c++ - 如何单独处理子ListBox WndProc？

Question

我想在它自己的 wndproc 中处理所有 ListBox 消息传递，用于自己的透明项目绘画与 MainWindow 中显示的图像混合。不幸的是，现在只有 WM_PAINT、WM_ERASEBKGND 和一些 LB_* 消息，没有 WM_DRAWITEM 到达 ListWndProc。

代码是:

#include <windows.h>

bool InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    wc.style         = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_UPDATER));
    wc.hCursor       = 0;
    //wc.hbrBackground = (HBRUSH) GetStockObject(BLACK_BRUSH);
    wc.hbrBackground = CreatePatternBrush(LoadBitmap(hInstance, MAKEINTRESOURCE(IDB_BITMAP1)));
    wc.lpszMenuName  = 0;
    wc.lpszClassName = szWindowClass;

if(!RegisterClass(&wc)) { return FALSE; }

// MainWindow
g_hWndMain = CreateWindowEx(WS_EX_NOANIMATION, 
    szWindowClass, 
    szTitle, 
    WS_VISIBLE,
    CW_USEDEFAULT, 
    CW_USEDEFAULT, 
    CW_USEDEFAULT, 
    CW_USEDEFAULT, 
    NULL, 
    NULL, 
    hInstance, 
    NULL);

_ASSERT(g_hWndMain != NULL);

if (!g_hWndMain) { return FALSE; }

ShowWindow(g_hWndMain, nCmdShow);
UpdateWindow(g_hWndMain);

主窗口过程:

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message) 
    {
    case WM_CREATE:
        {
        g_hWndList = CreateWindowEx(0,
            _T("LISTBOX"), 
            NULL, 
            WS_CHILD | WS_VISIBLE | LBS_NOSEL | LBS_HASSTRINGS,
            10,     // Top X coord
            10,     // Top Y coord
            600,    // Width
            400,    // Height
            hWnd,
            NULL,
            g_hInst,
            NULL);

        _ASSERT(g_hWndList != NULL);
        defProcList = (WNDPROC)SetWindowLong(g_hWndList, GWL_WNDPROC, (LPARAM)(ListWndProc));

    }
}

列表框 wndproc:

LRESULT CALLBACK ListWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    case WM_ERASEBKGND:
    {
        return TRUE;
    }

    case WM_DRAWITEM:
    {
    }
    break;
}

Answer 1

来自 the documentation :

WM_DRAWITEM message

Sent to the parent window of an owner-drawn button, combo box, list box, or menu when a visual aspect of the button, combo box, list box, or menu has changed.

列表框不应该收到该消息，即使是所有者绘制的。它的父窗口，即您的主窗口，获取它们，因此您不必子类化列表框。