How to get Words length and height, when drawing the images on a canvas in GDI+ - c++

Question

I draw a string on a canvas, using GDI+ in C++.
Is there any API to get the out layer (width, height ) of a string in a certain font?
Thanks very much!
Many thanks to Windows programmer's solution.
I wrote the following code.
Bitmap bitmap(1000,1000);
Graphics graphics(&bitmap);
RectF rec;
RectF useless;
graphics.MeasureString(m_sWords, -1, m_pFont.get(), useless, &rec);
int WordWidth = rec.Width + 1;
int WordHeight Height = rec.Height + 1;
Need I use a real graphics to call MeasureString? Is there any way to get wordwidth,wordheight, without create a large Graphics Instance? I found it is resource comsuming.

Answer 1

Graphics::MeasureString computes an approximation.

Answer 2

To make the picture complete: it can simply be done with a GraphicsPath, which is better since it requires no DeviceContext:
Dim p As New GraphicsPath
Using stringFormat As New StringFormat()
stringFormat.Trimming = StringTrimming.EllipsisCharacter
stringFormat.LineAlignment = StringAlignment.Center
stringFormat.Alignment = StringAlignment.Near
p.AddString(text, font.FontFamily, font.Style, font.SizeInPoints, Point.Empty, stringFormat)
End Using
Return p.GetBounds.Size
Where text is a given string and font a given font. Returns a SizeF-Structure. I've found the results to be much more precise than Graphics.MeasureString aka GdipMeasureString-API.

Answer 3

Unfortunately you do need to use a Graphics object to do this.
The C# code I use (which returns a RectangleF, because I want to know both the width and the height) is as follows:
/// <summary> The text bounding box. </summary>
private static readonly RectangleF __boundingBox = new RectangleF(29, 25, 90, 40);
/// <summary>
/// Gets the width of a given string, in the given font, with the given
/// <see cref="StringFormat"/> options.
/// </summary>
/// <param name="text">The string to measure.</param>
/// <param name="font">The <see cref="Font"/> to use.</param>
/// <param name="fmt">The <see cref="StringFormat"/> to use.</param>
/// <returns> The floating-point width, in pixels. </returns>
private static RectangleF GetStringBounds(string text, Font font,
StringFormat fmt)
{
CharacterRange[] range = { new CharacterRange(0, text.Length) };
StringFormat myFormat = fmt.Clone() as StringFormat;
myFormat.SetMeasurableCharacterRanges(range);
using (Graphics g = Graphics.FromImage(
new Bitmap((int) __boundingBox.Width, (int) __boundingBox.Height)))
{
Region[] regions = g.MeasureCharacterRanges(text, font,
__boundingBox, myFormat);
return regions[0].GetBounds(g);
}
}
This will return a RectangleF of the size of the entire text string, word-wrapped as necessary, according to the bounding box specified as __boundingBox. On the plus side, the Graphics object is destroyed as soon as the using statement is complete…
As an aside, GDI+ seems to be pretty unreliable at this; I've found it to be quite buggy (see my question “Graphics.MeasureCharacterRanges giving wrong size calculations in C#.Net?”, for example). If you can use TextRenderer.DrawText from System.Windows.Forms, then do.