ImageManager.d

module playground.ImageManager;

import std.stdio;
import std.string;
import derelict.sdl2.sdl;

struct ImageInfo
{
    SDL_Surface *image;
    string friendlyName;
    string fileName;
}


/**
 * Manages loading and caching of image resources.
 *
 */
class ImageManager
{
    ImageInfo[string] images;

    this()
    {

    }

    ~this()
    {
        foreach(string name, ImageInfo iInfo; images)
        {
            debug writeln("Freeing image ", name);
            SDL_FreeSurface(iInfo.image);
        }
    }

    /**
     * Determines if a specific image has been loaded
     */
    private bool HasImage(string friendlyName)
    {
        ImageInfo tmp;
        return images.get(friendlyName, tmp) != tmp;
    }

    /**
     * Frees the underlying image, as well as removes the ImageInfo from the cache.
     * @param friendlyName The 'friendly' name of the image (i.e. 'HelloWorld')
     */
    private void FreeImage(string friendlyName)
    {
        if(!HasImage(friendlyName))
            return;
        debug writeln("Freeing image ", friendlyName);
        SDL_FreeSurface(images[friendlyName].image);
        debug writeln("Removing ", friendlyName);
        images.remove(friendlyName);
    }

    /**
     * Loads and caches the specified image.
     * @param friendlyName The 'friendly' name of the image (i.e. 'HelloWorld')
     * @param fileName The filename of the image to load.
     * @return True if successful, otherwise false.
     */
    public bool CacheImage(string friendlyName, string fileName)
    {
        if(HasImage(friendlyName))
        {
            if(images[friendlyName].fileName == fileName)
            {
                debug writeln("Ignoring cache request for ",friendlyName);
                return true;
            } else {
                debug writefln("CacheImage: Filepaths differ for [%s]. Reloading.", friendlyName);
                FreeImage(friendlyName);
            }

        }

        SDL_Surface *loadedImage;
        loadedImage = SDL_LoadBMP(toStringz(fileName));
        if(loadedImage != null)
        {
            debug writeln("Caching image ", friendlyName);
            ImageInfo iInfo;
            iInfo.image = loadedImage;
            iInfo.fileName = fileName;
            iInfo.friendlyName = friendlyName;
            images[friendlyName] = iInfo;
            return true;
        }

        debug writefln("Failed to cache image [%s] @ [%s] with error: %s.", friendlyName, fileName, SDL_GetError());
        return false;
    }

    public SDL_Surface* LoadImage(string friendlyName, string filename)
    {
        SDL_Surface *loadedImage;
        loadedImage = SDL_LoadBMP(toStringz(filename));
        if(loadedImage != null)
        {
            debug writeln("Loading image ", friendlyName);
            ImageInfo iInfo;
            iInfo.image = loadedImage;
            iInfo.fileName = filename;
            iInfo.friendlyName = friendlyName;
            images[friendlyName] = iInfo;
            return loadedImage;
        }
        return null;
    }


    public SDL_Surface* GetImage(string friendlyName)
    {
        if(HasImage(friendlyName))
        {
            images[friendlyName].image.refcount++;
            return images[friendlyName].image;
        }

        debug writefln("Error: Failed to retrieve image [%s].", friendlyName);
        return null;
    }
}