Resizing and Graphical Content
How does resizing affect graphical content displayed inside the window?
Resizing a window can have significant implications for the graphical content displayed within it. Here's how it typically affects rendering:
Stretching or Distortion
If your content is rendered using fixed coordinates or dimensions, resizing will stretch or shrink the content to fit the new window size.
For example, if a rectangle spans from (0, 0) to (200, 200) in a 400x400 window and the window is resized to 800x800, it will occupy only one-fourth of the space unless adjustments are made.
Re-rendering and Scaling
Modern applications often re-render content based on the new size. This ensures that the content scales appropriately.
Using SDL, you might handle this in the event loop by responding to SDL_WINDOWEVENT_SIZE_CHANGED or SDL_WINDOWEVENT_RESIZED.
Here's an example that redraws content upon resizing:
#include <SDL.h>
#include <iostream>
void DrawRectangle(SDL_Renderer*, int, int) {/*...*/};
int main() {
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window =
SDL_CreateWindow("Resize Example",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
400, 400,
SDL_WINDOW_RESIZABLE);
SDL_Renderer* renderer =
SDL_CreateRenderer(
window, -1, SDL_RENDERER_ACCELERATED);
bool running = true;
SDL_Event event;
while (running) {
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
running = false;
}
if (event.type == SDL_WINDOWEVENT &&
(event.window.event ==
SDL_WINDOWEVENT_SIZE_CHANGED ||
event.window.event ==
SDL_WINDOWEVENT_RESIZED)) {
int width, height;
SDL_GetWindowSize(window, &width,
&height);
SDL_SetRenderDrawColor(
renderer, 0, 0, 0, 255);
SDL_RenderClear(renderer);
DrawRectangle(renderer, width, height);
SDL_RenderPresent(renderer);
}
}
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}On resizing the window, the rectangle redraws proportionally in the new dimensions.Best Practices
- Use relative coordinates or scaling factors to adapt your content dynamically.
- Test how resizing affects performance since re-rendering large scenes can be costly.
- Consider locking aspect ratios to avoid unwanted distortions if your application has strict graphical requirements.
By properly handling resizing, you can ensure a polished experience for users regardless of window size.
Window Sizing
Learn how to resize, constrain, and manage SDL2 windows