Transparent ContextMenuStrip with non-transparent text

  • Thread starter Thread starter Hans Merkl
  • Start date Start date
H

Hans Merkl

Hi,

I am trying to implement a context menu that is 50% transparent. Setting
the opacity to 0.5 works but unfortunately the texts are also displayed
with transparency which makes them very hard to read.

Now I would like to draw the menu background with transparency but the text
without.

I have tried various approaches without success:

- Implement a ToolstripRenderer: Draws a gray background despite overriding
all overridable methods
- Handle Paint event of each menu item: Text gets drawn with transparency

Does anybody have an idea how to approach this?

Thanks in advance,

Hans
 
Sorry about that. I don't think the example would be useful. Have you
tried to override the onpaint method and draw the text using
Graphics.DrawString?
 
Sorry about that. I don't think the example would be useful. Have you
tried to override the onpaint method and draw the text using
Graphics.DrawString?
Click to expand...

Yes. I have tried that but the string gets drawn with the opacity setting
of the menu.

Here is some sample code I have written with a ToolStripRenderer.
It works fine but it seems the menu is also drawing a gray background
behind the transparent background colors that I am drawing. I wonder if
it's possible to prevent the drawing of the gray background.

private void cmdTestScenario_Click(object sender, EventArgs e)
{
System.Windows.Forms.ContextMenuStrip cm = new
ContextMenuStrip();
cm.Renderer = new MyRenderer();
cm.ShowCheckMargin = false;
cm.ShowImageMargin = false;

cm.Items.Add(new ToolStripLabel("Label"));
ToolStripItem it = null;
it = cm.Items.Add("Item1");
it.BackColor = Color.Transparent;

cm.Items.Add("Item2");

cm.Show();
}

private class MyRenderer : ToolStripRenderer
{
protected override void
OnRenderToolStripBackground(ToolStripRenderEventArgs e)
{
//draw background with transparent white
Color bgColor = Color.FromArgb(100,Color.Yellow);
Brush b = new SolidBrush(bgColor);

e.Graphics.FillRectangle(b, e.AffectedBounds);

base.OnRenderToolStripBackground(e);
}

protected override void
OnRenderItemBackground(ToolStripItemRenderEventArgs e)
{
base.OnRenderItemBackground(e);
}

protected override void
OnRenderMenuItemBackground(ToolStripItemRenderEventArgs e)
{
//draw background with transparent white
Color bgColor = Color.FromArgb(100, Color.LightBlue);
Brush b = new SolidBrush(bgColor);

e.Graphics.FillRectangle(b, e.Item.ContentRectangle);

base.OnRenderMenuItemBackground(e);
}

protected override void
OnRenderItemText(ToolStripItemTextRenderEventArgs e)
{
//draw with solid red
Color bgColor = Color.Red;
Brush b = new SolidBrush(bgColor);

e.Graphics.DrawString(e.Text,e.TextFont,b,e.TextRectangle);

base.OnRenderItemText(e);
}
 
Remove the override for OnRenderMenuItemBackground. That is where the
gray looking background is coming from.

Also, I was able to disable the opacity change for the drawstring by NOT
calling base.OnRenderItemText(e); in the override for OnRenderItemText.
The text looks almost crisp. Let me know if this works for you.
 
Bryan,

I have commented out the calls to the base class but I still don't get
transparency. BTW but I am using Windows 2000.

Can you post your code so I can see what the difference is?

Hans
 
Problem with shortcuts

I'm working on the same problem and with:
protected override void OnRenderItemText(ToolStripItemTextRenderEventArgs e)
{
//draw with solid red
Color bgColor = Color.Red;
Brush b = new SolidBrush(bgColor);

e.Graphics.DrawString(e.Text,e.TextFont,b,e.TextRe ctangle);

base.OnRenderItemText(e);
}

... the text is overdrawn on the different position. If I exclude the line base.OnRenderItemText(e); than everything is OK except the shortcuts are drawn over the text. Anyone know how to avoid it?
 
virtual_from_croatia said:
I'm working on the same problem and with:
protected override void OnRenderItemText(ToolStripItemTextRenderEventArgs e)
{
//draw with solid red
Color bgColor = Color.Red;
Brush b = new SolidBrush(bgColor);

e.Graphics.DrawString(e.Text,e.TextFont,b,e.TextRe ctangle);

base.OnRenderItemText(e);
}

... the text is overdrawn on the different position. If I exclude the line base.OnRenderItemText(e); than everything is OK except the shortcuts are drawn over the text. Anyone know how to avoid it?
Click to expand...


OK, found the answer on my question. Instead to use e.Graphics... use:

TextRenderer.DrawText(e.Graphics, e.Text, e.TextFont, e.TextRectangle, b, e.TextFormat);

and delete the line base.OnRenderItemText(e);
 
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