>>> While we are on the subject, how does one manage to add
>>> drag and drop from desktop application functionality to rev
>>> based application icons and stacks?
>>
>> What are you trying to drag from "outside" into Revolution? Text,
>> images,
>> ... ?
>
> Text and Images would be a start, 3D models would an eventuality.

OK. Here we go:

TEXT

First of all, you should be able to drag raw text from another application to a Rev field automatically with no special setup or intervention whatsoever.

However, if you want to drag text files into a field and have the contents of the text file be put into the field, you can do this:

(script of field)
on dragEnter
  set the acceptDrop to true
  pass dragEnter
end dragEnter

on dragDrop
  put the dragData["files"] into tFileList
  if tFileList <> "" then
    put url("file:" & (line 1 of tFileList)) into me
  else
    beep
  end if
end dragDrop

Now the script above makes a number of assumptions: (1) that if the user were dragging multiple files, that you only care about the first one, and (2) that the file being dropped is actually a text file.

Let's deal with these one at a time:

1. The dragData["files"] contains a return-delimited list of full paths to files that are being dragged into Revolution. You could certainly do a repeat loop through the files to find what you want, or alert the user if there was more than one (the number of lines of the dragData["files"] > 1), etc.
2. This is where Rev kind of breaks down. There's no quick way to determine what the type of file being dropped *is*, although there is a laborious way (which I'll detail below after we talk about images). However you could do something simple, like assume the text file needs to have a .txt extension, and do a "filter" on the dragData["files"] on ".txt", as in:

   put the dragData["files"] into tFiles
   filter tFiles with "*.txt"

IMAGES

Suppose you wanted to drag a graphic from disk into an image object. This is very similar to the text example above.

on dragEnter
  set the acceptDrop to true
  pass dragEnter
end dragEnter

on dragDrop
  put the dragData["files"] into tFileList
  if tFileList <> "" then
    set the fileName of me to (line 1 of tFileList)
  else
    beep
  end if
end dragDrop

This assumes:

1. that you have an image object already created into which you want to drag the image file from disk*
2. that if the user were dragging multiple files, that you only care about the first one, and
3. that the file being dropped is actually an image file.

* You might have an empty image (perhaps through create image) or a pre-existing one. If you set the lockLocation of the image to TRUE, the incoming image would be scaled up/down to fit the rect of the image object. If the lockLocation of the image is FALSE, the image object would be scaled to fit the rect of the incoming image. I would recommend turning on the border and turning off the 3D if you want to have an image "drop region".

Now perhaps you don't want to have a pre-existing image object, but just want to import the image when it is dropped on "the card". You can do it this by having only a single object (it doesn't have to be an image) that is the size of the card and is transparent (like a button) that has this code:

on dragEnter
  set the acceptDrop to true
  pass dragEnter
end dragEnter

on dragDrop
  put the dragData["files"] into tFileList
  if tFileList <> "" then
    create image
    set the fileName of it to (line 1 of tFileList)
  else
    beep
  end if
end dragDrop

Same basic assumptions apply as the earlier code, and of course you might want to size the image object and lock it first, like:

create image
set the rect of it to 200,200,400,400
set the lockLocation of it to true
set the fileName of it to (line 1 of tFileList)

You get the idea.

Now we get to the fun part - the way to determine if the file(s) being dropped are OK for the field/image/etc. Here's an example of how to bring in text files ONLY for a field, which BTW concatenates the text from all files dropped on the field (watch the line wraps):

on dragEnter
  if hasTextFiles(the dragData["files"]) then
    set the acceptDrop to true
    focus me
  end if
end dragEnter

function hasTextFiles pFileList
  -- assumes all files are from the same folder, looks for
  -- any file that is a text file
  -- If found, sets a custom prop to be used during the drop
  -- looks for both file extension and type of file
  put the directory into tOldDir
  set the itemDel to "/"
  put "" into tTextFiles
  repeat for each line tFile in pFileList
    if tTextFiles = "" then
      put tFile into tDir
      delete item -1 of tDir
      if tDir = "" then put "/" into tDir  -- happens at root
      set the directory to tDir
      put the detailed files into tFiles
      replace "," with "/" in tFiles
    end if
    put lineOffset(cr& urlEncode(item -1 of tFile)&"/",cr&tFiles) into tLine
    if tLine <> 0 then  -- which should always be the case
      if the number of items of (line tLine of tFiles) = 10 then
        -- no type/creator
        put "" into tTypeCreator
      else
        put item -1 of line tLine of tFiles into tTypeCreator
      end if
      if (char -4 to -1 of tTypeCreator = "TEXT") or \
        (char -4 to -1 of tFile = ".txt") then put tFile & \
        cr after tTextFiles
    end if
  end repeat
  set the directory to tOldDir
  delete last char of tTextFiles
  set the uTextFiles of me to tTextFiles
  return (tTextFiles <> "")
end hasTextFiles

on dragDrop
  put the uTextFiles of me into tFiles
  repeat for each line tFile in tFiles
   put me & url ("file:" & tFile) & cr into me
  end repeat
end dragDrop

You can extend this model for checking for images, etc.

Hope this helps,

Posted on 9/11/04 by Ken Ray to the Use Revolution list