TrueTypeHinting.vb
''
'' This code is part of GrapeCity Documents for Imaging samples.
'' Copyright (c) GrapeCity, Inc. All rights reserved.
''
Imports System.IO
Imports System.Drawing
Imports GrapeCity.Documents.Imaging
Imports GrapeCity.Documents.Text
Imports GrapeCity.Documents.Drawing

'' This sample demonstrates how to use TrueType font hinting instructions.
''
'' Many TrueType fonts include low-level hinting instructions.
'' The original purpose of introducing hinting instructions was 
'' to improve the look of glyphs when the font size Is comparable
'' to the device resolution. But such instructions are now also used
'' (especially in CJK fonts) to reuse some glyph parts in different
'' glyphs regardless of the font size.
'' GcGraphics supports hinting instructions. To enable it, set
'' TextFormat.EnableFontHinting property to true when rendering text.
'' 
'' This sample renders a Latin text in a small size with hinting off And on,
'' And then renders a CJK text also with hinting off And on.
Public Class TrueTypeHinting
    Function GenerateImage(
        ByVal pixelSize As Size,
        ByVal dpi As Single,
        ByVal opaque As Boolean,
        Optional ByVal sampleParams As String() = Nothing) As GcBitmap

        Dim bmp = New GcBitmap(pixelSize.Width, pixelSize.Height, True, dpi, dpi)
        Dim dy = dpi / 2
        Dim ip = New PointF(dpi, dpi)
        Using g = bmp.CreateGraphics(Color.White)
            '' Turning anti-aliasing off makes the hinting effect on small text more obvious:
            g.Renderer.Aliased = True

            Const sOff = "Hinting OFF: "
            Const sOn = "Hinting ON: "

            '' Draw a Latin string with hinting instructions off And on:
            Const sLat = "The quick brown fox jumps over the lazy dog."

            Dim tfLat = New TextFormat() With
                {
                    .Font = Font.FromFile(Path.Combine("Resources", "Fonts", "arial.ttf")),
                    .FontSize = 12,
                    .FontName = "Arial",
                    .EnableFontHinting = False
                }
            g.DrawString(sOff + sLat, tfLat, ip)
            ip.Y += dy

            tfLat.FontSize = 10
            g.DrawString(sOff + sLat, tfLat, ip)
            ip.Y += dy * 2

            tfLat.EnableFontHinting = True
            tfLat.FontSize = 12
            g.DrawString(sOn + sLat, tfLat, ip)
            ip.Y += dy

            tfLat.FontSize = 10
            g.DrawString(sOn + sLat, tfLat, ip)
            ip.Y += dy * 2

            '' Draw a CJK string with hinting instructions off And on
            '' "Best year in spring, best day in morning"
            Const sCJK = "一年之计在于春,一日之计在于晨"

            '' For CJK text, we can turn anti-aliasing on as the effect of
            '' hinting Is obvious in the characters' form itself:
            g.Renderer.Aliased = False

            Dim tfCJK = New TextFormat() With
                {
                    .Font = Font.FromFile(Path.Combine("Resources", "Fonts", "kaiu.ttf")),
                    .FontSize = 30,
                    .EnableFontHinting = False
                }
            g.DrawString(sOff + vbNewLine + sCJK, tfCJK, ip)
            ip.Y += dy * 3

            tfCJK.EnableFontHinting = True
            g.DrawString(sOn + vbNewLine + sCJK, tfCJK, ip)
        End Using
        '' Done
        Return bmp
    End Function
End Class