我想在我的应用程序中有一张图片，我可以旋转以指示方向，例如风向。甚至时间。我用什么代码来旋转图片？谢谢
更新：我正在使用 .NET 2.0、Windows 2000、VS C# 2005
【问题讨论】：
这是一个可以用来在 C# 中旋转图像的方法：
/// <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;
}
【讨论】：
这是一个旧线程，还有其他几个关于 C# WinForms 图像旋转的线程，但现在我已经提出了我的解决方案，我认为这是一个发布它的好地方。
/// <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;
}
这是来自 StackOverflow 和其他地方的许多灵感来源的结果。 Naveen 在this thread 上的回答特别有帮助。
【讨论】：
upsizeOk=true，在不旋转时也会使我的图像比原始图像更小.. .我在旋转图像时在互联网上找到的所有解决方案，使其变小或剪切它......（我的图像没有空格）。你知道如何避免这个问题吗？
简单方法：
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;
}
【讨论】：
Bitmap 并返回到 Image。 img.RotateFlip(RotateFlipType.Rotate270FlipNone);
我找到了这个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;
}
【讨论】：
我写了一个简单的旋转图像类。您所要做的就是以度为单位输入图像和旋转角度。角度必须在 -90 到 +90 之间。
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;
}
}
}
【讨论】：
老问题，但我必须在接受的答案中解决 MrFox 的评论。当尺寸改变时旋转图像会切断图像的边缘。一种解决方案是在较大的图像上重绘原始图像，居中，其中较大图像的尺寸补偿了不剪裁边缘的需要。例如，我希望能够以正常角度设计游戏的图块，但以 45 度角重新绘制它们以获得等距视图。
这里是示例图片（黄色边框是为了方便查看）。
代码（部分基于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;
}
【讨论】：
Richard Cox 对我过去使用过的 https://stackoverflow.com/a/5200280/1171321 有一个很好的解决方案。还值得注意的是，DPI 必须为 96 才能正常工作。此页面上的一些解决方案根本不起作用。
【讨论】：
旋转图像是一回事，正确的图像边界是另一回事。这是一个可以帮助任何人的代码。我很久以前根据互联网上的一些搜索创建了这个。
/// <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());
}
【讨论】：
只要您要旋转的图像已经在您的属性资源文件夹中，这将起作用。
在部分课程中：
Bitmap bmp2;
加载时：
bmp2 = new Bitmap(Tycoon.Properties.Resources.save2);
pictureBox6.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox6.Image = bmp2;
按钮或点击
private void pictureBox6_Click(object sender, EventArgs e)
{
if (bmp2 != null)
{
bmp2.RotateFlip(RotateFlipType.Rotate90FlipNone);
pictureBox6.Image = bmp2;
}
}
【讨论】：
您可以通过调用此方法轻松完成：
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;
}
不要忘记在您的项目中添加对 System.Drawing.dll 的引用
此方法调用示例：
Image image = new Bitmap("waves.png");
Image newImage = RotateImage(image, 360);
newImage.Save("newWaves.png");
【讨论】：
我修改了Mr.net_prog的功能，它只获取图片框并旋转其中的图像。
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;
}
【讨论】：
此解决方案假定您要在图片框中绘制图像，并且图像方向将跟随鼠标在此图片框上的移动。没有图像分配给图片框。相反，我从项目资源中获取图像。
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);
}
在您将此代码复制/粘贴到表单后，请确保在图片框的属性窗口中为这些事件选择鼠标事件处理程序PictureBox_MouseMove 和PictureBox_Paint。
注意：您也可以使用简单的Panel 或任何其他控件，例如标签；但是，PictureBox 的优势在于默认使用双缓冲，从而消除了闪烁。
【讨论】：