accessible/windows/msaa/nsWinUtils.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:expandtab:shiftwidth=2:tabstop=2:
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #include "nsWinUtils.h"
   9
  10 #include "Compatibility.h"
  11 #include "DocAccessible.h"
  12 #include "nsAccessibilityService.h"
  13 #include "nsCoreUtils.h"
  14
  15 #include "mozilla/a11y/DocAccessibleParent.h"
  16 #include "mozilla/Preferences.h"
  17 #include "mozilla/StaticPrefs_accessibility.h"
  18 #include "nsArrayUtils.h"
  19 #include "nsICSSDeclaration.h"
  20 #include "mozilla/dom/Document.h"
  21 #include "mozilla/dom/Element.h"
  22 #include "nsXULAppAPI.h"
  23
  24 using namespace mozilla;
  25 using namespace mozilla::a11y;
  26 using mozilla::dom::Element;
  27
  28 // Window property used by ipc related code in identifying accessible
  29 // tab windows.
  30 const wchar_t* kPropNameTabContent = L"AccessibleTabWindow";
  31
  32 /**
  33  * WindowProc to process WM_GETOBJECT messages, used in windows emulation mode.
  34  */
  35 static LRESULT CALLBACK WindowProc(HWND hWnd, UINT msg, WPARAM wParam,
  36                                    LPARAM lParam);
  37
  38 bool nsWinUtils::sWindowEmulationStarted = false;
  39
  40 already_AddRefed<nsICSSDeclaration> nsWinUtils::GetComputedStyleDeclaration(
  41     nsIContent* aContent) {
  42   nsIContent* elm = nsCoreUtils::GetDOMElementFor(aContent);
  43   if (!elm) return nullptr;
  44
  45   // Returns number of items in style declaration
  46   nsCOMPtr<nsPIDOMWindowInner> window = elm->OwnerDoc()->GetInnerWindow();
  47   if (!window) return nullptr;
  48
  49   ErrorResult dummy;
  50   nsCOMPtr<Element> domElement(do_QueryInterface(elm));
  51   nsCOMPtr<nsICSSDeclaration> cssDecl =
  52       window->GetComputedStyle(*domElement, u""_ns, dummy);
  53   dummy.SuppressException();
  54   return cssDecl.forget();
  55 }
  56
  57 bool nsWinUtils::MaybeStartWindowEmulation() {
  58   // Register window class that'll be used for document accessibles associated
  59   // with tabs.
  60   if (IPCAccessibilityActive()) return false;
  61
  62   if (Compatibility::IsJAWS() || Compatibility::IsWE() ||
  63       Compatibility::IsDolphin() || Compatibility::IsVisperoShared()) {
  64     RegisterNativeWindow(kClassNameTabContent);
  65     sWindowEmulationStarted = true;
  66     return true;
  67   }
  68
  69   return false;
  70 }
  71
  72 void nsWinUtils::ShutdownWindowEmulation() {
  73   // Unregister window call that's used for document accessibles associated
  74   // with tabs.
  75   if (IsWindowEmulationStarted()) {
  76     ::UnregisterClassW(kClassNameTabContent, GetModuleHandle(nullptr));
  77     sWindowEmulationStarted = false;
  78   }
  79 }
  80
  81 void nsWinUtils::RegisterNativeWindow(LPCWSTR aWindowClass) {
  82   WNDCLASSW wc;
  83   wc.style = CS_GLOBALCLASS;
  84   wc.lpfnWndProc = WindowProc;
  85   wc.cbClsExtra = 0;
  86   wc.cbWndExtra = 0;
  87   wc.hInstance = GetModuleHandle(nullptr);
  88   wc.hIcon = nullptr;
  89   wc.hCursor = nullptr;
  90   wc.hbrBackground = nullptr;
  91   wc.lpszMenuName = nullptr;
  92   wc.lpszClassName = aWindowClass;
  93   ::RegisterClassW(&wc);
  94 }
  95
  96 HWND nsWinUtils::CreateNativeWindow(LPCWSTR aWindowClass, HWND aParentWnd,
  97                                     int aX, int aY, int aWidth, int aHeight,
  98                                     bool aIsActive,
  99                                     NativeWindowCreateProc* aOnCreateProc) {
 100   return ::CreateWindowExW(
 101       WS_EX_TRANSPARENT, aWindowClass, L"NetscapeDispatchWnd",
 102       WS_CHILD | (aIsActive ? WS_VISIBLE : 0), aX, aY, aWidth, aHeight,
 103       aParentWnd, nullptr, GetModuleHandle(nullptr), aOnCreateProc);
 104 }
 105
 106 void nsWinUtils::ShowNativeWindow(HWND aWnd) { ::ShowWindow(aWnd, SW_SHOW); }
 107
 108 void nsWinUtils::HideNativeWindow(HWND aWnd) {
 109   ::SetWindowPos(
 110       aWnd, nullptr, 0, 0, 0, 0,
 111       SWP_HIDEWINDOW | SWP_NOSIZE | SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
 112 }
 113
 114 LRESULT CALLBACK WindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
 115   // Note, this window's message handling should not invoke any call that
 116   // may result in a cross-process ipc call. Doing so may violate RPC
 117   // message semantics.
 118
 119   switch (msg) {
 120     case WM_CREATE: {
 121       // Mark this window so that ipc related code can identify it.
 122       ::SetPropW(hWnd, kPropNameTabContent, reinterpret_cast<HANDLE>(1));
 123
 124       auto createStruct = reinterpret_cast<CREATESTRUCT*>(lParam);
 125       auto createProc = reinterpret_cast<nsWinUtils::NativeWindowCreateProc*>(
 126           createStruct->lpCreateParams);
 127
 128       if (createProc && *createProc) {
 129         (*createProc)(hWnd);
 130       }
 131
 132       return 0;
 133     }
 134     case WM_GETOBJECT: {
 135       // Do explicit casting to make it working on 64bit systems (see bug 649236
 136       // for details).
 137       int32_t objId = static_cast<DWORD>(lParam);
 138       if (objId == OBJID_CLIENT) {
 139         RefPtr<IAccessible> msaaAccessible;
 140         DocAccessible* document =
 141             reinterpret_cast<DocAccessible*>(::GetPropW(hWnd, kPropNameDocAcc));
 142         if (document) {
 143           document->GetNativeInterface(getter_AddRefs(msaaAccessible));
 144         } else {
 145           DocAccessibleParent* docParent = static_cast<DocAccessibleParent*>(
 146               ::GetPropW(hWnd, kPropNameDocAccParent));
 147           if (docParent) {
 148             if (StaticPrefs::accessibility_cache_enabled_AtStartup()) {
 149               msaaAccessible = MsaaAccessible::GetFrom(docParent);
 150             } else {
 151               docParent->GetCOMInterface(getter_AddRefs(msaaAccessible));
 152             }
 153           }
 154         }
 155         if (msaaAccessible) {
 156           LRESULT result =
 157               ::LresultFromObject(IID_IAccessible, wParam,
 158                                   msaaAccessible);  // does an addref
 159           return result;
 160         }
 161       }
 162       return 0;
 163     }
 164     case WM_NCHITTEST: {
 165       LRESULT lRet = ::DefWindowProc(hWnd, msg, wParam, lParam);
 166       if (HTCLIENT == lRet) lRet = HTTRANSPARENT;
 167       return lRet;
 168     }
 169   }
 170
 171   return ::DefWindowProcW(hWnd, msg, wParam, lParam);
 172 }