How to use TBrush pattern?
lazarus / 39-Graphics

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wp · 2017-02-07 17:18

Can anybody give me a short example how the BrushStyle bsPattern (of
TBrush) is used? I suppose it is needed to extend the built-in fill
patterns (bsCross, bsHorizontal, etc). Why are the more usual
BrushStyles (such as bsSolid, bsClear etc) redeclared in graphics, but
bsPattern and bsImage not? They require unit FPCanvas.

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LuizAmérico · 2017-02-07 20:42

Try https://bitbucket.org/blikblum/pascal-demos/src/4fcb11397f1aa6b41e
b9cd53379351c97de61b3a/lazarus/LCLTests/PatternBrush/?at=master

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wp · 2017-02-07 21:17

Thank you - this works fine, it is the "Windows" way, though. I would
have expected that bsPattern for TBrush could be supported in way
analogous to TPen's psPattern - you set Pen.Style := psPattern and
call Pen.SetPattern().

Can I interpret your answer in a way that the LCL itself does not
support the BrushStyle bsPattern, at least at the moment? In this
case, I should write a feature request.

The background of the question is that I wrote a TChartCombobox which
can be used to edit series pointer styles, pen styles, pen widths, and
brush styles, and could not find a reasonable solution for the
BrushStyle bsPattern.

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LuizAmérico · 2017-02-08 09:03

Set TBrush.Bitmap to the bitmap you want to use as pattern and
TBrush.Style = bsPattern

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wp · 2017-02-08 09:48

So easy? I can't believe it...

But: What is the difference to bsImage then? Look at the attached
demo. It contains four paintboxes, two paint standard brushes (bsCross
and bsFDiagonal), one paints bsPattern, and one paints psImage, the
latters ones with an alternating black/white bitmap. The paintboxes
with bsPattern and psImage look the same. I would have expected that
the pattern color of bsPattern could be controlled by changing the
Brush.Color (as with the standard patterns). But nothing happens. Then
I thought, maybe the bsPattern bitmap should be a 1-bit pixelformat
(use FBitmap1 in Paintbox1Paint), but then the entire paintbox goes
black.

Another related question: Is there a way to control the background
color of non-solid fills in an LCL-conformal way (without going the
Windows way as in your demo)?

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LuizAmérico · 2017-02-08 13:53

QuoteBut: What is the difference to bsImage then?
I dont know

QuoteLook at the attached demo
Sorry no time for now


QuoteAnother related question: Is there a way to control the
background color of non-solid fills in an LCL-conformal way (without
going the Windows way as in your demo)?
AFAIK bsPattern with no mono bitmap is always solid. I tried with a
transparent bitmap (png) and it did not work. For mono bitmaps play
with Brush.Color, Font.Color

Luiz