- 1 year ago
WM_SIZE and WM_MOUSEMOVE: different behaviour during repainting client area
The behavior of the WM_SIZE
and WM_MOUSEMOVE
messages during the repainting of the client area can differ due to their distinct purposes and the way they are processed by the Windows message loop.
WM_SIZE
message: This message is sent to a window when its size is changing, such as when it is being resized by the user or programmatically. TheWM_SIZE
message provides information about the new size and allows you to handle the resizing event in your application. It is typically used to update the layout, adjust the rendering, or perform other tasks related to the window's size change.
During resizing, the WM_SIZE
message may be sent multiple times, depending on the type of resizing operation. For example, when the user drags the window border, you might receive multiple WM_SIZE
messages with intermediate sizes before the final size is settled. This behavior allows your application to update its visual appearance or adjust its content dynamically during the resizing process.
WM_MOUSEMOVE
message: This message is sent to a window when the mouse cursor moves within the window's client area. TheWM_MOUSEMOVE
message provides information about the mouse's current position, allowing you to respond to mouse movements and update the user interface accordingly. It is commonly used for tasks such as tracking mouse position, highlighting elements, or updating tooltips.
During the repainting of the client area, which can occur during resizing or other events, the WM_MOUSEMOVE
message may be generated as the mouse cursor moves over the updated areas of the window. This behavior allows you to update the UI in response to mouse movements, even during resizing or other ongoing operations.
In summary, the WM_SIZE
message primarily focuses on handling window size changes, while the WM_MOUSEMOVE
message is specifically related to mouse movements within the client area. They serve different purposes and may be generated in different contexts, but both can be useful for updating the user interface during various window operations.