Image.RotateFlip 似乎没有旋转位图

Question

我有三个带有齿轮图像的 PictureBox（post 中的图片）。
当我将鼠标悬停在它们上面时，它们会旋转。我正在使用 System.Drawing.Image.RotateFlip(RotateFlipType).
看起来只有齿轮的中心在旋转，而边缘是静止的。

private void rotationTimer_Tick(object sender, EventArgs e)
{
    Image flipImage = pictureBox1.Image;
    flipImage.RotateFlip(RotateFlipType.Rotate90FlipXY);
    pictureBox1.Image = flipImage;
}

private void rotationTimer2_Tick(object sender, EventArgs e)
{
    Image flipImage = pictureBox2.Image;
    flipImage.RotateFlip(RotateFlipType.Rotate90FlipNone);
    pictureBox2.Image = flipImage;
}

private void rotationTimer3_Tick(object sender, EventArgs e)
{
    Image flipImage = pictureBox3.Image;
    flipImage.RotateFlip(RotateFlipType.Rotate270FlipXY);
    pictureBox3.Image = flipImage;
}

private void pictureBox1_MouseHover(object sender, EventArgs e)
{
    rotationTimer.Start();
    rotationTimer2.Start();
    rotationTimer3.Start();
} //etc...

Answer 1

这是使用 Matrix.RotateAt() 方法旋转图像的示例。
这是一个非常简单的过程：

从图像文件（或项目资源）创建位图对象；请注意位图是 [Cloned][2]：这样，我们将它从 FileStream 中分离出来（GDI+ 不会在使用时锁定文件）。当你完成它（或应用程序关闭）时记得Dispose()
定义适合图像形状的旋转角度
设置生成旋转速度（结合旋转角度）的定时器间隔。我们也在使用 System.Windows.Form.Timer of course: we want it to tick in the UI thread (note that this object needs to be Disposed)
当计时器计时时，Invalidate() canvas（这里是 PictureBox 控件）
使用 Matrix.RotateAt(gearCurrentRotationAngle, [ImageCentre]) 并应用 Matrix to the Graphics geometric world transformation using its Transform 属性
在每次旋转时将选择的旋转角度添加到当前旋转角度。当它达到 360 度时，重新设置为最小值（gearRotationAngle 字段值，此处）

这里还有一些其他例子：

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

Bitmap gear = null;
RectangleF gearRect = Rectangle.Empty;
int gearRotateSpeed = 100;
int gearRotationAngle = 24;
int gearCurrentRotationAngle = 0;

System.Windows.Forms.Timer gearTimer = new System.Windows.Forms.Timer();

public Form1() {
    InitializeComponent();
    gear = Image.FromStream(new MemoryStream(File.ReadAllBytes(@"File Path")));

    // Assuming the Gear Image is square shaped and the PictureBox size remains constant
    // otherwise, recalculate in the Control.Resize event
    var gearScale = Math.Min(pictureBox1.Width, pictureBox1.Height) / (float)Gear.Width;
    var gearSize = new SizeF(gear.Width * gearScale, gear.Height * gearScale);
    gearRect = new RectangleF(new PointF((pictureBox1.Width - gearSize.Width) / 2.0f, (pictureBox1.Height - gearSize.Height) / 2.0f), gearSize);

    gearTimer.Tick += (s, e) => {
        gearCurrentRotationAngle += gearRotationAngle;
        if (gearCurrentRotationAngle > 360) gearCurrentRotationAngle = gearRotationAngle;
        pictureBox1.Invalidate();
    }
}

private void pictureBox1_MouseEnter(object sender, EventArgs e) {
    gearTimer.Interval = gearRotateSpeed;
    gearTimer.Start();
}

private void pictureBox1_MouseLeave(object sender, EventArgs e) => gearTimer.Stop();

private void pictureBox1_Paint(object sender, PaintEventArgs e) {
    var canvas = sender as PictureBox;
    e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
    e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;

    PointF centerImage = new PointF(canvas.Width / 2, canvas.Height / 2);
    using (var mx = new Matrix()) {
        mx.RotateAt(gearCurrentRotationAngle, centerImage);
        e.Graphics.Transform = mx;
        e.Graphics.DrawImage(gear, gearRect);
    }
}

Image.RotateFlip 似乎没有旋转位图

Image.RotateFlip doesn't seem to rotate the Bitmap

c#

winforms

graphics

bitmap

image-rotation