[.NET] How to implement rotate image in user control. -优快云博客

本文介绍了一种在用户控件中实现图像旋转的方法。通过重写OnPaint方法并利用Graphics.RotateTransform来完成图像的旋转操作。示例代码展示了如何设置平滑模式、计算旋转中心及偏移量，并提供了不同旋转角度的图像效果。

Introduction
Sometimes we need to rotate image in user control.
I override OnPaint method, and use Graphics.RotateTransform to rotate image.

Source Code

protected override void OnPaint(PaintEventArgs e) { e.Graphics.SmoothingMode = SmoothingMode.Default; Rectangle rect=new Rectangle(0,0,this.Width,this.Height); PointF center=new PointF(rect.Width/2,rect.Height/2); float offsetX=0; float offsetY=0; offsetX = center.X - DoorWidth / 2; offsetY = center.Y - DoorHeight / 2; picRect = new RectangleF(offsetX, offsetY, DoorWidth, DoorHeight); PointF Pcenter=new PointF(picRect.X+picRect.Width/2, picRect.Y+picRect.Height/2); e.Graphics.TranslateTransform(Pcenter.X, Pcenter.Y); e.Graphics.RotateTransform(-m_i4Angle); e.Graphics.TranslateTransform(-Pcenter.X, -Pcenter.Y); if (m_bIsOpened) { int t_i4doorWidth = (DoorWidth - DoorOpenWidth) / 2; RectangleF picRect1 = new RectangleF(offsetX, offsetY, t_i4doorWidth, DoorHeight); e.Graphics.FillRectangle(new SolidBrush(m_OpenColor), picRect1); RectangleF picRect2 = new RectangleF(offsetX + DoorOpenWidth + t_i4doorWidth, offsetY, t_i4doorWidth, DoorHeight); e.Graphics.FillRectangle(new SolidBrush(m_OpenColor), picRect2); } else { e.Graphics.FillRectangle(new SolidBrush(m_CloseColor), picRect); } e.Graphics.ResetTransform(); }

Image