C#中如何修改Label控件部分文本的颜色与字号

Hey there! If you're working with WinForms, you probably noticed the standard Label control doesn't natively support rich text formatting—meaning you can't change color/size for just parts of the text out of the box. But don't worry, we've got two straightforward solutions to get this done.

Method 1: Use a RichTextBox (Quick & Easy) #

We can repurpose a RichTextBox to look and act like a Label, while leveraging its built-in rich text support. Just tweak its properties to match your Label's style, then apply formatting to specific text segments.

Here's how to adapt your existing code for this approach:

// For label3 equivalent (using RichTextBox)
RichTextBox rtbx3 = new RichTextBox();
rtbx3.Width = pictureBox1.Width * 2 - 100;
rtbx3.Top = pictureBox1.Top + pictureBox1.Height - 50;
rtbx3.Left = pictureBox1.Left - 75;
rtbx3.Height = 200;
rtbx3.BorderStyle = BorderStyle.None; // Remove border to look like Label
rtbx3.BackColor = this.BackColor; // Match form background
rtbx3.ReadOnly = true; // Prevent editing
rtbx3.Text = "Regele Carol al II-lea(1930-1940) si fiul sau Mihai I(9 ani) cu prilejul proclamarii principelui Carol al II-lea, Rege al Romaniei, de catre Parlamewntul de la Bucuresti, la 8 Iunie 1930";

// Format the year segments (1930-1940) and 8 Iunie 1930
int yearStart1 = rtbx3.Text.IndexOf("1930-1940");
if (yearStart1 != -1)
{
    rtbx3.SelectionStart = yearStart1;
    rtbx3.SelectionLength = "1930-1940".Length;
    rtbx3.SelectionColor = Color.Blue;
    rtbx3.SelectionFont = new Font(rtbx3.Font.FontFamily, rtbx3.Font.Size + 2, FontStyle.Bold); // Larger size
}

int yearStart2 = rtbx3.Text.IndexOf("8 Iunie 1930");
if (yearStart2 != -1)
{
    rtbx3.SelectionStart = yearStart2;
    rtbx3.SelectionLength = "8 Iunie 1930".Length;
    rtbx3.SelectionColor = Color.Blue;
    rtbx3.SelectionFont = new Font(rtbx3.Font.FontFamily, rtbx3.Font.Size + 2, FontStyle.Bold);
}

this.Controls.Add(rtbx3);

// Repeat similar steps for label4 equivalent
RichTextBox rtbx4 = new RichTextBox();
rtbx4.Width = pictureBox2.Width * 2 - 75;
rtbx4.Top = pictureBox2.Top + pictureBox2.Height - 50;
rtbx4.Left = pictureBox2.Left - 75;
rtbx4.Height = 150;
rtbx4.BorderStyle = BorderStyle.None;
rtbx4.BackColor = this.BackColor;
rtbx4.ReadOnly = true;
rtbx4.Text = "Clasa de elevi cu Mihai I ce poarta titlul de: 'Mare Voievod de ALBA IULIA' in 1937, de Craciun 25 XII";

// Format "1937" and "25 XII"
int yearStart3 = rtbx4.Text.IndexOf("1937");
if (yearStart3 != -1)
{
    rtbx4.SelectionStart = yearStart3;
    rtbx4.SelectionLength = "1937".Length;
    rtbx4.SelectionColor = Color.Blue;
    rtbx4.SelectionFont = new Font(rtbx4.Font.FontFamily, rtbx4.Font.Size + 2, FontStyle.Bold);
}

int dateStart = rtbx4.Text.IndexOf("25 XII");
if (dateStart != -1)
{
    rtbx4.SelectionStart = dateStart;
    rtbx4.SelectionLength = "25 XII".Length;
    rtbx4.SelectionColor = Color.Blue;
    rtbx4.SelectionFont = new Font(rtbx4.Font.FontFamily, rtbx4.Font.Size + 2, FontStyle.Bold);
}

this.Controls.Add(rtbx4);

Method 2: Custom Drawn Label (More Control, Native Label Feel) #

If you prefer to stick with a Label-like control without using RichTextBox, you can create a custom Label that overrides the OnPaint method to draw text with different formats manually.

First, create the custom control:

public class FormattedLabel : Label
{
    // Define segments with custom formatting
    public List<TextSegment> FormattedSegments { get; set; } = new List<TextSegment>();

    protected override void OnPaint(PaintEventArgs e)
    {
        // Draw default text first (unformatted parts)
        e.Graphics.Clear(this.BackColor);
        var currentPosition = new PointF(0, 0);
        string remainingText = this.Text;

        foreach (var segment in FormattedSegments)
        {
            // Find the segment in the remaining text
            int index = remainingText.IndexOf(segment.Text);
            if (index == -1) continue;

            // Draw the unformatted text before the segment
            if (index > 0)
            {
                string preText = remainingText.Substring(0, index);
                e.Graphics.DrawString(preText, this.Font, new SolidBrush(this.ForeColor), currentPosition);
                currentPosition.X += e.Graphics.MeasureString(preText, this.Font).Width;
            }

            // Draw the formatted segment
            e.Graphics.DrawString(segment.Text, segment.Font, new SolidBrush(segment.Color), currentPosition);
            currentPosition.X += e.Graphics.MeasureString(segment.Text, segment.Font).Width;

            // Update remaining text
            remainingText = remainingText.Substring(index + segment.Text.Length);
        }

        // Draw any remaining unformatted text
        if (!string.IsNullOrEmpty(remainingText))
        {
            e.Graphics.DrawString(remainingText, this.Font, new SolidBrush(this.ForeColor), currentPosition);
        }
    }

    public class TextSegment
    {
        public string Text { get; set; }
        public Font Font { get; set; }
        public Color Color { get; set; }
    }
}

Then use it in your form code:

// For label3 equivalent
FormattedLabel lbl3 = new FormattedLabel();
lbl3.Width = pictureBox1.Width * 2 - 100;
lbl3.Top = pictureBox1.Top + pictureBox1.Height - 50;
lbl3.Left = pictureBox1.Left - 75;
lbl3.Height = 200;
lbl3.Text = "Regele Carol al II-lea(1930-1940) si fiul sau Mihai I(9 ani) cu prilejul proclamarii principelui Carol al II-lea, Rege al Romaniei, de catre Parlamewntul de la Bucuresti, la 8 Iunie 1930";

// Add formatted segments
var largerBlueFont = new Font(lbl3.Font.FontFamily, lbl3.Font.Size + 2, FontStyle.Bold);
lbl3.FormattedSegments.Add(new FormattedLabel.TextSegment
{
    Text = "1930-1940",
    Font = largerBlueFont,
    Color = Color.Blue
});
lbl3.FormattedSegments.Add(new FormattedLabel.TextSegment
{
    Text = "8 Iunie 1930",
    Font = largerBlueFont,
    Color = Color.Blue
});

this.Controls.Add(lbl3);

// Repeat for label4 equivalent
FormattedLabel lbl4 = new FormattedLabel();
lbl4.Width = pictureBox2.Width * 2 - 75;
lbl4.Top = pictureBox2.Top + pictureBox2.Height - 50;
lbl4.Left = pictureBox2.Left - 75;
lbl4.Height = 150;
lbl4.Text = "Clasa de elevi cu Mihai I ce poarta titlul de: 'Mare Voievod de ALBA IULIA' in 1937, de Craciun 25 XII";

lbl4.FormattedSegments.Add(new FormattedLabel.TextSegment
{
    Text = "1937",
    Font = largerBlueFont,
    Color = Color.Blue
});
lbl4.FormattedSegments.Add(new FormattedLabel.TextSegment
{
    Text = "25 XII",
    Font = largerBlueFont,
    Color = Color.Blue
});

this.Controls.Add(lbl4);

Quick Notes: #

• For the RichTextBox method, double-check that BackColor matches your form's background so it blends in seamlessly.
• The custom FormattedLabel gives you full control over text rendering, making it ideal if you need consistent behavior across multiple labels in your app.

内容的提问来源于stack exchange，提问作者Abdul Asam