如何使用invalidate方法強制重新繪制圖形

Question

我正在努力使表單在屏幕上消失時不能使用invalidate方法重繪該圖形，而該圖形沒有重繪，我試圖從該圖形中創建一個圖像，以使其使用invalidate方法重繪，但它沒有工作可以有人幫助編輯代碼並以簡單的方式完成代碼，因為我仍然是初學者，非常感謝

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();

當您不需要永久性圖形時，可以使用CreateGraphics對象。 如果是在按鈕單擊事件中，它將在表面上繪制，但是一旦系統要重新繪制，它就不會停留。

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));
}