print preview error

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Hi,
i have a bug in print preview this is my PrintDocument code:

private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
        {
            float linesPerPage = 0;
            float yPosition = 0;
            int count = 0;
            float leftMargin = e.MarginBounds.Left;
            float topMargin = e.MarginBounds.Top;
            string line = null;
            Font printFont = this.rtbWord.Font;
            SolidBrush myBrush = new SolidBrush(Color.Black);
            linesPerPage = e.MarginBounds.Height / printFont.GetHeight(e.Graphics);

            while (count < linesPerPage && ((line = myReader.ReadLine()) != null))
            {
                yPosition = topMargin + (count * printFont.GetHeight(e.Graphics));
                // draw the next line in the rich edit control
                e.Graphics.DrawString(line, printFont, myBrush, leftMargin, yPosition, new StringFormat());
                count++;
            }
            // If there are more lines, print another page.
            if (line != null)
                e.HasMorePages = true;
            else
                e.HasMorePages = false;
            myBrush.Dispose();
        }

and this is my PrintPreview code:

C#

private void printPreView_Click(object sender, EventArgs e)
        {
            PrintPreviewDialog PrintPreviewDialog = new PrintPreviewDialog();
            PrintPreviewDialog.Document = printDocument1;
            if (PrintPreviewDialog.ShowDialog() == DialogResult.OK)
            {
                printDocument1.Print();
            }
        }

in the line

while (count < linesPerPage && ((line = myReader.ReadLine()) != null))

i have this error:

Object reference not set to an instance of an object.

plz help me.

Posted 30-Sep-12 18:49pm

amirmohamad

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**JF2015** · Answer 1 · 2012-09-30T18:57:00

Solution 1

Since you don't show us more of your code, my guess is, that you did not instantiate the instance of myReader as in this sample:

C#

private StringReader myReader;
public Form1()
{
   InitializeComponent();
   string line = myReader.ReadLine(); //throws: Object reference not set to an instance of an object.
}

To solve that issue you need to create the StringReader object as in this sample, but you need to fill it with your content.

C#

private StringReader myReader;
public Form1()
{
   InitializeComponent();
   myReader = new StringReader("HelloWorld");
   string line = myReader.ReadLine();
}

Posted 30-Sep-12 18:57pm

JF2015

Updated 30-Sep-12 19:17pm

v2

Comments

amirmohamad 1-Oct-12 1:15am

this is myReader
private StringReader myReader;

JF2015 1-Oct-12 1:19am

The solution is the same. You need to instantiate the StringReader object before you can use it - just fill it with your content. In my sample I just filled it with "HelloWorld", but you have your own content in there - probably the text you want to print.

amirmohamad 1-Oct-12 1:28am

you are good man tank's for help.
vote 5+