This page is about how to print without using a report generator.

Writing directly to the printer's canvas provides more control than using someone else's components.

Unfortunately, Delphi 5 does not properly handle some functions. As a result, you must access the Windows API yourself.

• Add printers to your uses clause
• Use the Printer function to access the global instance of TPrinter
• Printer.BeginDoc starts the print job
• Printer.EndDoc stops the print job and sends it to the printer
• Printer.NewPage forces a new page
• Printer.Canvas is used to generate the output page

A print job is started whenever any rendering is done through a Text variable or the printer’s canvas.

Canvas example

  Printer.BeginDoc;
  Printer.Canvas.TextOut(0,0,'Place any text here');
  Printer.EndDoc;

procedure TForm1.Button1Click(Sender: TObject);
var
  MyFile: TextFile;
begin
  AssignPrn(MyFile);
  Rewrite(MyFile);
  Writeln(MyFile, 'Print this text');
  System.CloseFile(MyFile);
end;

This is from Printers.pas

{ AssignPrn - Assigns a Text variable to the currently selected printer.  Any
  Write or Writeln's going to that file variable will be written on the
  printer using the Canvas property's font.  A new page is automatically
  started if a CR is encountered on (or a Writeln is written to) the last
  line on the page.  Closing the text file will imply a call to the
  Printer.EndDoc method. Note: only one Text variable can be open on the
  printer at a time.  Opening a second will cause an exception.}

As far as I can tell, all the canvas commands work ... except those that copy a TGraphic or a TCanvas. Basically, canvas methods based on the Windows StretchDraw method fail. (Of course, this is not documented anywhere in Delphi 5 since Windows XP was not written back then.)

The following Canvas commands fail when printing under Windows XP.

• Draw(X, Y: Integer; Graphic: TGraphic);
• StretchDraw(const Rect: TRect; Graphic: TGraphic );
• CopyRect(Dest: TRect; Canvas: TCanvas; Source: TRect);

Actually, with Delphi 5 and Windows 98, the provided documentation is pretty good. The problem is that with Windows 2000 and Windows XP, the technique used with Windows 98 no longer works. (Some references imply that this is a problem with all versions of Windows. However, my experience is that an *.exe file that worked perfectly with Windows 98 failed to print the images with Windows XP. Same printer, but different drivers - obviously.)

With Windows 98, you just copy the image canvas to the printer canvas. This example is from the Delphi 5 Printer function help.

  with Printer do begin
    BeginDoc;
    Canvas.Draw((PageWidth  - Bmp.Width ) div 2,
                (PageHeight - Bmp.Height) div 2,
                Bmp);
    EndDoc;
  end;

var
  Info      : PBitmapInfo;
  InfoSize  : DWORD;
  Image     : Pointer;
  ImageSize : DWORD;
  Bits      : HBITMAP;
begin
     Bits := bmp.Handle;  // bmp is passed as a parameter
     GetDIBSizes(Bits, InfoSize, ImageSize);
     Info := AllocMem(InfoSize);
     try
       Image := AllocMem(ImageSize);
       try
         GetDIB(Bits, 0, Info^, Image^);
          
         StretchDIBits(Printer.Canvas.Handle,
             5, 30, Bmp.Width, bmp.Height,
             0,  0, bmp.Width, bmp.Height,
             Image, Info^, DIB_RGB_COLORS, SRCCOPY);
          
       finally
         FreeMem(Image, ImageSize);
       end;
     finally
       FreeMem(Info, InfoSize);
     end;
end;

  Bmp := TBitmap.Create;
  bmp.HandleType := bmDIB ; // Device independent

  // Draw on bmp.canvas

  Printer.Canvas.StretchDraw(
       rect(0, bmp.Height, Bmp.Width, 0),
               bmp);

procedure TForm1.FormCreate(Sender: TObject);
var
 i : integer;
begin
  i := Printer.Printers.IndexOf('Brother PT-2500PC');
  if i >= 0 then Printer.PrinterIndex := i;

  // set PaperSize - without this,  
  //   the Print and Print Setup dialog boxes produce access errors
end;

Be sure to set the paper size ... even if you set it to a nonsense value. Using the Brother PT-2500PC barcode printer on a Windows 2000 system, just setting the printer produced access errors when I tried to open either the Print or Print Setup dialog boxes. Setting the paper size to an non-existent value ('11') fixed the problem.

In the final application, the printer name will be read from an ini file - never hard code strings.

PageHeight   PageWidth   PageNumber

Copies   Orientation

Normally, you won't need this ... but just in case.

var
 buffer1 : array[0..250] of char;
 buffer2 : array[0..250] of char;
 buffer3 : array[0..250] of char;
 ADevice, ADriver, APort : pchar;
 hDm :  THandle;
  dm :  DEVMODE; // For help, click on DEVMODE and press F1
 Pdm : ^DEVMODE;
 s : string;
 i : integer;
begin
  ADevice := buffer1;
  ADriver := buffer2;
  APort   := buffer3;
  Printer.GetPrinter(ADevice, ADriver, APort, hDm);
  Pdm := GlobalLock (hDm);
    // get and set individual parameters here
    // just type "Pdm^." to get a list of available parameters
    // Some useful parameters include
    //    PaperSize - Letter, Legal, A4 etc.
    //    PaperLength, PaperWidth - values in millimeters
    //      - use Printer.PageHeight & .PageWidth to read values in pixels
    //    PrintQuality, YResolution - pixels per inch

  GlobalUnlock(hDm);
  printer.SetPrinter(ADevice, ADriver, APort, hDm); // maybe not necessary
end;

In the above example, instead of

 buffer1 : array[0..250] of char;
 ADevice : pchar;

  ADevice := buffer1;

 ADevice : array[0..250] of char;

  dm := Pdm^;

For alternate syntax, see Changing the papersize of a print job - by Borland Developer Support Staff. This reference also sets Printer.PrinterIndex to its current value before executing GetPrinter and after executing SetPrinter. I have no idea why (or if) that is necessary. (In one of the news groups, I was told that it fixed an obscure problem.)

Also see Macro to Obtain a List of Paper Names Supported by the Active Printer.

Selecting Paper Source (Paper Tray) shows how to modify parameters.

I've been working with an HP 4 Plus - a fairly common, but old, printer that reports 7 paper sources (bins) ... it actually only has 2 physical bins and 2 auto-select "bins" - the other 3 are options but not present.

The currently selected paper source is provided by

k := Pdm^.dmDefaultSource;

cnt := DeviceCapabilities(ADevice, APort, DC_BINNAMES, buffer4, nil);

cnt := DeviceCapabilities(Device, Port, DC_BINS	, buffer, nil);

15   1   1   4   2   5   11

The default bin is 15 - Automatically Select
The problem is bin 257 - Auto Select (257 = 256 + 1 - It is actually the first "1")

The constants 1 through 15 are defined in windows.pas - device specific bins start at 256.

result := Pdm^.dmFormName;

cnt := DeviceCapabilities(ADevice, APort, DC_PAPERNAMES, buffer4, nil);

Several paper names are over 32 characters long.

Letter Extra Transverse 9\275 x 12 in
123456789 123456789 123456789 123456789

  PDeviceModeA = ^TDeviceModeA;
  PDeviceMode  = PDeviceModeA;
  _devicemodeA = packed record
      // these are the fields described in the Windows API help file
      // for DEVMODE 
  end;
  TDeviceMode  = TDeviceModeA;
  TDeviceModeA = _devicemodeA;
  DEVMODEA     = _devicemodeA;
  DEVMODE      = DEVMODEA;
  PDevMode = PDeviceMode;  {compatibility with Delphi 1.0}
  TDevMode = TDeviceMode;  {compatibility with Delphi 1.0}

• efg provides lots of information and links

• A Better Way To Print a Form - by Borland Developer Support Staff

• Changing the papersize of a print job - by Borland Developer Support Staff shows how to set device properties.

• Blitting Between DCs for Different Devices Is Unsupported states that device-dependent blitting operations, such as BitBlt() or StretchBlt(), can not be used to transfer data from a screen bitmap to a printer bitmap. Instead, use GetDIBits() to convert the image to a device-independent bitmap and use either SetDIBits() or StretchDIBits() to copy the converted image. (blit refers to a type of data copying.)

  Interestingly, About Printing in the Windows SDK help file specifically states that BitBlt should be used to print bitmapped images.

• Printing in Delphi 5 - very good

URL: http:// cpcug.org / user / clemenzi / technical / Languages / Delphi / Printing.html