Develop Reference

Scrolling cause flickering when controlling MouseWheel events

I'm trying to understand what is executing before the MouseWheel event.
What I've done:
I have a form which has AutoScroll property set to true. There is a control (ZEDGRAPH) at the top and the bottom of this form.
To overcome the issue of scrolling and zooming at the same time I captured the mousewheel += new MouseEvenHandler(mymethod) for the form.Then using a bool variable I keep track of when the control (ZEDGRAPH) has focus and when it does not.
When it has focus I make verticalscroll.value = (int)mydesiredposition;
This works in accomplishing what I wanted which is to ignore the mousewheel event in the form and focus on the control.
What I am struggling with is the fact that when I scroll the form flickers every time and scrolls down before coming to the set scrollbar value.
So what I am wondering is what is getting triggered before this mouseeventhandler that causes it to flicker and is there a relatively simple workaround this?
My code snapshot:
public Form(Form1 f)
{
InitializeComponent();
this.MouseWheel += new MouseEventHandler(mousewheel);
}//end of constructor
//
//
bool mousehoverZedGraph1 = false;
bool mousehoverZedGraph2 = false;
//
//
private void zedGraphControl1_MouseHover(object sender, EventArgs e)
{
mousehoverZedGraph1 = true;
return;
}
private void mousewheel(object sender, MouseEventArgs e)
{
if (mousehoverZedGraph1 == true)
{
VerticalScroll.Enabled = false;
VerticalScroll.Value = 0;
return;
}
else if (mousehoverZedGraph2 == true)
{
VerticalScroll.Value = 429;
VerticalScroll.Enabled = false;
}
else
{
//VerticalScroll.Value += e.Delta;
}
}
private void Form_MouseEnter(object sender, EventArgs e)
{
mousehoverZedGraph1 = mousehoverZedGraph2 = false;
VerticalScroll.Enabled = true;
}
A small video highlighting the flicker:

WinForms User Control has ComboBox that causes ToolStripDropDown to auto-close

I have a custom WinForms user control that looks like a combobox but instead opens a ToolStripDropDown that contains another custom user control, called NumericFilterPanel, that has a checkbox, a combobox, and a textbox.
The problem is that when the user click-selects an option for the combobox embedded in the dropdown control, it causes the parent dropdown to hide.
I have set ToolStripDropDown.AutoClose = false, which fixes the original problem, but now I am having difficulty detecting all the situations where the dropdown loses focus, such as when the user clicks on the parent form or switches programs. Sometimes the dropdown remains visible and topmost.
Is there a way to either keep AutoClose = true and prevent the embedded combobox from closing the parent dropdown, or is there a way to always detect when the dropdown has lost focus so I can manually close it?
using System;
using System.Drawing;
using System.Windows.Forms;
namespace mviWinControls
{
public partial class NumericRangeDropDown : UserControl
{
private const int ARROW_HEIGHT = 4;
private Brush arrowBrush = new SolidBrush(Color.FromArgb(77, 97, 133));
private ToolStripDropDown _dropdown;
private ToolStripControlHost _host;
private NumericFilterPanel _filter;
public NumericRangeDropDown()
{
InitializeComponent();
_filter = new NumericFilterPanel();
_filter.DropDown = this;
_host = new ToolStripControlHost(_filter);
_host.Margin = Padding.Empty;
_host.Padding = Padding.Empty;
_dropdown = new ToolStripDropDown();
_dropdown.Margin = Padding.Empty;
_dropdown.Padding = Padding.Empty;
_dropdown.AutoClose = false; // Use this because panel has a combobox. https://social.msdn.microsoft.com/Forums/windows/en-US/dd95b982-820e-4807-8a1f-79c74acab3f8/two-problems-toolstripdropdown?forum=winforms
_dropdown.Items.Add(_host);
_dropdown.Leave += new System.EventHandler(this.DropDown_Leave);
this.Leave += new System.EventHandler(this.DropDown_Leave);
}
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (components != null) components.Dispose();
if (_dropdown != null) _dropdown.Dispose();
}
base.Dispose(disposing);
}
public override string Text
{
get
{
return base.Text;
}
set
{
base.Text = value;
_filter.SetValue(value);
}
}
protected override void OnPaint(PaintEventArgs e)
{
//base.OnPaint(e);
TextBox _txtDraw = new TextBox();
_txtDraw.Width = this.Width;
using (Bitmap bmp = new Bitmap(_txtDraw.Width, _txtDraw.Height))
{
_txtDraw.DrawToBitmap(bmp, new Rectangle(0, 0, _txtDraw.Width, _txtDraw.Height));
e.Graphics.DrawImage(bmp, 0, 0);
}
StringFormat format = new StringFormat();
format.Alignment = StringAlignment.Near;
format.FormatFlags = StringFormatFlags.NoWrap;
format.LineAlignment = StringAlignment.Center;
using (Brush b = new SolidBrush(this.ForeColor))
e.Graphics.DrawString(this.Text, this.Font, b, this.DisplayRectangle, format);
Point[] arrowPoints = new Point[] { new Point(this.Width - ARROW_HEIGHT * 3 - 2, (this.Height - ARROW_HEIGHT) / 2),
new Point(this.Width - ARROW_HEIGHT + 1 - 2, (this.Height - ARROW_HEIGHT) / 2),
new Point(this.Width - ARROW_HEIGHT * 2 - 2, this.Height - (this.Height - ARROW_HEIGHT) / 2) };
e.Graphics.FillPolygon(arrowBrush, arrowPoints );
}
private void DropDown_Leave(object sender, EventArgs e)
{
HideDropDown();
this.Text = _filter.SummaryText();
}
private void NumericRangeDropDown_Click(object sender, EventArgs e)
{
if (_dropdown.Visible)
HideDropDown();
else
ShowDropDown();
}
public void ShowDropDown()
{
_dropdown.Show(this, new Point(0, this.Height), ToolStripDropDownDirection.Default);
_dropdown.BringToFront();
//_dropdown.Focus();
_filter.Select();
_filter.Focus();
}
public void HideDropDown()
{
_dropdown.Close();
this.Invalidate();
}
}
}

Here's a combobox that can automatically disable and enable the AutoClose property on the host control for you.
Source(I modified it for a combobox versus the DatePicker in their example): http://www.queasy.me/programming/questions/13919634/tool+strip+toolstripdropdownbutton+close+and+lose+window+focus
public partial class CComboBox : ComboBox
{
private bool savedAutoClose;
public CComboBox()
{
InitializeComponent();
}
protected override void OnDropDownClosed(EventArgs e)
{
if (this.Parent != null)
{
var dropDownHost = this.Parent.Parent as ToolStripDropDown; // recursive instead?
if (dropDownHost != null)
dropDownHost.AutoClose = savedAutoClose; // restore the parent's AutoClose preference
}
base.OnDropDownClosed(e);
}
protected override void OnDropDown(EventArgs e)
{
if (this.Parent != null)
{
var dropDownHost = this.Parent.Parent as ToolStripDropDown; // recursive instead?
if (dropDownHost != null)
{
savedAutoClose = dropDownHost.AutoClose;
// ensure that our parent doesn't close while the calendar is open
dropDownHost.AutoClose = false;
}
}
base.OnDropDown(e);
}
}

Having taken a good look at the source code, the bug (and it is a bug) lies in the fact that ToolStripManager, which sets up a message filter to catch mouse-clicks outside the active ToolStrip, checks if the click is within the bounds of a child window.
The problem is that it uses activeToolStrip.ClientRectangle to verify this, and does not check child windows of the window that was clicked. In the case of a ComboBox, the drop-down is a separate child window which floats above everything, and can actually be out of the bounds of the main combo window if the drop-down is large.
The relevant line is:
if (!activeToolStrip.ClientRectangle.Contains(pt.x, pt.y)) {
I have found another solution to temporarily disable the automatic close while the dropdown is open.
Ideally, you are supposed to use a ToolStripComboBox within a ToolStrip rather than just a bare ComboBox. However if you would like to just us a bare one, you can add events to call the relevant private methods to suspend and resume the message filter.
static class ToolStripComboBoxFilter
{
private static Action SuspendMenuMode = (Action) typeof(ToolStripManager)
.GetNestedType("ModalMenuFilter", BindingFlags.NonPublic)
.GetMethod(nameof(SuspendMenuMode), BindingFlags.NonPublic | BindingFlags.Static)
.CreateDelegate(typeof(Action));
private static Action ResumeMenuMode = (Action)typeof(ToolStripManager)
.GetNestedType("ModalMenuFilter", BindingFlags.NonPublic)
.GetMethod(nameof(ResumeMenuMode), BindingFlags.NonPublic | BindingFlags.Static)
.CreateDelegate(typeof(Action));
public static void AddToolStripFilterEvents(this ComboBox combo)
{
combo.DropDown += OnDropDown;
combo.DropDownClosed += OnDropDownClosed;
}
private static void OnDropDown(object sender, EventArgs e)
{
SuspendMenuMode();
}
private static void OnDropDownClosed(object sender, EventArgs e)
{
ResumeMenuMode();
}
}
You can use it like this
myComboBox.AddToolStripFilterEvents();

Custom ComboBox not closing properly

I am trying to make my custom ComboBox inheriting from ContainerControl. I used this article as a base but rewrote it, but I use a ToolStripControlHost, my own custom ListBox & a ToolStripDropDown.
Now the ComboBox is a button where you click on to show the DropDowncontaining my ListBox, works fine with overriding OnMouseClick.
The problems starts when I try to close the DropDown, with the DropDown's 'AutoClose' property to true, the DropDown closes if you click somewhere outside the DropDown (including the button) ...
protected override void OnMouseClick(MouseEventArgs e)
{
base.OnMouseClick(e);
/* listboxControl = ToolStripDropDown */
if (!listboxControl.Visible)
{
listboxControl.Show(this, GetDropLocation(), ToolStripDropDownDirection.BelowRight);
//listbox.Capture = true;
}
}
This is the code for the click on the button .. so what happens if you click it ?
If the DropDown is shown, it first closes the DropDown, then it fires the OnMouseClick event. Meaning: listboxControl.Visible is already false & it will show the DropDown again. All of this causing a quick close-open.
I have been stuck with this problem for some time now and google doesn't seem to know a lot about this subject (that article on CodeProject has the same bug).
What I have tried is disabling AutoClose and capturing the mouse after I show the DropDown, this works partially but it affects the working of my hosted ListBox. The ListBox contains a set of controls (the items), these items have a hover paint effect. Capturing the mouse in the ListBox control prevents the OnMouseEnter to be fired.
All input would be greatly appreciated !

You need a variable to track the cursor position when the DropDown is closing.
Here is a quick and dirty example control:
public class CustomDropBox : Control {
private ListBox box = new ListBox() { IntegralHeight = false };
private ToolStripControlHost host;
private ToolStripDropDown drop;
private bool wasShowing = false;
public CustomDropBox() {
box.MinimumSize = new Size(120, 120);
box.MouseUp += box_MouseUp;
box.KeyPress += box_KeyPress;
box.Items.AddRange(new string[] { "aaa", "bbb", "ccc" });
host = new ToolStripControlHost(box) { Padding = Padding.Empty };
drop = new ToolStripDropDown() { Padding = Padding.Empty };
drop.Closing += drop_Closing;
drop.Items.Add(host);
}
private Rectangle GetDownRectangle() {
return new Rectangle(this.ClientSize.Width - 16, 0, 16, this.ClientSize.Height);
}
void drop_Closing(object sender, ToolStripDropDownClosingEventArgs e) {
if (e.CloseReason == ToolStripDropDownCloseReason.AppClicked) {
wasShowing = GetDownRectangle().Contains(this.PointToClient(Cursor.Position));
} else {
wasShowing = false;
}
}
void box_KeyPress(object sender, KeyPressEventArgs e) {
if (e.KeyChar == (char)Keys.Enter && box.SelectedIndex > -1) {
drop.Close();
}
}
void box_MouseUp(object sender, MouseEventArgs e) {
int index = box.IndexFromPoint(e.Location);
if (index > -1) {
drop.Close();
}
}
protected override void OnMouseDown(MouseEventArgs e) {
if (e.Button == MouseButtons.Left && GetDownRectangle().Contains(e.Location)) {
if (wasShowing) {
wasShowing = false;
} else {
drop.Show(this, new Point(0, this.Height));
}
}
base.OnMouseDown(e);
}
protected override void OnPaint(PaintEventArgs e) {
e.Graphics.Clear(Color.White);
ControlPaint.DrawComboButton(e.Graphics, GetDownRectangle(), ButtonState.Normal);
base.OnPaint(e);
}
}

How to prevent tooltip from flickering in custom control?

I have made a custom control and when a condition is met, I want to show a tooltip:
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
var plannedItem = GetPlannedItemByPosition(e.Location);
if (plannedItem != null)
_tooltip.SetToolTip(this, plannedItem.Description);
else
_tooltip.RemoveAll();
}
This code works fine, excepts for the face that the tooltip flickers.
This custom control, paints all the information in the OnPaint event, maybe this has something to do with it? And if it does, how can I prevent the tooltip from flickering?

Remember last mouse position and set the tooltip only when the mouse position changes.
public partial class Form1 : Form
{
private int lastX;
private int lastY;
private void button1_MouseMove(object sender, MouseEventArgs e)
{
if (e.X != this.lastX || e.Y != this.lastY)
{
toolTip1.SetToolTip(button1, "test");
this.lastX = e.X;
this.lastY = e.Y;
}
}

This will happen when you display the tooltip at the mouse cursor position. As soon as the tip window shows up, Windows notices that the mouse is located in that window and posts a MouseMove message. Which makes the tooltip disappear. Which makes Windows send a MouseMove message to your control, running your OnMouseMove() method. Which makes the tooltip appear again. Etcetera, you'll see the tooltip rapidly flickering.
Solve this by any of the following methods:
show the tooltip well away from the mouse position so it won't overlap the mouse cursor
only update/show the tooltip when it needs to be changed
set the control's Capture property to true so the tooltip won't get a MouseMove message

Since this is a painted custom control, I think it might be easier to just have a variable hold the last shown tip, and instead of always "setting" the tooltip, just show it.
Simple example (using just a form):
public partial class Form1 : Form {
private List<TipRect> _Tips = new List<TipRect>();
private TipRect _LastTip;
private ToolTip _tooltip = new ToolTip();
public Form1() {
InitializeComponent();
_Tips.Add(new TipRect(new Rectangle(32, 32, 32, 32), "Tip #1"));
_Tips.Add(new TipRect(new Rectangle(100, 100, 32, 32), "Tip #2"));
}
private void Form1_Paint(object sender, PaintEventArgs e) {
foreach (TipRect tr in _Tips)
e.Graphics.FillRectangle(Brushes.Red, tr.Rect);
}
private void Form1_MouseMove(object sender, MouseEventArgs e) {
TipRect checkTip = GetTip(e.Location);
if (checkTip == null) {
_LastTip = null;
_tooltip.Hide(this);
} else {
if (checkTip != _LastTip) {
_LastTip = checkTip;
_tooltip.Show(checkTip.Text, this, e.Location.X + 10, e.Location.Y + 10, 1000);
}
}
}
private TipRect GetTip(Point p) {
TipRect value = null;
foreach (TipRect tr in _Tips) {
if (tr.Rect.Contains(p))
value = tr;
}
return value;
}
}
Here is the TipRect class I created to simulate whatever your PlannedItem class is:
public class TipRect {
public Rectangle Rect;
public string Text;
public TipRect(Rectangle r, string text) {
Rect = r;
Text = text;
}
}

I imagine your mouse does move a little when you think it is still. I suggest you do some kind of caching here - only call _tooltip.SetToolTip if the plannedItem has changed.

For the visitors of this thread, here is what I did, following suggestions above (VB.NET):
Dim LastToolTip As String
Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
Dim NewToolTip = CalculateTooltipText(e.X, e.Y)
If LastToolTip <> NewToolTip Then
ToolTip1.SetToolTip(PictureBox1, NewToolTip)
LastToolTip = NewToolTip
End If
End Sub
It stopped the flickering.

c# (works on tooltip chart):
Point mem = new Point();
private void xxx_MouseMove(MouseEventArgs e){
// start
Point pos = e.Location;
if (pos == mem) { return; }
// your code here
// end
mem = pos
}

How to make image button

I was wondering how could I do this. I know I can use the button component but it has the little gray stuff around it when I give it a image. With image button how could I show another image for the hover effect

You want to create a button with no border but displays different images when the user hovers over it with the mouse? Here's how you can do it:
Add an ImageList control to your form at add two images, one for the button's normal appearance and one for when the mouse is hovering over.
Add your button and set the following properties:
FlatStyle = Flat
FlatAppearance.BorderColor (and maybe MouseOverBackColor & MouseDownBackColor) to your form's background color
ImageList = the ImageList you added to the form
ImageIndex to the index value of your normal image
Code the MouseHover and MouseLeave events for the button like this:
// ImageList index value for the hover image.
private void button1_MouseHover(object sender, EventArgs e) => button1.ImageIndex = 1;
// ImageList index value for the normal image.
private void button1_MouseLeave(object sender, EventArgs e) => button1.ImageIndex = 0;
I believe that will give you the visual effect you're looking for.

Small summary (Border, MouseDownBackColor, MouseOverBackColor)
FlatApperance
BorderColor = Black or what ever you want
BorderSize = can be set to 0
MouseDownBackColor = Transparent
MouseOverBackColor = Transparent
Text = none
For MouseDown:
// ImageList index value for the mouse down image.
private void button1_MouseDown(object sender, MouseEventArgs e) => button1.ImageIndex = 2;

You can assign the BackgroundImage property for the button. You can also use the OnMouseEnter and OnMouseExit events to change the background as per your request.
See BackgroundImage OnMouseEnter OnMouseLeave

I also needed an image button, but I wanted one like the ToolstripMenuButton.
With the correct borders and colors on hover.
So I made a custom control to do just that:
using System;
using System.ComponentModel;
using System.Windows.Forms;
namespace LastenBoekInfrastructure.Controls.Controls
{
[DefaultEvent("Click")]
public class ImageButton : UserControl
{
public string ToolTipText
{
get { return _bButton.ToolTipText; }
set { _bButton.ToolTipText = value; }
}
public bool CheckOnClick
{
get { return _bButton.CheckOnClick; }
set { _bButton.CheckOnClick = value; }
}
public bool DoubleClickEnabled
{
get { return _bButton.DoubleClickEnabled; }
set { _bButton.DoubleClickEnabled = value; }
}
public System.Drawing.Image Image
{
get { return _bButton.Image; }
set { _bButton.Image = value; }
}
public new event EventHandler Click;
public new event EventHandler DoubleClick;
private ToolStrip _tsMain;
private ToolStripButton _bButton;
public ImageButton()
{
InitializeComponent();
}
private void InitializeComponent()
{
var resources = new ComponentResourceManager(typeof(ImageButton));
_tsMain = new ToolStrip();
_bButton = new ToolStripButton();
_tsMain.SuspendLayout();
SuspendLayout();
//
// tsMain
//
_tsMain.BackColor = System.Drawing.Color.Transparent;
_tsMain.CanOverflow = false;
_tsMain.Dock = DockStyle.Fill;
_tsMain.GripMargin = new Padding(0);
_tsMain.GripStyle = ToolStripGripStyle.Hidden;
_tsMain.Items.AddRange(new ToolStripItem[] {
_bButton});
_tsMain.Location = new System.Drawing.Point(0, 0);
_tsMain.Name = "_tsMain";
_tsMain.Size = new System.Drawing.Size(25, 25);
_tsMain.TabIndex = 0;
_tsMain.Renderer = new ImageButtonToolStripSystemRenderer();
//
// bButton
//
_bButton.DisplayStyle = ToolStripItemDisplayStyle.Image;
_bButton.Image = ((System.Drawing.Image)(resources.GetObject("_bButton.Image")));
_bButton.ImageTransparentColor = System.Drawing.Color.Magenta;
_bButton.Name = "_bButton";
_bButton.Size = new System.Drawing.Size(23, 22);
_bButton.Click += bButton_Click;
_bButton.DoubleClick += bButton_DoubleClick;
//
// ImageButton
//
Controls.Add(_tsMain);
Name = "ImageButton";
Size = new System.Drawing.Size(25, 25);
_tsMain.ResumeLayout(false);
_tsMain.PerformLayout();
ResumeLayout(false);
PerformLayout();
}
void bButton_Click(object sender, EventArgs e)
{
if (Click != null)
{
Click(this, e);
}
}
void bButton_DoubleClick(object sender, EventArgs e)
{
if(DoubleClick != null)
{
DoubleClick(this, e);
}
}
public class ImageButtonToolStripSystemRenderer : ToolStripSystemRenderer
{
protected override void OnRenderToolStripBorder(ToolStripRenderEventArgs e)
{
//base.OnRenderToolStripBorder(e);
}
}
}
}