What is the purpose of WM destroy message?

It is sent to the window procedure of the window being destroyed after the window is removed from the screen. This message is sent first to the window being destroyed and then to the child windows (if any) as they are destroyed. During the processing of the message, it can be assumed that all child windows still exist.

What are window messages?

The operating system communicates with your application window by passing messages to it. A message is simply a numeric code that designates a particular event. For example, if the user presses the left mouse button, the window receives a message that has the following message code.

What is Wm_syskeydown?

WM_SYSKEYDOWN simulates system commands like ALT + TAB used to switch windows. WM_CHAR simulates user input like input in a text box for instance. WM_KEYDOWN is usually used together with WM_KEYUP . See WM_KEYDOWN message (Windows). Most probably you will want to use WM_CHAR .

What is Wm_create?

A WM_CREATE message is sent to your window procedure during the window’s CreateWindowEx call. The lp argument contains a pointer to a CREATESTRUCT which contains the arguments passed to CreateWindowEx . If an application returns 0 from WM_CREATE, the window is created.

What message displayed when a window is destroyed?

The DestroyWindow function sends the WM_NCDESTROY message to the window following the WM_DESTROY message. WM_DESTROY is used to free the allocated memory object associated with the window. The WM_NCDESTROY message is sent after the child windows have been destroyed.

How do I check my Windows messages?

To open a Messages view for a window, process, or thread

  1. Move the focus to a Windows View, Processes View, or Threads View window.
  2. Find the node for the item whose messages you want to examine, and select it.
  3. From the Spy menu, choose Log Messages.
  4. Select the options for the message you want to display.

Which messages are sent directly to Windows?

Most other messages, which are sent directly to a window procedure, are called nonqueued messages.

  • Queued Messages.
  • Nonqueued Messages.

What is Lparam and Wparam?

According to this, LPARAM is defined as LONG_PTR , which in 64-bit Windows is a signed, 64-bit value. WPARAM is defined as UINT_PTR , which in 64-bit Windows is an unsigned, 64-bit value. If you are defining your own message, you might want to assign its parameters accordingly.

What is subclass of window?

Subclassing is a technique that allows an application to intercept and process messages sent or posted to a particular window before the window has a chance to process them. By subclassing a window, an application can augment, modify, or monitor the behavior of the window.

What is Wndclass?

The WNDCLASS structure holds most of the information defining a window class. This information is used by any windows which belong to the class. The only item which this structure does not hold is a handle to the class’s small icon. (The more advanced WNDCLASSEX structure does.)