how do i handle the forms paint event

Question

I have created a form and would like to use this code example:

https://msdn.microsoft.com/en-us/library/5ey6h79d%28v=vs.110%29.aspx

The instruction with the code is:

To run this example, paste it into a form and handle the form's Paint event by calling the LockUnlockBitsExample method, passing e as PaintEventArgs.

I have pasted the code into the form but I have no idea how to handle the form's paint event.

    namespace Laser_Control2
    {
    public partial class LaserControlForm : Form
    {
        public LaserControlForm()
        {
            InitializeComponent();
        }

        // Manipulate a bitmap image
        // Extract the pixel map data
        // To run this example, paste it into a form and handle the form's Paint event
        //  by calling the LockUnlockBitsExample method, passing e as PaintEventArgs.
        private void LockUnlockBitsExample(PaintEventArgs e)
        {

            // Create a new bitmap.
            Bitmap bmp = new Bitmap("c:\\fakePhoto.jpg");

            // Lock the bitmap's bits.  
            Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            System.Drawing.Imaging.BitmapData bmpData =
                bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite,
                bmp.PixelFormat);

            // Get the address of the first line.
            IntPtr ptr = bmpData.Scan0;

            // Declare an array to hold the bytes of the bitmap.
            int bytes = Math.Abs(bmpData.Stride) * bmp.Height;
            byte[] rgbValues = new byte[bytes];

            // Copy the RGB values into the array.
            System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes);

            // Set every third value to 255. A 24bpp bitmap will look red.  
            for (int counter = 2; counter < rgbValues.Length; counter += 3)
                rgbValues[counter] = 255;

            // Copy the RGB values back to the bitmap
            System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes);

            // Unlock the bits.
            bmp.UnlockBits(bmpData);

            // Draw the modified image.
            e.Graphics.DrawImage(bmp, 0, 150);

        }
        private void loadPdfButton_Click(object sender, EventArgs e)
        {
            if(openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                PdfDocument doc = new PdfDocument();                                                // Create Spire object - a new document
                doc.LoadFromFile(@"E:/Test/test2.pdf");                                             // Load test2.pdf into new document
                Image bmp = doc.SaveAsImage(0, 0, 32, 32);                                          // Save the .pdf doc as a .bmp

                pictureBox1.Image = bmp;
                bmp.Save("convertToBmp.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
                System.Diagnostics.Process.Start("convertToBmp.bmp");

            }
        }

        private void clearButton_Click(object sender, EventArgs e)
        {
            this.Close();
        }

    }
}

You need to [hook up](http://stackoverflow.com/questions/33275763/copy-datagridview-values-to-textbox/33276161?s=2|0.5622#33276161) the code of the event you have copied! Goto the event pane of the properties tab and doubleclick the Paint event. — TaW, Feb 12 '16 at 21:34
@TaW, thanks that's a very useful feature that I was unaware of! — rwvb, Feb 12 '16 at 22:18

score 1 · Accepted Answer · answered Feb 12 '16 at 21:22

1

You should be able to override the OnPaint Method

protected override void OnPaint(PaintEventArgs e)
{
    //base.OnPaint(e);
    LockUnlockBitsExample(e)
}

answered Feb 12 '16 at 21:22

dsolimano

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how do i handle the forms paint event

1 Answers1