Flickering in ListView control (OwnerDraw, Virtual)

This question might be considered a follow-up to Flickering in listview with ownerdraw and virtualmode.

I've got a ListView control in Virtual mode and I attempt to perform custom drawing. Item rendering is done via the following method override:

protected override void OnDrawItem(DrawListViewItemEventArgs eventArgs)

As mentioned in the referenced question, custom drawing introduces flickering on mouse over events. Debugger tells me this happens due to an excessive amount of custom draw events which are fired.

Now - the accepted answer to the referenced question tells us:

This is a bug in .NET's ListView and you cannot get around it by double buffering.

So, how reliable is that information? Is that really a bug? Or maybe we simply attempt to cut off a part of the messages and hope that it won't alter the visible behavior?
Is this true that if I have my owner drawing routine for the ListView in Virtual Mode, I can suppress these Custom Draw events and only perform my drawing in WM_PAINT or, maybe, this is incorrect for some cases?
What are the prerequisities for the System.Windows.Forms control to be able to do all the painting in WM_PAINT without altering it's initial behavior?

I've seen this flickering issue with ListView control in any custom rendering event handlers (DrawItem, DrawSubItem). I tried BeginUpdate()/EndUpdate() and double buffering with no success. I think .NET triggers additional WM_PAINT to all columns to the right of the custom drawn column.

However I found this workaround to a single custom rendered column ListView. It works just fine!

In the columnheader editor, set the custom drawn column as the last column
Change the "DisplayIndex" of the position you want

This should solve the flickering in mouseover or run-time rendering.

At least for double buffering for OnDrawItem, it is incorrect that there is a bug, but it is a little bit stupid: there is a protected attribute you can set, but you need to override the ListView. I created this kind of class:

public class MyListView : ListView
{
    public MyListView()
        : base()
    {
        DoubleBuffered = true;
    }
}

And then in my MyForm.Designer.cs file I change the instantiation of the ListView with the following line:

private ListView myListView;

this.myListView = new MyListView();

And OnDrawItem will work like a charm!

Writwick

Like This Answer in Here, though not sure but,

I think that ListView.BeginUpdate() and ListView.EndUpdate() will solve the problem.

MSDN Thread about This

Maybe In This Way :

protected override void OnDrawItem(DrawListViewItemEventArgs eventArgs)
{
    ListView.BeginUpdate();
    //Do Works Here
    ListView.EndUpdate();
}

Update

Another Alternative may be using a new Thread in BackgroundWorker to Update the ListView... I implemented this along with BeginUpdate()/EndUpDate() in my application and found it relatively faster than only the BeginUpdate()/EndUpDate()..

Update

I found another working Solution at SO, a Helper class provided by Brian Gillespie :

public enum ListViewExtendedStyles
{
    /// <summary>
    /// LVS_EX_GRIDLINES
    /// </summary>
    GridLines = 0x00000001,
    /// <summary>
    /// LVS_EX_SUBITEMIMAGES
    /// </summary>
    SubItemImages = 0x00000002,
    /// <summary>
    /// LVS_EX_CHECKBOXES
    /// </summary>
    CheckBoxes = 0x00000004,
    /// <summary>
    /// LVS_EX_TRACKSELECT
    /// </summary>
    TrackSelect = 0x00000008,
    /// <summary>
    /// LVS_EX_HEADERDRAGDROP
    /// </summary>
    HeaderDragDrop = 0x00000010,
    /// <summary>
    /// LVS_EX_FULLROWSELECT
    /// </summary>
    FullRowSelect = 0x00000020,
    /// <summary>
    /// LVS_EX_ONECLICKACTIVATE
    /// </summary>
    OneClickActivate = 0x00000040,
    /// <summary>
    /// LVS_EX_TWOCLICKACTIVATE
    /// </summary>
    TwoClickActivate = 0x00000080,
    /// <summary>
    /// LVS_EX_FLATSB
    /// </summary>
    FlatsB = 0x00000100,
    /// <summary>
    /// LVS_EX_REGIONAL
    /// </summary>
    Regional = 0x00000200,
    /// <summary>
    /// LVS_EX_INFOTIP
    /// </summary>
    InfoTip = 0x00000400,
    /// <summary>
    /// LVS_EX_UNDERLINEHOT
    /// </summary>
    UnderlineHot = 0x00000800,
    /// <summary>
    /// LVS_EX_UNDERLINECOLD
    /// </summary>
    UnderlineCold = 0x00001000,
    /// <summary>
    /// LVS_EX_MULTIWORKAREAS
    /// </summary>
    MultilWorkAreas = 0x00002000,
    /// <summary>
    /// LVS_EX_LABELTIP
    /// </summary>
    LabelTip = 0x00004000,
    /// <summary>
    /// LVS_EX_BORDERSELECT
    /// </summary>
    BorderSelect = 0x00008000,
    /// <summary>
    /// LVS_EX_DOUBLEBUFFER
    /// </summary>
    DoubleBuffer = 0x00010000,
    /// <summary>
    /// LVS_EX_HIDELABELS
    /// </summary>
    HideLabels = 0x00020000,
    /// <summary>
    /// LVS_EX_SINGLEROW
    /// </summary>
    SingleRow = 0x00040000,
    /// <summary>
    /// LVS_EX_SNAPTOGRID
    /// </summary>
    SnapToGrid = 0x00080000,
    /// <summary>
    /// LVS_EX_SIMPLESELECT
    /// </summary>
    SimpleSelect = 0x00100000
}

public enum ListViewMessages
{
    First = 0x1000,
    SetExtendedStyle = (First + 54),
    GetExtendedStyle = (First + 55),
}

/// <summary>
/// Contains helper methods to change extended styles on ListView, including enabling double buffering.
/// Based on Giovanni Montrone's article on <see cref="http://www.codeproject.com/KB/list/listviewxp.aspx"/>
/// </summary>
public class ListViewHelper
{
    private ListViewHelper()
    {
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern int SendMessage(IntPtr handle, int messg, int wparam, int lparam);

    public static void SetExtendedStyle(Control control, ListViewExtendedStyles exStyle)
    {
        ListViewExtendedStyles styles;
        styles = (ListViewExtendedStyles)SendMessage(control.Handle, (int)ListViewMessages.GetExtendedStyle, 0, 0);
        styles |= exStyle;
        SendMessage(control.Handle, (int)ListViewMessages.SetExtendedStyle, 0, (int)styles);
    }

    public static void EnableDoubleBuffer(Control control)
    {
        ListViewExtendedStyles styles;
        // read current style
        styles = (ListViewExtendedStyles)SendMessage(control.Handle, (int)ListViewMessages.GetExtendedStyle, 0, 0);
        // enable double buffer and border select
        styles |= ListViewExtendedStyles.DoubleBuffer | ListViewExtendedStyles.BorderSelect;
        // write new style
        SendMessage(control.Handle, (int)ListViewMessages.SetExtendedStyle, 0, (int)styles);
    }
    public static void DisableDoubleBuffer(Control control)
    {
        ListViewExtendedStyles styles;
        // read current style
        styles = (ListViewExtendedStyles)SendMessage(control.Handle, (int)ListViewMessages.GetExtendedStyle, 0, 0);
        // disable double buffer and border select
        styles -= styles & ListViewExtendedStyles.DoubleBuffer;
        styles -= styles & ListViewExtendedStyles.BorderSelect;
        // write new style
        SendMessage(control.Handle, (int)ListViewMessages.SetExtendedStyle, 0, (int)styles);
    }
}

来源：https://stackoverflow.com/questions/10484265/flickering-in-listview-control-ownerdraw-virtual

标签

winforms

listview

flicker

ownerdrawn