Rotated text align in C#

问题:

I need to be able to rotate text in a label and align it to the left, right or center. So far I am able to do rotation with this code in the derived label's onPaint method:

 float width = graphics.MeasureString(Text, this.Font).Width;
 float height = graphics.MeasureString(Text, this.Font).Height;

 double angle = (_rotationAngle / 180) * Math.PI;
 graphics.TranslateTransform(
     (ClientRectangle.Width + (float)(height * Math.Sin(angle)) - (float)(width * Math.Cos(angle))) / 2,
     (ClientRectangle.Height - (float)(height * Math.Cos(angle)) - (float)(width * Math.Sin(angle))) / 2);
 graphics.RotateTransform(270f);
 graphics.DrawString(Text, this.Font, textBrush, new PointF(0,0), stringFormat);
 graphics.ResetTransform();

And it works fine. I can see text rotated 270 degrees.

But when I try to set alignment in stringFormat it goes crazy, and I can't figure out what's going on.

How can I have text rotated by 270 degrees and align it to up?

回答1:

In case somebody was looking for tips, here is the solution for 0, 90, 180, 270, and 360 degrees rotation, where StringAligment works.

One thing was choosing the right point for moving the origin to, and the second one was to modify the display rectangle according to rotation.

StringFormat format = new StringFormat();
format.Alignment = StringAlignment.Center;

SizeF txt = e.Graphics.MeasureString(Text, this.Font);
SizeF sz = e.Graphics.VisibleClipBounds.Size;

//90 degrees
e.Graphics.TranslateTransform(sz.Width, 0);
e.Graphics.RotateTransform(90);
e.Graphics.DrawString(Text, this.Font, Brushes.Black, new RectangleF(0, 0, sz.Height, sz.Width), format);
e.Graphics.ResetTransform();

//180 degrees
e.Graphics.TranslateTransform(sz.Width, sz.Height);
e.Graphics.RotateTransform(180);
e.Graphics.DrawString(Text, this.Font, Brushes.Black, new RectangleF(0, 0, sz.Width, sz.Height), format);
e.Graphics.ResetTransform();

//270 degrees
e.Graphics.TranslateTransform(0, sz.Height);
e.Graphics.RotateTransform(270);
e.Graphics.DrawString(Text, this.Font, Brushes.Black, new RectangleF(0, 0, sz.Height, sz.Width), format);
e.Graphics.ResetTransform();

//0 = 360 degrees
e.Graphics.TranslateTransform(0, 0);
e.Graphics.RotateTransform(0);
e.Graphics.DrawString(Text, this.Font, Brushes.Black, new RectangleF(0, 0, sz.Width, sz.Height), format);
e.Graphics.ResetTransform();

If you put this code in label's OnPaint event, it would display your rotated form's title four times.

回答2:

Extension of Adrian Serafin's answer if you need to draw at a non-0 X,Y:

//90 degrees
e.Graphics.TranslateTransform(sz.Width, 0);
e.Graphics.RotateTransform(90);
e.Graphics.DrawString(Text, this.Font, Brushes.Black,
  new RectangleF(sz.ToPointF().Y, sz.ToPointF().X, sz.Height, sz.Width), format);
e.Graphics.ResetTransform();
//180 degrees
e.Graphics.TranslateTransform(sz.Width, sz.Height);
e.Graphics.RotateTransform(180 this.Font, Brushes.Black,
  new RectangleF(-sz.ToPointF().X, -sz.ToPointF().Y, sz.Width, sz.Height), format);
e.Graphics.ResetTransform();
//270 degrees
e.Graphics.TranslateTransform(0, sz.Height);
e.Graphics.RotateTransform(270);
e.Graphics.DrawString(Text, this.Font, Brushes.Black,
  new RectangleF(-sz.ToPointF().Y, sz.ToPointF().X, sz.Height, sz.Width), format);
//0 = 360 degrees
e.Graphics.TranslateTransform(0, 0);
e.Graphics.RotateTransform(0);
e.Graphics.DrawString(Text, this.Font, Brushes.Black,
  new RectangleF(sz.ToPointF().X, sz.ToPointF().Y, sz.Width, sz.Height), format);
e.Graphics.ResetTransform();