Spectre/Graphics/PixelFormat: Rework

source/Graphics/Image/IcoFormat.cpp: use new PixelFormat.
source/Graphics/Image.cpp: update to confirm with new PixelFormat
Spectre/Graphics/PixelFormat: add PF_getNumChannels()
Spectre/Graphics/PixelFormat: Rework the enum with proper naming convention and documentation.

engine.build.lua

@@ -100,6 +100,7 @@ local graphics_module = Module("source/Graphics", {
 	"Image.cpp",
 	"ImageLoader.cpp",
 	"Image/IcoFormat.cpp",
+	"PixelFormat.cpp",
 
 	"OpenGL.cpp",
 	"GL/glad.c",

include/Spectre/Graphics/PixelFormat.h

@@ -1,18 +1,49 @@
 #ifndef SPECTRE_GRAPHICS_PIXELFORMAT_H
 #define SPECTRE_GRAPHICS_PIXELFORMAT_H
 
+#include <cstdint>
+
 namespace sp {
 
 enum PixelFormat
 {
 	PF_Unknown	= 0,
-	PF_RGB		= 1,	// Standard RGB: 24 bits per pixel, 8 bits are used for red, green, blue.
+	PF_Alpha	= 1,	// 8 bit alpha channel.
-	PF_RGBA		= 2,	// Standard RGBA: 32 bits per pixel, 8 bits are used for red, green, blue, alpha.
+
-	PF_32BGR	= 3,	// 32 bits per pixel, 8 bits are used for blue, green, red. Last 8 bits are unused.
+	// Byte-order formats.
-	PF_32BGRA	= 4,	// 32 bits per pixel, 8 bits are used for blue, green, red, alpha.
+	// Pixels are always ordered with the first channel at the first byte, second channel at the second byte.
-	PF_Alpha	= 5,	// 8 bit alpha channel.
+	// ---------------------------
+
+	PF_RGB		= 2,	// Standard RGB: 24 bits per pixel, 8 bits are used for red, green, blue.
+	PF_RGBX     = 3,	// 32 bits per pixel, 8 bits are used for red, green, Last 8 bits are unused.
+	PF_RGBA		= 4,	// Standard RGBA: 32 bits per pixel, 8 bits are used for red, green, blue, alpha.
+	PF_BGR		= 5,	// 24 bits per pixel, 8 bits are used for blue, green, red.
+	PF_BGRX		= 6,	// 32 bits per pixel, 8 bits are used for blue, green, red. Last 8 bits are unused.
+	PF_BGRA		= 7,	// 32 bits per pixel, 8 bits are used for blue, green, red, alpha.
+
+	// Packed formats.
+	// ---------------------------
+
+	// 32-bit: Pixels are in ordered in 32-bit words. where the first channel is stored at the most significant byte (MSB).
+	// these formats are architecture dependant (litte/big-endian).
+	//			     (MSB) | byte 0    | byte 1    | byte 2    | byte 3    | (LSB)
+	PF_RGBX32     = 8,  // | rrrr rrrr | gggg gggg | bbbb bbbb | xxxx xxxx |
+	PF_RGBA32	  = 9,  // | rrrr rrrr | gggg gggg | bbbb bbbb | aaaa aaaa |
+	PF_BGRX32	  = 10, // | bbbb bbbb | gggg gggg | rrrr rrrr | xxxx xxxx |
+	PF_BGRA32	  = 11, // | bbbb bbbb | gggg gggg | rrrr rrrr | aaaa aaaa |
+
+	// 24-bit (unsuppored for now)
+	//PF_RGB24	  = 12, // | rrrr rrrr | gggg gggg | bbbb bbbb |
+	//PF_BGR24	  = 13, // | bbbb bbbb | gggg gggg | rrrr rrrr |
+
+	// 16-bit (unsuppored for now)
+	//PF_RGB565	  = 14, // | rrrr rggg | gggb bbbb |
+	//PF_RGBA5551 = 15  // | rrrr rggg | ggb bbbba |
+	//PF_RGBX5551 = 16  // | rrrr rggg | ggb bbbbx |
 };
 
+uint8_t PF_getNumChannels(enum PixelFormat format);
+
 } // namespace
 
 #endif /* SPECTRE_GRAPHICS_PIXELFORMAT_H */

source/Graphics/Image.cpp

@@ -165,29 +165,28 @@ void Image::flipY()
 
 void Image::setPixels(const void *pixels, PixelFormat format)
 {
-	switch(format) {
+	switch(PF_getNumChannels(format)) {
-	case PixelFormat::PF_RGB :
+	case 4:
-	case PixelFormat::PF_32BGR :
-		m_channels = RGB;
-		break;
-	case PixelFormat::PF_RGBA :
-	case PixelFormat::PF_32BGRA :
 		m_channels = RGBA;
 		break;
+	case 3:
+		m_channels = RGB;
+		break;
 	default :
 		m_channels = Alpha;
 	}
 
 	m_pixels.resize(m_size.y * getStride());
 
-	if (format == PixelFormat::PF_32BGR || format == PixelFormat::PF_32BGRA) {
+	// TODO: Move pixel format convertion to it's own function(s)
+	if (format == PixelFormat::PF_BGR || format == PixelFormat::PF_BGRA) {
 		const uint8_t *ptr = (const uint8_t *) pixels;
 
 		for(int i = 0; i < m_pixels.size(); i += 4) {
 			m_pixels[i+0] = ptr[2];
 			m_pixels[i+1] = ptr[1];
 			m_pixels[i+2] = ptr[0];
-			if (format == PixelFormat::PF_32BGRA) {
+			if (format == PixelFormat::PF_BGRA) {
 				m_pixels[i+3] = ptr[3];
 			}
 			ptr += 4;

source/Graphics/Image/IcoFormat.cpp

@@ -61,9 +61,9 @@ bool IcoFormat::decode(Image& img, const unsigned char *data, unsigned size)
 	largest = findLargestImage(ent, num_ent);
 
 	if (largest->bpp == 32) {
-		format = PixelFormat::PF_32BGRA;
+		format = PixelFormat::PF_BGRA;
 	} else {
-		format = PixelFormat::PF_32BGR;
+		format = PixelFormat::PF_BGR;
 	}
 
 	// NOTE: plus 40 bytes here to skip over the DIB header.

source/Graphics/PixelFormat.cpp

@@ -0,0 +1,26 @@
+
+#include <Spectre/Graphics/PixelFormat.h>
+
+namespace sp {
+
+uint8_t PF_getNumChannels(enum PixelFormat format)
+{
+	switch(format) {
+	case PixelFormat::PF_RGBA :
+	case PixelFormat::PF_RGBA32 :
+	case PixelFormat::PF_BGRA :
+	case PixelFormat::PF_BGRA32 :
+		return 4;
+	case PixelFormat::PF_RGB :
+	case PixelFormat::PF_RGBX :
+	case PixelFormat::PF_RGBX32 :
+	case PixelFormat::PF_BGR :
+	case PixelFormat::PF_BGRX :
+	case PixelFormat::PF_BGRX32 :
+		return 3;
+	default :
+		return 1;
+	}
+}
+
+} // namespace sp