Develop Reference

Disable all mouse messages on control

I have a graph control that plots data points. The data points are plotted as 1 point per pixel. If the number of data points get larger than a certain amount, or the size of the window is increased the performance of the plotting when you move your mouse over the control suffers. If you move quickly the plotting actually stops during the motion.
Is there a way to disable all the messages when the mouse is over that control except for button clicks?
I have not been able to find anything.

Based on your description, I believe that it should be sufficient to filter out MouseMove messages sent to the control. This can be accomplished by having the Form implement IMessageFilter similar to the example presented below. Returning true from IMessageFilter.PreFilterMessage prevents the message from being sent to the control (a panel in the example). A registered filter is active application wide, so it is added/removed when the form actives/deactivates.
public partial class Form1 : Form, IMessageFilter
{
private Panel pnl;
public Form1()
{
InitializeComponent();
pnl = new Panel { Size = new Size(200, 200), Location = new Point(20, 20), BackColor = Color.Aqua };
Controls.Add(pnl);
pnl.Click += panel_Click;
pnl.MouseMove += panel_MouseMove;
pnl.MouseHover += panel_MouseHover;
}
private void panel_MouseHover(sender As Object, e As EventArgs)
{
// this should not occur
throw new NotImplementedException();
}
private void panel_MouseMove(object sender, MouseEventArgs e)
{
// this should not occur
throw new NotImplementedException();
}
private void panel_Click(object sender, EventArgs e)
{
MessageBox.Show("panel clicked");
}
protected override void OnActivated(EventArgs e)
{
base.OnActivated(e);
// install message filter when form activates
Application.AddMessageFilter(this);
}
protected override void OnDeactivate(EventArgs e)
{
base.OnDeactivate(e);
// remove message filter when form deactivates
Application.RemoveMessageFilter(this);
}
bool IMessageFilter.PreFilterMessage(ref Message m)
{
bool handled = false;
if (m.HWnd == pnl.Handle && (WM) m.Msg == WM.MOUSEMOVE)
{
handled = true;
}
return handled;
}
public enum WM : int
{
#region Mouse Messages
MOUSEFIRST = 0x200,
MOUSEMOVE = 0x200,
LBUTTONDOWN = 0x201,
LBUTTONUP = 0x202,
LBUTTONDBLCLK = 0x203,
RBUTTONDOWN = 0x204,
RBUTTONUP = 0x205,
RBUTTONDBLCLK = 0x206,
MBUTTONDOWN = 0x207,
MBUTTONUP = 0x208,
MBUTTONDBLCLK = 0x209,
MOUSELAST = 0x209
#endregion
}
}

Move Item from one cell to another

I have a tableLayoutPanel with 16 cells. 15 of the cells have controls. I want to be able to move the controls from one cell to another at runtime.
I have used
private void button15_Click(object sender, EventArgs e)
{
tableLayoutPanel1.Controls.Remove(button15);
tableLayoutPanel1.Controls.Add(button15, 3, 3);
}
This works well but i want to know if there is any better way to do this???

In Winforms, you can only move a control inside its parent (of course there are some exceptions to some controls which in fact don't have any Parent). So the idea here is if you want to move a control of your TableLayoutPanel, you have to set its Parent to your Form of another container when mouse is held down, when moving, the position of the control is in the new parent, after mouse is released, we have to set the Parent of the control to the TableLayoutPanel back, of course we have to find the drop-down cell position and use SetCellPosition method to position the control on the TableLayoutPanel, here is the demo code for you (works great), I use 2 Buttons in this demo, you can replace them with any control you want:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
//This will prevent flicker
typeof(TableLayoutPanel).GetProperty("DoubleBuffered", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance).SetValue(tableLayoutPanel1, true, null);
}
Point downPoint;
bool moved;
//This is used to store the CellBounds together with the Cell position
//so that we can find the Cell position later (after releasing mouse).
Dictionary<TableLayoutPanelCellPosition, Rectangle> dict = new Dictionary<TableLayoutPanelCellPosition, Rectangle>();
//MouseDown event handler for all your controls (on the tableLayoutPanel1)
private void Buttons_MouseDown(object sender, MouseEventArgs e) {
Control button = sender as Control;
button.Parent = this;
button.BringToFront();
downPoint = e.Location;
}
//MouseMove event handler for all your controls (on the tableLayoutPanel1)
private void Buttons_MouseMove(object sender, MouseEventArgs e) {
Control button = sender as Control;
if (e.Button == MouseButtons.Left) {
button.Left += e.X - downPoint.X;
button.Top += e.Y - downPoint.Y;
moved = true;
tableLayoutPanel1.Invalidate();
}
}
//MouseUp event handler for all your controls (on the tableLayoutPanel1)
private void Buttons_MouseUp(object sender, MouseEventArgs e) {
Control button = sender as Control;
if (moved) {
SetControl(button, e.Location);
button.Parent = tableLayoutPanel1;
moved = false;
}
}
//This is used to set the control on the tableLayoutPanel after releasing mouse
private void SetControl(Control c, Point position) {
Point localPoint = tableLayoutPanel1.PointToClient(c.PointToScreen(position));
var keyValue = dict.FirstOrDefault(e => e.Value.Contains(localPoint));
if (!keyValue.Equals(default(KeyValuePair<TableLayoutPanelCellPosition, Rectangle>))) {
tableLayoutPanel1.SetCellPosition(c, keyValue.Key);
}
}
//CellPaint event handler for your tableLayoutPanel1
private void tableLayoutPanel1_CellPaint(object sender, TableLayoutCellPaintEventArgs e) {
dict[new TableLayoutPanelCellPosition(e.Column, e.Row)] = e.CellBounds;
if (moved) {
if (e.CellBounds.Contains(tableLayoutPanel1.PointToClient(MousePosition))) {
e.Graphics.FillRectangle(Brushes.Yellow, e.CellBounds);
}
}
}
}

Remove Lock & set dock to none and move!

2D Array of RectangleShapes

I am developing a very rudimentary drawing program: A 2D grid comprised of multiple RectangleShapes, around 20x30 pixels each, which when clicked change color based on user RGB input, which works just fine:
Color SelectedColor = new Color();
private void Pixel_1_1_Click(object sender, EventArgs e) // on Rectangle click
{
Pixel_1_1.FillColor = SelectedColor; // change to currently desired color.
}
Since the number of squares is rising dramatically, I'm looking for a way to arrange the "pixel" rectangles into a 2D array. (I really don't want to have to make a Pixel_Click method for every single Rectangle on the screen!) Hoping eventually to be able to call something like:
private void Pixel_[x]_[y]_Click(object sender, EventArgs e)
{
Pixel_[x]_[y].FillColor = SelectedColor;
}
My friends suggest the use of an anonymous delegate, but I don't understand how to fully use one to solve my problem.
What would be the best way to generate a 2D array of rectangles in a C# Windows Form? And once generated, how can I access them with a single method for variant values of x and y?

While you are probably correct in thinking of each rectangle as an object, it probably isn't correct to think of each rectangle as a windows control, especially since you have so many of them.
So try creating your own rectangle object:
public class MyRect {
public Color FillColor { get; set; }
public Rectangle Rectangle { get; set; }
public MyRect(Rectangle r, Color c) {
this.Rectangle = r;
this.FillColor = c;
}
}
Now you just need to keep a list of your objects and paint on a single Panel control (or PictureBox) all of your rectangles:
private List<MyRect> myRectangles = new List<MyRect>();
public Form1() {
InitializeComponent();
myRectangles.Add(new MyRect(new Rectangle(10, 10, 64, 16), Color.Blue));
myRectangles.Add(new MyRect(new Rectangle(20, 48, 16, 64), Color.Red));
}
private void panel1_Paint(object sender, PaintEventArgs e) {
foreach (MyRect mr in myRectangles) {
using (SolidBrush sb = new SolidBrush(mr.FillColor)) {
e.Graphics.FillRectangle(sb, mr.Rectangle);
}
}
}
To handle the "click" event of the rectangles, you just handle the MouseDown or MouseClick event of your container control and determine yourself which rectangle is being clicked on:
void panel1_MouseDown(object sender, MouseEventArgs e) {
if (e.Button == MouseButtons.Left) {
foreach (MyRect mr in myRectangles) {
if (mr.Rectangle.Contains(e.Location)) {
ChangeColor(mr, Color.Green);
}
}
panel1.Invalidate();
}
}
private void ChangeColor(MyRect mr, Color newColor) {
mr.FillColor = newColor;
}

If you want to maintain the rectangles as components on screen then you can assign all of them the same click event, the click event will have a little dropdown to pick an existing event. To know which recantangle was clicked use the sender parameter ((Pixel)sender).FillColor = SelectedColor;
For ease I would recommend using something like a panel and drawing rectangles on it, That means you only have a single click event to deal with. So now your question becomes "How do I draw a grid of rectangles on a panel" and "How do I know which rectangle was clicked"
So for the first part you could use this not the very efficient way.
Create a class which stores the information about your pixels
class MyPixel
{
public Color PixelColour;
public Rectangle Bounds;
}
Keep a list of them in memory
List<MyPixels> MyGrid = new List<MyPixels>();
then in the onpaint event of the panel Draw the pixels on the panel
foreach(MyPixel Pixel in MyGrid)
{
using(Brush B = new SolidBrush(Pixel.PixelColor))
{
e.Graphics.DrawRectangle(B, Pixel.Bounds);
}
}
Now in the click event you'll need to know which pixel was clicked
foreach(MyPixel Pixel in MyGrid)
{
if (Pixel.Bounds.Contains(e.Location))
{
PixelClicked(Pixel);
}
}

I believe you're going about this the wrong way. What you want to do is to draw directly into a bitmap. Here is some code that uses a PictureBox to allow the user to draw into it.
using System;
using System.Drawing;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
private Pen _pen;
private bool _mouseDown;
private int _startX;
private int _startY;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
pictureBox1.Image = new Bitmap(pictureBox1.Width, pictureBox1.Height);
_pen = new Pen(Color.Black);
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
_mouseDown = true;
_startX = e.X;
_startY = e.Y;
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
_mouseDown = false;
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (_mouseDown)
{
using (var graphics = Graphics.FromImage(pictureBox1.Image))
{
graphics.DrawLine(_pen, _startX, _startY, e.X, e.Y);
_startX = e.X;
_startY = e.Y;
}
pictureBox1.Invalidate();
}
}
}
}
This is the normal method to write a painting app and is quite performant as well. You can also easily save, write new tools or manipulate images better in this way.

How do I draw a rectangle based on the movement of the mouse?

I found sample code here for drawing on a form:
http://msdn.microsoft.com/en-us/library/aa287522(v=vs.71).aspx
As a followup to this requirement (discovering which controls are beneath a rectangle described by
the user dragging the mouse):
There seems to be a mismatch between the location of my controls and the location of my MouseDown and -Up events
...I want to provide the user instant/constant feedback about just what they are about to select
(when/if they release the mouse button). I want to not just draw a line following the mouse's
movement, but draw the rectangle that is being described by their mousewrangling efforts.
I'm thinking the MouseMove event, coupled with code from the two links above, could do the trick, but is that fired too often/would that have a malevolent impact on performance? If so, what would be a preferable event to hook, or would a timer be the way to go here?
UPDATE
This code, adapted from John's example below (the only difference is the StackOverflow-inducing calls to base.* are commented out, and I changed the color from red to black (no reference to Stendahl intended)), works except that previously drawn rectangles display again after releasing the mouse. IOW, the first rectangle draws perfectly - it disappears with the mouse up click (as intended). However, when I describe a second rectangle by depressing the left mouse key and dragging down and to the right, the first rectangle displays again! And this continues to happen - every previously drawn rectangle is remembered and brought back to the fore when a new rectangle is being drawn.
public partial class Form1 : Form
{
private Point? _start;
private Rectangle _previousBounds;
public Form1()
{
InitializeComponent();
}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
_start = e.Location;
//base.OnMouseDown(e);
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (_start.HasValue)
DrawFrame(e.Location);
//base.OnMouseMove(e);
}
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
ReverseFrame();
_start = null;
//base.OnMouseUp(e);
}
private void ReverseFrame()
{
ControlPaint.DrawReversibleFrame(_previousBounds, Color.Black, FrameStyle.Dashed);
}
private void DrawFrame(Point end)
{
ReverseFrame();
var size = new Size(end.X - _start.Value.X, end.Y - _start.Value.Y);
_previousBounds = new Rectangle(_start.Value, size);
_previousBounds = this.RectangleToScreen(_previousBounds);
ControlPaint.DrawReversibleFrame(_previousBounds, Color.Black, FrameStyle.Dashed);
}
}

ControlPaint.DrawReversibleFrame() will do what you want. Performance is not generally a problem - just keep it small and clean.
--
EDIT: Added a code sample. StackOverflowException indicates something is wrong - but without seeing yours, can't answer directly.
private Point? _start;
private Rectangle _previousBounds;
protected override void OnMouseDown(MouseEventArgs e)
{
_start = e.Location;
base.OnMouseDown(e);
}
protected override void OnMouseMove(MouseEventArgs e)
{
if( _start.HasValue ) {
ReverseFrame();
DrawFrame(e.Location);
}
base.OnMouseMove(e);
}
protected override void OnMouseUp(MouseEventArgs e)
{
ReverseFrame();
_start = null;
base.OnMouseUp(e);
}
private void ReverseFrame()
{
ControlPaint.DrawReversibleFrame(_previousBounds, Color.Red, FrameStyle.Dashed);
}
private void DrawFrame(Point end)
{
ReverseFrame();
var size = new Size(end.X - _start.Value.X, end.Y - _start.Value.Y);
_previousBounds = new Rectangle(_start.Value, size);
_previousBounds = this.RectangleToScreen(_previousBounds);
ControlPaint.DrawReversibleFrame(_previousBounds, Color.Red, FrameStyle.Dashed);
}

How do I add a mouse over tooltip to an Image using .DrawImage()

Hey all, I am not sure if this is possible, but I am trying to dynamically add a tooltip to an image using the Graphics method - DrawImage. I dont see any properties or events for when the image is moused over or anything so I don't know where to begin. I am using WinForms (in C# - .NET 3.5). Any ideas or suggestions would be appreciated. Thanks.

I would guess that you have some sort of UserControl and you call DrawImage() in the OnPaint method.
Given that, your tooltip will have to controlled explicitly. Basically, create a Tooltip on your Form, give that to your control via a property, show the tooltip when your control received a MouseHover event and hide the tooltip when you receive a MouseLeave event.
Something like this:
public partial class UserControl1 : UserControl
{
public UserControl1() {
InitializeComponent();
}
protected override void OnPaint(PaintEventArgs e) {
base.OnPaint(e);
// draw image here
}
public ToolTip ToolTip { get; set; }
protected override void OnMouseLeave(EventArgs e) {
base.OnMouseLeave(e);
if (this.ToolTip != null)
this.ToolTip.Hide(this);
}
protected override void OnMouseHover(EventArgs e) {
base.OnMouseHover(e);
if (this.ToolTip == null)
return;
Point pt = this.PointToClient(Cursor.Position);
String msg = this.CalculateMsgAt(pt);
if (String.IsNullOrEmpty(msg))
return;
pt.Y += 20;
this.ToolTip.Show(msg, this, pt);
}
private string CalculateMsgAt(Point pt) {
// Calculate the message that should be shown
// when the mouse is at thegiven point
return "This is a tooltip";
}
}

Remember, you have to store bounds of the Image that you are drawing
and in the mouseMove event check if the location of current Mouse cursor at that region, then display ToolTip else hide it.
ToolTip t;
private void Form1_Load(object sender, EventArgs e)
{
t = new ToolTip(); //tooltip to control on which you are drawing your Image
}
Rectangle rect; //to store the bounds of your Image
private void Panel1_Paint(object sender, PaintEventArgs e)
{
rect =new Rectangle(50,50,200,200); // setting bounds to rect to draw image
e.Graphics.DrawImage(yourImage,rect); //draw your Image
}
private void Panel1_MouseMove(object sender, MouseEventArgs e)
{
if (rect.Contains(e.Location)) //checking cursor Location if inside the rect
{
t.SetToolTip(Panel1, "Hello");//setting tooltip to Panel1
}
else
{
t.Hide(Panel1); //hiding tooltip if the cursor outside the rect
}
}