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Fix issue 14808: CheckBox/RadioButton: ToggleSwitch overlaps text when RightToLeft is enabled and AutoSize is false #14815

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Fix issue 14808: CheckBox/RadioButton: ToggleSwitch overlaps text when RightToLeft is enabled and AutoSize is false #14815

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0558a09
Fix issue 14808: CheckBox/RadioButton: ToggleSwitch overlaps text whe…
Jul 27, 2026
4a4f5bf
Fixed the issue where images were being cut.
Jul 28, 2026
bb21e4f
Handle feedback
Jul 28, 2026
b30729a
Fix the test issue
Jul 31, 2026
93891c6
Optimize the code
Aug 3, 2026
9b9e213
Update character encoding from UTF-8-BOM to UTF-8.
Aug 5, 2026
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76 changes: 63 additions & 13 deletions ...tem.Windows.Forms/System/Windows/Forms/Rendering/CheckBox/AnimatedToggleSwitchRenderer.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Licensed to the .NET Foundation under one or more agreements.
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Drawing;
Expand Down Expand Up @@ -79,14 +79,12 @@ public override void RenderControl(Graphics graphics)
ToggleSwitchMetrics metrics = ToggleSwitchMetrics.Create(Control);
Size textSize = TextRenderer.MeasureText(Control.Text, Control.Font);
Rectangle contentBounds = ToggleSwitchMetrics.GetContentBounds(Control);

@LeafShi1 LeafShi1 Aug 11, 2026

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ToggleSwitchMetrics.GetPreferredSize still measures with the default TextRenderer.MeasureText(control.Text, control.Font) flags, while this path now measures and renders with flags that honor UseMnemonic. When UseMnemonic is false, a literal & is included during rendering but can still be treated as a mnemonic marker during preferred-size calculation. As a result, an auto-sized ToggleSwitch can be too narrow and clip or wrap the text (the separate text bounds should still prevent overlap with the switch). Could preferred-size calculation use the same flags, with a regression test such as Text = "A&B" and UseMnemonic = false?

int totalHeight = Math.Max(textSize.Height, metrics.SwitchHeight);
int contentTop = contentBounds.Top + Math.Max(0, (contentBounds.Height - totalHeight) / 2);
int textY = contentTop + ((totalHeight - textSize.Height) / 2);
Rectangle switchBounds = GetSwitchBounds(
Control,
RtlTranslatedCheckAlign,
metrics,
textSize);
Rectangle textBounds = GetTextBounds(contentBounds, switchBounds, metrics, RtlTranslatedCheckAlign);

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graphics.Clear(Control.BackColor);

Expand All @@ -97,14 +95,13 @@ public override void RenderControl(Graphics graphics)

if (IsSwitchOnRight(RtlTranslatedCheckAlign))
{
int textX = Math.Max(contentBounds.Left, switchBounds.Left - metrics.TextGap - textSize.Width);
RenderSwitch(graphics, switchBounds, metrics);
RenderText(graphics, new Point(textX, textY));
RenderText(graphics, textBounds);
}
else
{
RenderSwitch(graphics, switchBounds, metrics);
RenderText(graphics, new Point(contentBounds.Left + metrics.SwitchWidth + metrics.TextGap, textY));
RenderText(graphics, textBounds);
}
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if (Control.Focused && ShowFocusCues)
Expand Down Expand Up @@ -165,23 +162,76 @@ private static Rectangle GetSwitchBounds(
int totalHeight = Math.Max(textSize.Height, metrics.SwitchHeight);
int contentTop = contentBounds.Top + Math.Max(0, (contentBounds.Height - totalHeight) / 2);
int switchY = contentTop + ((totalHeight - metrics.SwitchHeight) / 2);
int switchX = IsSwitchOnRight(checkAlign)
? Math.Max(contentBounds.Left, contentBounds.Right - metrics.SwitchWidth)
: contentBounds.Left;
int minimumSwitchX = contentBounds.Left;
int maximumSwitchX = Math.Max(minimumSwitchX, contentBounds.Right - metrics.SwitchWidth);
int edgeInset = Math.Max(1, (metrics.BorderThickness / 2) + 1);
int targetSwitchX = IsSwitchOnRight(checkAlign)
? maximumSwitchX - edgeInset
: minimumSwitchX + edgeInset;
int switchX = Math.Max(minimumSwitchX, Math.Min(maximumSwitchX, targetSwitchX));

return new Rectangle(switchX, switchY, metrics.SwitchWidth, metrics.SwitchHeight);
}

private void RenderText(Graphics graphics, Point position)
internal static Rectangle GetTextBounds(
Control control,
ContentAlignment checkAlign,
ToggleSwitchMetrics metrics)
{
Size textSize = TextRenderer.MeasureText(control.Text, control.Font);
Rectangle contentBounds = ToggleSwitchMetrics.GetContentBounds(control);
Rectangle switchBounds = GetSwitchBounds(control, checkAlign, metrics, textSize);
return GetTextBounds(contentBounds, switchBounds, metrics, checkAlign);
}

private static Rectangle GetTextBounds(
Rectangle contentBounds,
Rectangle switchBounds,
ToggleSwitchMetrics metrics,
ContentAlignment checkAlign)
{
int thresholdExtension = Math.Max(1, metrics.BorderThickness / 2) + 1;
if (IsSwitchOnRight(checkAlign))
{
int right = Math.Min(
contentBounds.Right,
switchBounds.Left - Math.Max(0, metrics.TextGap - thresholdExtension));
right = Math.Max(contentBounds.Left, right);
return Rectangle.FromLTRB(contentBounds.Left, contentBounds.Top, right, contentBounds.Bottom);
}

int left = Math.Max(
contentBounds.Left,
switchBounds.Right + Math.Max(0, metrics.TextGap - thresholdExtension));
left = Math.Min(contentBounds.Right, left);
return Rectangle.FromLTRB(left, contentBounds.Top, contentBounds.Right, contentBounds.Bottom);
}

private void RenderText(Graphics graphics, Rectangle textBounds)
{
if (textBounds.Width <= 0 || textBounds.Height <= 0)
{
return;
}

TextFormatFlags flags = GetTextFormatFlags();

TextRenderer.DrawText(
graphics,
Control.Text,
Control.Font,
position,
GetTextColor());
textBounds,
GetTextColor(),
flags);
}

private TextFormatFlags GetTextFormatFlags() => Control switch
{
Forms.CheckBox checkBox => checkBox.CreateTextFormatFlags(),
Forms.RadioButton radioButton => radioButton.CreateTextFormatFlags(),
_ => TextFormatFlags.WordBreak | TextFormatFlags.TextBoxControl
};

internal Color GetTextColor()
=> Control.Enabled
? Control.ForeColor
Expand Down
18 changes: 15 additions & 3 deletions src/test/unit/System.Windows.Forms/System/Windows/Forms/CheckBoxTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -773,9 +773,21 @@ public void CheckBox_ToggleSwitch_CheckAlign_PositionsSwitch(
metrics);
Rectangle contentBounds = Rendering.CheckBox.ToggleSwitchMetrics.GetContentBounds(box);

Assert.Equal(
switchOnRight ? contentBounds.Right : contentBounds.Left,
switchOnRight ? switchBounds.Right : switchBounds.Left);
const int EdgeTolerance = 2;
if (switchOnRight)
{
Assert.InRange(
switchBounds.Right,
contentBounds.Right - EdgeTolerance,
contentBounds.Right);
}
else
{
Assert.InRange(
switchBounds.Left,
contentBounds.Left,
contentBounds.Left + EdgeTolerance);
}
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}

[WinFormsTheory]
Expand Down