Add panning ability to message views

[Matthias Schoettle]

Currently, it is not possible to move the message view around, especially if it exceeds the screen.

Potentially zooming should be supported as well.

[Matthias Schoettle]

References #265: Moved general gesture capabilities of StructuralDiagramView into super-class AbstractView. This includes scale, zoom, panning and dragging. An AbstractViewHandler is used to take care of these (moved out of StructuralViewHandler).

Other views can then build upon this when required. This also supports the addition of a menu to the view in the future.

→ <<cset e11bd9996db8>>

[Matthias Schoettle]

References #265: Changes state view related view and handler to new AbstractView and AbstractViewHandler.

→ <<cset 9ba182fd5895>>

[Matthias Schoettle]

References #265: Moves the responsibility to register input processors to the sub-class of AbstractView.

• Renames unistroke drawing layer
• fixes issues related to the parent of the view

→ <<cset 0028dfb42364>>

[Matthias Schoettle]

References #265: Fixes some small problems in the AbstractViewHandler, such as wrong target. For wheel events, it is important to make sure that the right handler handles the event, since it is global, all handlers receive the event. This makes it necessary to ensure that the targets handler is responsible for handling the event.

→ <<cset faa7d3933b39>>

[Matthias Schoettle]

References #265: Changes the message view handler to use AbstractViewHandler. Currently, it supports only drag/pan events. Zooming does not work nicely (the arrows and lines are often placed incorrectly once the lines are updated).

To work properly, the position used for drawing needs to be relative to the parent (the container layer). However, the end view of messages is located on the lifeline and on one of the event containers. Therefore, the global position is used and translated into a relative position to the lifeline's parent.

Layouting still uses the global position, because only heights and their differences are calculated.

→ <<cset 9cd391a6f7c3>>

[Matthias Schoettle]

References #265: Moves handling of event(s) on message into a separate handler just for messages, to better separate different responsibilities.

→ <<cset 84610172384c>>

[Matthias Schoettle]

References #265: Fixes problems with layouting and overwritten methods.

• If the layout mechanism is used, the actual view will never receive if the container layer is an MTComponent and has no layout. It is now a RamRectangleComponent with a "fake" default layout.
• When containsChild or removeChild is called with an actual component reference, in case it is one of the two layers, the super methods need to be called. However, other methods that use indices have no effect when dealing with actual children of the view (and not the container layer).

→ <<cset 55ebe72df100>>

[Matthias Schoettle]

Merged in Issues/265-MessageView-Panning (pull request #16)

[Matthias Schoettle]

Zooming generally works, but creates weird effects. It seems that the end positions of the messages are not correctly translated into relative positions. They are slightly off. Also, when creating new messages, they can appear in the wrong place.

[Matthias Schoettle]

References #265: Reverts partial change from commit 55ebe72 that removed scaleGlobal from AbstractView. This is required in order to allow a view to scale itself.

→ <<cset 54c34d89cb00>>

[Matthias Schoettle]

References #265: Fixes the positioning of create lifelines. The position used a global position, whereas a relative to parent position is required for the lifeline.

→ <<cset e5d522a6fc7f>>