public static void DrawText(
this DeviceContextHdcScope hdc,
string?text,
FontCache.Scope font,
Rectangle bounds,
Color foreColor,
User32.DT flags,
Color backColor = default,
TextPaddingOptions padding = default)
=> DrawText(hdc.HDC, text, font, bounds, foreColor, flags, backColor, padding);
/// <summary>
/// Draws the text in the given bounds, using the given Font, foreColor and backColor, and according to the specified
/// TextFormatFlags flags.
///
/// If font is null, the font currently selected in the hdc is used.
///
/// If foreColor and/or backColor are Color.Empty, the hdc current text and/or background color are used.
/// </summary>
public static void DrawText(
this Gdi32.HDC hdc,
ReadOnlySpan <char> text,
FontCache.Scope font,
Rectangle bounds,
Color foreColor,
User32.DT flags,
Color backColor = default,
TextPaddingOptions padding = default)
{
if (text.IsEmpty || foreColor == Color.Transparent)
{
return;
}
ValidateFlags(flags);
// DrawText requires default text alignment.
using var alignment = new Gdi32.SetTextAlignmentScope(hdc, default);
// Color empty means use the one currently selected in the dc.
using var textColor = foreColor.IsEmpty ? default : new Gdi32.SetTextColorScope(hdc, foreColor);
using var fontSelection = new Gdi32.SelectObjectScope(hdc, (Gdi32.HFONT)font);
Gdi32.BKMODE newBackGroundMode = (backColor.IsEmpty || backColor == Color.Transparent) ?
Gdi32.BKMODE.TRANSPARENT :
Gdi32.BKMODE.OPAQUE;
using var backgroundMode = new Gdi32.SetBkModeScope(hdc, newBackGroundMode);
using var backgroundColor = newBackGroundMode != Gdi32.BKMODE.TRANSPARENT
? new Gdi32.SetBackgroundColorScope(hdc, backColor)
: default;
User32.DRAWTEXTPARAMS dtparams = GetTextMargins(font, padding);
bounds = AdjustForVerticalAlignment(hdc, text, bounds, flags, ref dtparams);
// Adjust unbounded rect to avoid overflow since Rectangle ctr does not do param validation.
if (bounds.Width == TextRenderer.MaxSize.Width)
{
bounds.Width -= bounds.X;
}
if (bounds.Height == TextRenderer.MaxSize.Height)
{
bounds.Height -= bounds.Y;
}
RECT rect = bounds;
User32.DrawTextExW(hdc, text, ref rect, flags, ref dtparams);
}
private static (User32.DT Flags, TextPaddingOptions Padding) SplitTextFormatFlags(TextFormatFlags flags)
{
if (((uint)flags & GdiUnsupportedFlagMask) == 0)
{
return((User32.DT)flags, TextPaddingOptions.GlyphOverhangPadding);
}
// Clear TextRenderer custom flags.
User32.DT windowsGraphicsSupportedFlags = (User32.DT)((uint)flags & ~GdiUnsupportedFlagMask);
TextPaddingOptions padding = flags.HasFlag(TextFormatFlags.LeftAndRightPadding)
? TextPaddingOptions.LeftAndRightPadding
: flags.HasFlag(TextFormatFlags.NoPadding)
? TextPaddingOptions.NoPadding
: TextPaddingOptions.GlyphOverhangPadding;
return(windowsGraphicsSupportedFlags, padding);
}
/// <summary>
/// Get the bounding box internal text padding to be used when drawing text.
/// </summary>
public static User32.DRAWTEXTPARAMS GetTextMargins(
this FontCache.Scope font,
TextPaddingOptions padding = default)
{
// DrawText(Ex) adds a small space at the beginning of the text bounding box but not at the end,
// this is more noticeable when the font has the italic style. We compensate with this factor.
int leftMargin = 0;
int rightMargin = 0;
float overhangPadding;
switch (padding)
{
case TextPaddingOptions.GlyphOverhangPadding:
// [overhang padding][Text][overhang padding][italic padding]
overhangPadding = font.Data.Height / 6f;
leftMargin = (int)Math.Ceiling(overhangPadding);
rightMargin = (int)Math.Ceiling(overhangPadding * (1 + ItalicPaddingFactor));
break;
case TextPaddingOptions.LeftAndRightPadding:
// [2 * overhang padding][Text][2 * overhang padding][italic padding]
overhangPadding = font.Data.Height / 6f;
leftMargin = (int)Math.Ceiling(2 * overhangPadding);
rightMargin = (int)Math.Ceiling(overhangPadding * (2 + ItalicPaddingFactor));
break;
case TextPaddingOptions.NoPadding:
default:
break;
}
return(new User32.DRAWTEXTPARAMS
{
iLeftMargin = leftMargin,
iRightMargin = rightMargin
});
}
