Develop Reference

How can I predict a XAML Label's height on a Canvas

I have an application where I need to dynamically build the content to a Canvas. Everything works just fine, but I am a little unsure of how I can set the y coordinates for the labels in the safest way. For example, I need to add three labels that are essentially lines of text. In Java Swing or C# GDI I would just query the the font for the line height and add that value to the y coordinate of the drawText command.
This is my code.
double y = 0.0;
_line1.Content = "Line1";
_line1.SetValue(Canvas.TopProperty, y);
_line1.SetValue(Canvas.LeftProperty, 0.0);
CanvasChart.Children.Add(_line1);
double textHeight = _line1.Height;
y += textHeight;
_line2.Content = "Line2";
_line2.SetValue(Canvas.TopProperty, 0.0);
_line2.SetValue(Canvas.LeftProperty, y);
CanvasChart.Children.Add(_line2);
This does not work because _line1.Height does not seem to be set to anything useful at this point. I suppose it has not rendered yet. The above code is in the loaded event for the window. ActualHeight does not help either.
Most code that I've seen seems to just set them to a hard coded value. That I suppose looks right on the developer's display, and you just hope looks good at other resolutions/DPI. In Swing and GDI I always had the best results finding out exactly how many pixels a string will be rendered at and using this to offset the next line.

You must call the Measure method, specifying an infinite available size. This will update the DesiredSize of the control:
_line1.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
double textHeight = _line1.DesiredSize.Height;
Another easy way to achieve the desired effect is to put the labels in a StackPanel.

In Swing and GDI I always had the best results finding out exactly how many pixels a string will be rendered at and using this to offset the next line.
This is possible in WPF as well. The GlyphTypeface class provides the AdvanceWidths and AdvanceHeights properties for each character in a typeface. By using CharacterToGlyphMap, you can map a character to an index within the AdvanceHeights, and use that to determine the actual height of any character.
For a detailed example, see GlyphRun and So Forth.

MeasureString() doesn't return enough width

I have the following code to create a Label on a PictureBox:
Label l = new Label();
l.Text = _name;
l.Size = CreateGraphics().MeasureString(_name, l.Font).ToSize();
l.BackColor = Color.White;
but the label is always dropping the last character. If I add a character to the call:
l.Size = CreateGraphics().MeasureString(_name+".", l.Font).ToSize();
it works fine, but that doesn't feel right.
There seems to be some white space just before the text in the label, but Padding is set to 0. How can I fix this the correct way?

Can't you use the AutoSize property?
MeasureString is notoriously inaccurate, though normally it returns a size bigger than you'd expect:
The MeasureString method is designed for use with individual strings and includes a small amount of extra space before and after the string to allow for overhanging glyphs. Also, the DrawString method adjusts glyph points to optimize display quality and might display a string narrower than reported by MeasureString. To obtain metrics suitable for adjacent strings in layout (for example, when implementing formatted text), use the MeasureCharacterRanges method or one of the MeasureString methods that takes a StringFormat, and pass GenericTypographic. Also, ensure the TextRenderingHint for the Graphics is AntiAlias.
http://msdn.microsoft.com/en-us/library/6xe5hazb.aspx

ToSize() truncates values of the SizeF to the next lower integer values.
So, to avoid losses you can do something like that:
l.Size = (CreateGraphics().MeasureString(_name, l.Font) + new SizeF(1, 0)).ToSize();

Is it something as simple as getting the size wrong when you declare your font compared to the UI font size?

How can I tell when the Text of a System.Windows.Forms.GroupBox wraps to the next line?

I'm creating a GroupBox at runtime and setting its Text property. Usually, the text is only on one line, but sometimes it wraps. The problem is that the controls contained in the GroupBox cover up the GroupBox's text.
What I'd like to do is determine if and when the text wraps. Specifically, I'd like to determine how much extra height the wrapped text takes up as compared to a single line. That way, I can reposition the GroupBox's controls and adjust its height.
Initially, I thought I'd do this by calling the GroupBox's CreateGraphics() method, and using the Graphics to measure the string. Something like this:
private void SetGroupBoxText(GroupBox grp, string text)
{
const int somePadding = 10;
Graphics g = grp.CreateGraphics();
SizeF textSize = g.MeasureString(text, grp.Font);
if (textSize.Width > (grp.Width - somePadding))
{
// Adjust height, etc.
}
}
The problem is that the size generated by g.MeasureString(text, grp.Font) doesn't seem to be accurate. I determined that it wasn't accurate by putting enough of a single character to cause a wrap, then measuring the resulting string.
For example, it took 86 pipes (|) to until a wrap happened. When I measured that string, its width was ~253. And it took 16 capital W's to force a wrap - its string had a width of ~164. These were the two extremes that I tested. My GroupBox's width was 189. (a's took 29 and had a width of ~180, O's took 22 and had a width of ~189)
Does anyone have any ideas? (hacks, WinAPI, etc. are welcome solutions)

This code was derived from the Reference Source, it should be very close. It returns the number of pixels added to the text height when it displays more than one line of text:
public static int GetGroupboxTextHeightExtra(GroupBox box) {
TextFormatFlags flags = TextFormatFlags.Default | TextFormatFlags.TextBoxControl | TextFormatFlags.WordBreak | TextFormatFlags.PreserveGraphicsTranslateTransform | TextFormatFlags.PreserveGraphicsClipping;
Rectangle rc = new Rectangle(0, 0, box.Width - 2 * 7, box.Height);
Size size;
using (Graphics gr = Application.OpenForms[0].CreateGraphics()) {
size = TextRenderer.MeasureText(gr, box.Text, box.Font, rc.Size, flags);
}
return size.Height - box.Font.Height;
}

I know this doesn't directly solve your problem, but you could try setting the minimum size of the group box to some number you knew the text wouldn't wrap.
In most cases you shouldn't have a lot of text on the heading of a group box. Think about adding a label below the group box that goes into more detail. Remember, a group box is meant to "group" similar controls. So the text on the actual group box should be minimal and mimic a title.

Why not use a layout manager for your problem? A layout manager layout controls on a container in a way that frees you from doing those calculations. You can find layout managers from vendors like DevXpress and Syncfusion. I think that there are layout manager in the .Net Framework too.

Determine Label Size based upon amount of text and font size in Winforms/C#

I'd like to know if there's a better approach to this problem. I want to resize a label (vertically) to accomodate certain amount of text. My label has a fixed width (about 60 chars wide before it must wrap), about 495 pixels. The font is also a fixed size (12points afaik), but the text is not.
What I want to do is increase the Label Height when there's a "NewLine" or the text must wrap; the idea is that the text is fully visible in the label. The AutoSize doesn't work because it will grow in width, not in height.
Of course I could count the number of NewLines and add: Newlines * LineHeight, and then -given that I manage to put 60 chars per line, just divide the number of chars and add as many LineHeight pixels as needed.
I was wondering if there was a more professional way to do it. Is my approach too "lame" ?
Thanks in advance.

How about Graphics.MeasureString, with the overload that accepts a string, the font, and the max width? This returns a SizeF, so you can round round-off the Height.
using(Graphics g = CreateGraphics()) {
SizeF size = g.MeasureString(text, lbl.Font, 495);
lbl.Height = (int) Math.Ceiling(size.Height);
lbl.Text = text;
}

System.Drawing.Graphics has a MeasureString method that you can use for this purpose. Use the overload that takes a string, a font, and an int "width" parameter; this last parameter specifies the maximum width allowed for the string - use the set width of your label for this parameter.
MeasureString returns a SizeF object. Use the Height property of this returned object to set the height of your label.
Note: to get a Graphics object for this purpose, you can call this.CreateGraphics.

Graphics.MeasureString() will probably help you.
This is also one of the only usecases for using the Control.CreateGraphics() call!

Size maxSize = new Size(495, int.MaxValue);
_label.Height = TextRenderer.MeasureText(_label.Text , _label.Font, maxSize).Height;

This "answer" is for future reference and to combat the initial assumption that AutoSize = true implies that it (a WinForms label) will never grow in height.
The following link shows the various effects of AutoSize = true with other properties such as MaximumSize. Depending upon the expected use of the question it may be appropriate to follow one of these approaches.
http://blogs.msdn.com/jfoscoding/articles/478299.aspx

I would like to propose an alternative since it's a label we are talking about and not just text rendering: GetPreferredSize. I tried Mark's answer and the problem is that it almost works: the label has some "padding" around the text and this needs to be taken into account in the width value of MeasureString. I couldn't find any apparent way to get this padding. While digging, I found this answer where the poster suggests to set the FlatStyle to System. That works, but unfortunately breaks the TextAlign which I wanted it to be MiddleLeft.
I poked into the Label code and I found out the GetPreferredSize which takes into account all the weird settings (FlatStyle, UseCompatibleTextRendering etc) and can give you the correct result for each case. So instead of g.MeasureString(text, lbl.Font, 495); you can do instead
lbl.GetPreferredSize(new Size(495, 0));
or even like this since the label size is already known:
lbl.GetPreferredSize(new Size(lbl.Width, 0));
In case you are wondering, 0 and 1 will be treated as int.MaxValue.
I don't know when GetPreferredSize was introduced, so back in 2008 when Mark wrote his answer, the above might not have been relevant. But if you still need something similar in 2021, GetPreferredSize might be a tiny bit handier -which returns a Size and not a SizeF.

I posted a user control which solves this problem in the accepted answer here:
Autoscale Font in a TextBox Control so that its as big as possible and still fits in text area bounds
The control extends RichTextBox. It has a method: ScaleFontToFit that will automatically resize the font to make all the text fit.
Neat thing is it respects the multiline property. If it's true it allows words to wrap, Otherwise it doesn't.

Well the 60 chars might be valid for your test text, but not all characters have the same width. For instance, compare
llllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
and
wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww
They both have 60 characters, and yet have vastly differing widths.

Is there any downside to using the TextRenderer class to measure the string (like in Marc's response) instead of going through the work to create a Graphics object, etc?

According to this article you should use TextRenderer if you are going to use a Windows Form control for the final output. TextRenderer and Graphics.MeasureString will give different results, so use the one that matches your final mode of output.

In some cases where you must use compact framework, which does not have any override methods for MeasureString(), you might consider calculating the height by yourself.
private int YukseklikAyarla(string p, Font font, int maxWidth)
{
int iHeight = 0;
using (Graphics g = CreateGraphics())
{
var sizes = g.MeasureString(p, font); // THE ONLY METHOD WE ARE ALLOWED TO USE
iHeight = (int)Math.Round(sizes.Height);
var multiplier = (int)Math.Round((double)sizes.Width) / maxWidth; // DIVIDING THE TEXT WIDTH TO SEE HOW MANY LINES IT CAN HAS
if (multiplier > 0)
{
iHeight = (int)(iHeight * (multiplier + 1)); // WE ADD 1 HERE BECAUSE THE TEXT ALREADY HAS A LINE
}
}
return iHeight;
}

Although, its an old thread, thought it might help new visitors.
In C#, you could use control.width

Multiple colors in a C# .NET label

I'm looking for a way to display multiple colors in a single C#/.NET label. E.g the label is displaying a series of csv separated values that each take on a color depending on a bucket they fall into. I would prefer not to use multiple labels, as the values are variable length and I don't want to play with dynamic layouts. Is there a native support for this?

There is no native control in .NET that does this. Your best bet is to write your own UserControl (call it RainbowLabel or something). Normally you would have a custom label control inherit directly from Label, but since you can't get multi-colored text in one label, you would just inherit from UserControl.
For rendering the text, your UserControl could split the text on commas and then dynamically load a differently-colored Label for each chunk. A better way, however, would be to render the text directly onto your UserControl using the DrawString and MeasureString methods in the Graphics namespace.
Writing UserControls in .NET is really not difficult, and this kind of unusual problem is exactly what custom UserControls are for.
Update: here's a simple method you can use for rendering the multi-colored text on a PictureBox:
public void RenderRainbowText(string Text, PictureBox pb)
{
// PictureBox needs an image to draw on
pb.Image = new Bitmap(pb.Width, pb.Height);
using (Graphics g = Graphics.FromImage(pb.Image))
{
// create all-white background for drawing
SolidBrush brush = new SolidBrush(Color.White);
g.FillRectangle(brush, 0, 0,
pb.Image.Width, pb.Image.Height);
// draw comma-delimited elements in multiple colors
string[] chunks = Text.Split(',');
brush = new SolidBrush(Color.Black);
SolidBrush[] brushes = new SolidBrush[] {
new SolidBrush(Color.Red),
new SolidBrush(Color.Green),
new SolidBrush(Color.Blue),
new SolidBrush(Color.Purple) };
float x = 0;
for (int i = 0; i < chunks.Length; i++)
{
// draw text in whatever color
g.DrawString(chunks[i], pb.Font, brushes[i], x, 0);
// measure text and advance x
x += (g.MeasureString(chunks[i], pb.Font)).Width;
// draw the comma back in, in black
if (i < (chunks.Length - 1))
{
g.DrawString(",", pb.Font, brush, x, 0);
x += (g.MeasureString(",", pb.Font)).Width;
}
}
}
}
Obviously this will break if you have more than 4 comma-delimited elements in your text, but you get the idea. Also, there appears to be a small glitch in MeasureString that makes it return a width that is a couple pixels wider than necessary, so the multi-colored string appears stretched out - you might want to tweak that part.
It should be straightforward to modify this code for a UserControl.
Note: TextRenderer is a better class to use for drawing and measuring strings, since it uses ints. Graphics.DrawString and .MeasureString use floats, so you'll get off-by-a-pixel errors here and there.
Update: Forget about using TextRenderer. It is dog slow.

You could try using a RichTextBox so that you can get multiple colors for the string and then make it read only and remove the border. Change the background color to the same as the Form it is on and you might get away with it.

As an alternative, you might do this as rtf or html in a suitable control (such as WebBrowser). It would probably take a bit more resources that you'd ideally like, but it'll work fairly quickly.

If you are building your Windows app for people with XP and up, you can use WPF. Even if it's a Windows Forms app, you can add a WPF UserControl.
I would then use a Label, and set the "Foreground" property to be a gradient of colors.
Or, in Windows Forms (no WPF), you could just use a "Flow Panel", and then in a for loop add multiple Labels as segments of your sentense... they will all "flow" together as if it was one label.

I'm using colored labels quite often to mark keywords in red color etc.
Like in Phil Wright's answer I use a RichTextBox control, remove the border and set the background color to SystemColors.Control.
To write colored text the control is first cleared and then I use this function to append colored text:
private void rtb_AppendText(Font selfont, Color color, Color bcolor,
string text, RichTextBox box)
{
// append the text to the RichTextBox control
int start = box.TextLength;
box.AppendText(text);
int end = box.TextLength;
// select the new text
box.Select(start, end - start);
// set the attributes of the new text
box.SelectionColor = color;
box.SelectionFont = selfont;
box.SelectionBackColor = bcolor;
// unselect
box.Select(end, 0);
// only required for multi line text to scroll to the end
box.ScrollToCaret();
}
If you want to run this function with "mono" then add a space before every new colored text, or mono will not set new the color correctly. This is not required with .NET
Usage:
myRtb.Text = "";
rtb_AppendText(new Font("Courier New", (float)10),
Color.Red, SystemColors.Control, " my red text", myRtb);
rtb_AppendText(new Font("Courier New", (float)10),
Color.Blue, SystemColors.Control, " followed by blue", myRtb);

Slightly off topic ... You could check also:
generate html color table
model colors in sql
the result

You can simply use multiple labels. Set the font properties you want and then use the left. top and width properties to display the words you want displayed differently. This is assuming you are using windows forms.

Try this,
labelId.Text = "Successfully sent to" + "<a style='color:Blue'> " + name + "</a>";

There is no native support for this; you will either have to use multiple labels or find a 3rd-party control that will provide this functionality.

I don't think so. You should create one yourself.

As per your Question your requirement is simple like
lable.Text = "This color is Red", So it have to display text like this
"The color is" will be in Blue and "Red" will be red color ..
This can be done like this
lable.Text = "<span style='Color:Blue'>" + " The color is " +"</span>" + "<span style='Color:Red'>"Red"</span>"