Is there a way to disable font smoothing when using TextRect (aka ExtTextOut in GDI32) in Delphi?

Question

I am using a custom sensor based on the example that came with Delphi (5 Enterprise). For those who don’t know this, it looks like a smooth progress bar, but displays the percentage or value in the center (vertical and horizontal) of the component.

In order for the text to be read both when the calibrator is full and when it is absent, the text is displayed using inverted colors.

When font smoothing is used, these inverted colors cause the edge of the font to appear in really crazy colors, which disrupts the appearance of the component.

Is there a way to disable font smoothing / anti-aliasing for only one component or disable it, draw text, and then turn it back on?

My current workaround is to use a font that is not anti-aliased, such as "MS Sans Serif", but I would like to use the same font as the rest of the user interface to ensure consistency.

Answer 1

Specifying NONANTIALIASED_QUALITY in the LOGFONT structure should disable anti-aliasing:

 procedure SetFontQuality(Font: TFont; Quality: Byte); var LogFont: TLogFont; begin if GetObject(Font.Handle, SizeOf(TLogFont), @LogFont) = 0 then RaiseLastOSError; LogFont.lfQuality := Quality; Font.Handle := CreateFontIndirect(LogFont); end; procedure TForm1.PaintBox1Paint(Sender: TObject); const FontQualities: array[Boolean] of Byte = (DEFAULT_QUALITY, NONANTIALIASED_QUALITY); var Canvas: TCanvas; begin Canvas := (Sender as TPaintBox).Canvas; SetFontQuality(Canvas.Font, FontQualities[CheckBox1.Checked]); Canvas.TextOut(12, 12, 'Hello, world!'); end;