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479484b631
Right now, extension specific actions on window positioning are implemented by wrapping the ScreenRec's PositionWindow() proc pointer: the extensions are storing the original pointer in their private data and putting in their own one. On each call, their proc restores the original one, calls it, and switches back again. When multiple extensions doing so, they're forming a kind of daisy chain. (the same is done for lots of other procs) While that approach is looking nice and elegant on the drawing board, it's complicated, dangerous like a chainsaw and makes debugging hard, leading to pretty blurred API borders. This commit introduces a simple approach for letting extension hook into the window positioning path safely, w/o having to care much about side effects with the call chain. Extensions now can simply register their hook proc (and an opaque pointer) and get called back - w/o ever having to mess with the ScreenRec's internal structures. These hooks are called before the original vector (usually handled by DDX/screen driver directly) is called. Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
113 lines
4.3 KiB
C
113 lines
4.3 KiB
C
/* SPDX-License-Identifier: MIT OR X11
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*
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* Copyright © 2024 Enrico Weigelt, metux IT consult <info@metux.net>
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*
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* @brief exported API entry points for hooking into screen operations
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*
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* These hooks are replacing the old, complicated approach of wrapping
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* ScreenRec's proc vectors. Unlike the wrapping, these hooks are designed
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* to be safe against changes in setup/teardown order and are called
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* independently of the ScreenProc call vectors. It is guaranteed that the
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* objects to operate on already/still exist (eg. destructors are callled
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* before the object is actually destroyed, while post-create hooks are
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* called after the object is created)
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*
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* Main consumers are extensions that need to associate extra data or
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* doing other things additional to the original operation. In some cases
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* they might even be used in drivers (in order to split device specific
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* from generic logic)
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*/
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#ifndef XORG_DIX_SCREEN_HOOKS_H
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#define XORG_DIX_SCREEN_HOOKS_H
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#include <X11/Xfuncproto.h>
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#include "include/callback.h" /* CallbackListPtr */
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#include "include/screenint.h" /* ScreenPtr */
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#include "include/window.h" /* WindowPtr */
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/* prototype of a window destructor */
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typedef void (*XorgScreenWindowDestroyProcPtr)(CallbackListPtr *pcbl,
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ScreenPtr pScreen,
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WindowPtr pWindow);
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/**
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* @brief register a window on the given screen
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*
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* @param pScreen pointer to the screen to register the destructor into
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* @param func pointer to the window destructor function
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* @param arg opaque pointer passed to the destructor
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*
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* Window destructors are the replacement for fragile and complicated wrapping of
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* pScreen->DestroyWindow(): extensions can safely register there custom destructors
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* here, without ever caring about anybody else.
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+
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* The destructors are run right before pScreen->DestroyWindow() - when the window
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* is already removed from hierarchy (thus cannot receive any events anymore) and
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* most of it's data already destroyed - and supposed to do necessary per-extension
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* cleanup duties. Their execution order is *unspecified*.
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*
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* Screen drivers (DDX'es, xf86 video drivers, ...) shall not use these, but still
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* set the pScreen->DestroyWindow pointer - and these should be the *only* ones
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* ever setting it.
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*
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* When registration fails, the server aborts.
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*
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**/
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void dixScreenHookWindowDestroy(ScreenPtr pScreen,
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XorgScreenWindowDestroyProcPtr func);
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/**
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* @brief unregister a window destructor on the given screen
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*
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* @param pScreen pointer to the screen to unregister the destructor from
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* @param func pointer to the window destructor function
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* @param arg opaque pointer passed to the destructor
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*
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* @see dixScreenHookWindowDestroy
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*
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* Unregister a window destructor hook registered via @ref dixScreenHookWindowDestroy
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**/
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void dixScreenUnhookWindowDestroy(ScreenPtr pScreen,
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XorgScreenWindowDestroyProcPtr func);
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typedef struct {
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WindowPtr window;
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int32_t x;
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int32_t y;
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} XorgScreenWindowPositionParamRec;
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/* prototype of a window move notification handler */
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typedef void (*XorgScreenWindowPositionProcPtr)(CallbackListPtr *pcbl,
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ScreenPtr pScreen,
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XorgScreenWindowPositionParamRec *param);
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/**
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* @brief register a position notify hook on the given screen
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*
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* @param pScreen pointer to the screen to register the notify hook into
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* @param func pointer to the window hook function
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* @param arg opaque pointer passed to the hook
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*
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* When registration fails, the server aborts.
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*
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**/
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void dixScreenHookWindowPosition(ScreenPtr pScreen,
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XorgScreenWindowPositionProcPtr func);
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/**
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* @brief unregister a window position notify hook on the given screen
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*
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* @param pScreen pointer to the screen to unregister the hook from
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* @param func pointer to the hook function
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* @param arg opaque pointer passed to the destructor
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*
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* @see dixScreenHookWindowPosition
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*
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* Unregister a window position notify hook registered via @ref dixScreenHookWindowPosition
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**/
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void dixScreenUnhookWindowPosition(ScreenPtr pScreen,
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XorgScreenWindowPositionProcPtr func);
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#endif /* DIX_SCREEN_HOOKS_H */
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