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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Provides a way to handle exceptions that happen while a WindowProc is
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// running. The behavior of exceptions generated inside a WindowProc is OS
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// dependent, but it is possible that the OS just ignores the exception and
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// continues execution, which leads to unpredictable behavior for Chrome.
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#ifndef BASE_WIN_WRAPPED_WINDOW_PROC_H_
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#define BASE_WIN_WRAPPED_WINDOW_PROC_H_
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#include "base/base_export.h"
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#include "base/strings/string16.h"
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// An exception filter for a WindowProc. The return value determines how the
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// exception should be handled, following standard SEH rules. However, the
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// expected behavior for this function is to not return, instead of returning
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// EXCEPTION_EXECUTE_HANDLER or similar, given that in general we are not
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// prepared to handle exceptions.
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typedef int (__cdecl *WinProcExceptionFilter)(EXCEPTION_POINTERS* info);
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// Sets the filter to deal with exceptions inside a WindowProc. Returns the old
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// exception filter, if any.
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// This function should be called before any window is created.
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BASE_EXPORT WinProcExceptionFilter SetWinProcExceptionFilter(
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WinProcExceptionFilter filter);
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// Calls the registered exception filter.
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BASE_EXPORT int CallExceptionFilter(EXCEPTION_POINTERS* info);
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// Initializes the WNDCLASSEX structure |*class_out| to be passed to
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// RegisterClassEx() making sure that it is associated with the module
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// containing the window procedure.
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BASE_EXPORT void InitializeWindowClass(
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const char16* class_name,
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const char16* menu_name,
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WNDCLASSEX* class_out);
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// Wrapper that supplies a standard exception frame for the provided WindowProc.
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// The normal usage is something like this:
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// LRESULT CALLBACK MyWinProc(HWND hwnd, UINT message,
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// WPARAM wparam, LPARAM lparam) {
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// WNDCLASSEX wc = {0};
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// wc.lpfnWndProc = WrappedWindowProc<MyWinProc>;
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// wc.lpszClassName = class_name;
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// RegisterClassEx(&wc);
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// CreateWindowW(class_name, window_name, ...
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template <WNDPROC proc>
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LRESULT CALLBACK WrappedWindowProc(HWND hwnd, UINT message,
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WPARAM wparam, LPARAM lparam) {
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rv = proc(hwnd, message, wparam, lparam);
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} __except(CallExceptionFilter(GetExceptionInformation())) {
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#endif // BASE_WIN_WRAPPED_WINDOW_PROC_H_