I really love this discussion :) Doru
On Fri, Aug 1, 2014 at 11:36 PM, Alexandre Bergel <alexandre.ber...@me.com> wrote: > This is an excellent start. > > Do you need the grid? If yes, then I can add this to Roassal. It is easy > to define an interaction that define a grid. > > I have added event to signal the beginning and ending of a > dragging-and-dropping. > Here is an example: > -=-=-=-=-=-=-=-= > | v e | > v := RTView new. > e := (RTEllipse new size: 30) element. > e @ RTDraggable. > v add: e. > e when: TRMouseDragStart do: [ :evt | Transcript show: evt printString; > cr. evt element trachelShape color: Color red. v signalUpdate ]. > e when: TRMouseDragEnd do: [ :evt | Transcript show: evt printString; cr ]. > v open > -=-=-=-=-=-=-=-= > > Let me know whether this helps. > > Cheers, > Alexandre > -- > _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: > Alexandre Bergel http://www.bergel.eu > ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. > > > > On Aug 1, 2014, at 2:36 PM, Peter Uhnák <i.uh...@gmail.com> wrote: > > Hi Alex, > > While the "snap to grid" might be complicated I thought of simpler > solution that might be achievable purely at Roassal level without the need > to change Trachel classes. You can look at Umlet, since I am trying to copy > it's grid behavior here. > Basically you don't move objects with mouse immediately but only after > fixed increments. However I've encountered a problem with > TRMouseDragging>>step, since I would probably need to continuously sum the > individual steps and then reset them when dragging has started. > > Here is a _very_ crude prototype: > --------------------- > "i subclassed RTDraggable and changed initializeElement: method as follows" > initializeElement: element > | sum gridSize | > gridSize := 20. > sum := 0 @ 0. > element > when: TRMouseDragging > do: [ :e | > | d t | > t := RTGroup withAll: groupToDrag. > (t includes: element) > ifFalse: [ t add: element ]. > d := element view canvas camera distanceFromPixelToSpace: e step. > sum := sum + d. > "move element only in increments of gridSize" > d := gridSize * ((sum x / gridSize) truncated @ (sum y / gridSize) > truncated). > sum := sum - d. > t translateBy: d. > e signalUpdate ] > --------------------- > > and here is a demo utilizing it > > ----------------------------- > | v e1 e2 line gridSize b1 b2 b3 b4 edge | > v := RTView new. > > "draw grid" > gridSize := 20. > > (-20 to: 20) do: [ :i | > b1 := RTBox element. > b2 := RTBox element. > b3 := RTBox element. > b4 := RTBox element. > b1 translateTo: (i * gridSize) @ -1000. "top side" > b2 translateTo: (i * gridSize) @ 1000. "bottom side" > b3 translateTo: -1000 @ (i * gridSize). "left side" > b4 translateTo: 1000 @ (i * gridSize). "right side" > "vertical line" > edge := RTLine edgeFrom: b1 to: b2. > v add: edge. > "horizontal line" > edge := RTLine edgeFrom: b3 to: b4. > v add: edge. > ]. > > e1 := (RTEllipse new size: 30; color: Color magenta) element. > e1 translateTo: -20 @ 0. > e1 @ RGGridDraggable. > > e2 := (RTEllipse new size: 30; color: Color magenta) element. > e2 translateTo: 20 @ 0. > e2 @ RGGridDraggable. > > (line := RTLine edgeFrom: e1 to: e2) shape color:Color black. > > v add: e1; add: e2; add: line. > > v open. > ----------------------------- > > Obviously it needs a lot of fine-tuning and such. Since RTInteraction > (RTDraggable) instances are not created directly the gridSize would have to > be stored probably class side. Also there is a problem with resetting the > "sum" variable when dragging starts. (There is no TRMouseDragStart event as > far as I've seen). And also drawing the grid itself the way I've done is > very brutal and doesn't really work if I want to move the canvas camera > (perhaps image pattern as a background would work better). > > What are your thoughts on this? > > Peter > > > > > On Fri, Aug 1, 2014 at 4:07 PM, Alexandre Bergel <alexandre.ber...@me.com> > wrote: > >> Hi Peter! >> >> > While playing with RTMultiLine I thought that it would be nice to have >> option for RTDraggable elements to snap to a grid / move only by fixed >> increments - for example the position could only be divisible by 10 (grid >> size would be 10), so dragging from 20@10 to 26@4 would jump to 30@0. Is >> something like this possible with current implementation? >> >> >> I first thought this would be easy. But actually it is not. >> The way to achieve the snap on grid behavior is to have an indirection in >> the Trachel classes. Each trachel shape knows its position (the position is >> contained in the matrix attached to each shape). The snap-on-grid means you >> need to slightly process the matrix coordinate. Maybe there are other way >> to do this, but it does not look like. Changing Trachel because of this >> seems a bit overkill... >> >> Cheers, >> Alexandre >> -- >> _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: >> Alexandre Bergel http://www.bergel.eu >> ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. >> >> >> >> On Jul 31, 2014, at 3:58 PM, Peter Uhnák <i.uh...@gmail.com> wrote: >> >> > While playing with RTMultiLine I thought that it would be nice to have >> option for RTDraggable elements to snap to a grid / move only by fixed >> increments - for example the position could only be divisible by 10 (grid >> size would be 10), so dragging from 20@10 to 26@4 would jump to 30@0. Is >> something like this possible with current implementation? >> > >> > The second question is: is it possible for element to subscribe for >> position updates of another element? (I.e. element A watches for movement >> of element B and moves accordingly). I know I could add both of them to a >> composite shape or RTGroup (RTDraggable>>groupToDrag:), however I would >> prefer something more loosely coupled. >> > >> > In RTDraggable>>initializeElement: i found >> > " element when: TRMouseDragging do: [ :e | e element translateBy: e >> step. e signalUpdate ]" >> > however it is commented out so perhaps there some other way? >> > >> > Peter >> >> >> > > -- www.tudorgirba.com "Every thing has its own flow"
