Hi,
I have also been thinking about states recently. I came up with an
idea that is similar to the state pattern, but states are not
represented by separate classes, which makes things very simple. Let
me explain:
Similar to the ButtonBars we have -- we never define them, we just tag
one in each button -- we could tag buttons with a state. If a button
of a certain state is selected, all buttons of the same state would
also be activated and vice versa.
In addition to that, the following two things would be useful:
- no need to have a button for a control. This would help to reduce
buttons when working with states. Only one main control for each state
would need to have a button.
- additional parameter for controls to define a modifier, ie. shift,
ctrl etc. This is supported by OL controls and would allow to combine
more controls into one state by using different modifiers.
Simple and effective, don't you think?
Regards,
Andreas.
On 10/25/07, Cameron Shorter <[EMAIL PROTECTED]> wrote:
> Thanks for resending.
>
> Have you looked into the State Pattern? (This might be what you are
> describing below). Effectively, you have a separate class for each
> state. Eg, an EditingState, NavigationState, etc.
> Each State class is responsible for processing mouse actions. Eg: When
> double click is pressed, do X.
>
> The State object is attached to a toolbar or MapPane when a button on
> the toolbar is selected.
>
> Steven M. Ottens wrote:
> > Right....
> >
> > This will teach me to never rush an email just before you need to
> > catch a train. Apparently the attachment ended up in the middle of the
> > email so most of you probably didn't read further than the first line.
> > Still I'd like to discuss this, so for the lazy ones here is the rest
> > of the mail without binairy information :)
> >
> >> In my continuing quest to a nice google-like interface for mapbuilder
> >> I ran into the following problem:
> >>
> >> I want a few 'states' for the application; right now I have a normal
> >> pan/zoom/featureinfo state and a measurement state (the latter is
> >> just a drawing state that calculates a distance of a line instead of
> >> just creating a line). In the future I might want to create more
> >> states. Just like google I don't want to have buttons for each
> >> function, just for the states. This means that the mousebuttons
> >> should be able to trigger different functions in a state:
> >>
> >> In normal pan/zoom mode I have these buttons:
> >>
> >> -double-left click: zoom in
> >>
> >> -left-drag: pan
> >>
> >> -scrollwheel: zoom in/out
> >>
> >> I want to add getFeatureInfo to the normal pan zoom mode, since I'd
> >> like to keep the amount of buttons to a minimum. However since double
> >> click and drag are already taken, it's hard to use single left click
> >> for this. (how do you tell whether it's going to be a double click or
> >> a drag instead of a single click)
> >>
> >> So I've decided to go for the right-mouse click.
> >>
> >>
> >> To get this I've modified MapPaneOL.updateMouse(e):
> >>
> >> MapPaneOL.prototype.updateMouse = function(e) {
> >>
> >> // get objRef from the event originator object (e.object),
> >>
> >> // where it was stored as mbPane property by paint().
> >>
> >> var objRef = e.object.mbMapPane;
> >>
> >>
> >> // update map pane cursor
> >>
> >> if (objRef.model.map.mbCursor) {
> >>
> >> objRef.model.map.div.style.cursor = objRef.model.map.mbCursor;
> >>
> >> }
> >>
> >> // Check if the left mouse button is used
> >>
> >> var isLeftClick = (((e.which) && (e.which == 1)) ||
> >>
> >> ((e.button) && (e.button == 1)));
> >>
> >> // fire Mapbuilder mouseup event
> >>
> >> if (isLeftClick) objRef.model.callListeners('mouseup', {evpl:
> >> [e.xy.x, e.xy.y]});
> >>
> >> // it is a right mouse uprequest
> >>
> >> else objRef.model.callListeners('rightmouseup', [e.xy.x, e.xy.y]);;
> >>
> >> }
> >>
> >>
> >> (also added oncontextmenu="return false" to <div mainMapPane> to
> >> disable the menu)
> >>
> >>
> >> I've modified getFeatureInfo to listen to the rightmouse up:
> >>
> >> this.model.addListener("rightmouseup",this.getFeatureInfo, this );
> >>
> >>
> >> Also I separated the actual getFeatureInfo function from the control.
> >> This way it is possible to trigger the getFeatureInfo request from
> >> the rightmouseup event instead of the zoombox it is now.
> >>
> >>
> >> A further benefit is that I can now switch between measurement mode
> >> en getfeatureinfo mode while keeping the panzoombar and the
> >> scrollwheel functionality. It doesn't do advanced mouse handling like
> >> being able to drag the map whilest drawing, but that is something
> >> that has to be solved on openlayers level and I believe they are
> >> working on it in the advacned vector editing project.
> >>
> >>
> >> And finally I hacked the popup function into getFeatureInfo to make
> >> sure that it shows it results in a popup (eliminating the template
> >> problem that has plagued us for years incidentaly) . The entire code
> >> is a series of hacks so please be careful with it.
> >>
> >> My question are:
> >>
> >> Does this look like a sensible approach to get:
> >>
> >> a. pan/zoom/featureinfo in one 'control'/state?
> >>
> >> b. be able to switch between pan/zoom/featureinfo state and drawing
> >> state?
> >>
> >> c. get getfeatureinfo produce its results in a popup?
> >>
> >>
> >> Attached are the modified MapPaneOL.js, GetFeatureInfoPZ.js (PZ
> >> stands for PanZoomBar) and the config so people can figure out how I
> >> used it.
> >>
> >> Regards,
> >>
> >> Steven
> >>
> >
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>
>
> --
> Cameron Shorter
> Geospatial Systems Architect
> Tel: +61 (0)2 8570 5050
> Mob: +61 (0)419 142 254
>
> Think Globally, Fix Locally
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>
>
>
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