Function for pixel size of given color format and data type per channel.

Also documented the formats a little.

src/AbstractTexture.cpp

@@ -46,6 +46,24 @@ static_assert((filter_or(NearestNeighbor, BaseLevel) == GL_NEAREST) &&
 #undef filter_or
 #endif
 
+size_t AbstractTexture::pixelSize(ColorFormat format, Type type) {
+    size_t size = TypeInfo::sizeOf(type);
+    switch(format) {
+        case ColorFormat::Red:
+            return 1*size;
+        case ColorFormat::RedGreen:
+            return 2*size;
+        case ColorFormat::RGB:
+        case ColorFormat::BGR:
+            return 3*size;
+        case ColorFormat::RGBA:
+        case ColorFormat::BGRA:
+            return 4*size;
+        default:
+            return 0;
+    }
+}
+
 void AbstractTexture::setMinificationFilter(Filter filter, Mipmap mipmap) {
     /* Only base mip level is supported on rectangle textures */
     if(target == GL_TEXTURE_RECTANGLE) mipmap = Mipmap::BaseLevel;

src/AbstractTexture.h

@@ -95,28 +95,43 @@ class MAGNUM_EXPORT AbstractTexture {
 
         /** @brief Internal format */
         enum class InternalFormat: GLint {
-            Red = GL_RED,
-            RedGreen = GL_RG,
-            RGB = GL_RGB,
-            RGBA = GL_RGBA,
-            BGR = GL_BGR,
-            BGRA = GL_BGRA,
+            Red = GL_RED,       /**< One-component (red channel) */
+            RedGreen = GL_RG,   /**< Two-component (red and green channel) */
+            RGB = GL_RGB,       /**< Three-component (RGB) */
+            RGBA = GL_RGBA,     /**< Four-component (RGBA) */
+            BGR = GL_BGR,       /**< Three-component (BGR) */
+            BGRA = GL_BGRA,     /**< Four-component (BGRA) */
+
+            /** Compressed red channel */
             CompressedRed = GL_COMPRESSED_RED,
+
+            /** Compressed red and green channel */
             CompressedRedGreen = GL_COMPRESSED_RG,
+
+            /** Compressed RGB */
             CompressedRGB = GL_COMPRESSED_RGB,
+
+            /** Compressed RGBA */
             CompressedRGBA = GL_COMPRESSED_RGBA
         };
 
         /** @brief Color format */
         enum class ColorFormat: GLenum {
-            Red = GL_RED,
-            RedGreen = GL_RG,
-            RGB = GL_RGB,
-            RGBA = GL_RGBA,
-            BGR = GL_BGR,
-            BGRA = GL_BGRA
+            Red = GL_RED,       /**< One-component (red channel) */
+            RedGreen = GL_RG,   /**< Two-component (red and green channel) */
+            RGB = GL_RGB,       /**< Three-component (RGB) */
+            RGBA = GL_RGBA,     /**< Four-component (RGBA) */
+            BGR = GL_BGR,       /**< Three-component (BGR) */
+            BGRA = GL_BGRA      /**< Four-component (BGRA) */
         };
 
+        /**
+         * @brief Pixel size (in bytes)
+         * @param format    Color format
+         * @param type      Data type per color channel
+         */
+        static size_t pixelSize(ColorFormat format, Type type);
+
         /**
          * @brief Constructor
          * @param layer     %Texture layer (number between 0 and 31)