/// <summary>
/// For internal use to improve performance. DO NOT use this method if you modify the Graphics Clip or Transform.
/// </summary>
internal Graphics GetOrCreateGraphicsInternal(Action <Graphics>?creationAction = null)
{
if (_graphics is null)
{
Debug.Assert(!_hdc.IsNull);
// We need to manually unset the palette here so this scope shouldn't be disposed
var paletteScope = Gdi32.SelectPaletteScope.HalftonePalette(
_hdc,
forceBackground: false,
realizePalette: false);
GC.SuppressFinalize(paletteScope);
_oldPalette = paletteScope.HPalette;
_graphics = Graphics.FromHdcInternal((IntPtr)_hdc);
_graphics.PageUnit = GraphicsUnit.Pixel;
creationAction?.Invoke(_graphics);
CheckGraphicsForState(_graphics, Flags);
}
return(_graphics);
}
/// <summary>
/// Internal version of constructor for performance. We try to avoid getting the graphics object until needed.
/// </summary>
public DrawingEventArgs(
Gdi32.HDC dc,
Rectangle clipRect,
DrawingEventFlags flags)
{
_hdc = dc;
_graphics = null;
_oldPalette = default;
Flags = flags;
ClipRectangle = clipRect;
}
public DrawingEventArgs(
Graphics graphics,
Rectangle clipRect,
DrawingEventFlags flags)
{
_graphics = graphics.OrThrowIfNull();
_hdc = default;
_oldPalette = default;
CheckGraphicsForState(graphics, flags);
ClipRectangle = clipRect;
Flags = flags;
}
public DrawingEventArgs(
Graphics graphics,
Rectangle clipRect,
DrawingEventFlags flags)
{
_graphics = graphics ?? throw new ArgumentNullException(nameof(graphics));
_hdc = default;
_oldPalette = default;
CheckGraphicsForState(graphics, flags);
ClipRectangle = clipRect;
Flags = flags;
}
internal void Dispose(bool disposing)
{
if (disposing)
{
// Only dispose the graphics object if we created it via the HDC.
if (_graphics is not null && !_hdc.IsNull)
{
_graphics.Dispose();
}
}
if (!_oldPalette.IsNull && !_hdc.IsNull)
{
Gdi32.SelectPalette(_hdc, _oldPalette, BOOL.FALSE);
_oldPalette = default;
}
}
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
// Only dispose the graphics object if we created it via the dc.
if (_graphics != null && !_dc.IsNull)
{
_graphics.Dispose();
}
}
if (!_oldPal.IsNull && !_dc.IsNull)
{
Gdi32.SelectPalette(_dc, _oldPal, BOOL.FALSE);
_oldPal = default;
}
}
/// <summary>
/// Internal version of constructor for performance. We try to avoid getting the graphics object until needed.
/// </summary>
public DrawingEventArgs(
Gdi32.HDC dc,
Rectangle clipRect,
DrawingEventFlags flags)
{
ArgumentValidation.ThrowIfNull(dc);
#if DEBUG
Gdi32.OBJ type = Gdi32.GetObjectType(dc);
Debug.Assert(type == Gdi32.OBJ.DC ||
type == Gdi32.OBJ.ENHMETADC ||
type == Gdi32.OBJ.MEMDC ||
type == Gdi32.OBJ.METADC);
#endif
_hdc = dc;
_graphics = null;
_oldPalette = default;
Flags = flags;
ClipRectangle = clipRect;
}
/// <summary>
/// Internal version of constructor for performance. We try to avoid getting the graphics object until needed.
/// </summary>
public DrawingEventArgs(
Gdi32.HDC dc,
Rectangle clipRect,
DrawingEventFlags flags)
{
if (dc.IsNull)
{
throw new ArgumentNullException(nameof(dc));
}
#if DEBUG
Gdi32.OBJ type = Gdi32.GetObjectType(dc);
Debug.Assert(type == Gdi32.OBJ.DC ||
type == Gdi32.OBJ.ENHMETADC ||
type == Gdi32.OBJ.MEMDC ||
type == Gdi32.OBJ.METADC);
#endif
_hdc = dc;
_graphics = null;
_oldPalette = default;
Flags = flags;
ClipRectangle = clipRect;
}
