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TBitmap to TBytes for ESC/POS Thermal Printer

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Actually I'm looking for a function which could convert TBitmap to TBytes for printing in ESC/POS Thermal Printer.

I'm trying to make working a code from here, but also got an effect as on the author picture - white lines and not correct text on an image as well.

Has someone a working code?

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22 hours ago, at3s said:

Actually I'm looking for a function which could convert TBitmap to TBytes

It really depends on the format that the ESC/POS is expecting.  It might be as simply as using TBitmap.SaveToStream() to save to a TBytesStream, and then using the stream's Bytes and Size properties.  Or it may be more complex, like having to extract the individual pixels, like that other code is doing.  You are going to have to provide more details about your particular situation.

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14 hours ago, Remy Lebeau said:

It really depends on the format that the ESC/POS is expecting.  It might be as simply as using TBitmap.SaveToStream() to save to a TBytesStream, and then using the stream's Bytes and Size properties.  Or it may be more complex, like having to extract the individual pixels, like that other code is doing.  You are going to have to provide more details about your particular situation.

Here is my code. It's mostly the same as is in the sources here or here.

And I'm getting the same result with the horizontal blank lines as here.

 

uses
  System
  , System.SysUtils
  , System.UITypes
  , FMX.Graphics
  ;

type
  TRgbTriple = packed record
    // do not change the order of the fields, do not add any fields
    Blue: Byte;
    Green: Byte;
    Red: Byte;
  end;

// ---------------------------

procedure TThermalPrinter.SendString(AValue: String);
var
  SND: TBytes;
begin
  SND := TEncoding.ASCII.GetBytes(AValue);
  LSockect.SendData(SND); // send data to the printer
end;

procedure TThermalPrinter.DoSetLineSpacing(AValue : integer);
begin
 if (AValue = 0) then begin
   SendString(#$1B#$32{, false});  //Resetset to default
 end else begin
   SendString(#$1B#$33 + AnsiChar(AValue){, false});
 end;
end;

procedure TThermalPrinter.DoPrintBitmap(const ABitmap : TBitmap; const  BitsPerSlice : Byte);
const
 Threshhold = 127;
type
 TBitArray = array of boolean;
 TRGBTripleArray = ARRAY[Word] of TRGBTriple;
 pRGBTripleArray = ^TRGBTripleArray; // Use a PByteArray for pf8bit color.
var
 BMPData: TBitmapData;
 vCol : integer;
 vRow : integer;
 vIndex : integer;
 vSliceIndex : integer;
 vBytePos : integer;
 vBitPos : integer;
 vOffset : integer;
 vLuminance : integer;
 vLine: pRGBTripleArray;
  vPixel: TAlphaColor;
 vDots: TBitArray;
 vSlice : Byte;
 vBit : Byte;
 vTmpBit: Byte;
 vVal: boolean;
 vTempStr : string;
begin
 if not Assigned(ABitmap) then exit;

 ABitmap.Map(TMapAccess.Read, BMPData);
 try
    SetLength(vDots, (ABitmap.Height * ABitmap.Width));
    vIndex := 0;

    for vRow := 0 to ABitmap.Height-1 do
    begin
      for vCol := 0 to ABitmap.Width-1 do
      begin
        vPixel := BMPData.GetPixel(vCol, vRow);
        vLuminance := Trunc((TAlphaColorRec(vPixel).R * 0.3)  + (TAlphaColorRec(vPixel).G * 0.59) + (TAlphaColorRec(vPixel).B * 0.11));
        vDots[vIndex] := (vLuminance < 127);
        Inc(vIndex);
      end;
    end;

   DoSetLineSpacing(24);
   SendString(' ');

   vOffset := 0;
   while (vOffset < ABitmap.Height) do
   begin
    SendString(#$1B'*'#33 + AnsiChar(Lo(ABitmap.Width)) + AnsiChar(Hi(ABitmap.Width)){, false});

     vTempStr := '';
     for vCol := 0 to ABitmap.Width-1 do begin
       for vSliceIndex := 0 to 2 do begin // Remember, 24 dots = 24 bits = 3 bytes.
         vSlice := 0;
         for vBit := 0 to 7 do begin
           vBytePos := (((vOffset div 8) + vSliceIndex) * 8) + vBit;
           vBitPos := (vBytePos * ABitmap.Width) + vCol;

           vVal := false;
           if (vBitPos < Length(vDots)) then begin
             vVal := vDots[vBitPos];
           end;

           if vVal then
             vTmpBit := 1
           else
             vTmpBit := 0;
           vSlice := vSlice or (vTmpBit shl (7 - vBit));
         end;

         vTempStr := vTempStr + AnsiChar(vSlice);
       end;
     end;

     Inc(vOffset, 24);
     SendString(vTempStr + #13#10);
   end;

   DoSetLineSpacing(0);
   SendString(' ');
 finally
    vDots := nil;
    ABitmap.Unmap(BMPData);
 end;
end;

 

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If I recall correctly, the GetPixel method is rather slow. Does FMX.Graphics' TBitmap also have a Scanline pointer property?

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On 2/24/2021 at 9:25 AM, at3s said:

Here is my code. It's mostly the same as is in the sources here or here.

And I'm getting the same result with the horizontal blank lines as here.

You are using examples from others that doesn't work or doesn't work in your case.

Maybe it's time to read the documentation of that printer, understand it and do it right.

 

From what I understood reading a little Nicholas Piasecki's article is that you need to send binary data. Not ASCII.

And from your code it's clear that you need (like in Nicholas Piasecki's article) a monochrome, one bit per pixel image. In top-bottom and right-left order. This is binary data. A sort of simplified PCX graphic format (long time ago I wrote a little procedure to save TBitmap to PCX format).

 

Your don't need SendString(AValue: String) function. Use directly LSockect.SendData() instead. And don't use String but TBytes like LSockect.SendData() is expecting.

 

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15 hours ago, Cristian Peța said:

You are using examples from others that doesn't work or doesn't work in your case.

Maybe it's time to read the documentation of that printer, understand it and do it right.

 

From what I understood reading a little Nicholas Piasecki's article is that you need to send binary data. Not ASCII.

And from your code it's clear that you need (like in Nicholas Piasecki's article) a monochrome, one bit per pixel image. In top-bottom and right-left order. This is binary data. A sort of simplified PCX graphic format (long time ago I wrote a little procedure to save TBitmap to PCX format).

 

Your don't need SendString(AValue: String) function. Use directly LSockect.SendData() instead. And don't use String but TBytes like LSockect.SendData() is expecting.

 

Actually Delphi code above should do exactly what Nicholas Piasecki did in his article using C#.

 

Can you please send me in PM your procedure of saving TBitmap to PCX format?

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14 hours ago, David Heffernan said:

Do you have a specification for what these s printer expects to receive? 

I used a lot of specification for ESC\POS printer.

Actually I tried to make my code working in RawBT application (something like virtual ESC\POS printer) and now I'm trying to use GOOJPRT PT-210 device.

I did not find a specification for this model of printer.

 

but I require more general solution to be able to print a receipt from my Android application.

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11 minutes ago, at3s said:

Actually Delphi code above should do exactly what Nicholas Piasecki did in his article using C#.

If you don't have the documentation then at least follow what that article says clearly: " This is because low-level programmers, such as those who designed the ESC/POS language, tend to blur the lines between data types: it’s all bytes at the end of the day."

You need to write binary data. Simply don't put binary data in String and convert using TEncoding.ASCII.GetBytes().

 

18 minutes ago, at3s said:

Can you please send me in PM your procedure of saving TBitmap to PCX format?

This won't help you. But if you want to know I used TBytes.

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7 hours ago, Cristian Peța said:

If you don't have the documentation then at least follow what that article says clearly: " This is because low-level programmers, such as those who designed the ESC/POS language, tend to blur the lines between data types: it’s all bytes at the end of the day."

You need to write binary data. Simply don't put binary data in String and convert using TEncoding.ASCII.GetBytes().

 

This won't help you. But if you want to know I used TBytes.

As you can see in my sample, I don't send a string to the POS printer but rather TBytes.

Probably a string type of AValue parameter of SendString procedure twice confusing you.

Sure, it AValue is not properly populated, SendString procedure shall send something weird.

But I got an image as output on printer, but it's just cutting by horizontal lines.

And this Lazarus implementation of Nicholas Piasecki's code doesn't work for me as well.

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Posted (edited)

Here you are sending String converted with TEncoding.ASCII.GetBytes() to TBytes.

On 2/24/2021 at 9:25 AM, at3s said:

SendString(#$1B'*'#33 + AnsiChar(Lo(ABitmap.Width)) + AnsiChar(Hi(ABitmap.Width)){, false});

Why not directly?

  LSockect.SendData([$1B, 42, 33, Lo(ABitmap.Width), Hi(ABitmap.Width)]);

 

Edited by Cristian Peța
  • Thanks 1

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8 minutes ago, Cristian Peța said:

Here you are sending String converted with TEncoding.ASCII.GetBytes() to TBytes.

Why not directly?


  LSockect.SendData([$1B] + [42] + [33] + [Lo(ABitmap.Width)] + [Hi(ABitmap.Width)]);

 

You're awesome! You've fixed my problem. Thanks a lot.

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Posted (edited)

If this was the fix then this was a lottery.

I was thinking you need to get rid of that SendString() everywhere.

At least when you send binary data. And Lo(ABitmap.Width) is binary data.

If you want to send text and to be readable in source you can use AnsiString and convert to TBytes.

Using String to store bytes is as @David Heffernan would say: perverse.

Edited by Cristian Peța

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To send text you could use this function.

If the previous change fixed the issue I suppose this will also fix it without to change anything else. You could also store binary data in AnsiString but I would not do this. It's better to use TBytes for this.

 

procedure TThermalPrinter.SendString(AValue: AnsiString);
var
  SND: TBytes;
begin
  SetLength(SND, Length(AValue));
  CopyMemory(@SND[0], @AValue[1], Length(AValue));
  LSockect.SendData(SND); // send data to the printer
end;

And better this in TThermalPrinter.DoPrintBitmap()

  vTempStr : AnsiString;
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