Delphi printing with Canvas, align text to the right - delphi

Question

I'm printing using TPrinter.Canvas and am trying to align the text to the right due to money displaying numbers.
The text is printed with this code:
Printer.Canvas.Textout(800, 100, 250.00); //charge1
Printer.Canvas.Textout(800, 200, 10.00); //charge2
Printer.Canvas.Textout(800, 300, 260.00); //Total Amount
How can I align the lines to display correctly?

Answer 1

Instead of using VCL's TextOut, you should use the Winapi DrawText and choose to align to the right using that within a given rectangle, specifically using DT_RIGHT. For example...
DrawText(Canvas.Handle, PChar(T), Length(T), R, DT_SINGLELINE or DT_RIGHT);

Answer 2

You could use the lower level device context Api's to more accurately control the text output, such as DrawText() as suggested by Jerry. However, doing this will require that you pre-calculate/set the bounding rectangle for your text output so that Windows knows the area which any alignment is relative to.
There are two potentially simpler alternatives:
Option 1 - For Fixed Width Fonts ONLY
This may be appropriate for you since you appear to be using a fixed-width font.
All we do here is introduce padding to your strings prior to output. This may be simpler than the calculations required for the output rectangles etc.
To do this, decide on the longest string you will accept for output and then add whatever spaces you need to the left of each string to ensure they are all the same length. With a fixed width font, a space takes up the same horizontal space as any other character so by making all strings the same length you will achieve "right alignment":
procedure PrintRightJustified(const aX, aY, aMaxLen: Integer; aValue: String);
var
s: String;
begin
s := aValue;
// Pad the string with spaces to the maximum length
if Length(s) < aMaxLen then
s := StringOfChar(' ', aMaxLen - Length(s)) + s;
Printer.Canvas.Textout(aX, aY, s);
end;
Then call this method to output your strings right-justified to a consistent maximum length, e.g. if 6 is your maximum length (999.99):
PrintRightJustified(800, 100, 6, '250.00'); //charge1
PrintRightJustified(800, 200, 6, '10.00'); //charge2
PrintRightJustified(800, 300, 6, '260.00'); //Total Amount
How to handle scenarios where the specified string is longer than the maximum width is left as an exercise.
Option 2 - For Any Font
Another way, which would work for fixed width or variable width fonts (e.g. Arial) would be to choose the position of the rightmost edge of the strings and calculate the X position relative to this based on the device width calculated for each string you are outputting:
procedure PrintRightJustified(const aRightX, aY; aValue: String);
var
leftX: Integer;
begin
leftX := aRightX - Printer.Canvas.TextWidth(aValue);
Printer.Canvas.Textout(leftX, aY, aValue);
end;
You don't need to specify a maximum width for this version, it works regardless of font being used:
PrintRightJustified(900, 100, '250.00'); //charge1
PrintRightJustified(900, 200, '10.00'); //charge2
PrintRightJustified(900, 300, '260.00'); //Total Amount
This does mean that text may potentially "bleed" too far to the left without some mechanism to detect and handle this. Again, If that is a concern then either move the right-edge further across or you will have to come up with a way of handling it (left as an exercise for you since we don't know what your precise requirements are).

Answer 3

To the precedent answer!
With the above given code (Answer 1) I couldn'get my number aligned with one space.
After some thinking, I check on Word with my font, Times New Roman, how many space I need to get the number aligned, (the decimal dot have to be vertically aligned).
I noticed that two spaces were necessary not only one.
I juste wrote the command two times:
s:= StringOfChar(' ', aMaxLen - Length(s)) + s;
s:= StringOfChar(' ', aMaxLen - Length(s)) + s;
Man could do
s:= StringOfChar(' ', aMaxLen - Length(s))+ StringOfChar(' ', aMaxLen -
Length(s)) + s;
Excuse my english but it is not my mother language.
I hope it is a bit more understandable.

Answer 4

To Option 1 - For Fixed Width Fonts ONLY
First on word you check how many space you need to align your number. For Times I did need 2 spaces so you just double the procedure line:
s := StringOfChar(' ', aMaxLen - Length(s)) + s;
s := StringOfChar(' ', aMaxLen - Length(s)) + s;