MeasureString 和 DrawString 的区别

Question

为什么我必须将MeasureString() 结果宽度增加 21% size.Width = size.Width * 1.21f; 在DrawString() 中逃避自动换行？

我需要一个解决方案来获得准确的结果。

两个函数使用相同的字体、相同的字符串格式、相同的文本。

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来自 OP 的回答：

  SizeF size = graphics.MeasureString(element.Currency, Currencyfont, new PointF(0, 0), strFormatLeft);
  size.Width = size.Width * 1.21f;
  int freespace = rect.Width - (int)size.Width;
  if (freespace < ImageSize) { if (freespace > 0) ImageSize = freespace; else ImageSize = 0; }
  int FlagY = y + (CurrencySize - ImageSize) / 2;
  int FlagX = (freespace - ImageSize) / 2;
  graphics.DrawImage(GetResourseImage(@"Flags." + element.Flag.ToUpper() + ".png"), 
         new Rectangle(FlagX, FlagY, ImageSize, ImageSize));
  graphics.DrawString(element.Currency, Currencyfont, Brushes.Black, 
       new Rectangle(FlagX + ImageSize, rect.Y, (int)(size.Width), CurrencySize), strFormatLeft);

我的代码。

Answer 1

MeasureString() 方法存在一些问题，尤其是在绘制非 ASCII 字符时。请改用 TextRenderer.MeasureText()。

Answer 2

Graphics.MeasureString、TextRenderer.MeasureText 和 Graphics.MeasureCharacterRanges all 返回一个大小，其中包括字形周围的空白像素以适应升序和降序。

换句话说，它们返回“a”的高度与“d”（上升）或“y”（下降）的高度相同。如果您需要字形的真实大小，唯一的方法是绘制字符串并计算像素：

Public Shared Function MeasureStringSize(ByVal graphics As Graphics, ByVal text As String, ByVal font As Font) As SizeF

    ' Get initial estimate with MeasureText
    Dim flags As TextFormatFlags = TextFormatFlags.Left + TextFormatFlags.NoClipping
    Dim proposedSize As Size = New Size(Integer.MaxValue, Integer.MaxValue)
    Dim size As Size = TextRenderer.MeasureText(graphics, text, font, proposedSize, flags)

    ' Create a bitmap
    Dim image As New Bitmap(size.Width, size.Height)
    image.SetResolution(graphics.DpiX, graphics.DpiY)

    Dim strFormat As New StringFormat
    strFormat.Alignment = StringAlignment.Near
    strFormat.LineAlignment = StringAlignment.Near

    ' Draw the actual text
    Dim g As Graphics = graphics.FromImage(image)
    g.SmoothingMode = SmoothingMode.HighQuality
    g.TextRenderingHint = Drawing.Text.TextRenderingHint.AntiAliasGridFit
    g.Clear(Color.White)
    g.DrawString(text, font, Brushes.Black, New PointF(0, 0), strFormat)

    ' Find the true boundaries of the glyph
    Dim xs As Integer = 0
    Dim xf As Integer = size.Width - 1
    Dim ys As Integer = 0
    Dim yf As Integer = size.Height - 1

    ' Find left margin
    Do While xs < xf
        For y As Integer = ys To yf
            If image.GetPixel(xs, y).ToArgb <> Color.White.ToArgb Then
                Exit Do
            End If
        Next
        xs += 1
    Loop
    ' Find right margin
    Do While xf > xs
        For y As Integer = ys To yf
            If image.GetPixel(xf, y).ToArgb <> Color.White.ToArgb Then
                Exit Do
            End If
        Next
        xf -= 1
    Loop
    ' Find top margin
    Do While ys < yf
        For x As Integer = xs To xf
            If image.GetPixel(x, ys).ToArgb <> Color.White.ToArgb Then
                Exit Do
            End If
        Next
        ys += 1
    Loop
    ' Find bottom margin
    Do While yf > ys
        For x As Integer = xs To xf
            If image.GetPixel(x, yf).ToArgb <> Color.White.ToArgb Then
                Exit Do
            End If
        Next
        yf -= 1
    Loop

    Return New SizeF(xf - xs + 1, yf - ys + 1)

End Function

Answer 3

如果对任何人有帮助，我会将答案从 smirkingman 转换为 C#，修复内存错误（使用 - Dispose）和外部循环中断（无 TODO）。我还在图形（和字体）上使用了缩放，所以我也添加了这一点（否则不起作用）。它返回 RectangleF，因为我想精确定位文本（使用 Graphics.DrawText）。

不完美但足够满足我的目的源代码：

static class StringMeasurer
{
    private static SizeF GetScaleTransform(Matrix m)
    {
        /*
         3x3 matrix, affine transformation (skew - used by rotation)
         [ X scale,     Y skew,      0 ]
         [ X skew,      Y scale,     0 ]
         [ X translate, Y translate, 1 ]

         indices (0, ...): X scale, Y skew, Y skew, X scale, X translate, Y translate
         */
        return new SizeF(m.Elements[0], m.Elements[3]);
    }

    public static RectangleF MeasureString(Graphics graphics, Font f, string s)
    {
        //copy only scale, not rotate or transform
        var scale = GetScaleTransform(graphics.Transform);

        // Get initial estimate with MeasureText
        //TextFormatFlags flags = TextFormatFlags.Left | TextFormatFlags.NoClipping;
        //Size proposedSize = new Size(int.MaxValue, int.MaxValue);
        //Size size = TextRenderer.MeasureText(graphics, s, f, proposedSize, flags);
        SizeF sizef = graphics.MeasureString(s, f);
        sizef.Width *= scale.Width;
        sizef.Height *= scale.Height;
        Size size = sizef.ToSize();

        int xLeft = 0;
        int xRight = size.Width - 1;
        int yTop = 0;
        int yBottom = size.Height - 1;

        // Create a bitmap
        using (Bitmap image = new Bitmap(size.Width, size.Height))
        {
            image.SetResolution(graphics.DpiX, graphics.DpiY);

            StringFormat strFormat = new StringFormat();
            strFormat.Alignment = StringAlignment.Near;
            strFormat.LineAlignment = StringAlignment.Near;

            // Draw the actual text
            using (Graphics g = Graphics.FromImage(image))
            {
                g.SmoothingMode = graphics.SmoothingMode;
                g.TextRenderingHint = graphics.TextRenderingHint;
                g.Clear(Color.White);
                g.ScaleTransform(scale.Width, scale.Height);
                g.DrawString(s, f, Brushes.Black, new PointF(0, 0), strFormat);
            }
            // Find the true boundaries of the glyph

            // Find left margin
            for (;  xLeft < xRight; xLeft++)
                for (int y = yTop; y <= yBottom; y++)
                    if (image.GetPixel(xLeft, y).ToArgb() != Color.White.ToArgb())
                        goto OUTER_BREAK_LEFT;
        OUTER_BREAK_LEFT: ;

            // Find right margin
            for (; xRight > xLeft; xRight--)
                for (int y = yTop; y <= yBottom; y++)
                    if (image.GetPixel(xRight, y).ToArgb() != Color.White.ToArgb())
                        goto OUTER_BREAK_RIGHT;
        OUTER_BREAK_RIGHT: ;

            // Find top margin
            for (; yTop < yBottom; yTop++)
                for (int x = xLeft; x <= xRight; x++)
                    if (image.GetPixel(x, yTop).ToArgb() != Color.White.ToArgb())
                        goto OUTER_BREAK_TOP;
        OUTER_BREAK_TOP: ;

            // Find bottom margin
            for (; yBottom > yTop; yBottom-- )
                for (int x = xLeft; x <= xRight; x++)
                    if (image.GetPixel(x, yBottom).ToArgb() != Color.White.ToArgb())
                        goto OUTER_BREAK_BOTTOM;
        OUTER_BREAK_BOTTOM: ;
        }

        var pt = new PointF(xLeft, yTop);
        var sz = new SizeF(xRight - xLeft + 1, yBottom - yTop + 1);
        return new RectangleF(pt.X / scale.Width, pt.Y / scale.Height,
            sz.Width / scale.Width, sz.Height / scale.Height);
    }
}

Answer 4

This codeproject 上的文章提供了两种方法来获取由 DrawString 呈现的字符的确切大小。

Answer 5

就个人而言，最有效的方式和我推荐的方式一直是：

 const TextFormatFlags _textFormatFlags = TextFormatFlags.NoPadding | TextFormatFlags.NoPrefix | TextFormatFlags.PreserveGraphicsClipping;
    
 // Retrieve width
 int width = TextRenderer.MeasureText(element.Currency, Currencyfont, new Size(short.MaxValue, short.MaxValue), _textFormatFlags).Width + 1;

 // Retrieve height
 int _tempHeight1 = TextRenderer.MeasureText("_", Currencyfont).Height;
 int _tempHeight2 = (int)Math.Ceiling(Currencyfont.GetHeight());
 int height = Math.Max(_tempHeight1, _tempHeight2) + 1;

Answer 6

您可能需要在StringFormat 标志中添加以下内容：

StringFormatFlags.FitBlackBox

Answer 7

试试这个解决方案：http://www.codeproject.com/Articles/2118/Bypass-Graphics-MeasureString-limitation （在https://stackoverflow.com/a/11708952/908936找到它）

代码：

static public int MeasureDisplayStringWidth(Graphics graphics, string text, Font font)
{
    System.Drawing.StringFormat format  = new System.Drawing.StringFormat ();
    System.Drawing.RectangleF   rect    = new System.Drawing.RectangleF(0, 0, 1000, 1000);
    var ranges  = new System.Drawing.CharacterRange(0, text.Length);
    System.Drawing.Region[] regions = new System.Drawing.Region[1];

    format.SetMeasurableCharacterRanges (new[] {ranges});

    regions = graphics.MeasureCharacterRanges (text, font, rect, format);
    rect    = regions[0].GetBounds (graphics);

    return (int)(rect.Right + 1.0f);
}