Added new image functions

- Added: ImageAlphaClear()
- Added: ImageAlphaPremultiply()
- Reorganized some functions

src/raylib.h

@@ -876,14 +876,16 @@ RLAPI void UpdateTexture(Texture2D texture, const void *pixels);
 RLAPI void SaveImageAs(const char *fileName, Image image);                                               // Save image to a PNG file
 
 // Image manipulation functions
+RLAPI Image ImageCopy(Image image);                                                                      // Create an image duplicate (useful for transformations)
 RLAPI void ImageToPOT(Image *image, Color fillColor);                                                    // Convert image to POT (power-of-two)
 RLAPI void ImageFormat(Image *image, int newFormat);                                                     // Convert image data to desired format
 RLAPI void ImageAlphaMask(Image *image, Image alphaMask);                                                // Apply alpha mask to 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 Image ImageCopy(Image image);                                                                      // Create an image duplicate (useful for transformations)
+RLAPI void ImageAlphaClear(Image *image, Color color, float threshold);                                  // Clear alpha channel to desired color
+RLAPI void ImageAlphaPremultiply(Image *image);                                                          // Premultiply alpha channel
 RLAPI void ImageCrop(Image *image, Rectangle crop);                                                      // Crop an image to a defined rectangle
 RLAPI void ImageResize(Image *image, int newWidth, int newHeight);                                       // Resize and image (bilinear filtering)
 RLAPI void ImageResizeNN(Image *image,int newWidth,int newHeight);                                       // Resize and image (Nearest-Neighbor scaling algorithm)
+RLAPI void ImageDither(Image *image, int rBpp, int gBpp, int bBpp, int aBpp);                            // Dither image data to 16bpp or lower (Floyd-Steinberg dithering)
 RLAPI Image ImageText(const char *text, int fontSize, Color color);                                      // Create an image from text (default font)
 RLAPI Image ImageTextEx(SpriteFont font, const char *text, float fontSize, int 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

src/textures.c

@@ -593,6 +593,74 @@ void SaveImageAs(const char *fileName, Image image)
 #endif
 }
 
+// Copy an image to a new image
+Image ImageCopy(Image image)
+{
+    Image newImage = { 0 };
+
+    int size = GetPixelDataSize(image.width, image.height, image.format);
+
+    newImage.data = malloc(size);
+
+    if (newImage.data != NULL)
+    {
+        // NOTE: Size must be provided in bytes
+        memcpy(newImage.data, image.data, size);
+
+        newImage.width = image.width;
+        newImage.height = image.height;
+        newImage.mipmaps = image.mipmaps;
+        newImage.format = image.format;
+    }
+
+    return newImage;
+}
+
+// Convert image to POT (power-of-two)
+// NOTE: It could be useful on OpenGL ES 2.0 (RPI, HTML5)
+void ImageToPOT(Image *image, Color fillColor)
+{
+    Color *pixels = GetImageData(*image);   // Get pixels data
+
+    // Calculate next power-of-two values
+    // NOTE: Just add the required amount of pixels at the right and bottom sides of image...
+    int potWidth = (int)powf(2, ceilf(logf((float)image->width)/logf(2)));
+    int potHeight = (int)powf(2, ceilf(logf((float)image->height)/logf(2)));
+
+    // Check if POT texture generation is required (if texture is not already POT)
+    if ((potWidth != image->width) || (potHeight != image->height))
+    {
+        Color *pixelsPOT = NULL;
+
+        // Generate POT array from NPOT data
+        pixelsPOT = (Color *)malloc(potWidth*potHeight*sizeof(Color));
+
+        for (int j = 0; j < potHeight; j++)
+        {
+            for (int i = 0; i < potWidth; i++)
+            {
+                if ((j < image->height) && (i < image->width)) pixelsPOT[j*potWidth + i] = pixels[j*image->width + i];
+                else pixelsPOT[j*potWidth + i] = fillColor;
+            }
+        }
+
+        TraceLog(LOG_WARNING, "Image converted to POT: (%ix%i) -> (%ix%i)", image->width, image->height, potWidth, potHeight);
+
+        free(pixels);                       // Free pixels data
+        free(image->data);                  // Free old image data
+
+        int format = image->format;         // Store image data format to reconvert later
+
+        // TODO: Image width and height changes... do we want to store new values or keep the old ones?
+        // NOTE: Issues when using image.width and image.height for sprite animations...
+        *image = LoadImageEx(pixelsPOT, potWidth, potHeight);
+
+        free(pixelsPOT);                    // Free POT pixels data
+
+        ImageFormat(image, format);  // Reconvert image to previous format
+    }
+}
+
 // Convert image data to desired format
 void ImageFormat(Image *image, int newFormat)
 {
@@ -806,75 +874,45 @@ void ImageAlphaMask(Image *image, Image alphaMask)
     }
 }
 
-// Convert image to POT (power-of-two)
-// NOTE: It could be useful on OpenGL ES 2.0 (RPI, HTML5)
-void ImageToPOT(Image *image, Color fillColor)
+// Clear alpha channel to desired color
+// NOTE: Threshold defines the alpha limit, 0.0f to 1.0f
+void ImageAlphaClear(Image *image, Color color, float threshold)
 {
-    Color *pixels = GetImageData(*image);   // Get pixels data
-
-    // Calculate next power-of-two values
-    // NOTE: Just add the required amount of pixels at the right and bottom sides of image...
-    int potWidth = (int)powf(2, ceilf(logf((float)image->width)/logf(2)));
-    int potHeight = (int)powf(2, ceilf(logf((float)image->height)/logf(2)));
-
-    // Check if POT texture generation is required (if texture is not already POT)
-    if ((potWidth != image->width) || (potHeight != image->height))
-    {
-        Color *pixelsPOT = NULL;
-
-        // Generate POT array from NPOT data
-        pixelsPOT = (Color *)malloc(potWidth*potHeight*sizeof(Color));
-
-        for (int j = 0; j < potHeight; j++)
-        {
-            for (int i = 0; i < potWidth; i++)
-            {
-                if ((j < image->height) && (i < image->width)) pixelsPOT[j*potWidth + i] = pixels[j*image->width + i];
-                else pixelsPOT[j*potWidth + i] = fillColor;
-            }
-        }
-
-        TraceLog(LOG_WARNING, "Image converted to POT: (%ix%i) -> (%ix%i)", image->width, image->height, potWidth, potHeight);
-
-        free(pixels);                       // Free pixels data
-        free(image->data);                  // Free old image data
-
-        int format = image->format;         // Store image data format to reconvert later
-
-        // TODO: Image width and height changes... do we want to store new values or keep the old ones?
-        // NOTE: Issues when using image.width and image.height for sprite animations...
-        *image = LoadImageEx(pixelsPOT, potWidth, potHeight);
-
-        free(pixelsPOT);                    // Free POT pixels data
+    Color *pixels = GetImageData(*image);
+    
+    for (int i = 0; i < image->width*image->height; i++) if (pixels[i].a <= (unsigned char)(threshold*255.0f)) pixels[i] = color;
 
-        ImageFormat(image, format);  // Reconvert image to previous format
-    }
+    UnloadImage(*image);
+    
+    int prevFormat = image->format;
+    *image = LoadImageEx(pixels, image->width, image->height);
+    
+    ImageFormat(image, prevFormat);
 }
 
-#if defined(SUPPORT_IMAGE_MANIPULATION)
-// Copy an image to a new image
-Image ImageCopy(Image image)
+// Premultiply alpha channel
+void ImageAlphaPremultiply(Image *image)
 {
-    Image newImage = { 0 };
-
-    int size = GetPixelDataSize(image.width, image.height, image.format);
-
-    newImage.data = malloc(size);
-
-    if (newImage.data != NULL)
+    float alpha = 0.0f;
+    Color *pixels = GetImageData(*image);
+    
+    for (int i = 0; i < image->width*image->height; i++) 
     {
-        // NOTE: Size must be provided in bytes
-        memcpy(newImage.data, image.data, size);
-
-        newImage.width = image.width;
-        newImage.height = image.height;
-        newImage.mipmaps = image.mipmaps;
-        newImage.format = image.format;
+        alpha = (float)pixels[i].a/255.0f;
+        pixels[i].r = (unsigned char)((float)pixels[i].r*alpha);
+        pixels[i].g = (unsigned char)((float)pixels[i].g*alpha);
+        pixels[i].b = (unsigned char)((float)pixels[i].b*alpha);
     }
 
-    return newImage;
+    UnloadImage(*image);
+    
+    int prevFormat = image->format;
+    *image = LoadImageEx(pixels, image->width, image->height);
+    
+    ImageFormat(image, prevFormat);
 }
 
+#if defined(SUPPORT_IMAGE_MANIPULATION)
 // Crop an image to area defined by a rectangle
 // NOTE: Security checks are performed in case rectangle goes out of bounds
 void ImageCrop(Image *image, Rectangle crop)
@@ -982,6 +1020,115 @@ void ImageResizeNN(Image *image,int newWidth,int newHeight)
     free(pixels);
 }
 
+// Dither image data to 16bpp or lower (Floyd-Steinberg dithering)
+// NOTE: In case selected bpp do not represent an known 16bit format,
+// dithered data is stored in the LSB part of the unsigned short
+void ImageDither(Image *image, int rBpp, int gBpp, int bBpp, int aBpp)
+{
+    if (image->format >= COMPRESSED_DXT1_RGB)
+    {
+        TraceLog(LOG_WARNING, "Compressed data formats can not be dithered");
+        return;
+    }
+
+    if ((rBpp+gBpp+bBpp+aBpp) > 16)
+    {
+        TraceLog(LOG_WARNING, "Unsupported dithering bpps (%ibpp), only 16bpp or lower modes supported", (rBpp+gBpp+bBpp+aBpp));
+    }
+    else
+    {
+        Color *pixels = GetImageData(*image);
+
+        free(image->data);      // free old image data
+
+        if ((image->format != UNCOMPRESSED_R8G8B8) && (image->format != UNCOMPRESSED_R8G8B8A8))
+        {
+            TraceLog(LOG_WARNING, "Image format is already 16bpp or lower, dithering could have no effect");
+        }
+
+        // Define new image format, check if desired bpp match internal known format
+        if ((rBpp == 5) && (gBpp == 6) && (bBpp == 5) && (aBpp == 0)) image->format = UNCOMPRESSED_R5G6B5;
+        else if ((rBpp == 5) && (gBpp == 5) && (bBpp == 5) && (aBpp == 1)) image->format = UNCOMPRESSED_R5G5B5A1;
+        else if ((rBpp == 4) && (gBpp == 4) && (bBpp == 4) && (aBpp == 4)) image->format = UNCOMPRESSED_R4G4B4A4;
+        else
+        {
+            image->format = 0;
+            TraceLog(LOG_WARNING, "Unsupported dithered OpenGL internal format: %ibpp (R%iG%iB%iA%i)", (rBpp+gBpp+bBpp+aBpp), rBpp, gBpp, bBpp, aBpp);
+        }
+
+        // NOTE: We will store the dithered data as unsigned short (16bpp)
+        image->data = (unsigned short *)malloc(image->width*image->height*sizeof(unsigned short));
+
+        Color oldPixel = WHITE;
+        Color newPixel = WHITE;
+
+        int rError, gError, bError;
+        unsigned short rPixel, gPixel, bPixel, aPixel;   // Used for 16bit pixel composition
+
+        #define MIN(a,b) (((a)<(b))?(a):(b))
+
+        for (int y = 0; y < image->height; y++)
+        {
+            for (int x = 0; x < image->width; x++)
+            {
+                oldPixel = pixels[y*image->width + x];
+
+                // NOTE: New pixel obtained by bits truncate, it would be better to round values (check ImageFormat())
+                newPixel.r = oldPixel.r >> (8 - rBpp);     // R bits
+                newPixel.g = oldPixel.g >> (8 - gBpp);     // G bits
+                newPixel.b = oldPixel.b >> (8 - bBpp);     // B bits
+                newPixel.a = oldPixel.a >> (8 - aBpp);     // A bits (not used on dithering)
+
+                // NOTE: Error must be computed between new and old pixel but using same number of bits!
+                // We want to know how much color precision we have lost...
+                rError = (int)oldPixel.r - (int)(newPixel.r << (8 - rBpp));
+                gError = (int)oldPixel.g - (int)(newPixel.g << (8 - gBpp));
+                bError = (int)oldPixel.b - (int)(newPixel.b << (8 - bBpp));
+
+                pixels[y*image->width + x] = newPixel;
+
+                // NOTE: Some cases are out of the array and should be ignored
+                if (x < (image->width - 1))
+                {
+                    pixels[y*image->width + x+1].r = MIN((int)pixels[y*image->width + x+1].r + (int)((float)rError*7.0f/16), 0xff);
+                    pixels[y*image->width + x+1].g = MIN((int)pixels[y*image->width + x+1].g + (int)((float)gError*7.0f/16), 0xff);
+                    pixels[y*image->width + x+1].b = MIN((int)pixels[y*image->width + x+1].b + (int)((float)bError*7.0f/16), 0xff);
+                }
+
+                if ((x > 0) && (y < (image->height - 1)))
+                {
+                    pixels[(y+1)*image->width + x-1].r = MIN((int)pixels[(y+1)*image->width + x-1].r + (int)((float)rError*3.0f/16), 0xff);
+                    pixels[(y+1)*image->width + x-1].g = MIN((int)pixels[(y+1)*image->width + x-1].g + (int)((float)gError*3.0f/16), 0xff);
+                    pixels[(y+1)*image->width + x-1].b = MIN((int)pixels[(y+1)*image->width + x-1].b + (int)((float)bError*3.0f/16), 0xff);
+                }
+
+                if (y < (image->height - 1))
+                {
+                    pixels[(y+1)*image->width + x].r = MIN((int)pixels[(y+1)*image->width + x].r + (int)((float)rError*5.0f/16), 0xff);
+                    pixels[(y+1)*image->width + x].g = MIN((int)pixels[(y+1)*image->width + x].g + (int)((float)gError*5.0f/16), 0xff);
+                    pixels[(y+1)*image->width + x].b = MIN((int)pixels[(y+1)*image->width + x].b + (int)((float)bError*5.0f/16), 0xff);
+                }
+
+                if ((x < (image->width - 1)) && (y < (image->height - 1)))
+                {
+                    pixels[(y+1)*image->width + x+1].r = MIN((int)pixels[(y+1)*image->width + x+1].r + (int)((float)rError*1.0f/16), 0xff);
+                    pixels[(y+1)*image->width + x+1].g = MIN((int)pixels[(y+1)*image->width + x+1].g + (int)((float)gError*1.0f/16), 0xff);
+                    pixels[(y+1)*image->width + x+1].b = MIN((int)pixels[(y+1)*image->width + x+1].b + (int)((float)bError*1.0f/16), 0xff);
+                }
+
+                rPixel = (unsigned short)newPixel.r;
+                gPixel = (unsigned short)newPixel.g;
+                bPixel = (unsigned short)newPixel.b;
+                aPixel = (unsigned short)newPixel.a;
+
+                ((unsigned short *)image->data)[y*image->width + x] = (rPixel << (gBpp + bBpp + aBpp)) | (gPixel << (bBpp + aBpp)) | (bPixel << aBpp) | aPixel;
+            }
+        }
+
+        free(pixels);
+    }
+}
+
 // 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)
@@ -1205,115 +1352,6 @@ void ImageFlipHorizontal(Image *image)
     image->data = processed.data;
 }
 
-// Dither image data to 16bpp or lower (Floyd-Steinberg dithering)
-// NOTE: In case selected bpp do not represent an known 16bit format,
-// dithered data is stored in the LSB part of the unsigned short
-void ImageDither(Image *image, int rBpp, int gBpp, int bBpp, int aBpp)
-{
-    if (image->format >= COMPRESSED_DXT1_RGB)
-    {
-        TraceLog(LOG_WARNING, "Compressed data formats can not be dithered");
-        return;
-    }
-
-    if ((rBpp+gBpp+bBpp+aBpp) > 16)
-    {
-        TraceLog(LOG_WARNING, "Unsupported dithering bpps (%ibpp), only 16bpp or lower modes supported", (rBpp+gBpp+bBpp+aBpp));
-    }
-    else
-    {
-        Color *pixels = GetImageData(*image);
-
-        free(image->data);      // free old image data
-
-        if ((image->format != UNCOMPRESSED_R8G8B8) && (image->format != UNCOMPRESSED_R8G8B8A8))
-        {
-            TraceLog(LOG_WARNING, "Image format is already 16bpp or lower, dithering could have no effect");
-        }
-
-        // Define new image format, check if desired bpp match internal known format
-        if ((rBpp == 5) && (gBpp == 6) && (bBpp == 5) && (aBpp == 0)) image->format = UNCOMPRESSED_R5G6B5;
-        else if ((rBpp == 5) && (gBpp == 5) && (bBpp == 5) && (aBpp == 1)) image->format = UNCOMPRESSED_R5G5B5A1;
-        else if ((rBpp == 4) && (gBpp == 4) && (bBpp == 4) && (aBpp == 4)) image->format = UNCOMPRESSED_R4G4B4A4;
-        else
-        {
-            image->format = 0;
-            TraceLog(LOG_WARNING, "Unsupported dithered OpenGL internal format: %ibpp (R%iG%iB%iA%i)", (rBpp+gBpp+bBpp+aBpp), rBpp, gBpp, bBpp, aBpp);
-        }
-
-        // NOTE: We will store the dithered data as unsigned short (16bpp)
-        image->data = (unsigned short *)malloc(image->width*image->height*sizeof(unsigned short));
-
-        Color oldPixel = WHITE;
-        Color newPixel = WHITE;
-
-        int rError, gError, bError;
-        unsigned short rPixel, gPixel, bPixel, aPixel;   // Used for 16bit pixel composition
-
-        #define MIN(a,b) (((a)<(b))?(a):(b))
-
-        for (int y = 0; y < image->height; y++)
-        {
-            for (int x = 0; x < image->width; x++)
-            {
-                oldPixel = pixels[y*image->width + x];
-
-                // NOTE: New pixel obtained by bits truncate, it would be better to round values (check ImageFormat())
-                newPixel.r = oldPixel.r >> (8 - rBpp);     // R bits
-                newPixel.g = oldPixel.g >> (8 - gBpp);     // G bits
-                newPixel.b = oldPixel.b >> (8 - bBpp);     // B bits
-                newPixel.a = oldPixel.a >> (8 - aBpp);     // A bits (not used on dithering)
-
-                // NOTE: Error must be computed between new and old pixel but using same number of bits!
-                // We want to know how much color precision we have lost...
-                rError = (int)oldPixel.r - (int)(newPixel.r << (8 - rBpp));
-                gError = (int)oldPixel.g - (int)(newPixel.g << (8 - gBpp));
-                bError = (int)oldPixel.b - (int)(newPixel.b << (8 - bBpp));
-
-                pixels[y*image->width + x] = newPixel;
-
-                // NOTE: Some cases are out of the array and should be ignored
-                if (x < (image->width - 1))
-                {
-                    pixels[y*image->width + x+1].r = MIN((int)pixels[y*image->width + x+1].r + (int)((float)rError*7.0f/16), 0xff);
-                    pixels[y*image->width + x+1].g = MIN((int)pixels[y*image->width + x+1].g + (int)((float)gError*7.0f/16), 0xff);
-                    pixels[y*image->width + x+1].b = MIN((int)pixels[y*image->width + x+1].b + (int)((float)bError*7.0f/16), 0xff);
-                }
-
-                if ((x > 0) && (y < (image->height - 1)))
-                {
-                    pixels[(y+1)*image->width + x-1].r = MIN((int)pixels[(y+1)*image->width + x-1].r + (int)((float)rError*3.0f/16), 0xff);
-                    pixels[(y+1)*image->width + x-1].g = MIN((int)pixels[(y+1)*image->width + x-1].g + (int)((float)gError*3.0f/16), 0xff);
-                    pixels[(y+1)*image->width + x-1].b = MIN((int)pixels[(y+1)*image->width + x-1].b + (int)((float)bError*3.0f/16), 0xff);
-                }
-
-                if (y < (image->height - 1))
-                {
-                    pixels[(y+1)*image->width + x].r = MIN((int)pixels[(y+1)*image->width + x].r + (int)((float)rError*5.0f/16), 0xff);
-                    pixels[(y+1)*image->width + x].g = MIN((int)pixels[(y+1)*image->width + x].g + (int)((float)gError*5.0f/16), 0xff);
-                    pixels[(y+1)*image->width + x].b = MIN((int)pixels[(y+1)*image->width + x].b + (int)((float)bError*5.0f/16), 0xff);
-                }
-
-                if ((x < (image->width - 1)) && (y < (image->height - 1)))
-                {
-                    pixels[(y+1)*image->width + x+1].r = MIN((int)pixels[(y+1)*image->width + x+1].r + (int)((float)rError*1.0f/16), 0xff);
-                    pixels[(y+1)*image->width + x+1].g = MIN((int)pixels[(y+1)*image->width + x+1].g + (int)((float)gError*1.0f/16), 0xff);
-                    pixels[(y+1)*image->width + x+1].b = MIN((int)pixels[(y+1)*image->width + x+1].b + (int)((float)bError*1.0f/16), 0xff);
-                }
-
-                rPixel = (unsigned short)newPixel.r;
-                gPixel = (unsigned short)newPixel.g;
-                bPixel = (unsigned short)newPixel.b;
-                aPixel = (unsigned short)newPixel.a;
-
-                ((unsigned short *)image->data)[y*image->width + x] = (rPixel << (gBpp + bBpp + aBpp)) | (gPixel << (bBpp + aBpp)) | (bPixel << aBpp) | aPixel;
-            }
-        }
-
-        free(pixels);
-    }
-}
-
 // Modify image color: tint
 void ImageColorTint(Image *image, Color color)
 {