无法更改菜单位图 [英] Unable To Change Menu Bitmap

问题描述

我有一个为应用程序定制的皮肤，它消除了标题/标题栏.所有菜单项和系统按钮都是所有者绘制的.一切正常，除了一个小错误.

I have a custom-drawn skin for an app, that eliminates the caption/title bar. All of the menu items and system buttons are owner-drawn. Everything works as it should, except one little bug.

当按下 Maximize 按钮，并且窗口最大化时，代码也应该更改按钮位图，从Maximize"图标，到恢复"图标.然而，我无法让它改变.这是处理该按钮命令的代码:

When the Maximize button is pressed, and the window maximizes, the code should also change the button bitmap, from the "Maximize" icon, to the "Restore" icon. Yet, I cannot get it to change. Here is the code that handles that button command:

case ID_MENUBAR_MAX: {
                    WINDOWPLACEMENT wp;
                    wp.length = sizeof(WINDOWPLACEMENT);
                    GetWindowPlacement(hwnd, &wp);
                    mII.cbSize = sizeof(MENUITEMINFO);
                    mII.fMask = MIIM_BITMAP;
                    GetMenuItemInfo(hMenu, NUMMI+2, TRUE, &mII);
                    if (wp.showCmd == SW_SHOWNORMAL){    mII.hbmpItem = hMBB.restore;  SendMessage(hwnd, WM_SYSCOMMAND, SC_MAXIMIZE, 0); }
                    if (wp.showCmd == SW_SHOWMAXIMIZED){ mII.hbmpItem = hMBB.max;      SendMessage(hwnd, WM_SYSCOMMAND, SC_RESTORE, 0);  }
                    SetMenuItemInfo(hMenu, NUMMI+2, TRUE, &mII);
                    DrawMenuBar(hwnd);
                    return 0;
                 }

正如我所提到的，一切正常.当按下按钮时，窗口会最大化或正常化，这是应该的.我只是无法让按钮上的位图随之改变.我错过了什么?一定很简单.

As I mentioned, everything works as it should. When the button is pressed the window maximizes or normalizes, as it should. I just can't get the bitmap on the button to change along with it. What am I missing? It must be something simple.

推荐答案

My Bad! 我忘记将 hMenu 声明为 static 变量.正因为如此，我失去了我的菜单句柄.这就是 SetMenuItemInfo() 稍后在命令代码块中不起作用的原因.我知道它必须很简单.

My Bad! I forgot to declare hMenu as a static variable. Because of that, I was losing my menu handle. That's why SetMenuItemInfo() would not work later, in the command code blocks. I knew that it had to be something simple.

无论如何，这是代码的最后部分.一、Max/Restore按钮的创建:

Anyway, here are the final bits of code. First, the creation of the Max/Restore buttons:

WINDOWPLACEMENT   wp;
wp.length = sizeof(WINDOWPLACEMENT);
GetWindowPlacement(hWnd, &wp);
if(wp.showCmd==SW_SHOWNORMAL){    mII.wID=ID_MENUBAR_MAX;      mII.hbmpItem=hMBB.max; }
if(wp.showCmd==SW_SHOWMAXIMIZED){ mII.wID=ID_MENUBAR_RESTORE;  mII.hbmpItem=hMBB.restore; }
InsertMenuItem(hMenu, NUMMI+2, TRUE, &mII);

这里是命令的处理:

case ID_MENUBAR_MAX:
     SendMessage(hWnd, WM_SYSCOMMAND, SC_MAXIMIZE, 0);
     return 0;

case ID_MENUBAR_RESTORE:
     SendMessage(hWnd, WM_SYSCOMMAND, SC_RESTORE, 0);
     return 0;

最后，我通过挂钩WM_SYSCOMMAND 来处理菜单按钮的更改.这样，即使命令来自系统菜单或其他系统命令，按钮也会改变:

Finally, I handled the changing of the menu button by hooking WM_SYSCOMMAND. That way, the button would change, even if the command came through the system menu, or some other system command:

case WM_SYSCOMMAND: {
     auto sysResult = DefWindowProc(hWnd, WM_SYSCOMMAND, wParam, lParam);
     if(wParam==SC_MAXIMIZE) {
         mII.cbSize = sizeof(MENUITEMINFO);
         mII.fMask = MIIM_ID | MIIM_BITMAP;
         mII.wID = ID_MENUBAR_RESTORE;
         mII.hbmpItem = hMBB.restore;
         SetMenuItemInfo(hMenu, NUMMI+2, TRUE, &mII);
         DrawMenuBar(hWnd);
       }
      if(wParam==SC_RESTORE) {
          mII.cbSize = sizeof(MENUITEMINFO);
          mII.fMask = MIIM_ID | MIIM_BITMAP;
          mII.wID = ID_MENUBAR_MAX;
          mII.hbmpItem = hMBB.max;
          SetMenuItemInfo(hMenu, NUMMI+2, TRUE, &mII);
          DrawMenuBar(hWnd);
        }
       return sysResult;
 }

注意:每当向系统或非客户端命令添加任何内容时，调用 DefWindowProc 很重要.使用消息参数的命令标题.typedef auto 用于处理函数返回的任何变量.

Note: It is important to call DefWindowProc whenever adding anything to system or non-client commands. Use the command title for the message parameter. The typedef auto is used, to handle whatever variable that the function returns.

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