我有一个在屏幕上绘制点的功能。在我添加panelGraphics.RotateTransform
行之前,此功能非常有效。当这条线存在时,进行一次重绘的过程非常漫长。我的点列表包含大约5000个点并且没有旋转,它在几毫秒内完成,但是使用该行可能需要500毫秒,这非常慢。您是否知道为什么RotateTransform如此缓慢?我还能做些什么来优化它?
private void panel1_Paint(object sender, PaintEventArgs e)
{
Pen myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
Graphics panelGraphics = panel1.CreateGraphics();
panelGraphics.TranslateTransform((panel1.Width / 2) + _panW, (panel1.Height / 2) + _panH);
//Problematic line...
panelGraphics.RotateTransform(230 - Convert.ToInt32(_dPan), System.Drawing.Drawing2D.MatrixOrder.Prepend);
PointF ptPrevious = new PointF(float.MaxValue, float.MaxValue);
foreach (PointF pt in _listPoint)
{
panelGraphics.FillRectangle(myBrush, (pt.X / 25) * _fZoomFactor, (pt.Y / 25) * _fZoomFactor, 2, 2);
}
myBrush.Dispose();
myPen.Dispose();
panelGraphics.Dispose();
}
答案 0 :(得分:2)
原因是每个矩形都必须旋转。旋转可能是一个缓慢的操作,特别是对于没有方角。
在这种情况下,更好的方法是先创建一个“隐藏”的位图,然后将矩形绘制成。 然后将旋转应用于主图形对象,并将隐藏的位图绘制到主位图(控件)上。像这样的东西 -
private void panel1_Paint(object sender, PaintEventArgs e)
{
Pen myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
Graphics panelGraphics = e.Graphics; //use the provided Graphics object
// create an internal bitmap to draw rectangles to
Bitmap bmp = new Bitmap(this.ClientSize.Width, _
this.ClientSize.Height, _
Imaging.PixelFormat.Format32bppPArgb);
using (Graphics g = Graphics.FromImage(bmp)) {
PointF ptPrevious = new PointF(float.MaxValue, float.MaxValue);
foreach (PointF pt in _listPoint) {
g.FillRectangle(myBrush, (pt.X / 25) * _fZoomFactor, _
(pt.Y / 25) * _fZoomFactor, 2, 2);
}
}
panelGraphics.TranslateTransform((panel1.ClientSize.Width / 2) + _panW, _
(panel1.ClientSize.Height / 2) + _panH);
//Problematic line...
panelGraphics.RotateTransform(230 - Convert.ToInt32(_dPan), _
System.Drawing.Drawing2D.MatrixOrder.Prepend);
panelGraphics.DrawImage(bmp, 0, 0); //adjust x/y as needed
bmp.Dispose;
myBrush.Dispose();
myPen.Dispose();
}