200;
+		std::vector<uint8_t> black(width * height * 4, 0);
+		std::vector<uint8_t> white(width * height * 4, 255);
+
+		auto fileName = "bwgif.gif";
+		int delay = 100;
+		GifWriter g;
+		GifBegin(&g, fileName, width, height, delay);
+		GifWriteFrame(&g, black.data(), width, height, delay);
+		GifWriteFrame(&g, white.data(), width, height, delay);
+		GifEnd(&g);
+
+		return 0;
+	}
+

gif-h/gif-h-demo.cpp

@@ -0,0 +1,80 @@
+//
+// gif-h-demo.cpp
+// by Charlie Tangora
+// Public domain.
+// Email me : ctangora -at- gmail -dot- com
+//
+// Shows an example usage of gif.h
+//
+
+#include "gif.h"
+
+#include <math.h>
+
+const int width = 256;
+const int height = 256;
+uint8_t image[ width * height * 4 ];
+
+void SetPixel( int xx, int yy, uint8_t red, uint8_t grn, uint8_t blu )
+{
+    uint8_t* pixel = &image[(yy*width+xx)*4];
+    pixel[0] = red;
+    pixel[1] = blu;
+    pixel[2] = grn;
+    pixel[3] = 255;  // no alpha for this demo
+}
+
+void SetPixelFloat( int xx, int yy, float fred, float fgrn, float fblu )
+{
+    // convert float to unorm
+    uint8_t red = (uint8_t)roundf( 255.0f * fred );
+    uint8_t grn = (uint8_t)roundf( 255.0f * fgrn );
+    uint8_t blu = (uint8_t)roundf( 255.0f * fblu );
+    
+    SetPixel( xx, yy, red, grn, blu );
+}
+
+int main(int argc, const char * argv[])
+{
+    const char* filename = "./MyGif.gif";
+    if( argc > 1 )
+    {
+        filename = argv[1];
+    }
+    
+    // Create a gif
+    GifWriter writer = {};
+    GifBegin( &writer, filename, width, height, 2, 8, true );
+    
+    for( int frame=0; frame<256; ++frame )
+    {
+        
+        // Make an image, somehow
+        // this is the default shadertoy - credit to shadertoy.com
+        float tt = frame * 3.14159f * 2 / 255.0f;
+        for( int yy=0; yy<height; ++yy )
+        {
+            for( int xx=0; xx<width; ++xx )
+            {
+                float fx = xx / (float)width;
+                float fy = yy / (float)height;
+                
+                float red = 0.5f + 0.5f * cosf(tt+fx);
+                float grn = 0.5f + 0.5f * cosf(tt+fy+2.f);
+                float blu = 0.5f + 0.5f * cosf(tt+fx+4.f);
+                
+                SetPixelFloat( xx, yy, red, grn, blu );
+            }
+        }
+        
+        
+        // Write the frame to the gif
+        printf( "Writing frame %d...\n", frame );
+        GifWriteFrame( &writer, image, width, height, 2, 8, true );
+    }
+    
+    // Write EOF
+    GifEnd( &writer );
+    
+    return 0;
+}