Thanks, but unfortunately that doesn’t work.
The object stored in the image variable is an ImagePresenter, not a Morph, so
it doesn’t understand globalPointToLocal:. However, the ImagePresenter contains
an adapter (an SpMorphicBoxAdapter) which has a variable called widget
containing an AlphaImageMorph which must represent the image. But if I send the
#globalPointToLocal: message to the AlphaImageMorph instance it just returns
the same point that it was given as argument. This must be because
Morph>>globalPointToLocal: is implemented as:
Morph>>globalPointToLocal: aPoint
^self point: aPoint from: nil
and:
Morph>>point: aPoint from: aReferenceMorph
owner ifNil: [^ aPoint].
^ (owner transformFrom: aReferenceMorph)
globalPointToLocal: aPoint
Since these definitions are the only one in any of the Morph subclasses,
aReferenceMorph will always be nil for all Morphs and Morph>>point: aPoint
from: aReferenceMorph (and Morph>>globalPointToLocal:) will always return the
same point that it was given as argument. This seems a bit strange.
After some more research, I found a similar question from 2012 where the
#globalPointToLocal: method was apparently working:
http://forum.world.st/Mouse-handler-on-a-morph-td4603302.html
So at the moment I am not sure if #globalPointToLocal: is the intended way of
transforming coordinates, perhaps with a bug, or if there is new way of
transforming coordinates and this is just old code that has not been removed
from the image. At first, I would have guessed that coordinate transformation
should have been handled by the different Layouts used, but this doesn’t seem
to be the case.
Any further suggestions are very welcome!
Kind regards,
Mikael
Från: sducasseatwork--- via Pharo-users [mailto:[email protected]]
Skickat: den 4 mars 2025 12:37
Till: Any question about pharo is welcome
Kopia: [email protected]
Ämne: [Pharo-users] Re: Converting global coordinates from a mouse event
I did a little search and I found
Morph >> globalPointToLocal: aPoint
^self point: aPoint from: nil
may be
image eventHandler whenMouseDownDo: [ :event |
self handleMouseDown: event
image globa…..
].
On 2 Mar 2025, at 22:00, Mikael Svane <[email protected]> wrote:
I have a presenter that is a subclass of SpPresenterWithModel and it contains,
among other things, an ImagePresenter with an autoscaling image (a Form). I
want to capture mouse clicks on the image and get the coordinate of the click
relative to the upper left corner of the Form.
My #initializePresenter method looks like this:
initializePresenter
image := self newImage
image: self emptyImage;
autoScale: true.
image eventHandler whenMouseDownDo: [ :event |
self handleMouseDown: event].
This works, and the #handleMouseDown: method is run whenever the mouse is
pressed on the ImagePresenter, but the MouseButtonEvent reports global
coordinates and I can’t find out how to convert these to coordinates relative
to the Form that the ImagePresenter holds. I have googled and found answers to
similar old questions, but nothing that seems to apply to Spec2.
There must be a very simple solution to this, it’s just that I can’t seem to
find it.
Kind regards,
Mikael
