Delphi 7 :: TDBGrid Print Results

This tip is similar to yesterday's and added upon request. There are 
several times when I need to send out a 
quick printout of a TDBGrid without having to worry about writting a 
report for it. There are a couple 
different ways of approaching this, we will be looking at the Delphi 
function AssignPrn(). Using 
AssignPrn() we can write to the printer as if we are writting to a file 
using WriteLn(). In this tip we will 
have to change the printer font to a fixed width font so our printout 
will have straight even columns. We will 
be using the Delphi functions Format(), AssignPrn(), WriteLn(), 
Rewrite(), and CloseFile(). 
 
 
    For this tip we will need a TButton with a TButton.OnClick event 
along with a TStringGrid 
    component. You can easily create these events through the Events tab 
of the Object Inspector. 
    First we will need to make sure we add Printers to our Units uses 
clause. 
    In our TButton.OnClick event we will first set our 
TPrinter.PrinterIndex to default printer by setting 
    this value to -1. 
    Next we will be saving our printers font and resetting it to 
'Courier New', a fixed width font. This will 
    make our columns print in a straight even line using the Format() 
Delphi function. 
    Next we will assign our printer textfile to our printer using 
AssignPrn(). 
    After assigning our file we need to initialize it using Rewrite(). 
    Before we loop through the TDBGrid rows, we will print out our 
header and a row of dashes to 
    seperate the header in our printout from the rest of the rows. We 
printout the DBGrid's table fieldnames 
    as the header. 
    We will use the Delphi function WriteLn() to printout each row to 
our assigned printer file. To format 
    the rows properly we will use the Delphi function Format() and input 
all our columns into a formatted 
    string. 
    Next we will loop through our TDBGrid and printout each row in the 
same fashion as we did with the 
    header row. 
    Finally we will need to close the file handle we created with 
AssignPrn() and rest our printer font to 
    its original value.. 
    Format() returns a string formated according to arguments that you 
send in. Format() can get quite 
    complex. Format looks to add the arguments in the order arranged 
into the next position in order 
    according to the percent sign "%" in your format string. In other 
words, you need as many arguments as 
    you have percent signs in your format string parameter. The number 
after the percent sign indicates the 
    max number of characters that will display. When you add a number, a 
period, and a number then this 
    indicates that you want to force that number of characters as 
percision. In other words if you want two 
    characters and your argument only returns one then the return forces 
in a leading character whether it be 
    a space for a string or a zero "0" for a numeric value. The "s" at 
the end of our width and percision 
    indicates that our argument will be passing in a string value to be 
formated into that position. Take a 
    look at the Delphi help file to see all the other values you can 
pass in through the argument parameter. 
    AssignPrn() assigns a textfile variable to the printer. The only 
parameter is the textfile variable. 
    Rewrite() creates a new file and opens it. The only parameter is the 
assigned textfile variable. 
    WriteLn() writes a line of text to our textfile variable. The first 
parameter is the string to write. The 
    second parameter is the textfile variable to write to. 
    CloseFile() gets rid of the association between our textfile and the 
printer file. The only parameter is 
    our assigned textfile variable. 
 
 
        Example 1 
 
 
        {...} 
 
 
        type 
          TForm1 = class(TForm) 
            Button1: TButton; 
            DBGrid1: TStringGrid; 
            procedure Button1Click(Sender: TObject); 
          private 
            { Private declarations }   
          public 
            { Public declarations } 
          end; 
 
 
        {...} 
 
 
        procedure TForm1.Button1Click(Sender: TObject); 
        var 
          MyTextFile     : TextFile; 
          tmpStr,OldFont : String; 
        begin 
          { set to default printer } 
          Printer.PrinterIndex := -1; 
 
 
          { save the printers old font } 
          OldFont := Printer.Canvas.Font.Name; 
 
 
          { set the printers font name to a fixed 
            width font so the printout will have 
            even looking columns } 
          Printer.Canvas.Font.Name := 'Courier New'; 
 
 
          { assign our textfile to the printer } 
          AssignPrn(MyTextFile); 
 
 
          try 
            { initialize our textfile } 
            Rewrite(MyTextFile); 
 
 
            { format and print out our header according 
              to the fieldnames, I only have 2 fields in 
              my table..you will have to add entries to 
              the Format() if you have more fields } 
            tmpStr := Format('%-20.20s %-20.20s', 
 
 
[dbGrid1.DataSource.DataSet.Fields[0].FieldName, 
 
 
dbGrid1.DataSource.DataSet.Fields[1].FieldName]); 
            Writeln(MyTextFile, tmpStr); 
 
 
            { format and print out a seperator between 
              the header and rows } 
            tmpStr := Format('%-20.20s %-20.20s', 
                             ['--------------------', 
                              '--------------------']); 
            Writeln(MyTextFile, tmpStr); 
 
 
            { start at the first record in the DBGrid's table } 
            dbGrid1.DataSource.DataSet.First; 
 
 
            { loop through the DBGrid's table, if the table is 
              too large then you may want to filter it down } 
            while ( not dbGrid1.DataSource.DataSet.EOF ) do 
            begin 
 
 
              { format each row and print them out } 
              tmpStr := Format('%-20.20s %-20.20s', 
 
 
[dbGrid1.DataSource.DataSet.Fields[0].AsString, 
 
 
dbGrid1.DataSource.DataSet.Fields[1].AsString]); 
              Writeln(MyTextFile, tmpStr); 
 
 
              { go to the next record in the DBGrid's table } 
              dbGrid1.DataSource.DataSet.Next; 
            end; 
 
 
          finally 
            { close our textfile } 
            CloseFile(MyTextFile); 
 
 
            { reset the printers font name } 
            Printer.Canvas.Font.Name := OldFont; 
          end; 
        end; 
 
 
        {...} 
                                              

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