I'm porting a little Morphic geometry program from Morphic to a Spec 2
application using GTK.

I need to draw a shape in an SpAthensPresenter but to draw it I need to know
the current dimensions (extent) of the presenter so it can still work OK
even when the  window is resized.

The old Morphic version also used An Athens canvas but I had no problem then
as a morph has an extent method that provides this information. But now that
I can't use a morph I find that the extent method of an SpPresenter always
seems to answer nil.

Is that right? How d you get the current size of a presenter? Is it a bug?

I'm using a very recent Pharo 9 image and headless VM on Linux.

Image

/home/kmp/Pharo/images/gtkRoses/gtkRoses.image
Pharo9.0.0
Build information:
Pharo-9.0.0+build.1399.sha.9ae8329dedfbad7915b7b2cdc4accc7ce8109ce0 (64 Bit)
Unnamed

Virtual Machine

/home/kmp/Pharo/vms/90-x64-headless/lib/pharo
CoInterpreter VMMaker-tonel.1 uuid: 286e9806-8e7d-0d00-ab06-4e280faf8631 Apr
30 2021
StackToRegisterMappingCogit VMMaker-tonel.1 uuid:
286e9806-8e7d-0d00-ab06-4e280faf8631 Apr 30 2021
5125110 - Commit: 5125110 - Date: 2021-04-30 10:05:04 +0200

Pharo 9.0.0 built on Apr 30 2021 10:22:47 Compiler: 5.4.0 20160609
VMMaker versionString 5125110 - Commit: 5125110 - Date: 2021-04-30 10:05:04
+0200
CoInterpreter VMMaker-tonel.1 uuid: 286e9806-8e7d-0d00-ab06-4e280faf8631 Apr
30 2021
StackToRegisterMappingCogit VMMaker-tonel.1 uuid:
286e9806-8e7d-0d00-ab06-4e280faf8631 Apr 30 2021

Any help woudl be appreciated.

--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

I'm afraid it still doesn't work for me.

If I have a drawBlock like this:

drawBlock

^ [ :aCanvas |
| paint surface |
surface := aCanvas surface.
paint := surface
createLinearGradient: {
(0 -> Color blue).
(1 -> Color black) }
start: 0 @ 0
stop: aCanvas surface extent.
surface clear.
aCanvas setPaint: paint.
aCanvas drawShape: (0 @ 0 corner: aCanvas surface extent) ]

I get just a blank canvas.- nothing is drawn.

If I replace the aCanvas surface extent with a fixed size like this:

drawBlock

^ [ :aCanvas | 
  | paint surface |
  surface := aCanvas surface.

  paint := surface
	           createLinearGradient: { 
			           (0 -> Color red).
			           (1 -> Color green) }
	           start: 0 @ 0
	           stop: 300 @ 300.
  surface clear.
  aCanvas setPaint: paint.
  aCanvas drawShape: (0 @ 0 corner: 300 @ 300) ]

then it works.

Any ideas what i might be doing wrong?

--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

I should also point out that nothing works unless I also set a surfaceExtent
when the presenter is set up -

initializePresenters

rosesAthensPresenter := RosesAthensPresenter new.
rosesAthensPresenter surfaceExtent: 400 @ 400.
rosesAthensPresenter drawBlock: [ :aCanvas | 
	| paint surface |
	surface := aCanvas surface.
	paint := surface
		         createLinearGradient: { 
				         (0 -> Color blue).
				         (1 -> Color black) }
		         start: 0 @ 0
		         stop: 300 @ 300.
	surface clear.
	aCanvas setPaint: paint.
	aCanvas drawShape: (0 @ 0 corner: 300 @ 300) ].

--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Hi Estaban.

Thank you for your helpful and prompt replies to my problem. Unfortunately,
your code does not work for me.

I pasted your code into a playground. When it runs I get no errors but I get
a completely blank window - no sign of the colour gradient.

If I change the backend to #Morphic, I get the gradient but, as you say, it
does not resize.

I just seem to be very unlucky with Gtk.

Ken

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Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

I'm running Xubuntu 20.04. I didn't install Gtk - it comes with the OS.

I'm using the Nvidia video driver. Perhaps that has an effect.

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