Canvas.Pen.Pattern
lazarus / 39-Graphics

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HomePlaneR · 2013-04-16 21:26

Hi everyone.

Following code does not want to work:
Code: [Select] Canvas.Pen.Color := clRed;
 Canvas.Pen.Style := psPattern;
 Canvas.Pen.Pattern := $AAAAAAAA;    //101010...
 Canvas.Line(0,0,100,0);

It gives a black line, but I expected to have red dotted line. What
I'm doing wrong?

Thanks in advance.

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Blaazen · 2013-04-16 22:00

Style psPattern does not work here too. Maybe it's not implemented yet
or it works only on some widgetsets. Of course there is psDot - you
probably know.

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HomePlaneR · 2013-04-17 15:23

Quote from: Blaazen on April 17, 2013, 12:00:25 amStyle psPattern does
not work here too. Maybe it's not implemented yet or it works only on
some widgetsets. Of course there is psDot - you probably know.

That's what I thought. Thanks anyway.

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Blaazen · 2014-12-20 18:54

Just for the case:

psPattern works but method SetPattern must be used (property Pattern
does nothing).

Code: [Select]var aPenPattern: TPenPattern;
begin
  Canvas.Pen.Style := psPattern;
  SetLength(aPenPattern, 2);
  aPenPattern[0] := 1;  //line [pixels]
  aPenPattern[1] := 1;  //space [pixels]
  ...
  Canvas.Pen.Width := 1;
  Canvas.Line(...);
This code will paint subtle dotted line.

The array can be longer, the first number is always length of dash,
the second is the space.

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PawelO · 2015-03-22 10:36

It works for me only when Pen.Width > 1. When Pen.Width=1, it draws
always black solid line (Lazarus v1.2.6, Win XP).

Code: [Select]    Canvas.Pen.Color := clRed;
    Canvas.Pen.Style := psPattern;
    SetLength(aPenPattern, 2);
    aPenPattern[0] := 3;  //line [pixels]
    aPenPattern[1] := 3;  //space [pixels]
    Canvas.Pen.SetPattern(aPenPattern);
    Canvas.Pen.Width := 1{2};
    Canvas.Line(50,50,100,50);