Line Spacing
You can send EM_SETPARAFORMAT
message to the rich text box control and pass PARAFORMAT2
as lparam
. To control line spacing, you should set the PFM_LINESPACING
flag in the dwMask
member and set bLineSpacingRule
and dyLineSpacing
members of PARAFORMAT2
to suitable values based on your requirements.
Since you need fine-tuning for line spacing, it seems 4 is suitable for bLineSpacingRule
and then you can set dyLineSpacing
to any value in twip unit. For more information about available options for bLineSpacingRule
, read PARAFORMAT2
documentations.
public void SetSelectionLineSpacing(byte bLineSpacingRule, int dyLineSpacing)
{
PARAFORMAT2 format = new PARAFORMAT2();
format.cbSize = Marshal.SizeOf(format);
format.dwMask = PFM_LINESPACING;
format.dyLineSpacing = dyLineSpacing;
format.bLineSpacingRule = bLineSpacingRule;
SendMessage(this.Handle, EM_SETPARAFORMAT, SCF_SELECTION, ref format);
}
Character Spacing
Based on documentation of sSpacing
in CHARFORMAT2
, setting character spacing has no effect on the text displayed by a rich edit control.
Code
public class ExRichText : RichTextBox
{
[DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
private static extern IntPtr SendMessage(IntPtr hWnd, Int32 msg,
Int32 wParam, ref PARAFORMAT2 lParam);
private const int SCF_SELECTION = 1;
public const int PFM_LINESPACING = 256;
public const int EM_SETPARAFORMAT = 1095;
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct PARAFORMAT2
{
public int cbSize;
public uint dwMask;
public Int16 wNumbering;
public Int16 wReserved;
public int dxStartIndent;
public int dxRightIndent;
public int dxOffset;
public Int16 wAlignment;
public Int16 cTabCount;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
public int[] rgxTabs;
public int dySpaceBefore;
public int dySpaceAfter;
public int dyLineSpacing;
public Int16 sStyle;
public byte bLineSpacingRule;
public byte bOutlineLevel;
public Int16 wShadingWeight;
public Int16 wShadingStyle;
public Int16 wNumberingStart;
public Int16 wNumberingStyle;
public Int16 wNumberingTab;
public Int16 wBorderSpace;
public Int16 wBorderWidth;
public Int16 wBorders;
}
public void SetSelectionLineSpacing(byte bLineSpacingRule, int dyLineSpacing)
{
PARAFORMAT2 format = new PARAFORMAT2();
format.cbSize = Marshal.SizeOf(format);
format.dwMask = PFM_LINESPACING;
format.dyLineSpacing = dyLineSpacing;
format.bLineSpacingRule = bLineSpacingRule;
SendMessage(this.Handle, EM_SETPARAFORMAT, SCF_SELECTION, ref format);
}
}
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