429 lines
14 KiB
C++
429 lines
14 KiB
C++
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// -------
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// Mag_Hook.cpp
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// Accessibility Event trapper for ScreenX. Uses an in-context WinEvent
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// hook to tell the applet where to magnify.
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// Mainly what we want this to do is to watch for focus changes, caret
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// movement, and mouse pointer movement, and then post the appropriate
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// location to the ScreenX applet so it can magnify the correct area.
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// -------
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#define STRICT
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#include <windows.h>
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#include <windowsx.h>
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// When building with VC5, we need winable.h since the active
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// accessibility structures are not in VC5's winuser.h. winable.h can
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// be found in the active accessibility SDK
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#ifdef VC5_BUILD___NOT_NT_BUILD_ENVIRONMENT
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#include <winable.h>
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#else
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// The Active Accessibility SDK used WINABLEAPI for the functions. When
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// the functions were moved to winuser.h, WINABLEAPI was replaced with WINUSERAPI.
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#define WINABLEAPI WINUSERAPI
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#endif
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#include <ole2.h>
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#include <oleacc.h>
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#define MAGHOOKAPI __declspec(dllexport)
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#include "Mag_Hook.h"
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// -------
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// Definitions so we don't have to statically link to OLEACC.DLL
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// We need the following three functions that were in the Active Accessibility SDK
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// STDAPI AccessibleObjectFromEvent(HWND hwnd, DWORD dwId, DWORD dwChildId, IAccessible** ppacc, VARIANT* pvarChild);
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// WINABLEAPI HWINEVENTHOOK WINAPI SetWinEventHook(DWORD eventMin, DWORD eventMax, HMODULE hmodWinEventProc, WINEVENTPROC lpfnWinEventProc, DWORD idProcess, DWORD idThread, DWORD dwFlags);
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// WINABLEAPI BOOL WINAPI UnhookWinEvent(HWINEVENTHOOK hEvent);
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// -------
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typedef HRESULT (_stdcall *_tagAccessibleObjectFromEvent)(HWND hwnd, DWORD dwId, DWORD dwChildId, IAccessible** ppacc, VARIANT* pvarChild);
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typedef WINABLEAPI HWINEVENTHOOK (WINAPI *_tagSetWinEventHook)(DWORD eventMin, DWORD eventMax, HMODULE hmodWinEventProc, WINEVENTPROC lpfnWinEventProc, DWORD idProcess, DWORD idThread, DWORD dwFlags);
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typedef WINABLEAPI BOOL (WINAPI *_tagUnhookWinEvent)(HWINEVENTHOOK hEvent);
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_tagAccessibleObjectFromEvent pAccessibleObjectFromEvent = NULL;
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_tagSetWinEventHook pSetWinEventHook = NULL;
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_tagUnhookWinEvent pUnhookWinEvent = NULL;
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// -------
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// GetAcctiveAccessibleFunctions()
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// This function attempts to load the active accessibility functions we need
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// from OLEACC.DLL and USER32.DLL
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// If the functions are availible, this returns TRUE
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// -------
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BOOL GetAcctiveAccessibleFunctions()
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{
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// JMC: HACK: Until OLEACC Works correctly
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return FALSE;
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HMODULE hOleAcc = NULL;
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HMODULE hUser;
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if(!(hOleAcc = LoadLibrary(__TEXT("oleacc.dll"))))
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return FALSE;
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if(!(pAccessibleObjectFromEvent = (_tagAccessibleObjectFromEvent)GetProcAddress(hOleAcc, "AccessibleObjectFromEvent")))
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return FALSE;
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if(!(hUser = GetModuleHandle(__TEXT("user32.dll"))))
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return FALSE;
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if(!(pSetWinEventHook = (_tagSetWinEventHook)GetProcAddress(hUser, "SetWinEventHook")))
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return FALSE;
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if(!(pUnhookWinEvent = (_tagUnhookWinEvent)GetProcAddress(hUser, "UnhookWinEvent")))
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return FALSE;
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return TRUE;
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};
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// -------
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// Per-process Variables
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// -------
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HMODULE g_hModEventDll;
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// -------
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// Shared Variables
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// -------
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#pragma data_seg("Shared")
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HWINEVENTHOOK g_hEventHook = NULL;
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HHOOK g_hMouseHook = NULL;
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HWND g_hwndEventPost = NULL;
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DWORD g_dwCursorHack = 0;
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#pragma data_seg()
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#pragma comment(linker, "/Section:Shared,RWS")
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// -------
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// Functions Prototypes (Foward References of callback functions
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// -------
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void CALLBACK NotifyProc(HWINEVENTHOOK hEvent, DWORD event, HWND hwndMsg, LONG idObject,
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LONG idChild, DWORD idThread, DWORD dwEventTime);
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LRESULT CALLBACK MouseProc(int code, WPARAM wParam, LPARAM lParam);
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// -------
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// DllMain()
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// -------
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BOOL WINAPI DllMain (HINSTANCE hInst, DWORD dwReason, LPVOID fImpLoad)
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{
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switch (dwReason) {
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case DLL_PROCESS_ATTACH:
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g_hModEventDll = hInst;
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break;
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}
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return(TRUE);
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}
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// -------
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// InstallEventHookWithOleAcc
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// This installs the WinEvent hook if hwndPostTo is not null, or removes the
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// hook if the parameter is null. Does no checking for a valid window handle.
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// If successful, this returns TRUE.
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// -------
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BOOL WINAPI InstallEventHookWithOleAcc (HWND hwndPostTo) {
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if (hwndPostTo != NULL) {
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if(g_hwndEventPost || g_hEventHook)
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return FALSE; // We already have a hook installed - you can only have one at a time
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// Install the hook
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g_hwndEventPost = hwndPostTo; // Must set this before installing the hook
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g_hEventHook = pSetWinEventHook(EVENT_MIN, EVENT_MAX, g_hModEventDll,
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NotifyProc, 0, 0, WINEVENT_SKIPOWNPROCESS | WINEVENT_OUTOFCONTEXT/*WINEVENT_INCONTEXT*/);
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if (!g_hEventHook) {
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// Something went wrong - reset g_hwndEventPost to NULL
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g_hwndEventPost = NULL;
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return FALSE;
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}
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} else {
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// NOTE - We never fail if they are trying to uninstall the hook
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g_hwndEventPost = NULL;
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// Uninstalling the hook
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if (g_hEventHook != NULL) {
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pUnhookWinEvent(g_hEventHook);
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g_hEventHook = NULL;
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}
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}
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return TRUE;
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}
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// -------
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// InstallEventHookWithoutOleAcc
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// This installs a mouse hook so we have some functionality when oleacc is
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// not installed
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// If successful, this returns TRUE.
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// -------
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BOOL WINAPI InstallEventHookWithoutOleAcc (HWND hwndPostTo) {
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if (hwndPostTo != NULL) {
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if(g_hwndEventPost || g_hMouseHook)
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return FALSE; // We already have a hook installed - you can only have one at a time
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// Install the hook
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g_hwndEventPost = hwndPostTo; // Must set this before installing the hook
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g_hMouseHook = SetWindowsHookEx(WH_MOUSE, MouseProc, g_hModEventDll, 0);
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if (!g_hMouseHook) {
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// Something went wrong - reset g_hwndEventPost to NULL
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g_hwndEventPost = NULL;
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return FALSE;
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}
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} else {
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// NOTE - We never fail if they are trying to uninstall the hook
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g_hwndEventPost = NULL;
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// Uninstalling the hook
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if (g_hMouseHook != NULL) {
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UnhookWindowsHookEx(g_hMouseHook);
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g_hMouseHook = NULL;
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}
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}
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return TRUE;
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}
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// -------
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// InstallEventHook
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// This function checks to see if Ole Accessibility is installed, and if so
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// uses the WinEvent hook. Otherwise, it uses a mouse hook.
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// If successful, this returns TRUE.
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// -------
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BOOL g_bOleAccInstalled = FALSE;
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BOOL g_bCheckOnlyOnceForOleAcc = TRUE;
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BOOL WINAPI InstallEventHook (HWND hwndPostTo) {
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// We check only the first time if Ole Acc is installed. From then on,
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// we assume it remains constant.
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if(g_bCheckOnlyOnceForOleAcc) {
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g_bCheckOnlyOnceForOleAcc = FALSE;
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g_bOleAccInstalled = GetAcctiveAccessibleFunctions();
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}
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if(g_bOleAccInstalled)
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return InstallEventHookWithOleAcc(hwndPostTo);
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else
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return InstallEventHookWithoutOleAcc(hwndPostTo);
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}
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// -------
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// GetCursorHack()
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// This function returns the last known user cursor handle.
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// -------
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DWORD WINAPI GetCursorHack()
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{
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return g_dwCursorHack;
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}
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// -------
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// NotifyProc()
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// This is the callback function for the WinEvent Hook we install. This
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// gets called whenever there is an event to process. The only things we
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// care about are focus changes and mouse/caret movement. The way we handle
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// the events is to post a message to the client (ScreenX) telling it
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// where the focus/mouse/caret is right now. It can then decide where it
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// should be magnifying.
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// Parameters:
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// hEvent A handle specific to this call back
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// event The event being sent
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// hwnd Window handle of the window generating the event or
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// NULL if no window is associated with the event.
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// idObject The object identifier or OBJID_WINDOW.
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// idChild The child ID of the element triggering the event,
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// or CHILDID_SELF if the event is for the object itself.
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// dwThreadId The thread ID of the thread generating the event.
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// Informational only.
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// dwmsEventTime The time of the event in milliseconds.
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// -------
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/* Forward ref */ BOOL GetObjectLocation(IAccessible * pacc, VARIANT* pvarChild, LPRECT lpRect);
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void CALLBACK NotifyProc(HWINEVENTHOOK hEvent, DWORD event, HWND hwndMsg, LONG idObject,
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LONG idChild, DWORD idThread, DWORD dwmsEventTime) {
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WPARAM wParam;
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LPARAM lParam;
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// Initialize pac to NULL so that we Release() pointers we've obtained.
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// Otherwise we will continually leak a heck of memory.
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IAccessible * pacc = NULL;
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RECT LocationRect;
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VARIANT varChild;
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HRESULT hr;
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// char sz[100];
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switch (event) {
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#if 0
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case EVENT_OBJECT_HIDE:
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switch (idObject) {
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case OBJID_CARET:
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OutputDebugString("Caret hidden\r\n"); break;
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case OBJID_CURSOR:
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OutputDebugString("Cursor hidden\r\n"); break;
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}
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break;
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case EVENT_OBJECT_SHOW:
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switch (idObject) {
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case OBJID_CARET:
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OutputDebugString("Caret shown\r\n"); break;
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case OBJID_CURSOR:
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OutputDebugString("Cursor shown\r\n"); break;
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}
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break;
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#endif
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case EVENT_OBJECT_FOCUS:
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if (!IsWindowVisible(hwndMsg))
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return;
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hr = pAccessibleObjectFromEvent(hwndMsg, idObject, idChild, &pacc, &varChild);
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if (!SUCCEEDED(hr))
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return;
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if (!GetObjectLocation(pacc,&varChild,&LocationRect))
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break;
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// center zoomed area on center of focus rect.
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wParam = MAKELONG(((LocationRect.left + LocationRect.right) / 2), ((LocationRect.bottom + LocationRect.top) / 2));
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lParam = dwmsEventTime;
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// JMC: TODO: Make sure the top left corner of the object is in the zoom rect
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PostMessage(g_hwndEventPost, WM_EVENT_FOCUSMOVE, wParam, lParam);
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break;
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case EVENT_OBJECT_LOCATIONCHANGE:
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switch (idObject) {
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case OBJID_CARET:
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hr = pAccessibleObjectFromEvent (hwndMsg,idObject,idChild, &pacc, &varChild);
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if (!SUCCEEDED(hr))
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return;
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if (!GetObjectLocation (pacc,&varChild,&LocationRect))
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break;
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// center zoomed area on center of focus rect.
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wParam = MAKELONG(((LocationRect.left + LocationRect.right) / 2), ((LocationRect.bottom + LocationRect.top) / 2));
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lParam = dwmsEventTime;
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PostMessage(g_hwndEventPost, WM_EVENT_CARETMOVE, wParam, lParam);
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break;
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case OBJID_CURSOR:
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hr = pAccessibleObjectFromEvent (hwndMsg,idObject,idChild, &pacc, &varChild);
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if (!SUCCEEDED(hr))
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return;
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if (!GetObjectLocation (pacc,&varChild,&LocationRect))
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break;
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wParam = MAKELONG(LocationRect.left, LocationRect.top);
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lParam = dwmsEventTime;
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PostMessage(g_hwndEventPost, WM_EVENT_MOUSEMOVE, wParam, lParam);
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break;
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}
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break;
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}
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if (pacc)
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pacc->Release();
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}
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// -------
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// GetObjectLocation()
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// This fills in a RECT that has the location of the Accessible object
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// specified by pacc and idChild. The coordinates returned are screen
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// coordinates.
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// -------
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BOOL GetObjectLocation(IAccessible * pacc, VARIANT* pvarChild, LPRECT lpRect) {
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HRESULT hr;
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SetRectEmpty(lpRect);
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hr = pacc->accLocation(&lpRect->left, &lpRect->top, &lpRect->right, &lpRect->bottom, *pvarChild);
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// the location is not a rect, but a top left, plus a width and height.
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// I want it as a real rect, so I'll convert it.
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lpRect->right = lpRect->left + lpRect->right;
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lpRect->bottom = lpRect->top + lpRect->bottom;
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if (!SUCCEEDED(hr))
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return(FALSE);
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return(TRUE);
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}
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
// -------
|
||
|
|
|
||
|
|
// MouseProc()
|
||
|
|
|
||
|
|
// This is the callback function for the Mouse Hook we install.
|
||
|
|
|
||
|
|
// Parameters:
|
||
|
|
// -------
|
||
|
|
LRESULT CALLBACK MouseProc(int code, WPARAM wParam, LPARAM lParam)
|
||
|
|
{
|
||
|
|
// For WM_MOUSEMOVE and WM_NCMOUSEMOVE messages, we post the main window
|
||
|
|
// WM_EVENT_MOUSEMOVE messages. We don't want to do this if we are in
|
||
|
|
// the address space of MAGNIFY.EXE. To avoid this, we also check taht
|
||
|
|
// g_bCheckOnlyOnceForOleAcc is TRUE. If g_bCheckOnlyOnceForOleAcc is TRUE,
|
||
|
|
// we are in another processes address space.
|
||
|
|
// If we posted ourselves WM_EVENT_MOUSEMOVE while in MAGNIFY.EXE, we got all
|
||
|
|
// sorts of weird crashes.
|
||
|
|
if((WM_MOUSEMOVE == wParam || WM_NCMOUSEMOVE == wParam) && g_bCheckOnlyOnceForOleAcc)
|
||
|
|
{
|
||
|
|
g_dwCursorHack = (DWORD)GetCursor(); // JMC: Hack to get cursor on systems that don't support new GetCursorInfo
|
||
|
|
MOUSEHOOKSTRUCT *pmhs = (MOUSEHOOKSTRUCT *)lParam;
|
||
|
|
PostMessage(g_hwndEventPost, WM_EVENT_MOUSEMOVE, MAKELONG(pmhs->pt.x, pmhs->pt.y), 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
return CallNextHookEx(g_hMouseHook, code, wParam, lParam);
|
||
|
|
}
|
||
|
|
|
||
|
|
// -------
|
||
|
|
|
||
|
|
// FakeCursorMove
|
||
|
|
|
||
|
|
// This function is called to 'fake' the cursor moving. It is used by the
|
||
|
|
// magnifier app when a MouseProc is used. We run into problems when
|
||
|
|
// posting ourselves messages from the MouseProc of our own process. To
|
||
|
|
// avoid these problems, MouseProc() does not post a WM_EVENT_MOUSEMOUVE
|
||
|
|
// if we are in the address space of MAGNIFY.EXE. Instead, MAGNIFY.EXE
|
||
|
|
// is responsible for calling FakeCursorMove() whenever the mouse moves over
|
||
|
|
// a window of its own process. (NOTE: This is really easy to accomplish in
|
||
|
|
// MFC. We just call FakeCursorMove() from PreTranslateMessage() - see
|
||
|
|
// MagBar.cpp and MagDlg.cpp
|
||
|
|
|
||
|
|
// -------
|
||
|
|
|
||
|
|
void WINAPI FakeCursorMove(POINT pt)
|
||
|
|
{
|
||
|
|
g_dwCursorHack = (DWORD)GetCursor(); // JMC: Hack to get cursor on systems that don't support new GetCursorInfo
|
||
|
|
PostMessage(g_hwndEventPost, WM_EVENT_MOUSEMOVE, MAKELONG(pt.x, pt.y), 0);
|
||
|
|
}
|