Demonstrates an issue with ListView_HitTest() when the header is displayed.

listview_hittest.cpp

/*********************************************************************************

  Demonstrates that ListView_HitTest() doesn't account for the header.

  If the mouse cursor is over the listview header and we translate the current 
  mouse cursor screen coordinates with ScreenToClient(hwndListView),
  the listview reports:
   * for the unscrolled view, hit on item 0,
   * for the scrolled view, hit on an item above the top visible item.
 
**********************************************************************************/

#include <windows.h>
#include <commctrl.h>
#include <tchar.h>
#include <windowsx.h>

#include <assert.h>

#pragma comment(lib, "comctl32")
#pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")
#pragma warning(disable : 4996)

HINSTANCE g_hInstance  = nullptr;
HWND      g_hMainFrame = nullptr;
HWND      g_hListView  = nullptr;

enum
{
    ID_ListView   = 1000,
    ID_TimerEvent = 10000,
};

void FatalError(LPCTSTR errorMessage)
{
    MessageBox(nullptr, errorMessage, _T("Fatal error"), MB_OK | MB_ICONERROR);
    exit(-1);
}

HWND CreateListView()
{
    HWND hListView = ::CreateWindow(WC_LISTVIEW,  _T(""), WS_CHILD | WS_VISIBLE | LVS_REPORT,
                         0, 0, 0, 0, g_hMainFrame, (HMENU)ID_ListView, g_hInstance, nullptr);
    if ( !hListView )
      FatalError(_T("Could not create the list view."));

    ListView_SetExtendedListViewStyle(hListView, LVS_EX_FULLROWSELECT | LVS_EX_ONECLICKACTIVATE | LVS_EX_UNDERLINEHOT);

    const size_t textSize = 1024;

    TCHAR    text[textSize];
    LVCOLUMN lvc = {};

    lvc.mask = LVCF_WIDTH | LVCF_TEXT;
    lvc.cx = 200;

    _tcscpy(text, _T("Item Column"));
    lvc.pszText = text;    
    if ( ListView_InsertColumn(hListView, 0, &lvc) == -1 )
        FatalError(_T("Could not create list view item column."));

    _tcscpy(text, _T("SubItem Column"));
    lvc.pszText = text;
    if ( ListView_InsertColumn(hListView, 1, &lvc) == -1 )
        FatalError(_T("Could not create list view subitem column."));

    LVITEM lvi = {};

    lvi.mask = LVIF_TEXT;

    for ( int i = 0; i < 10; ++i )
    {
        lvi.iItem  = i;

        _stprintf(text, _T("Item %d"), i);
        lvi.pszText = text;
        lvi.iSubItem  = 0;
        if ( ListView_InsertItem(hListView, &lvi) == -1 )
            FatalError(_T("Could not add list view item."));

        _stprintf(text, _T("SubItem %d"), i);
        lvi.pszText = text;
        lvi.iSubItem  = 1;
        if ( ListView_SetItem(hListView, &lvi) == -1 )
            FatalError(_T("Could not add list view subitem."));
    }

    return hListView;
}

LRESULT CALLBACK MainFrameWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

HWND CreateMainFrame()
{
    LPCTSTR className = _T("TestFrame");

    WNDCLASSEX wcex = {};

    wcex.cbSize         = sizeof(WNDCLASSEX);
    wcex.lpfnWndProc    = MainFrameWndProc;
    wcex.hInstance      = g_hInstance;
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszClassName  = className;

    if ( !RegisterClassEx(&wcex) )
        FatalError(_T("Could not register the class for the application window."));

    HWND hFrame = CreateWindow(className, _T("Test ListView_HitTest()"), WS_OVERLAPPEDWINDOW,
                    CW_USEDEFAULT, CW_USEDEFAULT, 800, 400, nullptr, nullptr, g_hInstance, nullptr);
    if ( !hFrame )
      FatalError(_T("Could not create the application window."));

    return hFrame;
}

void UpdateListItemInfo()
{
    const size_t  textSize = 1024;

    static DWORD msgPosPrev = (DWORD)-1;

    DWORD         msgPos = GetMessagePos();    
    POINT         mousePosScreen, mousePosClient;
    LVHITTESTINFO lvhti;
    TCHAR         infoText[textSize];
    int           itemHit;

    if ( msgPos == msgPosPrev )
        return;
    msgPosPrev = msgPos;
    mousePosScreen.x = GET_X_LPARAM(msgPos);
    mousePosScreen.y = GET_Y_LPARAM(msgPos);
    mousePosClient = mousePosScreen;
    ScreenToClient(g_hListView, &mousePosClient);
    lvhti.pt = mousePosClient;
    itemHit = ListView_HitTest(g_hListView, &lvhti);

    assert(itemHit == lvhti.iItem);

    if ( lvhti.iItem < 0 )
    {
        _stprintf(infoText, _T("Cursor (screen: %d, %d; client: %d, %d) is not over an item"), 
            mousePosScreen.x, mousePosScreen.y, mousePosClient.x, mousePosClient.y);
    }
    else
    {
        TCHAR itemText[textSize];
        RECT  itemRect;

        ListView_GetItemText(g_hListView, lvhti.iItem, 0, itemText, textSize)
        ListView_GetItemRect(g_hListView, lvhti.iItem, &itemRect, LVIR_BOUNDS);
        _stprintf(infoText, _T("Cursor (%d, %d) over item '%s' (index %d, rect %d, %d, %d, %d)"),
            mousePosClient.x, mousePosClient.y, itemText, lvhti.iItem, 
            itemRect.left, itemRect.top, itemRect.right, itemRect.bottom);
    }    
    SetWindowText(g_hMainFrame, infoText);    

    _stprintf(infoText, _T("Cursor screen: %d, %d\n"), mousePosScreen.x, mousePosScreen.y);
    OutputDebugString(infoText);
}

LRESULT CALLBACK MainFrameWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    const size_t textSize = 1024;
    TCHAR        text[textSize];
    RECT         r;
    POINT        p;

    auto LogRect = [&text, &r](LPCTSTR label)
    {
         _stprintf(text, _T("%s: %d, %d, %d, %d\n"), label, r.left, r.top, r.right, r.bottom);
         OutputDebugString(text);
    };

    switch ( message )
    {
        case WM_SIZE:
            MoveWindow(g_hListView, 0, 0, LOWORD(lParam), HIWORD(lParam), TRUE);
            GetWindowRect(g_hListView, &r);
            LogRect(_T("ListView WindowRect"));
            ListView_GetViewRect(g_hListView, &r);
            LogRect(_T("ListView ViewRect  "));
            ListView_GetOrigin(g_hListView, &p);
            _stprintf(text, _T("ListView Origin: %d, %d\n"), p.x, p.y);
            OutputDebugString(text);
            break;

        case WM_TIMER:
            UpdateListItemInfo();
            break;

        case WM_DESTROY:
            PostQuitMessage(0);
            break;

        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
    }

    return 0;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR, int nCmdShow)
{
    g_hInstance = hInstance;
    SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);

    INITCOMMONCONTROLSEX icex = {};

    icex.dwICC = ICC_LISTVIEW_CLASSES;
    InitCommonControlsEx(&icex);

    g_hMainFrame = CreateMainFrame();
    g_hListView = CreateListView();
    ShowWindow(g_hMainFrame, nCmdShow);
    UpdateWindow(g_hMainFrame);

    UINT_PTR timerID = SetTimer(g_hMainFrame, ID_TimerEvent, 25, nullptr);

    if ( !timerID )
        FatalError(_T("Could not create the timer."));

    // run the message pump
    MSG msg;

    while ( GetMessage(&msg, nullptr, 0, 0) )
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    KillTimer(g_hMainFrame, timerID);

    return (int)msg.wParam;
}