How to Integrate Custom Drawing Methods with a PictureBox's Paint Event?

Integrate custom drawing methods in the Paint event of PictureBox

If you only have a PictureBox control and plan to use a custom method to draw circles, it is crucial to first determine the target drawing surface. You wish to draw:

• Into a PictureBox image: Use the Image property of the PictureBox as the drawing canvas.
• To the PictureBox control: Draw directly on the surface of the PictureBox control.

Case 1: Drawing on the control

To draw directly on the control, you can utilize the PaintEventArgs parameter in the Paint event of the PictureBox control. For example:

private void PictureBox_Paint(object sender, PaintEventArgs e)
{
    // e.Graphics表示PictureBox控件的绘图表面
    e.Graphics.DrawEllipse(Pens.Red, new Rectangle(3, 4, 44, 44));
}

Case 2: Drawing in Image

Alternatively, you can draw into the PictureBox's Image property, allowing for more complex and persistent drawing operations.

void DrawIntoImage()
{
    using (Graphics g = Graphics.FromImage(pictureBox1.Image))
    {
        g.DrawEllipse(Pens.Orange, new Rectangle(13, 14, 44, 44));
    }

    pictureBox1.Refresh(); // 刷新PictureBox显示
}

Please note that the choice of drawing method depends on your specific needs and desired drawing persistence. Choose a method that matches your expected functionality.

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