Morphic magician requested. What is referencePosition?

#referencePostion returns the specified center for the morph in global coordinates.

By default this will be the same as “self bounds origin + (self bounds extent/2.0)” but can have other depending on what #rotationCenter returns.

#referencePositon: on the other hand do not set a new centre, but moves the morph to a new position by using the referencePosition as origin instead of its top left corner.

Example:

| m |

m := Morph new

               color: Color orange;

               extent: 200@72;

               openCenteredInWorld;

               yourself.

m on: #click send: #value to: [ m referencePosition: (m referencePosition + (10@10)) ]   .

Looking at Morph>>#handleDropMorph: referencePosition is used to place the dropped morph in centre of the new owner.

“

observation:

‘(self transformedFrom: anEvent hand world) globalPointToLocal: aMorph referencePosition’ looks incomplete as it will always be equal to just doing ‘aMorph referencePosition’ because #transformedFrom: always returns an IdentityTransform where # globalPointToLocal: just returns the point given to it.

“

Best regards,

Henrik

From: Pharo-dev [mailto:[hidden email]] On Behalf Of Aliaksei Syrel
Sent: Wednesday, January 27, 2016 4:12 PM
To: Pharo Development List <[hidden email]>
Subject: [Pharo-dev] Morphic magician requested. What is referencePosition?

#referencePostion returns the specified center for the morph in global coordinates.

By default this will be the same as “self bounds origin + (self bounds extent/2.0)” but can have other depending on what #rotationCenter returns.

#referencePositon: on the other hand do not set a new centre, but moves the morph to a new position by using the referencePosition as origin instead of its top left corner.

Example:

| m |

m := Morph new

               color: Color orange;

               extent: 200@72;

               openCenteredInWorld;

               yourself.

m on: #click send: #value to: [ m referencePosition: (m referencePosition + (10@10)) ]   .

Looking at Morph>>#handleDropMorph: referencePosition is used to place the dropped morph in centre of the new owner.

“

observation:

‘(self transformedFrom: anEvent hand world) globalPointToLocal: aMorph referencePosition’ looks incomplete as it will always be equal to just doing ‘aMorph referencePosition’ because #transformedFrom: always returns an IdentityTransform where # globalPointToLocal: just returns the point given to it.

“

Correction:

#transformedFrom: translates the dropped morph “center” to the receiving morph local coordinates (local from the owning transformationMorph) if it has an owner which is a transformation type Morph (see implementors #tranformFrom:) .

Best regards,

Henrik

From: Pharo-dev [[hidden email]] On Behalf Of Aliaksei Syrel
Sent: Wednesday, January 27, 2016 4:12 PM
To: Pharo Development List <[hidden email]>
Subject: [Pharo-dev] Morphic magician requested. What is referencePosition?