History: OpenGL Image Loader Using DevIL Image Library

Source of version: 1 (current)

The OpenGL platform for MyGUI lacks a built-in image loading class.  An abstract class is provided (OpenGLImageLoader) to allow you to create your own.  I've taken it a step further by creating a class for you, using the excellent open source DevIL library!

Note: the image format conversion code (e.g. MyGUI doesn't support BGR, so it gets converted to RGB) hasn't been tested (all the files so far have been of a supported format), but it should work, at least with a little tweaking.  Enjoy!

{CODE(caption="OpenGL DevIL Image Loader Class",wrap="1",colors="c++",wiki="0",rtl="0",ishtml="0")}#ifndef __OPENGL_IMAGE_LOADER_DEVIL__
#define __OPENGL_IMAGE_LOADER_DEVIL__

#include <algorithm>
#include <cctype>
#include <cstdlib>

#include <MyGUI_DataManager.h>
#include <MyGUI_OpenGLImageLoader.h>

#include <IL/il.h>

class OpenGLImageLoader_Devil : public MyGUI::OpenGLImageLoader
{
public:
    OpenGLImageLoader_Devil() :
        MyGUI::OpenGLImageLoader()
    {
        // Take this out of here if you initialise DevIL elsewhere
        ilInit();
    }

	virtual ~OpenGLImageLoader_Devil()
    {
    }

    void* loadImage(
        int& _width, 
        int& _height, 
        MyGUI::PixelFormat& _format, 
        const std::string& _filename)
    {
        // Generate an image name and bind it so we can use it
        ILuint image;
        ilGenImages(1, &image);
        ilBindImage(image);

        // Load the image as a resource
        MyGUI::IDataStream* stream = MyGUI::DataManager::getInstancePtr()->getData(_filename);
        size_t lumpSize = stream->size();
        void* lumpData = malloc(lumpSize);
        stream->read(lumpData, lumpSize);

#ifdef _UNICODE
        // Convert filename to a std::wstring
        std::wstring filename(_filename.length(), L' ');
        std::copy(_filename.begin(), _filename.end(), filename.begin());
#else
        std::string filename = _filename;
#endif

        // Try to determine the image type
        ILenum imageType = ilDetermineType(filename.c_str());
        if (imageType == IL_TYPE_UNKNOWN)
        {
            imageType = ilDetermineTypeL(lumpData, lumpSize);
        }

        // Try to load the image
        if (ilLoadL(imageType, lumpData, lumpSize) == IL_FALSE)
        {
            free(lumpData);
            return 0;
        }

        free(lumpData);

        // Retrieve image information
        _width = ilGetInteger(IL_IMAGE_WIDTH);
        _height = ilGetInteger(IL_IMAGE_HEIGHT);
        ILenum format = ilGetInteger(IL_IMAGE_FORMAT);
        ILenum type = ilGetInteger(IL_IMAGE_TYPE);

        // If the format is not supported, convert to a supported format
        // Also convert if the pixel type is not unsigned byte
        ILenum convertToFormat = format;

        switch (format)
        {
        case IL_COLOUR_INDEX: convertToFormat = IL_RGB; break;
        case IL_ALPHA: convertToFormat = IL_LUMINANCE_ALPHA; break;
        case IL_BGR: convertToFormat = IL_RGB; break;
        case IL_BGRA: convertToFormat = IL_RGBA; break;
        default: break;
        }

        if ((convertToFormat != format) || (type != IL_UNSIGNED_BYTE))
        {
            if (ilConvertImage(convertToFormat, IL_UNSIGNED_BYTE) == IL_FALSE)
            {
                return 0;
            }
        }

        // Determine MyGUI pixel formats
        switch (format)
        {
        case IL_RGB: _format = MyGUI::PixelFormat::R8G8B8; break;
        case IL_RGBA: _format = MyGUI::PixelFormat::R8G8B8A8; break;
        case IL_LUMINANCE: _format = MyGUI::PixelFormat::L8; break;
        case IL_LUMINANCE_ALPHA: _format = MyGUI::PixelFormat::L8A8; break;
        default: _format = MyGUI::PixelFormat::Unknow; break;
        }

        // Copy the image data into some new memory
        ILint size = ilGetInteger(IL_IMAGE_SIZE_OF_DATA);
        void* _data = malloc(size);
        ILubyte* data = ilGetData();
        memcpy(_data, data, size);

        return _data;
    }
};

#endif // __OPENGL_IMAGE_LOADER_DEVIL__{CODE}
History: OpenGL Image Loader Using DevIL Image Library

Source of version: 1 (current)

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