Size Changed vs Resized Events

Both SDL_WINDOWEVENT_SIZE_CHANGED and SDL_WINDOWEVENT_RESIZED are window events related to size changes, but they differ in when and how they are triggered.

This event occurs when the window size changes and rendering must be updated. It's typically triggered after the user completes a resize action or when the window is resized programmatically using functions like SDL_SetWindowSize().

Here's how you might handle it:

1if (event.type == SDL_WINDOWEVENT &&
2    event.window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
3  int width = event.window.data1;
4  int height = event.window.data2;
5  std::cout << "Size changed to: "
6    << width << "x" << height << "\n";
7}

This event is sent more broadly and includes platform-specific behavior. It's triggered whenever a resize operation occurs, including intermediate steps while the user is actively resizing the window.

To handle this:

1if (event.type == SDL_WINDOWEVENT &&
2    event.window.event == SDL_WINDOWEVENT_RESIZED) {
3  int width = event.window.data1;
4  int height = event.window.data2;
5  std::cout << "Resizing in progress: "
6    << width << "x" << height << "\n";
7}

• Frequency: SDL_WINDOWEVENT_RESIZED fires multiple times during a resize operation, while SDL_WINDOWEVENT_SIZE_CHANGED fires once after the size stabilizes.
• Purpose: Use SDL_WINDOWEVENT_RESIZED for tasks like logging or real-time feedback, and SDL_WINDOWEVENT_SIZE_CHANGED for updating rendering or layouts after resizing.

By distinguishing between these events, you can optimize your application's response to resizing and avoid unnecessary recalculations or redraws.