bitmap rotation question.

[news]

Hi Guys,

Sorry if this is an obvious question but Im trying to rotate a bitmap and
then save it. So far Ive only found how to rotates a Graphic but I can't
find how to save it. I also want to crop the image and resize it, but I
assume thats straight foward and for the code below Ive set the resize to
0.5 the original size and left the crop out.

This is what Ive got so far :-

float imageRotationAngle = 30.0f;
System.Drawing.Graphics myGraphic;

myGraphic = Graphics.FromImage(bitmapOriginal);

Matrix myMatrix = new Matrix();

PointF point = new PointF(bitmapOriginal.Width * 0.5f, bitmapOriginal.Height
* 0.5f);

myMatrix.RotateAt(imageRotationAngle, point, MatrixOrder.Append);

myGraphic.Transform = myMatrix;

myGraphic.ScaleTransform(0.5f * size.Width, 0.5f * size.Height);

myGraphic.DrawImage(bitmapOriginal, destRect, cropRect, GraphicsUnit.Pixel);




So, how do I save this rotated image as a jpg or tiff ?



Thanks in advance,

Todd.

 

[Guest]

Hi,
the Bitmap class has a save method which allows you to specify various
file formats while saving.

Mark R Dawson
http://www.markdawson.org

 

[news]

Hi Mark

Thanks for the reply. Yes, I know about the bitmap rotation save and am
using it, but the image is not saved with the transformation applied (or
does not appear to be). In the code snippet I supplied if I just put :-

bitMapOrigina.save (filename....);

the image saved will be identical to the original and not rotated by 30
degrees.

Perhaps I am approaching the problem the wrong way ? All Im trying to do is
allow the user to view an image on the screen and specify a rotation and a
crop region. Then I want to save the rotated&cropped image. So far I have
only found the Graphics.RotateAt method and am using that... but I can't
seem to save the rotated image.

Any further ideas now I've explained myself a bit more ?

Thanks,

Todd.

 

[news]

Ive actually just sussed it out but Im not sure if its a valid way to do
it...

I doing this :-

Graphics first = Graphics.FromImage (sourceImage);
myMatrix = new Matrix ();

PointF point = new PointF(sourceImage.Width * 0.5f, sourceImage.Height *
0.5f);

myMatrix.RotateAt(myAngle, point, MatrixOrder.Append);

Bitmap target = new Bitmap (sourceImage.Width, sourceImage.Height);

Graphics second = Graphics.FromImage (target);

second.Transform = myMatrix;

second.DrawImage(sourceImage, destRect, cropRect, GraphicsUnit.Pixel);


target.Save(filename, myImageCodecInfo, myEncoderParameters);

dispose.first, ();

dispose.second ();

dispose.myMatrix ();

dispose.target ();



It this the best way ?

Thanks

Todd