Is it possible to draw a line as shown in the pic on a single form? The line in the image is drawn on a second form which is transparent so form1 is visible.
|
| OmidQRose Wednesday, December 27, 2006 5:06 AM |
Try this instead:
using System;
using System.Drawing;
using System.Windows.Forms;
public class Line : Control {
protected override CreateParams CreateParams {
get {
// Turn on the WS_EX_TRANSPARENT style
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x20;
return cp;
}
}
protected override void OnPaintBackground(PaintEventArgs pevent) {
// Do *not* paint the background
}
protected override void OnPaint(PaintEventArgs e) {
// Draw the line, just a demo here:
e.Graphics.DrawLine(Pens.Black, 0, 0, this.Width, this.Height);
base.OnPaint(e);
}
}
If you animate the line in any way, you'll need to invalidate the control's Parent so the background is redrawn correctly.
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| nobugz Thursday, December 28, 2006 6:01 PM |
No. You've got two distinct windows here. One for the form, another for the control. You can't draw on both.
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| nobugz Wednesday, December 27, 2006 1:03 PM |
Can we then create the line as a control and set its background to transparent so the list box is visible through? |
| OmidQRose Thursday, December 28, 2006 7:01 AM |
Yes, that would work. Very similar to what you did with the transparent form.
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| nobugz Thursday, December 28, 2006 2:06 PM |
So why does my line control cover the listbox?
class Line : Control
{
Pen _Pen;
Line()
{
this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
this.BackColor = Color.Transparent;
}
public void SetBounds(int Width)
{
_Pen = new Pen(new SolidBrush(Color.Red));
_Pen.Width = Width;
this.Location = new Point(0, 0);
this.Height = Form1.ClientRectangle.Height;
this.Width = Form1.ClientRectangle.Width;
Invalidate();
}
protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
base.OnPaint(e);
_Pen.DashCap = DashCap.Flat;
_Pen.DashStyle = DashStyle.DashDotDot;
_Pen.StartCap = LineCap.Flat;
_Pen.EndCap = LineCap.ArrowAnchor;
Graphics g = this.CreateGraphics;
g.DrawBezier(_Pen, 20, 20, 500, 300, 550, 320, 510, 60);
}
} |
| OmidQRose Thursday, December 28, 2006 5:44 PM |
Because this.BackColor = Color.Transparent; doesn't realy work as expected. |
| JRQ Thursday, December 28, 2006 5:48 PM |
So any alternatives? |
| OmidQRose Thursday, December 28, 2006 5:53 PM |
Try this instead:
using System;
using System.Drawing;
using System.Windows.Forms;
public class Line : Control {
protected override CreateParams CreateParams {
get {
// Turn on the WS_EX_TRANSPARENT style
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x20;
return cp;
}
}
protected override void OnPaintBackground(PaintEventArgs pevent) {
// Do *not* paint the background
}
protected override void OnPaint(PaintEventArgs e) {
// Draw the line, just a demo here:
e.Graphics.DrawLine(Pens.Black, 0, 0, this.Width, this.Height);
base.OnPaint(e);
}
}
If you animate the line in any way, you'll need to invalidate the control's Parent so the background is redrawn correctly.
|
| nobugz Thursday, December 28, 2006 6:01 PM |
Thats a really working one thanks. BTW, could you please explain what it does in the CreateParams? |
| OmidQRose Thursday, December 28, 2006 6:29 PM |
As indicated, it turns on the WS_EX_TRANSPARENT window style. With this style set, Windows ensures that all windows "below" the window get painted first and the transparent window last.
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| nobugz Thursday, December 28, 2006 7:09 PM |
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