[SDL] Bad math in SDL_RenderCopy Mason Wheeler to sdl When I tried to render an image using something other than NULL for srcrect, it got horribly distorted. I traced it down to the fact that the math in the rectangle adjustments performed just before the call to renderer->RenderCopy is written inside out. It should look like this: if (dstrect->w != real_dstrect.w) { int deltax = (dstrect->x - real_dstrect.x); int deltaw = (dstrect->w - real_dstrect.w); real_srcrect.x += (deltax * real_srcrect.w) / dstrect->w; real_srcrect.w += (deltaw * real_srcrect.w) / dstrect->w; } if (dstrect->h != real_dstrect.h) { int deltay = (dstrect->y - real_dstrect.y); int deltah = (dstrect->h - real_dstrect.h); real_srcrect.y += (deltay * real_srcrect.h) / dstrect->h; real_srcrect.h += (deltah * real_srcrect.h) / dstrect->h;

#include "testnative.h"

#ifdef TEST_NATIVE_X11

static void *CreateWindowX11(int w, int h);
static void DestroyWindowX11(void *window);

NativeWindowFactory X11WindowFactory = {
    "x11",
    CreateWindowX11,
    DestroyWindowX11
};

static Display *dpy;

static void *
CreateWindowX11(int w, int h)
{
    Window window = 0;

    dpy = XOpenDisplay(NULL);
    if (dpy) {
        window =
            XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0, w, h, 0, 0,
                                0);
        XMapRaised(dpy, window);
        XSync(dpy, False);
    }
    return (void *) window;
}

static void
DestroyWindowX11(void *window)
{
    if (dpy) {
        XDestroyWindow(dpy, (Window) window);
        XCloseDisplay(dpy);
    }
}

#endif