[Cuis] mouseButton2Up:localPosition:

[Dan Norton]

On 1 May 2015 at 15:55, Juan Vuletich wrote:

> 
> Hi Dan,
> 
> On 4/29/2015 11:45 AM, Dan Norton wrote:
>     On 27 Apr 2015 at 8:10, Juan Vuletich wrote:
> 
>     > Hi Dan,
>     >
>     > So, where's the bug? It's in your
> #mouseButton2Up:localPosition: .
>     > You get
>     > a point in local coordinates (you can check this bu just
> adding
>     > 'localEventPosition print'). And you ask for the menu to open
> there.
>     > But
>     > the menu is not a submorph. It will be a submorph of the
> world.
>     > (this is
>     > again easy to check by opening an inspector on the menu, by
> doing
>     > 'self
>     > inspect').
>     >
>     Interesting. Please allow me to state my understanding of the
> case. When writing code for a 
>     Morph subclass, it's easy to assume that the "localPosition"
> refers to that of the receiver and 
>     it does. But PopUpMenu inherits from Object rather than Morph
> and when told to position 
>     itself 'at: localPosition', PopUpMenu has the display screen as
> its reference and interprets 
>     localPosition accordingly.
> 
> Well, no. The position of a morph is expressed in the coordinate
> system of the owner, i.e. the 
> morph containing it. The morph getting the event gets the mouse
> position in its own coordinates. 
> But it doesn't add the Menu as its submorph: the menu is added as a
> submorph of the world. 
> Therefore, the position must be expressed in world coordinates.
> 
Ah, the owner of the pop-up is the PasteUpMorph called [world].

>     > What you want is, instead of just using 'localEventPosition'
> to use
>     > '(self
>     > externalizeToWorld: localEventPosition)'.
> 
>     #externalizeToWorld: transforms the parameter from the
> coordinates of self to the 
>     coordinates of the display screen. Using this as the location
> for PopUpMenu will cause it to 
>     appear over the top morph where the click occurred - the
> receiver.
> 
> In my experiment, doing 'self externalizeToWorld: localEventPositon'
> made the menu open 
> exactly under the mouse pointer. Wasn't this the case for you?
> 

Yes, under the mouse and over the morph :)

>     Your alternative
>     > #xmouseButton2Activity is perfectly fine too.
>     >
> 
>     This gets "right to the point." Is this sent from
> MouseClickState>handleEvent:from: ?.
> 
>     I hope I got all this right.
> 
>      - Dan
>      
> 
> If you want to see where stuff is called from, add  'self halt' at
> that point. Doing this in Morphic 
> code sometimes is risky, as it might result in an infinite sequence
> of debuggers opening. Doing 
> 'thisContext printStack: 10' is safer.
> 

Great. I'll try that. The red blizzard is no fun.