Drag inside a DataGrid

[lohill]

I would like to be able to drag down a column in a DataGrid and get the sum of the values for those cells through which I've passed. As a starting point I am just trying to identify the start line and the end line of a 'columnar drag'. The following on DragStart handler will get the start line just fine:

Code: Select all

on dragStart
   put the dgDataControl of the target into theDataControl
   if theDataControl is empty then pass dragStart
   put the dgLine of the dgDataControl of the target into theLine
   --answer theLIne
end dragStart

My difficulty comes in trying to get the last line of the drag. The following is one of a few attempts I have made but it doesn't seem to do the job:

Code: Select all

on mouseRelease
  put the dgDataControl of the target into theDataControl
   if theDataControl is empty then pass mouseRelease
   get the dgDragDrop of theDataControl  
   put it into theDropLine
   answer theDropLine
end mouseRelease

I would greatly appreciate any suggestion for getting this second half to work. I think that once I cross that hurdle I will be able to do the rest. References to further documentation also appreciated.

Thanks,
Larry

[trevordevore]

When you say it doesn't seem to do the job what do you mean? Where does the code fail? Does mouseRelease get called? Is theDropLine always empty?

[lohill]

Trevor,

When you say it doesn't seem to do the job what do you mean? Where does the code fail? Does mouseRelease get called? Is theDropLine always empty?

MouseRelease does get called but both 'it' and theDropLine were empty as far as I could tell. Either that or I don't know how to look at their contents. Is the dgDragDrop some kind of structure or array that I don't know how to access? I can see in the library something about the "dropped after index" but I'm not sure how to get to it.

Larry

[trevordevore]

dgDragDrop is a message that is sent, not a property of any control. Have you tried getting the dgLine of theDataControl?

[lohill]

Trevor,

My original approach was to get the dgLine from the dragStart and put it and the dgColumn in a global variable. Then in the mouseRelease event I got the dgLine again but it was always the same number as the one from the dragStart. Then I moved on to the code I first showed in this message. Should I go Back and look at that original approach again?

Larry

[lohill]

The following code for dragStart and mouseRelease in my Default Column button answers with the line I start the drag on, not the one I finish the drag on.
Larry

Code: Select all

on dragStart
   put the dgDataControl of the target into theDataControl
   if theDataControl is empty then pass dragStart
   put the dgLine of the dgDataControl of the target into theLine
   --answer theLIne
end dragStart

on mouseRelease pMouseBtnNum
   put the dgDataControl of the target into theDataControl
   if theDataControl is empty then pass mouseRelease
   put the dgLine of the dgDataControl of the target into theLine
   answer theLine
   pass mouseRelease
end mouseRelease

Larry

[trevordevore]

The mouseRelease message is sent to the control you initially clicked on. What if you check the mouseControl rather than the target?

[lohill]

Trevor,
Here is my latest attempt. It is getting pretty convoluted but still doesn't give me what I want. If I start the drag on line 3 and release the mouse on line 8, the answer I get is field "Value 0003" rather than 0008

Code: Select all

on dragStart
   put the dgDataControl of the target into theDataControl
   if theDataControl is empty then pass dragStart
   put the dgLine of the dgDataControl of the target into theLine
   --answer theLIne
end dragStart

on mouseRelease pMouseBtnNum
   put the mouseControl  into theControl
   send mouseup to the target
   pass mouseRelease
end mouseRelease

on mouseUp
   put the mouseControl  into theControl
   answer the name  theControl
   pass mouseUp
end mouseUp

Any more ideas?
Thanks,
Larry

[trevordevore]

I just fiddled with this a bit and you need to use the drag messages to get it to work. The following code will print out the line you star on and the line you end on.

Code: Select all

local sDataA

on dragStart   
   put the dgDataControl of the target into theDataControl
   if theDataControl is empty then pass dragStart
   
   put the dgLine of theDataControl into sDataA["start line"]
   set the dragData["private"] to "tracking"
end dragStart


on dragEnter
   ## make sure all controls in data grid accep drop
   set the dragAction to "move"
   pass dragEnter
end dragEnter


on dragDrop
   put the dragDestination into theControlDroppedOn
   if theControlDroppedOn is not empty then
      put the dgDataControl of theControlDroppedOn into theControlDroppedOn
      if theControlDroppedOn is not empty then
      put the dgLine of theControlDroppedOn into sDataA["end line"]
      put printkeys(sDataA)
      end if
   end if
end dragDrop


function printkeys pArray
   local theData
   
   repeat for each key theKey in pArray
      put theKey & ":" && pArray[theKey] & cr after theData
   end repeat
   return theData
end printkeys

[lohill]

Thanks Trevor. That certainly does work. All I have to do now is figure out how and why.

Larry

[lohill]

Trevor,
I have a dumb question for you. At one point you put the dgLine of theDataControl into sDataA["start line"] and then later you put the dgLine of theControlDroppedOn into sDataA["end line"]. Why then, if you put a break point just before the printkeys, do you not see both the starting value and the ending value in sDataA? Am I not looking at it correctly?

Thanks for your help, even if I am a bit dense.

Larry

[trevordevore]

Not sure. I never try to use the debugger during drag/drop operations as I've run into problems with everything locking up in the past. I just print out the data in the message box.