Clear A Bitmap in .Net

Question

I'm using PictureBox control to draw complicated charts, and to optimize for performance i use a cache Bitmap for each layer of the drawing, and draw them on the control image, the upper layers have transparent backgrounds, i need to clear them and redraw on every change.

Assuming g instance of Graphics class of the Bitmap, using g.Clear(Color.White) draws a white rectangle over everything and so hiding lower layers, and g.Clear(Color.Transparent) draws Transparent rectangle over, what means doing nothing.

Isn't there a way to clear the Bitmap returning it to its original state?

user_10355957 · Answer

private void btn_CancelImage_Click(object sender, EventArgs e)
    {
        DialogResult dialogResult = MessageBox.Show("Cancel and delete this Image?", "Cancel", MessageBoxButtons.YesNo);
        if (dialogResult == DialogResult.Yes)
        {
            ClearImage();
            pictureBox1.Refresh();
        }
        else if (dialogResult == DialogResult.No)
        {
            return;
        }
    }
    public void ClearImage()
    {
        Graphics g = Graphics.FromImage(ImageBitmap);
        g.Clear(Color.White);
    }

Clear A Bitmap in .Net

2 Answers