Object subclass:#DragAndDropManager

	instanceVariableNames:'dragView motionAction releaseAction initialPoint previousPoint

		rememberedDelegate dragBlock lineMode dropAction opaque saveUnder

		dragSize dragOffset dropObjects saveCursor lastView'

	classVariableNames:''

	poolDictionaries:''

	category:'Interface-Support'

!

View subclass:#DemoView

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	privateIn:DragAndDropManager

!

View subclass:#DemoView2

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	privateIn:DragAndDropManager

!

View subclass:#DemoView3

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	privateIn:DragAndDropManager

!

!DragAndDropManager class methodsFor:'documentation'!

documentation

"

    this class provides low-level drag & drop mechanisms.

    [author:]

        Claus Gittinger

"

!

history

    "Created: 26.10.1996 / 15:02:00 / cg"

    "Modified: 26.10.1996 / 15:21:42 / cg"

! !

!DragAndDropManager class methodsFor:'simple start'!

startDrag:anObjectOrCollection from:aView

    "start a drop at the current pointer position"

    (self new) startDrag:anObjectOrCollection from:aView offset:0@0

    "

     |o v|

     v := (Button label:'press me').

     v pressAction:[

                |o|

                o := DropObject newFile:('.').

                DragAndDropManager startDrag:o from:v.

                v turnOff

              ].

     v openAt:100@100

    "

!

startDrag:anObjectOrCollection from:aView offset:offset

    "start a drop at the current pointer position"

    (self new) startDrag:anObjectOrCollection from:aView offset:offset

    "

     |o v|

     v := (Button label:'press me').

     v pressAction:[

                |o|

                o := DropObject newFile:('.').

                DragAndDropManager startDrag:o from:v offset:10@10.

                v turnOff

              ].

     v openAt:100@100

    "

! !

!DragAndDropManager methodsFor:'accessing'!

dropObjects

    ^ dropObjects

!

dropObjects:anObjectOrCollection

    anObjectOrCollection isCollection ifTrue:[

        dropObjects := anObjectOrCollection

    ] ifFalse:[

        dropObjects := Array with:anObjectOrCollection

    ].

! !

!DragAndDropManager methodsFor:'dragging - generic'!

doGenericDragX:x y:y

    |view|

    previousPoint notNil ifTrue:[

        opaque ifTrue:[

            self restoreGenericAt:previousPoint

        ] ifFalse:[

            self invertGenericAt:previousPoint

        ]

    ].

    previousPoint := x @ y.

    view := self destinationViewAt:previousPoint.

    view ~~ lastView ifTrue:[

        view isNil ifTrue:[

            "/ alien view

            dragView cursor:(Cursor questionMark) now:true

        ] ifFalse:[

            "/ ST/X view

            (view canDrop:dropObjects) ifTrue:[

                dragView cursor:(Cursor thumbsUp) now:true.

            ] ifFalse:[

                dragView cursor:(Cursor thumbsDown) now:true

            ]

        ].

        lastView := view

    ].

    opaque ifTrue:[

        self drawGenericAt:previousPoint.

    ] ifFalse:[

        self invertGenericAt:previousPoint

    ].

!

drawGenericAt:ip

    |t offs p rootView|

    rootView := dragView device rootView.

    p := ip.

    "

     get device coordinates

    "

    (t := dragView transformation) notNil ifTrue:[

        p := t applyTo:p.

    ].

    "

     translate to screen

    "

    offs := dragView device 

                translatePoint:0@0 

                from:(dragView id) to:(rootView id).

    p := p + offs.

    rootView clippedByChildren:false.

    saveUnder isNil ifTrue:[

        saveUnder := Form width:dragSize x height:dragSize y depth:rootView device depth on:dragView device.

        saveUnder clippedByChildren:false.

    ].

    saveUnder 

        copyFrom:rootView 

        x:p x - dragOffset x 

        y:p y - dragOffset y

        toX:0 

        y:0 

        width:dragSize x 

        height:dragSize y.

    rootView lineWidth:0. 

    dragBlock value:p value:rootView.

    rootView flush

!

endGenericDragX:x y:y

    previousPoint notNil ifTrue:[

        opaque ifTrue:[

            self restoreGenericAt:previousPoint

        ] ifFalse:[

            self invertGenericAt:previousPoint

        ]

    ].

    previousPoint := nil.

    self uncatchEvents.

    self endDragAt:x @ y

    "Created: 26.10.1996 / 15:17:20 / cg"

    "Modified: 26.10.1996 / 15:22:41 / cg"

!

invertGenericAt:ip

    |t offs p rootView|

    rootView := dragView device rootView.

    p := ip.

    "

     get device coordinates

    "

    (t := dragView transformation) notNil ifTrue:[

        p := t applyTo:p.

    ].

    "

     translate to screen

    "

    offs := dragView device 

                translatePoint:0@0 

                from:(dragView id) to:(rootView id).

    p := p + offs.

    rootView clippedByChildren:false.

    rootView xoring:[

        rootView lineWidth:0. 

        dragBlock value:p value:rootView.

        rootView flush

    ].

    "Created: 26.10.1996 / 15:15:26 / cg"

    "Modified: 26.10.1996 / 15:27:09 / cg"

!

restoreGenericAt:ip

    |t offs p rootView|

    rootView := dragView device rootView.

    p := ip.

    "

     get device coordinates

    "

    (t := dragView transformation) notNil ifTrue:[

        p := t applyTo:p.

    ].

    "

     translate to screen

    "

    offs := dragView device 

                translatePoint:0@0 

                from:(dragView id) to:(rootView id).

    p := p + offs.

    rootView clippedByChildren:false.

    rootView 

        copyFrom:saveUnder 

        x:0 

        y:0 

        toX:p x - dragOffset x

        y:p y - dragOffset y

        width:dragSize x 

        height:dragSize y.

!

startGenericDrag:aTwoArgDragBlock in:aView at:p atEnd:aFourArgEndBlock

    "start a generic (caller-provided drag);

     the dragBlock, aTwoArgDragBlock will be called with two args

     aPoint and a drawingGC, to perform the drawing at some dragPoint.

     The drag starts in aView at point p.

     When finished, the endAction is called with four args:

     the targetView, the targetViews windowID (useful, if its an alien view),

     the dropPoint in root-coordinates and the dropPoint within the targetView"

    self catchEventsFrom:aView.

    motionAction := #doGenericDragX:y:.

    releaseAction := #endGenericDragX:y:.

    initialPoint := p.

    previousPoint := nil.

    dragBlock := aTwoArgDragBlock.

    dropAction := aFourArgEndBlock.

    "Modified: 26.10.1996 / 15:09:26 / cg"

    "Created: 26.10.1996 / 15:16:13 / cg"

!

startOpaqueDrag:aTwoArgDragBlock offset:offs extent:ext in:aView at:p atEnd:aFourArgEndBlock

    "start a generic opaque (caller-provided drag);

     opaque drag means, that the drawing cannot be undone by two inverting

     draws, but instead, the area under the dragged object must be saved

     and restored. The areas size to be saved/restored is passed in ext.

     the dragBlock, aTwoArgDragBlock will be called with two args

     aPoint and a drawingGC, to perform the drawing at some dragPoint.

     The drag starts in aView at point p.

     When finished, the endAction is called with four args:

     the targetView, the targetViews windowID (useful, if its an alien view),

     the dropPoint in root-coordinates and the dropPoint within the targetView"

    self catchEventsFrom:aView.

    motionAction := #doGenericDragX:y:.

    releaseAction := #endGenericDragX:y:.

    initialPoint := p.

    previousPoint := nil.

    dragBlock := aTwoArgDragBlock.

    dropAction := aFourArgEndBlock.

    opaque := true.

    dragSize := ext.

    dragOffset := offs.

    "Modified: 26.10.1996 / 15:09:26 / cg"

    "Created: 26.10.1996 / 15:16:13 / cg"

! !

!DragAndDropManager methodsFor:'dragging - lines'!

doLineDragX:x y:y

    previousPoint notNil ifTrue:[

        self invertLineFrom:initialPoint to:previousPoint

    ].

    previousPoint := x @ y.

    self invertLineFrom:initialPoint to:previousPoint

    "Modified: 26.10.1996 / 15:16:59 / cg"

!

endLineDragX:x y:y

    previousPoint notNil ifTrue:[

        self invertLineFrom:initialPoint to:previousPoint

    ].

    previousPoint := nil.

    self uncatchEvents.

    self endDragAt:x @ y

    "Created: 26.10.1996 / 15:17:20 / cg"

    "Modified: 26.10.1996 / 15:22:41 / cg"

!

invertLineFrom:ip1 to:ip2

    |t offs p1 p2 rootView a|

    rootView := dragView device rootView.

    p1 := ip1.

    p2 := ip2.

    "

     get device coordinates

    "

    (t := dragView transformation) notNil ifTrue:[

        p1 := t applyTo:p1.

        p2 := t applyTo:p2.

    ].

    "

     translate to screen

    "

    offs := dragView device 

                translatePoint:0@0 

                from:(dragView id) to:(rootView id).

    p1 := p1 + offs.

    p2 := p2 + offs.

    rootView clippedByChildren:false.

    rootView xoring:[

        rootView lineWidth:0. 

        lineMode == #arrow ifTrue:[

            a := Arrow from:p1 to:p2.

            a arrowHeadLength:(rootView device horizontalPixelPerMillimeter * 4) rounded.

            a displayFilledOn:rootView.

        ] ifFalse:[

            rootView displayLineFrom:p1 to:p2.

        ].

        rootView flush

    ].

    "Created: 26.10.1996 / 15:15:26 / cg"

    "Modified: 26.10.1996 / 15:27:09 / cg"

!

startArrowDragIn:aView at:p atEnd:aBlock

    "start a line-drag of an arrow-line.

     The drag starts in aView at point p.

     When finished, the endAction is called with four args:

     the targetView, the targetViews windowID (useful, if its an alien view),

     the dropPoint in root-coordinates and the dropPoint within the targetView"

    self catchEventsFrom:aView.

    motionAction := #doLineDragX:y:.

    releaseAction := #endLineDragX:y:.

    initialPoint := p.

    previousPoint := nil.

    dragBlock := nil.

    lineMode := #arrow.

    dropAction := aBlock.

    "Modified: 26.10.1996 / 15:09:26 / cg"

    "Created: 26.10.1996 / 15:16:13 / cg"

!

startLineDragIn:aView at:p atEnd:aFourArgEndBlock

    "start a line-drag of a normal line.

     The drag starts in aView at point p.

     When finished, the endAction is called with four args:

     the targetView, the targetViews windowID (useful, if its an alien view),

     the dropPoint in root-coordinates and the dropPoint within the targetView"

    self catchEventsFrom:aView.

    motionAction := #doLineDragX:y:.

    releaseAction := #endLineDragX:y:.

    initialPoint := p.

    previousPoint := nil.

    dragBlock := nil.

    lineMode := nil.

    dropAction := aFourArgEndBlock.

    "Modified: 26.10.1996 / 15:09:26 / cg"

    "Created: 26.10.1996 / 15:16:13 / cg"

! !

!DragAndDropManager methodsFor:'drawing'!

showDragging:items in:aView at:p

    |offs|

    items size > 1 ifTrue:[

        offs := 0.

        items do:[:item |

            item displayOn:aView at:p + (0@offs).

            offs := offs + (item heightOn:self)

        ]

    ] ifFalse:[

        items first displayOn:aView at:p.

    ]

    "Created: 14.11.1996 / 15:31:31 / cg"

    "Modified: 14.11.1996 / 16:32:00 / cg"

! !

!DragAndDropManager methodsFor:'easy drag & drop'!

startDrag:anObjectOrCollection from:aView offset:offset

    "start a drop at the current pointer position"

    |pos displayObjects device width height|

    self dropObjects:anObjectOrCollection.

    device := aView device.

    pos := device translatePoint:(device pointerPosition)

                            from:(device rootView id) 

                              to:(aView id).

    displayObjects := dropObjects collect:[:each | each displayObject on:device].

    height := displayObjects inject:0 into:[:sum :each | sum + (each heightOn:aView)].

    width  := displayObjects inject:0 into:[:max :each | max max:(each widthOn:aView)].

    self startOpaqueDrag:[:aPoint :aView|self showDragging:displayObjects in:aView at:(aPoint - offset)]

                  offset:offset

                  extent:(width @ height)

                      in:aView

                      at:pos

                   atEnd:nil.

! !

!DragAndDropManager methodsFor:'event catching'!

buttonMotion:button x:x y:y view:aView

    self perform:motionAction with:x with:y

    "Created: 26.10.1996 / 15:09:00 / cg"

!

buttonRelease:button x:x y:y view:aView

    self perform:releaseAction with:x with:y

    "Created: 26.10.1996 / 15:09:14 / cg"

!