DrawLabelBackground
(
DrawingContext oDrawingContext,
GraphDrawingContext oGraphDrawingContext,
FormattedText oFormattedText,
Color oFormattedTextColor,
Byte btBackgroundAlpha,
Point oTextOrigin
)
{
Debug.Assert(oDrawingContext != null);
Debug.Assert(oGraphDrawingContext != null);
Debug.Assert(oFormattedText != null);
AssertValid();
if (oFormattedText.Width == 0 || oFormattedText.Height == 0)
{
return;
}
// Note: Don't make the background any more opaque than the text, which
// might be translucent itself.
Color oBackgroundColor = WpfGraphicsUtil.SetWpfColorAlpha(
oGraphDrawingContext.BackColor,
Math.Min(btBackgroundAlpha, oFormattedTextColor.A));
SolidColorBrush oBackgroundBrush = CreateFrozenSolidColorBrush(
oBackgroundColor);
Rect oBackgroundRectangle = WpfGraphicsUtil.GetFormattedTextBounds(
oFormattedText, oTextOrigin);
// Draw a rounded rectangle with a small amount of padding.
const Int32 Padding = 1;
const Int32 Radius = 2;
oBackgroundRectangle.Inflate(Padding, Padding);
oDrawingContext.DrawRoundedRectangle(oBackgroundBrush, null,
oBackgroundRectangle, Radius, Radius);
}
