c# - 如何使用 invalidate 方法强制重新绘制图形

Question

当表单进入屏幕时，我正在努力使用 invalidate 方法重绘图形 图形未重绘 我试图从图形中创建一个图像，以便使用 invalidate 方法重绘它，但它没有工作可以有人帮助编辑代码并以简单的方式完成，因为我仍然是初学者，非常感谢

private void squareButton_Click(object sender, EventArgs e)
        {

            // Declaring a new graphics object has been assigned null
            Graphics objGraphics = null;
            // This will create the picture graphics to be drawn in the picturebox
            objGraphics = PictureBox1.CreateGraphics();
            // This will redraw the picture box with a fill chosen after the systemcolors
            objGraphics.Clear(SystemColors.ControlDark);
            // This will draw the rectangle with a red pen 10,10 represent position and 50,50 reprsent the width and height 
            objGraphics.DrawRectangle(Pens.Red, 10, 10, 50, 50);
            // This will draw the rectangle
            objGraphics.Dispose();
Bitmap imgbit = (Bitmap)Picturebox.Image;
Graphics.FromImage(imgbit);
picturebox.invalidate();


// This is not redrawing the graphic it just shows a blank form

        }

Answer 1

使用DrawToBitmap方法。

Bitmap bmp = new Bitmap(pb.Width, pb.Height);
pb.DrawToBitmap(bmp, pb.ClientRectangle);
bmp.Save({your path});
bmp.Dispose();

CreateGraphics当您不想要持久绘图时，您可以使用该对象。如果这是在按钮单击事件中，它将在表面上绘制，但一旦系统想要重绘，它就不会停留。

using (Graphics g = pb.CreateGraphics)
{
g.FillRectangle(Brushes.Blue, new Rectangle(20, 20, 20, 20));
g.DrawRectangle(Pens.Red, new Rectangle(20, 20, 20, 20));
}