Listbox Drag & Drop

#pragma TextEncoding="UTF-8"
#pragma rtGlobals=3
#pragma version=1.70
 
constant kJitter = 3 // pixels
 
menu "Macros"
    "Drag and Drop Demo"
end
 
function DragAndDropDemo()
    KillWindow/Z demo
    Make/O/T LB1ListWave = {"cat","dog","rabbit","horse","pig","cow"}
    Make/O/T LB2ListWave = {"blue","green","red","yellow","orange","pink"}
    redimension/N=(-1,1) LB2ListWave
    SetDimLabel 1, 0, Title, LB2ListWave
    Make/O/N=6 LB1SelWave = 0, LB2SelWave = 0
    NewPanel/K=1/N=demo/W=(100,100,400,350) as "drag & drop demo"
    ListBox LB1, win=demo, pos={10, 40}, size={130, 200}, listwave=LB1ListWave
    ListBox LB1, win=demo, selwave=LB1SelWave, mode=9, focusring=0
    ListBox LB1, win=demo, fsize=16, Proc=ListBoxProc
    ListBox LB2, win=demo, pos={160, 40}, size={130, 200}, listwave=LB2ListWave
    ListBox LB2, win=demo, selwave=LB2SelWave, mode=9, focusring=0
    ListBox LB2, win=demo, fsize=9, Proc=ListBoxProc
    PopupMenu DragPop, win=demo, pos={10, 10}, value="Drag Between Boxes;Drag to Reorder;", Proc=PopupDragType
end
 
function PopupDragType(STRUCT WMPopupAction &s)
    // mode 1 for reordering, mode 9 for drag between boxes
    ListBox LB1, win=$s.win, selRow=-1, mode=(s.popNum==1) ? 9 : 1
    ListBox LB2, win=$s.win, selRow=-1, mode=(s.popNum==1) ? 9 : 1
end
 
function ListBoxProc(STRUCT WMListboxAction &lba)
    ControlInfo/W=$lba.win DragPop
    if (V_Value == 1)
        DragAndDrop(lba)
    else
        DragReorder(lba)
    endif
end
 
function DragAndDrop(STRUCT WMListboxAction &lba)
 
    if (!(lba.eventCode & 3)) // neither mouseup nor mousedown
        return 0
    endif
 
    variable f = 72/PanelResolution(lba.win) // point/pixel
    int dragStarted = strlen(GetUserData(lba.win, lba.ctrlName, "drag"))
    string otherListBox = SelectString(cmpstr(lba.ctrlName, "LB1")==0, "LB1", "LB2")
 
    if (lba.eventCode==2 && dragStarted) // mouseup, drag completed
        // find whether mouse is within OTHER listbox
        if (isInControl(lba.mouseLoc, lba.win, otherListBox))
            ControlInfo/W=$lba.win $otherListBox
            variable beforeItem = round(V_startRow + (lba.mouseLoc.v-V_top/f)/V_rowHeight)
            wave/SDFR=$S_DataFolder otherListBoxWave=$S_Value
            beforeItem = limit(beforeItem, 0, numpnts(otherListBoxWave))
            MoveSelection(otherListBox, lba.selwave, lba.listwave, beforeItem)
        endif
        ListBox $lba.ctrlName, win=$lba.win, userdata(drag)=""
    endif
 
    if (lba.eventCode==1 && dragStarted==0) // mousedown, new drag
        if ( lba.row < 0 || lba.row >= (DimSize(lba.listWave, 0)) )
            return 0
        endif
 
        // prevent a single click on an already selected item from deselecting items
        // unless it's a command-click or shift-click
        // resetting lba.selwave in the selection event doesn't have the desired effect.
        wave/Z sel = $lba.ctrlName
        if (lba.eventmod<2 && waveexists(sel) && (numpnts(sel)==numpnts(lba.selwave)) && (sel[lba.row] & 9))
            duplicate/O sel lba.selwave
        else
            duplicate/O lba.selwave $lba.ctrlName
        endif
 
        // don't start drag until the mouse has moved sufficiently far
        variable dx, dy, buttondown
        do
            GetMouse/W=$lba.win
            buttondown = V_flag & 1
            dx = v_left - lba.mouseLoc.h // pixels
            dy = v_top - lba.mouseLoc.v // pixels
        while (buttondown && sqrt(dx^2+dy^2)<kJitter)
        if (!buttondown)
            return 0
        endif
 
        variable i, titlerow, startrow, endrow, numBoxes, mode, fontSize
 
        // figure out visible rows
        titlerow = (waveexists(lba.titlewave) || strlen(getdimlabel(lba.listwave, 1, 0))>0)
        ControlInfo/W=$lba.win $lba.ctrlName
        startrow = V_startRow
        endrow = min(numpnts(lba.selwave)-1, startrow + ceil((V_height/f/V_rowHeight)-1.1-titlerow))
        // record current value of mode & fsize
        string strMode, strFsize
        SplitString/E=("mode=\s?([[:digit:]]+)") S_recreation, strMode
        mode = strlen(strMode) ? str2num(strMode) : 1
        SplitString/E=("fSize=\s?([[:digit:]]+)") S_recreation, strFsize
        fontSize = strlen(strFsize) ? str2num(strFsize) : 9
        // stops cell selection as mouse moves by setting mode=0
        ListBox $lba.ctrlName, win=$lba.win, userdata(drag)="started", mode=0
        // userdata(drag) indicates dragging is active, cleared on mouseup
 
        // create a titlebox for every visible selected item
        numBoxes = 0
        string DBname, strTitle
        variable height, width, top , left
        for (i=startrow;i<=endrow;i++)
            if (lba.selwave[i] & 0x09)
                wave/T listwave=lba.listWave
                DBname = "DragBox" + num2str(numBoxes)
                height = f * (V_rowHeight - 1)
                width  = f * (lba.ctrlRect.right - lba.ctrlRect.left)
                top    = f * (lba.ctrlRect.top + (i - startrow + titlerow)*V_rowHeight + 1.5)
                left   = f * lba.ctrlRect.left
                sprintf strTitle, "\\sa%+03d\\x%+03d %s", 3-(fontSize>12), (20-fontSize)*0.625, listwave[i]
                TitleBox $DBname, win=$lba.win, title=strTitle, labelBack=(41760,52715,65482), pos={left, top}
                TitleBox $DBname, win=$lba.win, fsize=fontSize, fixedSize=1, frame=0, size={width, height}
                numBoxes ++
            endif
        endfor
 
        // save coordinates of other listbox
        ControlInfo/W=$lba.win $otherListBox
        struct rect pixelRect
        pixelRect.left   = v_left/f // point -> pixel
        pixelRect.right  = v_right/f
        pixelRect.top    = v_top/f
        pixelRect.bottom = pixelRect.top + v_height/f
 
        // monitor mouse movement until mouseup
        do
            GetMouse/W=$lba.win
            buttondown = V_flag & 1
            dx = v_left - lba.mouseLoc.h // pixels
            dy = v_top - lba.mouseLoc.v // pixels
            // keep current mouse position updated as mouse moves
            lba.mouseLoc.h = v_left
            lba.mouseLoc.v = v_top
 
            // move titleboxes with mouse
            for (i=0; i<numBoxes; i++)
                TitleBox/Z $"DragBox"+num2str(i), win=$lba.win, pos+={dx,dy}
            endfor
 
            // draw focus ring when mouse is over other listbox
            if (PointInRect(lba.mouseLoc, pixelRect)) // all units are pixels
                ListBox $otherListBox, win=$lba.win, focusRing=1
                ModifyControl $otherListBox activate
            else
                ModifyControl $lba.ctrlName activate
            endif
 
            DoUpdate/W=$lba.win
        while (buttondown) // this is blocking code :(
 
        // clear titleboxes and return listboxes to normal mode
        for (i=0; i<numBoxes; i++)
            KillControl/W=$lba.win $"DragBox"+num2str(i)
        endfor
        ListBox $otherListBox, win=$lba.win, focusRing=0
        ListBox $lba.ctrlName, win=$lba.win, mode=mode
        ModifyControl $lba.ctrlName activate
    endif // end of drag
    return 0
end
 
// point and rect structures must have same units
function PointInRect(STRUCT point &pnt, STRUCT rect &r)
    return (pnt.h>r.left && pnt.h<r.right && pnt.v>r.top && pnt.v<r.bottom)
end
 
function isInControl(STRUCT point &mouse, string strWin, string strCtrl)
    ControlInfo/W=$strWin $strCtrl
    variable f = 72/PanelResolution(strWin)
    variable hpoint = mouse.h * f
    variable vpoint = mouse.v * f
    return ( hpoint>V_left && hpoint<(V_right) && vpoint>V_top && vpoint<(V_top+V_height) )
end
 
function MoveSelection(string toLB, wave selwave, wave/T listwave, variable beforeItem)
    Extract/free/T listwave, switchwave, (selwave & 0x09)
    Extract/O/T listwave, listwave, !(selwave & 0x09)
    Extract/O selwave, selwave, !(selwave & 0x09)
    wave destSelWave = $toLB + "SelWave"
    wave/T destListWave = $toLB + "ListWave"
    destSelWave = 0
    variable numItems = numpnts(switchwave)
    InsertPoints beforeItem, numItems, destSelWave, destListWave
    destSelWave[beforeItem, beforeItem+numItems-1] = 1
    destListWave[beforeItem, beforeItem+numItems-1] = switchwave[p-beforeItem]
 
    // save new selection for modified selection behaviour
    Duplicate/O destSelWave $toLB
end
 
function DragReorder(STRUCT WMListboxAction &lba)
 
    if (lba.eventCode == 2) // mouseup
        ListBox $lba.ctrlName, win=$lba.win, userdata(drag)=""
    endif
 
    if (lba.eventCode == 1) // mousedown
        ListBox $lba.ctrlName, win=$lba.win, userdata(drag)=num2str(lba.row)
        //userdata(drag) indicates dragging is active, cleared on mouseup
    endif
 
    if (lba.eventCode == 4) // selection of lba.row
        variable dragNum = str2num(GetUserData(lba.win,lba.ctrlName,"drag"))
        if(numtype(dragNum)!=0 || min(dragNum,lba.row)<0 || max(dragNum,lba.row)>=numpnts(lba.listwave))
            return 0
        endif
        Duplicate/free lba.selwave order
        order = (p == dragNum) ? lba.row - 0.5 + (lba.row > dragNum) : x
        Sort order, lba.listwave
        ListBox $lba.ctrlName, win=$lba.win, userdata(drag)=num2str(lba.row)
    endif
end