我正在使用sdl库,但该库支持缩放/调整大小表面,因此我下载了

SDL_image 1.2和SDL_gfx库。我的功能/代码有效,但图像显示为不良/不足

质量。

假设我得到的图像是100X100,如果我缩小到95X95或放大到110X110,

质量看起来很低,但是如果我将其保留为100X100,它的尺寸与

高品质。如果按比例缩小图像,大多数图像质量较好,但是...

我的代码是:

int drawImage(SDL_Surface* display, const char * filename, int x, int y, int xx, int yy , const double newwidth, const double newheight, int transparent = NULL)
{



    SDL_Surface *image;
    SDL_Surface *temp;
    temp = IMG_Load(filename); if (temp == NULL) { printf("Unable to load image: %s\n", SDL_GetError()); return 1; }
    image = SDL_DisplayFormat(temp); SDL_FreeSurface(temp);

        // Zoom function uses doubles for rates of scaling, rather than
    // exact size values. This is how we get around that:
    double zoomx = newwidth  / (float)image->w;
    double zoomy = newheight / (float)image->h;

    // This function assumes no smoothing, so that any colorkeys wont bleed.
    SDL_Surface* sized = zoomSurface( image, zoomx, zoomy, SMOOTHING_OFF );



    // If the original had an alpha color key, give it to the new one.
    if( image->flags & SDL_SRCCOLORKEY )
    {
        // Acquire the original Key
        Uint32 colorkey = image->format->colorkey;

        // Set to the new image
        SDL_SetColorKey( sized, SDL_SRCCOLORKEY, colorkey );
    }



    // The original picture is no longer needed.
    SDL_FreeSurface( image );

    // Set it instead to the new image.
    image =  sized;



    SDL_Rect src, dest;
    src.x = xx; src.y = yy; src.w = image->w; src.h = image->h; // size
    dest.x =  x; dest.y = y; dest.w = image->w; dest.h = image->h;

    if(transparent == true )
     {

         //Set the color as transparent
         SDL_SetColorKey(image,SDL_SRCCOLORKEY|SDL_RLEACCEL,SDL_MapRGB(image->format,0x0,0x0,0x0));

     }

    else {

    }


    SDL_BlitSurface(image, &src, display, &dest);

    return true;
}

drawImage(display, "Image.png", 50, 100, NULL, NULL, 100, 100,true);

最佳答案

缩放后不允许平滑的图像将出现伪像。如果从SVG开始并以所需的比例进行渲染,则可能会更好。 Here's an SVG -> SDL surface库。

关于c++ - SDL图像比例,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/8645476/

10-11 22:45
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