基本的窗口创建 [英] Basic window creation
问题描述
即使我以前曾经这样操作过Windows窗口，但在处理Windows窗口时还是遇到了问题，并且运行良好.在阅读了有关此问题的最常见建议之后，它仍然存在.有人可以告诉我为什么输入处理被破坏了吗?
I have a problem handling a Windows window, even though I did it this way once before and it worked fine. After reading through the most common suggestions for this problem, it still resides. Could someone tell me why Input-handling is broken?
预期行为:
- 创建一个名为"FirstTry"的窗口
- 使用PatBlt将背景设为黑色
- 在第一次进入主循环时以及在按下"w"之后显示一个消息框.
- 按下Alt + F4，Escape或关闭"按钮时关闭窗口，显示关闭消息.
观察到的行为
- 按预期
- 按预期
- MessageBox第一次出现，但不能用'w'重新触发
- 除了TaskManager以外，它无法关闭窗口(一次显示了关闭应用程序" -MessageBox的预期显示，但只有一次)
- 可拖动窗口，直到第一个进入循环" -MessageBox关闭，然后将其固定
- 在第一个MessageBox之后，全天显示Windows10的蓝色小忙"圈
- as intended
- as intended
- MessageBox shows up the first time, but is not retriggerable with 'w'
- Window it not closable, except with TaskManager (one time it showed the 'closing Application'-MessageBox as intended, but only one time)
- window draggable until the first 'entered loop'-MessageBox is closed, after that its fixed
- little blue 'busy'-circle of windows10 is shown full-time, after the first MessageBox
结论:消息处理已损坏. 而且我不知道为什么...
Conclusion: The Message-handling is broken. And i cannot figure out why...
系统:
- 64位Windows 10版本1803(内部版本17134.81)
VS 2017社区版的编译器:
Compiler from VS 2017 Community Edition:
-
vcvarsall.bat amd64
vcvarsall.bat amd64
cl -MTd -nologo -FC -Zi -W4 -WX -wd4100 -wd4312 FirstTry.cpp/link User32.lib Gdi32.lib
cl -MTd -nologo -FC -Zi -W4 -WX -wd4100 -wd4312 FirstTry.cpp /link User32.lib Gdi32.lib
#include "windows.h"
static bool bAppIsRunning = false;
static bool bMessageAlreadyShown = false;
LRESULT CALLBACK win_MainWNDCallback(HWND wnd, UINT msg, WPARAM wParam, LPARAM lParam){
LRESULT result = 0;
switch(msg){
case WM_SYSKEYDOWN:
case WM_SYSKEYUP:
case WM_KEYDOWN:
case WM_KEYUP:{
WPARAM vKeyCode = wParam;
bool bWasDown = ((lParam & (1 << 30)) != 0);
bool bIsDown = ((lParam & (1 << 31)) == 0);
if (bWasDown != bIsDown)
{
switch (vKeyCode)
{
case VK_ESCAPE:{
bAppIsRunning = false;
}break;
default:{
result = DefWindowProc(wnd,msg,wParam,lParam);
}break;
}
}
}break;
default:{
result = DefWindowProc(wnd,msg,wParam,lParam);
}break;
}
return result;
}
int CALLBACK WinMain(HINSTANCE HInstance, HINSTANCE HPrevInstance, LPSTR LpCmdLine, int NCmdShow){
WNDCLASSA wndCLass = {};
wndCLass.style = CS_HREDRAW | CS_VREDRAW;
wndCLass.lpfnWndProc = win_MainWNDCallback;
wndCLass.hInstance = HInstance;
wndCLass.lpszClassName = (LPCSTR)"WindowClass";
if(RegisterClassA(&wndCLass)){
HWND wnd = CreateWindowExA(
0, wndCLass.lpszClassName, (LPCSTR)"FirstTry",
WS_OVERLAPPEDWINDOW | WS_VISIBLE,
CW_USEDEFAULT, CW_USEDEFAULT,
1240, 720,
0, 0, HInstance, 0);
if(wnd){
bAppIsRunning = true;
HDC DeviceContext = GetDC(wnd);
PatBlt(DeviceContext, 0, 0, 1240, 720, BLACKNESS);
ReleaseDC(wnd, DeviceContext);
while(bAppIsRunning){
if(!bMessageAlreadyShown){
MessageBoxA(NULL, (LPCSTR)"Successfully entered loop.", (LPCSTR)"Success!", MB_ICONINFORMATION | MB_OK);
bMessageAlreadyShown = true;
}
MSG msg;
while(PeekMessageA(&msg, 0, 0, 0, PM_REMOVE)){
switch(msg.message){
case WM_SYSKEYDOWN:
case WM_SYSKEYUP:
case WM_KEYDOWN:
case WM_KEYUP:{
WPARAM vKeyCode = msg.wParam;
bool bWasDown = ((msg.lParam & (1<<30)) != 0);
bool bIsDown = ((msg.lParam & (1<<31)) != 0);
if(bIsDown != bWasDown){
switch(vKeyCode){
case 'W':{
bMessageAlreadyShown = false;
}break;
default:{
TranslateMessage(&msg);
DispatchMessageA(&msg);
}break;
}
}
}
}
}
}
MessageBoxA(NULL, (LPCSTR)"Closing Application.", (LPCSTR)"Bye bye!", MB_ICONINFORMATION | MB_OK);
}
}
return ERROR_SUCCESS;
}
推荐答案
您的代码的主要问题是仅在收到某些按键消息时才调用TranslateMessage()和DispatchMessage().您需要在主消息循环中为所有消息调用它们.并且您应该在WndProc回调中处理所有消息.
The main problem with your code is that you are calling TranslateMessage() and DispatchMessage() only when you receive certain key press messages. You need to call them in your main message loop for ALL messages instead. And you should be processing ALL of the messages in your WndProc callback.
您还使用了基于TCHAR的API，但是滥用了LPCTSTR类型转换.将字符串/字符常量转换为TCHAR时，需要使用TEXT()宏.
You are also using TCHAR-based APIs, but are misusing LPCTSTR typecasts. You need to use the TEXT() macro instead when casting string/char literals to TCHAR.
请尝试以下类似操作:
#include <windows.h>
static bool bMessageAlreadyShown = false;
LRESULT CALLBACK win_MainWNDCallback(HWND wnd, UINT msg, WPARAM wParam, LPARAM lParam) {
switch (msg) {
case WM_DESTROY:
PostQuitMessage(0);
return 0;
case WM_SYSKEYDOWN:
case WM_SYSKEYUP:
case WM_KEYDOWN:
case WM_KEYUP: {
WPARAM vKeyCode = wParam;
bool bWasDown = ((lParam & (1 << 30)) != 0);
bool bIsDown = ((lParam & (1 << 31)) == 0);
if (bWasDown != bIsDown) {
switch (vKeyCode) {
case 'W':
case VK_ESCAPE:
DestroyWindow(wnd);
return 0;
}
}
break;
}
case WM_ERASEBKGND:
PatBlt((HDC)wParam, 0, 0, 1240, 720, BLACKNESS);
return 0;
}
return DefWindowProc(wnd, msg, wParam, lParam);;
}
int CALLBACK WinMain(HINSTANCE HInstance, HINSTANCE HPrevInstance, LPSTR LpCmdLine, int NCmdShow) {
WNDCLASS wndCLass = {};
wndCLass.style = CS_HREDRAW | CS_VREDRAW;
wndCLass.lpfnWndProc = win_MainWNDCallback;
wndCLass.hInstance = HInstance;
wndCLass.lpszClassName = TEXT("WindowClass");
if (RegisterClass(&wndCLass)) {
HWND wnd = CreateWindowEx( 0, wndCLass.lpszClassName, TEXT("FirstTry"), WS_OVERLAPPEDWINDOW | WS_VISIBLE, CW_USEDEFAULT, CW_USEDEFAULT, 1240, 720, 0, 0, HInstance, 0);
if (wnd) {
MSG msg;
while (GetMessage(&msg, 0, 0, 0)) {
if (!bMessageAlreadyShown) {
bMessageAlreadyShown = true;
MessageBox(NULL, TEXT("Successfully entered loop."), TEXT("Success!"), MB_ICONINFORMATION | MB_OK);
}
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
}
MessageBox(NULL, TEXT("Closing Application."), TEXT("Bye bye!"), MB_ICONINFORMATION | MB_OK);
return ERROR_SUCCESS;
}
请注意，我删除了bAppIsRunning变量，因为一旦消息循环处理了WM_QUIT消息，它就会变得多余.
Note that I removed your bAppIsRunning variable, as it has beecome redundant once the message loop processes the WM_QUIT message instead.
我还删除了对 ALT-F4 的处理，因为操作系统会自动为您处理.它关闭窗口，触发WM_CLOSE消息.默认情况下，DefWindowProc()通过销毁窗口来处理WM_CLOSE，这会触发WM_DESTROY消息.
I also removed handling of ALT-F4, as the OS handles that for you automatically. It closes the window, triggering a WM_CLOSE message. By default, DefWindowProc() handles WM_CLOSE by destroying the window, which triggers a WM_DESTROY message.
我还添加了对WM_ERASEBKGND的处理，以在窗口上绘制背景.从消息循环外部进行绘制是错误的.一旦需要在屏幕上刷新窗口，您所做的任何绘图都会丢失，因此您必须重新绘制所有内容以响应WM_ERASEBKGND和WM_PAINT.
I also added handling for WM_ERASEBKGND to draw a background on the window. Drawing from outside of the message loop is wrong. As soon as the window needs to be refreshed onscreen, any drawing you do is lost, so you have to redraw everything in response to WM_ERASEBKGND and WM_PAINT.
这篇关于基本的窗口创建的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
