Get resulting size of RotateTransform

Get resulting size of RotateTransform - c#

I've got the following code for rotating an image in C#:
private Bitmap RotateImage(Bitmap b, float angle)
{
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap(b.Width, b.Height);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(returnBitmap);
//move rotation point to center of image
g.TranslateTransform((float)returnBitmap.Width / 2, (float)returnBitmap.Height / 2);
//rotate
g.RotateTransform(angle);
//move image back
g.TranslateTransform(-(float)b.Width / 2, -(float)b.Height / 2);
//draw passed in image onto graphics object
g.DrawImage(b, new Rectangle(new Point(0, 0), new Size(b.Width, b.Height)));
return returnBitmap;
}
It works very well, except that it clips the result when it exceeds original bounds.
As I understood, I have to set returnBitmap's size to the size of image after rotation. But how do I find how big the result will be, to set size of the new bitmap accordingly?

You need to rotate the four corners of your original image and calculate the bounding box for the new coordinates:
private static Bitmap RotateImage(Image b, float angle)
{
var corners = new[]
{new PointF(0, 0), new Point(b.Width, 0), new PointF(0, b.Height), new PointF(b.Width, b.Height)};
var xc = corners.Select(p => Rotate(p, angle).X);
var yc = corners.Select(p => Rotate(p, angle).Y);
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap((int)Math.Abs(xc.Max() - xc.Min()), (int)Math.Abs(yc.Max() - yc.Min()));
...
}
/// <summary>
/// Rotates a point around the origin (0,0)
/// </summary>
private static PointF Rotate(PointF p, float angle)
{
// convert from angle to radians
var theta = Math.PI*angle/180;
return new PointF(
(float) (Math.Cos(theta)*(p.X) - Math.Sin(theta)*(p.Y)),
(float) (Math.Sin(theta)*(p.X) + Math.Cos(theta)*(p.Y)));
}

Pythagoras. It is anywhere from original to sqrt(w^2 + h^2) at 90/270 angle. And I d bet it is determined by sine (max at 90).

Related

C# how to rotate an image painted in picturebox [duplicate]

I want to have one picture in my application that I can rotate to indicate directions, like wind direction. Or even the time. What code do I use to rotate the picture? Thanks
Update: I am using .NET 2.0, Windows 2000, VS C# 2005

Here's a method you can use to rotate an image in C#:
/// <summary>
/// method to rotate an image either clockwise or counter-clockwise
/// </summary>
/// <param name="img">the image to be rotated</param>
/// <param name="rotationAngle">the angle (in degrees).
/// NOTE:
/// Positive values will rotate clockwise
/// negative values will rotate counter-clockwise
/// </param>
/// <returns></returns>
public static Image RotateImage(Image img, float rotationAngle)
{
//create an empty Bitmap image
Bitmap bmp = new Bitmap(img.Width, img.Height);
//turn the Bitmap into a Graphics object
Graphics gfx = Graphics.FromImage(bmp);
//now we set the rotation point to the center of our image
gfx.TranslateTransform((float)bmp.Width / 2, (float)bmp.Height / 2);
//now rotate the image
gfx.RotateTransform(rotationAngle);
gfx.TranslateTransform(-(float)bmp.Width / 2, -(float)bmp.Height / 2);
//set the InterpolationMode to HighQualityBicubic so to ensure a high
//quality image once it is transformed to the specified size
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
//now draw our new image onto the graphics object
gfx.DrawImage(img, new Point(0, 0));
//dispose of our Graphics object
gfx.Dispose();
//return the image
return bmp;
}

This is an old thread, and there are several other threads about C# WinForms image rotation, but now that I've come up with my solution I figure this is as good a place to post it as any.
/// <summary>
/// Method to rotate an Image object. The result can be one of three cases:
/// - upsizeOk = true: output image will be larger than the input, and no clipping occurs
/// - upsizeOk = false & clipOk = true: output same size as input, clipping occurs
/// - upsizeOk = false & clipOk = false: output same size as input, image reduced, no clipping
///
/// A background color must be specified, and this color will fill the edges that are not
/// occupied by the rotated image. If color = transparent the output image will be 32-bit,
/// otherwise the output image will be 24-bit.
///
/// Note that this method always returns a new Bitmap object, even if rotation is zero - in
/// which case the returned object is a clone of the input object.
/// </summary>
/// <param name="inputImage">input Image object, is not modified</param>
/// <param name="angleDegrees">angle of rotation, in degrees</param>
/// <param name="upsizeOk">see comments above</param>
/// <param name="clipOk">see comments above, not used if upsizeOk = true</param>
/// <param name="backgroundColor">color to fill exposed parts of the background</param>
/// <returns>new Bitmap object, may be larger than input image</returns>
public static Bitmap RotateImage(Image inputImage, float angleDegrees, bool upsizeOk,
bool clipOk, Color backgroundColor)
{
// Test for zero rotation and return a clone of the input image
if (angleDegrees == 0f)
return (Bitmap)inputImage.Clone();
// Set up old and new image dimensions, assuming upsizing not wanted and clipping OK
int oldWidth = inputImage.Width;
int oldHeight = inputImage.Height;
int newWidth = oldWidth;
int newHeight = oldHeight;
float scaleFactor = 1f;
// If upsizing wanted or clipping not OK calculate the size of the resulting bitmap
if (upsizeOk || !clipOk)
{
double angleRadians = angleDegrees * Math.PI / 180d;
double cos = Math.Abs(Math.Cos(angleRadians));
double sin = Math.Abs(Math.Sin(angleRadians));
newWidth = (int)Math.Round(oldWidth * cos + oldHeight * sin);
newHeight = (int)Math.Round(oldWidth * sin + oldHeight * cos);
}
// If upsizing not wanted and clipping not OK need a scaling factor
if (!upsizeOk && !clipOk)
{
scaleFactor = Math.Min((float)oldWidth / newWidth, (float)oldHeight / newHeight);
newWidth = oldWidth;
newHeight = oldHeight;
}
// Create the new bitmap object. If background color is transparent it must be 32-bit,
// otherwise 24-bit is good enough.
Bitmap newBitmap = new Bitmap(newWidth, newHeight, backgroundColor == Color.Transparent ?
PixelFormat.Format32bppArgb : PixelFormat.Format24bppRgb);
newBitmap.SetResolution(inputImage.HorizontalResolution, inputImage.VerticalResolution);
// Create the Graphics object that does the work
using (Graphics graphicsObject = Graphics.FromImage(newBitmap))
{
graphicsObject.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphicsObject.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphicsObject.SmoothingMode = SmoothingMode.HighQuality;
// Fill in the specified background color if necessary
if (backgroundColor != Color.Transparent)
graphicsObject.Clear(backgroundColor);
// Set up the built-in transformation matrix to do the rotation and maybe scaling
graphicsObject.TranslateTransform(newWidth / 2f, newHeight / 2f);
if (scaleFactor != 1f)
graphicsObject.ScaleTransform(scaleFactor, scaleFactor);
graphicsObject.RotateTransform(angleDegrees);
graphicsObject.TranslateTransform(-oldWidth / 2f, -oldHeight / 2f);
// Draw the result
graphicsObject.DrawImage(inputImage, 0, 0);
}
return newBitmap;
}
This is the result of many sources of inspiration, here at StackOverflow and elsewhere. Naveen's answer on this thread was especially helpful.

Simple method:
public Image RotateImage(Image img)
{
var bmp = new Bitmap(img);
using (Graphics gfx = Graphics.FromImage(bmp))
{
gfx.Clear(Color.White);
gfx.DrawImage(img, 0, 0, img.Width, img.Height);
}
bmp.RotateFlip(RotateFlipType.Rotate270FlipNone);
return bmp;
}

I found this article
/// <summary>
/// Creates a new Image containing the same image only rotated
/// </summary>
/// <param name=""image"">The <see cref=""System.Drawing.Image"/"> to rotate
/// <param name=""offset"">The position to rotate from.
/// <param name=""angle"">The amount to rotate the image, clockwise, in degrees
/// <returns>A new <see cref=""System.Drawing.Bitmap"/"> of the same size rotated.</see>
/// <exception cref=""System.ArgumentNullException"">Thrown if <see cref=""image"/">
/// is null.</see>
public static Bitmap RotateImage(Image image, PointF offset, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
//create a new empty bitmap to hold rotated image
Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(rotatedBmp);
//Put the rotation point in the center of the image
g.TranslateTransform(offset.X, offset.Y);
//rotate the image
g.RotateTransform(angle);
//move the image back
g.TranslateTransform(-offset.X, -offset.Y);
//draw passed in image onto graphics object
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}

I've written a simple class for rotating image. All you've to do is input image and angle of rotation in Degree. Angle must be between -90 and +90.
public class ImageRotator
{
private readonly Bitmap image;
public Image OriginalImage
{
get { return image; }
}
private ImageRotator(Bitmap image)
{
this.image = image;
}
private double GetRadian(double degree)
{
return degree * Math.PI / (double)180;
}
private Size CalculateSize(double angle)
{
double radAngle = GetRadian(angle);
int width = (int)(image.Width * Math.Cos(radAngle) + image.Height * Math.Sin(radAngle));
int height = (int)(image.Height * Math.Cos(radAngle) + image.Width * Math.Sin(radAngle));
return new Size(width, height);
}
private PointF GetTopCoordinate(double radAngle)
{
Bitmap image = CurrentlyViewedMappedImage.BitmapImage;
double topX = 0;
double topY = 0;
if (radAngle > 0)
{
topX = image.Height * Math.Sin(radAngle);
}
if (radAngle < 0)
{
topY = image.Width * Math.Sin(-radAngle);
}
return new PointF((float)topX, (float)topY);
}
public Bitmap RotateImage(double angle)
{
SizeF size = CalculateSize(radAngle);
Bitmap rotatedBmp = new Bitmap((int)size.Width, (int)size.Height);
Graphics g = Graphics.FromImage(rotatedBmp);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.TranslateTransform(topPoint.X, topPoint.Y);
g.RotateTransform(GetDegree(radAngle));
g.DrawImage(image, new RectangleF(0, 0, size.Width, size.Height));
g.Dispose();
return rotatedBmp;
}
public static class Builder
{
public static ImageRotator CreateInstance(Image image)
{
ImageRotator rotator = new ImageRotator(image as Bitmap);
return rotator;
}
}
}

Old question but I had to address MrFox's comment in the accepted answer. Rotating an image when the size changes cuts off the edges of the image. One solution is to redraw the original on a larger image, centered, where the larger image's dimensions compensate for the need of not clipping the edges. For example, I wanted to be able to design a game's tiles at a normal angle but re-draw them at a 45-degree angle for an isometric view.
Here are example images (yellow borders are to make it easier to see here).
The original image:
The centered tile in a larger image:
The rotated image (where you rotate the larger image, not the original):
The code (based in part on this answer in another question):
private Bitmap RotateImage(Bitmap rotateMe, float angle)
{
//First, re-center the image in a larger image that has a margin/frame
//to compensate for the rotated image's increased size
var bmp = new Bitmap(rotateMe.Width + (rotateMe.Width / 2), rotateMe.Height + (rotateMe.Height / 2));
using (Graphics g = Graphics.FromImage(bmp))
g.DrawImageUnscaled(rotateMe, (rotateMe.Width / 4), (rotateMe.Height / 4), bmp.Width, bmp.Height);
bmp.Save("moved.png");
rotateMe = bmp;
//Now, actually rotate the image
Bitmap rotatedImage = new Bitmap(rotateMe.Width, rotateMe.Height);
using (Graphics g = Graphics.FromImage(rotatedImage))
{
g.TranslateTransform(rotateMe.Width / 2, rotateMe.Height / 2); //set the rotation point as the center into the matrix
g.RotateTransform(angle); //rotate
g.TranslateTransform(-rotateMe.Width / 2, -rotateMe.Height / 2); //restore rotation point into the matrix
g.DrawImage(rotateMe, new Point(0, 0)); //draw the image on the new bitmap
}
rotatedImage.Save("rotated.png");
return rotatedImage;
}

Richard Cox has a good solution to this https://stackoverflow.com/a/5200280/1171321 I have used in the past. It is also worth noting the DPI must be 96 for this to work correctly. Several of the solutions on this page do not work at all.

Rotating image is one thing, proper image boundaries in another. Here is a code which can help anyone. I created this based on some search on internet long ago.
/// <summary>
/// Rotates image in radian angle
/// </summary>
/// <param name="bmpSrc"></param>
/// <param name="theta">in radian</param>
/// <param name="extendedBitmapBackground">Because of rotation returned bitmap can have different boundaries from original bitmap. This color is used for filling extra space in bitmap</param>
/// <returns></returns>
public static Bitmap RotateImage(Bitmap bmpSrc, double theta, Color? extendedBitmapBackground = null)
{
theta = Convert.ToSingle(theta * 180 / Math.PI);
Matrix mRotate = new Matrix();
mRotate.Translate(bmpSrc.Width / -2, bmpSrc.Height / -2, MatrixOrder.Append);
mRotate.RotateAt((float)theta, new Point(0, 0), MatrixOrder.Append);
using (GraphicsPath gp = new GraphicsPath())
{ // transform image points by rotation matrix
gp.AddPolygon(new Point[] { new Point(0, 0), new Point(bmpSrc.Width, 0), new Point(0, bmpSrc.Height) });
gp.Transform(mRotate);
PointF[] pts = gp.PathPoints;
// create destination bitmap sized to contain rotated source image
Rectangle bbox = BoundingBox(bmpSrc, mRotate);
Bitmap bmpDest = new Bitmap(bbox.Width, bbox.Height);
using (Graphics gDest = Graphics.FromImage(bmpDest))
{
if (extendedBitmapBackground != null)
{
gDest.Clear(extendedBitmapBackground.Value);
}
// draw source into dest
Matrix mDest = new Matrix();
mDest.Translate(bmpDest.Width / 2, bmpDest.Height / 2, MatrixOrder.Append);
gDest.Transform = mDest;
gDest.DrawImage(bmpSrc, pts);
return bmpDest;
}
}
}
private static Rectangle BoundingBox(Image img, Matrix matrix)
{
GraphicsUnit gu = new GraphicsUnit();
Rectangle rImg = Rectangle.Round(img.GetBounds(ref gu));
// Transform the four points of the image, to get the resized bounding box.
Point topLeft = new Point(rImg.Left, rImg.Top);
Point topRight = new Point(rImg.Right, rImg.Top);
Point bottomRight = new Point(rImg.Right, rImg.Bottom);
Point bottomLeft = new Point(rImg.Left, rImg.Bottom);
Point[] points = new Point[] { topLeft, topRight, bottomRight, bottomLeft };
GraphicsPath gp = new GraphicsPath(points, new byte[] { (byte)PathPointType.Start, (byte)PathPointType.Line, (byte)PathPointType.Line, (byte)PathPointType.Line });
gp.Transform(matrix);
return Rectangle.Round(gp.GetBounds());
}

This will work as long as the image you want to rotate is already in your Properties resources folder.
In Partial Class:
Bitmap bmp2;
OnLoad:
bmp2 = new Bitmap(Tycoon.Properties.Resources.save2);
pictureBox6.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox6.Image = bmp2;
Button or Onclick
private void pictureBox6_Click(object sender, EventArgs e)
{
if (bmp2 != null)
{
bmp2.RotateFlip(RotateFlipType.Rotate90FlipNone);
pictureBox6.Image = bmp2;
}
}

You can easily do it by calling this method :
public static Bitmap RotateImage(Image image, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
PointF offset = new PointF((float)image.Width / 2, (float)image.Height / 2);
//create a new empty bitmap to hold rotated image
Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(rotatedBmp);
//Put the rotation point in the center of the image
g.TranslateTransform(offset.X, offset.Y);
//rotate the image
g.RotateTransform(angle);
//move the image back
g.TranslateTransform(-offset.X, -offset.Y);
//draw passed in image onto graphics object
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}
don't forget to add a reference to System.Drawing.dll on your project
Example of this method call :
Image image = new Bitmap("waves.png");
Image newImage = RotateImage(image, 360);
newImage.Save("newWaves.png");

I have modified the function of Mr.net_prog which gets only the picture box and rotate the image in it.
public static void RotateImage(PictureBox picBox)
{
Image img = picBox.Image;
var bmp = new Bitmap(img);
using (Graphics gfx = Graphics.FromImage(bmp))
{
gfx.Clear(Color.White);
gfx.DrawImage(img, 0, 0, img.Width, img.Height);
}
bmp.RotateFlip(RotateFlipType.Rotate270FlipNone);
picBox.Image = bmp;
}

This solution assumes that you want to draw the image in a picture box and that the image orientation will follow the mouse movements over this picture box. No image is assigned to the picture box. Instead I'm getting the image from a project resource.
private float _angle;
public Form1()
{
InitializeComponent();
}
private void PictureBox_MouseMove(object sender, MouseEventArgs e)
{
(float centerX, float centerY) = GetCenter(pictureBox1.ClientRectangle);
_angle = (float)(Math.Atan2(e.Y - centerY, e.X - centerX) * 180.0 / Math.PI);
pictureBox1.Invalidate(); // Triggers redrawing
}
private void PictureBox_Paint(object sender, PaintEventArgs e)
{
Bitmap image = Properties.Resources.ExampleImage;
float scale = (float)pictureBox1.Width / image.Width;
(float centerX, float centerY) = GetCenter(e.ClipRectangle);
e.Graphics.TranslateTransform(centerX, centerY);
e.Graphics.RotateTransform(_angle);
e.Graphics.TranslateTransform(-centerX, -centerY);
e.Graphics.ScaleTransform(scale, scale);
e.Graphics.DrawImage(image, 0, 0);
}
// Uses C# 7.0 value tuples / .NET Framework 4.7.
// For previous versions, return a PointF instead.
private static (float, float) GetCenter(Rectangle rect)
{
float centerX = (rect.Left + rect.Right) * 0.5f;
float centerY = (rect.Top + rect.Bottom) * 0.5f;
return (centerX, centerY);
}
Make sure to to select the mouse event handlers PictureBox_MouseMove and PictureBox_Paint in properties window of the picture box for these events, after you copy/pasted this code into the form.
Note: You could also use a simple Panel or any other control, like a label; however, the PictureBox has the advantage to use double buffering by default, which eliminates flickering.

How do you rotate a bitmap an arbitrary number of degrees?

I have a bitmap:
Bitmap UnitImageBMP
And I need to rotate it an arbitrary number of degrees. How do I do this? The RotateFlip method will only rotate in increments of 90 degrees.

I did some searching for you and found this:
public static Bitmap RotateImage(Bitmap b, float angle)
{
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap(b.Width, b.Height);
//make a graphics object from the empty bitmap
using(Graphics g = Graphics.FromImage(returnBitmap))
{
//move rotation point to center of image
g.TranslateTransform((float)b.Width / 2, (float)b.Height / 2);
//rotate
g.RotateTransform(angle);
//move image back
g.TranslateTransform(-(float)b.Width / 2, -(float)b.Height / 2);
//draw passed in image onto graphics object
g.DrawImage(b, new Point(0, 0));
}
return returnBitmap;
}

How to rotate picturebox

I need to solve a problem by rotating an image, but I have this code to rotate the image does not rotate completely
public static Image RotateImage(Image img, float rotationAngle)
{
//create an empty Bitmap image
Bitmap bmp = new Bitmap(img.Width, img.Height);
//turn the Bitmap into a Graphics object
Graphics gfx = Graphics.FromImage(bmp);
//now we set the rotation point to the center of our image
gfx.TranslateTransform((float)bmp.Width / 2, (float)bmp.Height / 2);
//now rotate the image
gfx.RotateTransform(rotationAngle);
gfx.TranslateTransform(-(float)bmp.Width / 2, -(float)bmp.Height / 2);
//set the InterpolationMode to HighQualityBicubic so to ensure a high
//quality image once it is transformed to the specified size
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
//now draw our new image onto the graphics object
gfx.DrawImage(img, new System.Drawing.Point(0, 0));
//dispose of our Graphics object
gfx.Dispose();
//return the image
return bmp;
}
And use this to call method. The right is rotate the image rectangle that contains, and to avoid cutting the image
Bitmap bitmap = (Bitmap)Pix.Image;
Pix.Image = (Bitmap)(RotateImage(bitmap, 20.0f));

private Bitmap RotateImageByAngle(Image oldBitmap, float angle)
{
var newBitmap = new Bitmap(oldBitmap.Width, oldBitmap.Height);
newBitmap.SetResolution(oldBitmap.HorizontalResolution, oldBitmap.VerticalResolution);
var graphics = Graphics.FromImage(newBitmap);
graphics.TranslateTransform((float)oldBitmap.Width / 2, (float)oldBitmap.Height / 2);
graphics.RotateTransform(angle);
graphics.TranslateTransform(-(float)oldBitmap.Width / 2, -(float)oldBitmap.Height / 2);
graphics.DrawImage(oldBitmap, new Point(0, 0));
return newBitmap;
}

I have used in the past the following code from this article.
http://www.switchonthecode.com/tutorials/csharp-tutorial-image-editing-rotate
Has some other solutions as well.
/// <summary>
/// Rotates the input image by theta degrees around center.
/// </summary>
public static Bitmap rotateCenter(Bitmap bmpSrc, float theta)
{
Matrix mRotate = new Matrix();
mRotate.Translate(bmpSrc.Width / -2, bmpSrc.Height / -2, MatrixOrder.Append);
mRotate.RotateAt(theta, new Point(0, 0), MatrixOrder.Append);
using (GraphicsPath gp = new GraphicsPath())
{ // transform image points by rotation matrix
gp.AddPolygon(new Point[] { new Point(0, 0), new Point(bmpSrc.Width, 0), new Point(0, bmpSrc.Height) });
gp.Transform(mRotate);
PointF[] pts = gp.PathPoints;
// create destination bitmap sized to contain rotated source image
Rectangle bbox = boundingBox(bmpSrc, mRotate);
Bitmap bmpDest = new Bitmap(bbox.Width, bbox.Height);
using (Graphics gDest = Graphics.FromImage(bmpDest))
{ // draw source into dest
Matrix mDest = new Matrix();
mDest.Translate(bmpDest.Width / 2, bmpDest.Height / 2, MatrixOrder.Append);
gDest.Transform = mDest;
gDest.DrawImage(bmpSrc, pts);
//drawAxes(gDest, Color.Red, 0, 0, 1, 100, "");
return bmpDest;
}
}
}
private static Rectangle boundingBox(Image img, Matrix matrix)
{
GraphicsUnit gu = new GraphicsUnit();
Rectangle rImg = Rectangle.Round(img.GetBounds(ref gu));
// Transform the four points of the image, to get the resized bounding box.
Point topLeft = new Point(rImg.Left, rImg.Top);
Point topRight = new Point(rImg.Right, rImg.Top);
Point bottomRight = new Point(rImg.Right, rImg.Bottom);
Point bottomLeft = new Point(rImg.Left, rImg.Bottom);
Point[] points = new Point[] { topLeft, topRight, bottomRight, bottomLeft };
GraphicsPath gp = new GraphicsPath(points,
new byte[] { (byte)PathPointType.Start, (byte)PathPointType.Line, (byte)PathPointType.Line, (byte)PathPointType.Line });
gp.Transform(matrix);
return Rectangle.Round(gp.GetBounds());
}

Rotating graphics?

I have this code, that draws an image.
private void timer1_Tick(object sender, EventArgs e)
{
Invalidate();
}
protected override void OnPaint(PaintEventArgs e)
{
var tempRocket = new Bitmap(Properties.Resources.rocket);
using (var g = Graphics.FromImage(tempRocket))
{
e.Graphics.DrawImage(tempRocket, 150, 150);
}
}
Yet what do I do to rotate it?

public static Bitmap RotateImage(Bitmap b, float angle)
{
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap(b.Width, b.Height);
//make a graphics object from the empty bitmap
using(Graphics g = Graphics.FromImage(returnBitmap))
{
//move rotation point to center of image
g.TranslateTransform((float)b.Width / 2, (float)b.Height / 2);
//rotate
g.RotateTransform(angle);
//move image back
g.TranslateTransform(-(float)b.Width / 2, -(float)b.Height / 2);
//draw passed in image onto graphics object
g.DrawImage(b, new Point(0, 0));
}
return returnBitmap;
}

There are overloads of Graphics.DrawImage that take an array of three points used to define a parallelogram for the destination, such as:
Graphics.DrawImage Method (Image, Point[])
Remarks
The destPoints parameter specifies
three points of a parallelogram. The
three Point structures represent the
upper-left, upper-right, and
lower-left corners of the
parallelogram. The fourth point is
extrapolated from the first three to
form a parallelogram.
The image represented by the image
parameter is scaled and sheared to fit
the shape of the parallelogram
specified by the destPoints
parameters.
There is also an article on MSDN describing the use of this method: How to: Rotate, Reflect, and Skew Images, with the following code example. Unfortunately, the example complicates the issue by also skewing the image.
Point[] destinationPoints = {
new Point(200, 20), // destination for upper-left point of original
new Point(110, 100), // destination for upper-right point of original
new Point(250, 30)}; // destination for lower-left point of original
Image image = new Bitmap("Stripes.bmp");
// Draw the image unaltered with its upper-left corner at (0, 0).
e.Graphics.DrawImage(image, 0, 0);
// Draw the image mapped to the parallelogram.
e.Graphics.DrawImage(image, destinationPoints);
The main differences compared to using the Graphics.Transform property are:
This method does not allow you to specify the rotation angle in degrees -- you have to use some simple trigonometry to derive the points.
This transformation applies only to the specific image.
Good if you only need to draw one rotated image and everything else is non-rotated since you don't have to reset Graphics.Transform afterward.
Bad if you want to rotate several things together (i.e., rotate the "camera").

Use Graphics.RotateTransform to rotate the image.
protected override void OnPaint(PaintEventArgs e)
{
var tempRocket = new Bitmap(Properties.Resources.rocket);
e.Graphics.RotateTransform(30.0F);
e.Graphics.DrawImage(tempRocket, 150, 150);
}

Version without clipping:
private Bitmap RotateBitmap(Bitmap bitmap, float angle)
{
int w, h, x, y;
var dW = (double)bitmap.Width;
var dH = (double)bitmap.Height;
double degrees = Math.Abs(angle);
if (degrees <= 90)
{
double radians = 0.0174532925 * degrees;
double dSin = Math.Sin(radians);
double dCos = Math.Cos(radians);
w = (int)(dH * dSin + dW * dCos);
h = (int)(dW * dSin + dH * dCos);
x = (w - bitmap.Width) / 2;
y = (h - bitmap.Height) / 2;
}
else
{
degrees -= 90;
double radians = 0.0174532925 * degrees;
double dSin = Math.Sin(radians);
double dCos = Math.Cos(radians);
w = (int)(dW * dSin + dH * dCos);
h = (int)(dH * dSin + dW * dCos);
x = (w - bitmap.Width) / 2;
y = (h - bitmap.Height) / 2;
}
var rotateAtX = bitmap.Width / 2f;
var rotateAtY = bitmap.Height / 2f;
var bmpRet = new Bitmap(w, h);
bmpRet.SetResolution(bitmap.HorizontalResolution, bitmap.VerticalResolution);
using (var graphics = Graphics.FromImage(bmpRet))
{
graphics.Clear(Color.White);
graphics.TranslateTransform(rotateAtX + x, rotateAtY + y);
graphics.RotateTransform(angle);
graphics.TranslateTransform(-rotateAtX - x, -rotateAtY - y);
graphics.DrawImage(bitmap, new PointF(0 + x, 0 + y));
}
return bmpRet;
}
Primary source

You need to apply transformation matrix.
Here you can find good example about transformations in GDI+

How do I rotate a picture in WinForms

I want to have one picture in my application that I can rotate to indicate directions, like wind direction. Or even the time. What code do I use to rotate the picture? Thanks
Update: I am using .NET 2.0, Windows 2000, VS C# 2005

Here's a method you can use to rotate an image in C#:
/// <summary>
/// method to rotate an image either clockwise or counter-clockwise
/// </summary>
/// <param name="img">the image to be rotated</param>
/// <param name="rotationAngle">the angle (in degrees).
/// NOTE:
/// Positive values will rotate clockwise
/// negative values will rotate counter-clockwise
/// </param>
/// <returns></returns>
public static Image RotateImage(Image img, float rotationAngle)
{
//create an empty Bitmap image
Bitmap bmp = new Bitmap(img.Width, img.Height);
//turn the Bitmap into a Graphics object
Graphics gfx = Graphics.FromImage(bmp);
//now we set the rotation point to the center of our image
gfx.TranslateTransform((float)bmp.Width / 2, (float)bmp.Height / 2);
//now rotate the image
gfx.RotateTransform(rotationAngle);
gfx.TranslateTransform(-(float)bmp.Width / 2, -(float)bmp.Height / 2);
//set the InterpolationMode to HighQualityBicubic so to ensure a high
//quality image once it is transformed to the specified size
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
//now draw our new image onto the graphics object
gfx.DrawImage(img, new Point(0, 0));
//dispose of our Graphics object
gfx.Dispose();
//return the image
return bmp;
}

This is an old thread, and there are several other threads about C# WinForms image rotation, but now that I've come up with my solution I figure this is as good a place to post it as any.
/// <summary>
/// Method to rotate an Image object. The result can be one of three cases:
/// - upsizeOk = true: output image will be larger than the input, and no clipping occurs
/// - upsizeOk = false & clipOk = true: output same size as input, clipping occurs
/// - upsizeOk = false & clipOk = false: output same size as input, image reduced, no clipping
///
/// A background color must be specified, and this color will fill the edges that are not
/// occupied by the rotated image. If color = transparent the output image will be 32-bit,
/// otherwise the output image will be 24-bit.
///
/// Note that this method always returns a new Bitmap object, even if rotation is zero - in
/// which case the returned object is a clone of the input object.
/// </summary>
/// <param name="inputImage">input Image object, is not modified</param>
/// <param name="angleDegrees">angle of rotation, in degrees</param>
/// <param name="upsizeOk">see comments above</param>
/// <param name="clipOk">see comments above, not used if upsizeOk = true</param>
/// <param name="backgroundColor">color to fill exposed parts of the background</param>
/// <returns>new Bitmap object, may be larger than input image</returns>
public static Bitmap RotateImage(Image inputImage, float angleDegrees, bool upsizeOk,
bool clipOk, Color backgroundColor)
{
// Test for zero rotation and return a clone of the input image
if (angleDegrees == 0f)
return (Bitmap)inputImage.Clone();
// Set up old and new image dimensions, assuming upsizing not wanted and clipping OK
int oldWidth = inputImage.Width;
int oldHeight = inputImage.Height;
int newWidth = oldWidth;
int newHeight = oldHeight;
float scaleFactor = 1f;
// If upsizing wanted or clipping not OK calculate the size of the resulting bitmap
if (upsizeOk || !clipOk)
{
double angleRadians = angleDegrees * Math.PI / 180d;
double cos = Math.Abs(Math.Cos(angleRadians));
double sin = Math.Abs(Math.Sin(angleRadians));
newWidth = (int)Math.Round(oldWidth * cos + oldHeight * sin);
newHeight = (int)Math.Round(oldWidth * sin + oldHeight * cos);
}
// If upsizing not wanted and clipping not OK need a scaling factor
if (!upsizeOk && !clipOk)
{
scaleFactor = Math.Min((float)oldWidth / newWidth, (float)oldHeight / newHeight);
newWidth = oldWidth;
newHeight = oldHeight;
}
// Create the new bitmap object. If background color is transparent it must be 32-bit,
// otherwise 24-bit is good enough.
Bitmap newBitmap = new Bitmap(newWidth, newHeight, backgroundColor == Color.Transparent ?
PixelFormat.Format32bppArgb : PixelFormat.Format24bppRgb);
newBitmap.SetResolution(inputImage.HorizontalResolution, inputImage.VerticalResolution);
// Create the Graphics object that does the work
using (Graphics graphicsObject = Graphics.FromImage(newBitmap))
{
graphicsObject.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphicsObject.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphicsObject.SmoothingMode = SmoothingMode.HighQuality;
// Fill in the specified background color if necessary
if (backgroundColor != Color.Transparent)
graphicsObject.Clear(backgroundColor);
// Set up the built-in transformation matrix to do the rotation and maybe scaling
graphicsObject.TranslateTransform(newWidth / 2f, newHeight / 2f);
if (scaleFactor != 1f)
graphicsObject.ScaleTransform(scaleFactor, scaleFactor);
graphicsObject.RotateTransform(angleDegrees);
graphicsObject.TranslateTransform(-oldWidth / 2f, -oldHeight / 2f);
// Draw the result
graphicsObject.DrawImage(inputImage, 0, 0);
}
return newBitmap;
}
This is the result of many sources of inspiration, here at StackOverflow and elsewhere. Naveen's answer on this thread was especially helpful.

Simple method:
public Image RotateImage(Image img)
{
var bmp = new Bitmap(img);
using (Graphics gfx = Graphics.FromImage(bmp))
{
gfx.Clear(Color.White);
gfx.DrawImage(img, 0, 0, img.Width, img.Height);
}
bmp.RotateFlip(RotateFlipType.Rotate270FlipNone);
return bmp;
}

I found this article
/// <summary>
/// Creates a new Image containing the same image only rotated
/// </summary>
/// <param name=""image"">The <see cref=""System.Drawing.Image"/"> to rotate
/// <param name=""offset"">The position to rotate from.
/// <param name=""angle"">The amount to rotate the image, clockwise, in degrees
/// <returns>A new <see cref=""System.Drawing.Bitmap"/"> of the same size rotated.</see>
/// <exception cref=""System.ArgumentNullException"">Thrown if <see cref=""image"/">
/// is null.</see>
public static Bitmap RotateImage(Image image, PointF offset, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
//create a new empty bitmap to hold rotated image
Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(rotatedBmp);
//Put the rotation point in the center of the image
g.TranslateTransform(offset.X, offset.Y);
//rotate the image
g.RotateTransform(angle);
//move the image back
g.TranslateTransform(-offset.X, -offset.Y);
//draw passed in image onto graphics object
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}

I've written a simple class for rotating image. All you've to do is input image and angle of rotation in Degree. Angle must be between -90 and +90.
public class ImageRotator
{
private readonly Bitmap image;
public Image OriginalImage
{
get { return image; }
}
private ImageRotator(Bitmap image)
{
this.image = image;
}
private double GetRadian(double degree)
{
return degree * Math.PI / (double)180;
}
private Size CalculateSize(double angle)
{
double radAngle = GetRadian(angle);
int width = (int)(image.Width * Math.Cos(radAngle) + image.Height * Math.Sin(radAngle));
int height = (int)(image.Height * Math.Cos(radAngle) + image.Width * Math.Sin(radAngle));
return new Size(width, height);
}
private PointF GetTopCoordinate(double radAngle)
{
Bitmap image = CurrentlyViewedMappedImage.BitmapImage;
double topX = 0;
double topY = 0;
if (radAngle > 0)
{
topX = image.Height * Math.Sin(radAngle);
}
if (radAngle < 0)
{
topY = image.Width * Math.Sin(-radAngle);
}
return new PointF((float)topX, (float)topY);
}
public Bitmap RotateImage(double angle)
{
SizeF size = CalculateSize(radAngle);
Bitmap rotatedBmp = new Bitmap((int)size.Width, (int)size.Height);
Graphics g = Graphics.FromImage(rotatedBmp);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.TranslateTransform(topPoint.X, topPoint.Y);
g.RotateTransform(GetDegree(radAngle));
g.DrawImage(image, new RectangleF(0, 0, size.Width, size.Height));
g.Dispose();
return rotatedBmp;
}
public static class Builder
{
public static ImageRotator CreateInstance(Image image)
{
ImageRotator rotator = new ImageRotator(image as Bitmap);
return rotator;
}
}
}

Old question but I had to address MrFox's comment in the accepted answer. Rotating an image when the size changes cuts off the edges of the image. One solution is to redraw the original on a larger image, centered, where the larger image's dimensions compensate for the need of not clipping the edges. For example, I wanted to be able to design a game's tiles at a normal angle but re-draw them at a 45-degree angle for an isometric view.
Here are example images (yellow borders are to make it easier to see here).
The original image:
The centered tile in a larger image:
The rotated image (where you rotate the larger image, not the original):
The code (based in part on this answer in another question):
private Bitmap RotateImage(Bitmap rotateMe, float angle)
{
//First, re-center the image in a larger image that has a margin/frame
//to compensate for the rotated image's increased size
var bmp = new Bitmap(rotateMe.Width + (rotateMe.Width / 2), rotateMe.Height + (rotateMe.Height / 2));
using (Graphics g = Graphics.FromImage(bmp))
g.DrawImageUnscaled(rotateMe, (rotateMe.Width / 4), (rotateMe.Height / 4), bmp.Width, bmp.Height);
bmp.Save("moved.png");
rotateMe = bmp;
//Now, actually rotate the image
Bitmap rotatedImage = new Bitmap(rotateMe.Width, rotateMe.Height);
using (Graphics g = Graphics.FromImage(rotatedImage))
{
g.TranslateTransform(rotateMe.Width / 2, rotateMe.Height / 2); //set the rotation point as the center into the matrix
g.RotateTransform(angle); //rotate
g.TranslateTransform(-rotateMe.Width / 2, -rotateMe.Height / 2); //restore rotation point into the matrix
g.DrawImage(rotateMe, new Point(0, 0)); //draw the image on the new bitmap
}
rotatedImage.Save("rotated.png");
return rotatedImage;
}

Richard Cox has a good solution to this https://stackoverflow.com/a/5200280/1171321 I have used in the past. It is also worth noting the DPI must be 96 for this to work correctly. Several of the solutions on this page do not work at all.

Rotating image is one thing, proper image boundaries in another. Here is a code which can help anyone. I created this based on some search on internet long ago.
/// <summary>
/// Rotates image in radian angle
/// </summary>
/// <param name="bmpSrc"></param>
/// <param name="theta">in radian</param>
/// <param name="extendedBitmapBackground">Because of rotation returned bitmap can have different boundaries from original bitmap. This color is used for filling extra space in bitmap</param>
/// <returns></returns>
public static Bitmap RotateImage(Bitmap bmpSrc, double theta, Color? extendedBitmapBackground = null)
{
theta = Convert.ToSingle(theta * 180 / Math.PI);
Matrix mRotate = new Matrix();
mRotate.Translate(bmpSrc.Width / -2, bmpSrc.Height / -2, MatrixOrder.Append);
mRotate.RotateAt((float)theta, new Point(0, 0), MatrixOrder.Append);
using (GraphicsPath gp = new GraphicsPath())
{ // transform image points by rotation matrix
gp.AddPolygon(new Point[] { new Point(0, 0), new Point(bmpSrc.Width, 0), new Point(0, bmpSrc.Height) });
gp.Transform(mRotate);
PointF[] pts = gp.PathPoints;
// create destination bitmap sized to contain rotated source image
Rectangle bbox = BoundingBox(bmpSrc, mRotate);
Bitmap bmpDest = new Bitmap(bbox.Width, bbox.Height);
using (Graphics gDest = Graphics.FromImage(bmpDest))
{
if (extendedBitmapBackground != null)
{
gDest.Clear(extendedBitmapBackground.Value);
}
// draw source into dest
Matrix mDest = new Matrix();
mDest.Translate(bmpDest.Width / 2, bmpDest.Height / 2, MatrixOrder.Append);
gDest.Transform = mDest;
gDest.DrawImage(bmpSrc, pts);
return bmpDest;
}
}
}
private static Rectangle BoundingBox(Image img, Matrix matrix)
{
GraphicsUnit gu = new GraphicsUnit();
Rectangle rImg = Rectangle.Round(img.GetBounds(ref gu));
// Transform the four points of the image, to get the resized bounding box.
Point topLeft = new Point(rImg.Left, rImg.Top);
Point topRight = new Point(rImg.Right, rImg.Top);
Point bottomRight = new Point(rImg.Right, rImg.Bottom);
Point bottomLeft = new Point(rImg.Left, rImg.Bottom);
Point[] points = new Point[] { topLeft, topRight, bottomRight, bottomLeft };
GraphicsPath gp = new GraphicsPath(points, new byte[] { (byte)PathPointType.Start, (byte)PathPointType.Line, (byte)PathPointType.Line, (byte)PathPointType.Line });
gp.Transform(matrix);
return Rectangle.Round(gp.GetBounds());
}

This will work as long as the image you want to rotate is already in your Properties resources folder.
In Partial Class:
Bitmap bmp2;
OnLoad:
bmp2 = new Bitmap(Tycoon.Properties.Resources.save2);
pictureBox6.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox6.Image = bmp2;
Button or Onclick
private void pictureBox6_Click(object sender, EventArgs e)
{
if (bmp2 != null)
{
bmp2.RotateFlip(RotateFlipType.Rotate90FlipNone);
pictureBox6.Image = bmp2;
}
}

You can easily do it by calling this method :
public static Bitmap RotateImage(Image image, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
PointF offset = new PointF((float)image.Width / 2, (float)image.Height / 2);
//create a new empty bitmap to hold rotated image
Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(rotatedBmp);
//Put the rotation point in the center of the image
g.TranslateTransform(offset.X, offset.Y);
//rotate the image
g.RotateTransform(angle);
//move the image back
g.TranslateTransform(-offset.X, -offset.Y);
//draw passed in image onto graphics object
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}
don't forget to add a reference to System.Drawing.dll on your project
Example of this method call :
Image image = new Bitmap("waves.png");
Image newImage = RotateImage(image, 360);
newImage.Save("newWaves.png");

I have modified the function of Mr.net_prog which gets only the picture box and rotate the image in it.
public static void RotateImage(PictureBox picBox)
{
Image img = picBox.Image;
var bmp = new Bitmap(img);
using (Graphics gfx = Graphics.FromImage(bmp))
{
gfx.Clear(Color.White);
gfx.DrawImage(img, 0, 0, img.Width, img.Height);
}
bmp.RotateFlip(RotateFlipType.Rotate270FlipNone);
picBox.Image = bmp;
}

This solution assumes that you want to draw the image in a picture box and that the image orientation will follow the mouse movements over this picture box. No image is assigned to the picture box. Instead I'm getting the image from a project resource.
private float _angle;
public Form1()
{
InitializeComponent();
}
private void PictureBox_MouseMove(object sender, MouseEventArgs e)
{
(float centerX, float centerY) = GetCenter(pictureBox1.ClientRectangle);
_angle = (float)(Math.Atan2(e.Y - centerY, e.X - centerX) * 180.0 / Math.PI);
pictureBox1.Invalidate(); // Triggers redrawing
}
private void PictureBox_Paint(object sender, PaintEventArgs e)
{
Bitmap image = Properties.Resources.ExampleImage;
float scale = (float)pictureBox1.Width / image.Width;
(float centerX, float centerY) = GetCenter(e.ClipRectangle);
e.Graphics.TranslateTransform(centerX, centerY);
e.Graphics.RotateTransform(_angle);
e.Graphics.TranslateTransform(-centerX, -centerY);
e.Graphics.ScaleTransform(scale, scale);
e.Graphics.DrawImage(image, 0, 0);
}
// Uses C# 7.0 value tuples / .NET Framework 4.7.
// For previous versions, return a PointF instead.
private static (float, float) GetCenter(Rectangle rect)
{
float centerX = (rect.Left + rect.Right) * 0.5f;
float centerY = (rect.Top + rect.Bottom) * 0.5f;
return (centerX, centerY);
}
Make sure to to select the mouse event handlers PictureBox_MouseMove and PictureBox_Paint in properties window of the picture box for these events, after you copy/pasted this code into the form.
Note: You could also use a simple Panel or any other control, like a label; however, the PictureBox has the advantage to use double buffering by default, which eliminates flickering.

We Keep Coding

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

Get resulting size of RotateTransform - c#

Pythagoras. It is anywhere from original to sqrt(w^2 + h^2) at 90/270 angle. And I d bet it is determined by sine (max at 90).

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