创建图形并将其另存为位图

Question

I have two questions:

1) I have a PictureBox and its Dock is set to Fill. When I resize the Form I cannot create a Graphic on the part of the PictureBox that is extended. What is the problem?

2) I want to convert the Graphic that is created on the PictureBox to Bitmap and save it as *.JPG or *.bmp. How can I do this?

Answer 1

you can use the handle device to get the bitmap out of the picture box

Graphics g = pictureBox1.CreateGraphics();          
Bitmap bitMap = Bitmap.FromHbitmap(g.GetHdc());
bitMap.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);

or even better, if the pictureBox does`nt modify the image, you can directly get the image from the pictureBox control

pictureBox1.Image.Save("path", System.Drawing.Imaging.ImageFormat.Jpeg);

Answer 2

Try this, works fine for me...

    private void SaveControlImage(Control ctr)
    {
        try
        {
            var imagePath = @"C:\Image.png";

            Image bmp = new Bitmap(ctr.Width, ctr.Height);
            var gg = Graphics.FromImage(bmp);
            var rect = ctr.RectangleToScreen(ctr.ClientRectangle);
            gg.CopyFromScreen(rect.Location, Point.Empty, ctr.Size);

            bmp.Save(imagePath);
            Process.Start(imagePath);

        }
        catch (Exception)
        {
            //
        }
    }

Answer 3

1) Your description is very vague. Do you get an exception? Does it display wrong results? What is happening?

2) You need to get the Image from the PictureBox and use its Save method .

Answer 4

When the Picturebox gets resized to fill the form, it seems it's Image property stays the same.

So what you need to do is handle the PictureBox.OnSizeChanged Event, and then use the following code to resize the image:

private void pictureBox1_SizeChanged(object sender, EventArgs e)
{
    if ((pictureBox1.Image != null))
    {
        pictureBox1.Image = new Bitmap(pictureBox1.Image, pictureBox1.Size);
    }
}

To save the image use:

pictureBox1.Image.Save(filename, System.Drawing.Imaging.ImageFormat.Jpeg);

Hope that helps!