Question

I have a Tree View positioned in the content area of a Tab Control (the Tree View is a sibling of the Tab Control). When I remove tree view items, add new tree view items, and select one of them, the tree view is not painted correctly; everything above the newly created+selected item is gray. Is there any way to make the tree view paint everything properly after removing and inserting items?

Before replacing items After replacing items

Observations:

If there are few enough tree view items that no scroll bar appears, then the tree view looks OK.
If there is no tab control adjacent to the tree view, then the tree view looks OK.
If the tree view is a child of the tab control, then the tree view looks OK (but the Tab key can’t navigate between the Tab Control and the Tree View using GetNextDlgTabItem/IsDialogMessage).
If I don’t select any items in the Tree View after inserting new nodes, then the tree view looks OK.

When I insert items into the tree, I call TreeView_InsertItem followed by TreeView_SelectItem. Full sample gist. In the sample program, the Ctrl+R accelerator replaces all the tree nodes and causes the artifacts.

Answer 1

这里有错误：

ACCEL accel[1]***; //change to accel[2]
accel[0].fVirt = FCONTROL | FVIRTKEY;
accel[0].key = 'R';
accel[0].cmd = IDM_REGENERATETREE;
accel[1].fVirt = FCONTROL | FVIRTKEY;
accel[1].key = 'S';
accel[1].cmd = IDM_SELECTRANDOM;
HACCEL haccel = CreateAcceleratorTable(accel, 2);

尝试保存先前的项目状态时会导致显示问题。如果您从previousStates删除addTreeItem，则不会出现显示问题。要正确保存状态，您可能需要std :: map和每个树项的一些用户标识。至少你应该使用std :: vector来更容易理解。

为了获得更好的视觉效果，您可以将TVS_LINESATROOT添加到TreeView，将WS_CLIPCHILDREN添加到主窗口。

编辑：

不应在addTreeItem中保存以前的项目状态。例如，刚刚插入的新项目还没有子项，因此无法展开。简化addTreeItem如下：

HTREEITEM addTreeItem(HWND htree, HTREEITEM par, HTREEITEM after, LPCTSTR str, LPARAM lp) 
{
    TVINSERTSTRUCT tvins;
    tvins.hParent = par;
    tvins.hInsertAfter = after;
    tvins.itemex.mask = TVIF_TEXT | TVIF_PARAM;
    tvins.itemex.pszText = const_cast<LPTSTR>(str);
    tvins.itemex.lParam = lp;
    HTREEITEM node = TreeView_InsertItem(htree, &tvins);
    return node; 
}

要保存上一个项目状态，每个项目应具有不同的ID。正如在这个示例中项目的名称对于每个节点而言是不同的，我们可以将其用于地图。但如果这是一个目录结构，它将无法工作，我们必须使用fullpath而不是节点名称。

void RootWindow::RegenerateTree()
{
    if (!m_hwndTreeView) return;
    if (!IsWindow(m_hwndTreeView)) return;
    HWND hwnd = m_hwndTreeView;

    //this will stop treeview from updating after every insert
    SetWindowRedraw(hwnd, 0);

    std::map<std::wstring, UINT> state;
    const int maxtext = 260;
    wchar_t buf[maxtext];
    std::wstring selection;

    UINT count = TreeView_GetCount(hwnd);
    if (count)
    {
        for (HTREEITEM item = TreeView_GetRoot(hwnd); item; item = nextItem(hwnd, item))
        {
            TVITEM tv{ 0 };
            tv.mask = TVIF_TEXT | TVIF_STATE;
            tv.stateMask = TVIF_TEXT | TVIF_STATE;
            tv.cchTextMax = maxtext;
            tv.pszText = buf;
            tv.hItem = item;
            if (TreeView_GetItem(hwnd, &tv))
                state[buf] = TreeView_GetItemState(hwnd, item, 
                TVIS_SELECTED | TVIS_EXPANDED);
        }
    }
    TreeView_DeleteAllItems(hwnd);

    addTreeItem...
    addTreeItem...
    addTreeItem...

    //restore previous item state here:
    if (count)
    {
        for (HTREEITEM item = TreeView_GetRoot(hwnd); item; item = nextItem(hwnd, item))
        {
            TVITEM tvitem{ 0 };
            tvitem.hItem = item;
            tvitem.mask = TVIF_TEXT;
            tvitem.cchTextMax = maxtext;
            tvitem.pszText = buf;
            if (TreeView_GetItem(hwnd, &tvitem))
                TreeView_SetItemState(hwnd, item, state[buf], 
                TVIS_SELECTED | TVIS_EXPANDED);
        }
    }

    SetWindowRedraw(hwnd, 1);
}

How to fix paint artifacts when replacing items in Tree View?

1 个答案: