How to get mouse position on mouse wheel event - mouseevent

Question

Contrary to MouseMotionEvent, MouseWheelEvent does not provide the mouse location (the fields x and y are used for horizontal and vertical scrolling instead).
SDL provides SDL_GetMouseState() to retrieve the current mouse position, but it is not expressed in the same coordinate system:
SDL_Event event;
while (SDL_WaitEvent(&event)) {
switch (event.type) {
case SDL_MOUSEMOTION: {
int x, y;
SDL_GetMouseState(&x, &y);
printf("event=(%d, %d) state=(%d, %d)\n",
event.motion.x, event.motion.y, x, y);
}
}
}
When I move the mouse, it prints something like:
event=(700, 184) state=(479, 126)
event=(702, 175) state=(480, 120)
event=(706, 168) state=(485, 111)
It seems that the motion event is expressed relative to the texture or renderer (which is scaled and centered in the window) while the state is expressed relative to the window, in pixels.
Is there a way to get the current mouse state matching the position filled in mouse events?

Answer 1

I ended up by converting the coordinates manually:
void convert_to_renderer_coordinates(SDL_Renderer *renderer, int *x, int *y) {
SDL_Rect viewport;
float scale_x, scale_y;
SDL_RenderGetViewport(renderer, &viewport);
SDL_RenderGetScale(renderer, &scale_x, &scale_y);
*x = (int) (*x / scale_x) - viewport.x;
*y = (int) (*y / scale_y) - viewport.y;
}
I use this function to convert the mouse state coordinates:
SDL_Event event;
while (SDL_WaitEvent(&event)) {
switch (event.type) {
case SDL_MOUSEMOTION: {
int x, y;
SDL_GetMouseState(&x, &y);
convert_to_renderer_coordinates(&x, &y);
printf("event=(%d, %d) state=(%d, %d)\n",
event.motion.x, event.motion.y, x, y);
}
}
}
Now, they match:
event=(1033, 14) state=(1033, 14)
event=(1034, 13) state=(1034, 13)
event=(1034, 11) state=(1036, 10) // this is racy, state already has a new position
event=(1036, 10) state=(1036, 10)
The mouse position is captured when the wheel event is handled (instead of when it is generated), so it is racy. But I think we can't do better with the current API.