From 2320c2febf50c76f0bc45b2d24ac455d6d7fbd79 Mon Sep 17 00:00:00 2001
From: Ray <raysan5@gmail.com>
Date: Mon, 8 Oct 2018 18:57:33 +0200
Subject: [PATCH] ADDED: ImageExtractPalette()

---
 src/raylib.h   |  1 +
 src/textures.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/src/raylib.h b/src/raylib.h
index 6549ba1d9..2bc37906d 100644
--- a/src/raylib.h
+++ b/src/raylib.h
@@ -1024,6 +1024,7 @@ RLAPI void ImageResizeNN(Image *image, int newWidth,int newHeight);
 RLAPI void ImageResizeCanvas(Image *image, int newWidth, int newHeight, int offsetX, int offsetY, Color color);  // Resize canvas and fill with color
 RLAPI void ImageMipmaps(Image *image);                                                                   // Generate all mipmap levels for a provided image
 RLAPI void ImageDither(Image *image, int rBpp, int gBpp, int bBpp, int aBpp);                            // Dither image data to 16bpp or lower (Floyd-Steinberg dithering)
+RLAPI Color *ImageExtractPalette(Image image, int maxPaletteSize, int *extractCount);                    // Extract color palette from image to maximum size (memory should be freed)
 RLAPI Image ImageText(const char *text, int fontSize, Color color);                                      // Create an image from text (default font)
 RLAPI Image ImageTextEx(Font font, const char *text, float fontSize, float spacing, Color tint);         // Create an image from text (custom sprite font)
 RLAPI void ImageDraw(Image *dst, Image src, Rectangle srcRec, Rectangle dstRec);                         // Draw a source image within a destination image
diff --git a/src/textures.c b/src/textures.c
index 3099bf659..7ee07d12d 100644
--- a/src/textures.c
+++ b/src/textures.c
@@ -1445,6 +1445,57 @@ void ImageDither(Image *image, int rBpp, int gBpp, int bBpp, int aBpp)
     }
 }
 
+// Extract color palette from image to maximum size
+// NOTE: Memory allocated should be freed manually!
+Color *ImageExtractPalette(Image image, int maxPaletteSize, int *extractCount)
+{
+    #define COLOR_EQUAL(col1, col2) ((col1.r == col2.r)&&(col1.g == col2.g)&&(col1.b == col2.b)&&(col1.a == col2.a))
+    
+    Color *pixels = GetImageData(image);
+    Color *palette = (Color *)malloc(maxPaletteSize*sizeof(Color));
+    
+    int palCount = 0;
+    for (int i = 0; i < maxPaletteSize; i++) palette[i] = BLANK;   // Set all colors to BLANK
+
+    for (int i = 0; i < image.width*image.height; i++)
+    {
+        if (pixels[i].a > 0)
+        {
+            bool colorInPalette = false;
+            
+            // Check if the color is already on palette
+            for (int j = 0; j < maxPaletteSize; j++)
+            {
+                if (COLOR_EQUAL(pixels[i], palette[j])) 
+                {
+                    colorInPalette = true;
+                    break;
+                }
+            }
+            
+            // Store color if not on the palette
+            if (!colorInPalette)
+            {
+                palette[palCount] = pixels[i];      // Add pixels[i] to palette
+                palCount++;
+                
+                // We reached the limit of colors supported by palette
+                if (palCount >= maxPaletteSize)
+                {
+                    i = image.width*image.height;   // Finish palette get
+                    printf("WARNING: Image palette is greater than %i colors!\n", maxPaletteSize);
+                }
+            }
+        }
+    }
+
+    free(pixels);
+    
+    *extractCount = palCount;
+    
+    return palette;
+}
+
 // Draw an image (source) within an image (destination)
 // TODO: Feel this function could be simplified...
 void ImageDraw(Image *dst, Image src, Rectangle srcRec, Rectangle dstRec)