Converting global coordinates from a mouse event
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
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 globaâ¦..
].
On 2 Mar 2025, at 22:00, Mikael Svane <mikael.svane@fridhem.org> 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 canât 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, itâs just that I canât seem to find it.
Kind regards, Mikael
Thanks, but unfortunately that doesnât work. The object stored in the image variable is an ImagePresenter, not a Morph, so it doesnât 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 doesnât seem to be the case. Any further suggestions are very welcome! Kind regards, Mikael FrÃ¥n: sducasseatwork--- via Pharo-users [mailto:pharo-users@lists.pharo.org] Skickat: den 4 mars 2025 12:37 Till: Any question about pharo is welcome Kopia: sducasseatwork@mailo.com Ãmne: [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 globaâ¦.. ]. On 2 Mar 2025, at 22:00, Mikael Svane <mikael.svane@fridhem.org> 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 canât 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, itâs just that I canât seem to find it. Kind regards, Mikael
Hi Mikael I assume you use spec with the Morphic underlying graphical library. In your presenter:Â - `anEvent position` will give you the event position in the global world coordinate. - `self adapter widget position.` will give you the top left corner underlying Morph position in the global world coordinate. `anEvent position - self adapter widget position` should give you the position you're looking for. Renaud Mar 3, 2025, 03:17 by mikael.svane@fridhem.org:
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.
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My #initializePresenter method looks like this:
initializePresenter
                          image := self newImage
                                                      image: self emptyImage;
                                                      autoScale: true.
                          image eventHandler whenMouseDownDo: [ :event |
                                                                                 self handleMouseDown: event].
Â
This works, and the #handleMouseDown: method is run whenever the mouse is pressed on the ImagePresenter, but the MouseButtonEvent reports global coordinates and I canât 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.
Â
There must be a very simple solution to this, itâs just that I canât seem to find it.
Â
Kind regards,
Mikael
Hi Renaud, Yes, I use Spec with the Morphic graphical library and with the calculation that you described, I got the correct answer for the coordinates within the Morph representing the image (Form). Because I was using an autoscaling image, I had then to do one more step by scaling the local coordinates according to the scale of the image, but that was very easy. Thanks! Kind regards, Mikael FrÃ¥n: Renaud de Villemeur via Pharo-users [mailto:pharo-users@lists.pharo.org] Skickat: den 5 mars 2025 02:13 Till: Any question about pharo is welcome Kopia: Any question about pharo is welcome; Renaud de Villemeur Ãmne: [Pharo-users] Re: Converting global coordinates from a mouse event Hi Mikael I assume you use spec with the Morphic underlying graphical library. In your presenter: - `anEvent position` will give you the event position in the global world coordinate. - `self adapter widget position.` will give you the top left corner underlying Morph position in the global world coordinate. `anEvent position - self adapter widget position` should give you the position you're looking for. Renaud Mar 3, 2025, 03:17 by mikael.svane@fridhem.org: 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 canât 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, itâs just that I canât seem to find it. Kind regards, Mikael
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Mikael Svane -
Renaud de Villemeur -
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