在打印时如何度量字符串？

在打印时如何度量字符串？

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-- 作者：未知
-- 发布日期： 2005-06-15

<Question>
   When programming printing code, how to measure string?
  <Answers>
  Yang Ning:
   You can't use Graphics.MeasureString Function, and must use typographic StringFormat object.
   Reason is: when printing string size is resolution-dependent.
   And if you using MeasureString function or use defaultgraphic StringFormat object, it is resolution-independent,
   the result will be smaller than the true one.
   Below is sample code:

   Public Shared Function GetTextSize(ByVal g As Graphics, _
   ByVal text As String, _
   ByVal textFont As Font) As SizeF

   If text.Length = 0 Then Return New SizeF(0, 0)

   Dim s As StringFormat = StringFormat.GenericTypographic
   s.FormatFlags = StringFormatFlags.MeasureTrailingSpaces

   Dim textRect As RectangleF
   Dim characterRanges As CharacterRange() = {New CharacterRange(0, text.Length)}
   s.SetMeasurableCharacterRanges(characterRanges)
   textRect = g.MeasureCharacterRanges(text, textFont, New RectangleF(0, 0, 4000, 4000), s)(0).GetBounds(g)
   Return New SizeF(textRect.Right, textRect.Bottom)
   End Function

  BTW:
   We found a bug when we use code like above. The bug is FlexGrid's column caption will display disorder. So We use following code instead

   Public Shared Function GetTextSize(ByVal g As Graphics, _
   ByVal text As String, _
   ByVal textFont As Font) As SizeF

   If text.Length = 0 Then Return New SizeF(0, 0)

   Dim s As StringFormat = StringFormat.GenericTypographic
   Dim oldFlags As StringFormatFlags

   oldFlags = s.FormatFlags
   s.FormatFlags = StringFormatFlags.MeasureTrailingSpaces
   Try
   Dim textRect As RectangleF
   Dim characterRanges As CharacterRange() = {New CharacterRange(0, text.Length)}
   s.SetMeasurableCharacterRanges(characterRanges)
   textRect = g.MeasureCharacterRanges(text, textFont, New RectangleF(0, 0, 4000, 4000), s)(0).GetBounds(g)
   Return New SizeF(textRect.Right, textRect.Bottom)
   Finally
   StringFormat.GenericTypographic.FormatFlags = oldFlags
   End Try
   End Function

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