; ------------------------------------------------------------------ ; ; Drag & Drop example with ListIconGadget ; By Timo 'fr34k' Harter ; ; ------------------------------------------------------------------ ; ; Hi, this is a rather basic example of how to do drag & drop with ; a ListIconGadget in PureBasic. It should give you a good start, of ; how to do such a thing in your own projects. This uses 2 Gadgets ; for the demonstration. It should not be hard to modify it to use ; more than that, or even to work with only one Gadget. ; ; Feel free, to copy & paste any of this code into your own, i don't ; care. ; ; ------------------------------------------------------------------ ; Ok, let's start with what we need global, so it is always accessible ; from the callback procedure. 'IsDraging' is used to see, if a drag&drop ; operation is in progress, 'DragImageList' is used to store the displayed ; drag&drop image. The rest should be pretty clear. Global IsDraging, DragImageList, SourceGadget, SourceItem, TargetGadget, TargetItem Declare WindowCallback(Window, Message, wParam, lParam) ; Here, the GUI is created, nothing fancy about this one... #ListIcon1 = 1 #ListIcon2 = 2 If OpenWindow(0, 0, 0, 600, 300, #PB_Window_Screencentered|#PB_Window_SystemMenu, "ListIcon Drag&Drop") If CreateGadgetList(WindowID()) ; callback is needed for the processing of the drag&drop messages SetWindowCallback(@WindowCallback()) ListIconGadget(#ListIcon1, 5, 5, 290, 290, "Testing...", 250) ListIconGadget(#ListIcon2, 305, 5, 290, 290, "Testing...", 250) For i = 0 To 10 AddGadgetItem(#ListIcon1, -1, "Gadget1 - Item"+Str(i)) AddGadgetItem(#ListIcon2, -1, "Gadget2 - Item"+Str(i)) Next i ; all drag&drop handling is done in the callback procedure, ; so nothing is needed here. Repeat Until WaitWindowEvent() = #PB_EventCloseWindow EndIf EndIf End ; If you are not familiar with the use of a WindowCallback procedure, ; you should read my basic explanation here: ; http://purebasic.myforums.net/viewtopic.php?p=39654#39654 Procedure WindowCallback(Window, Message, wParam, lParam) Result = #PB_ProcessPureBasicEvents ; The first message we need is #LVN_BEGINDRAG. This is a so called ; Notification message. This means, that you don't get a message called ; #LVN_BEGINDRAG, but you get a #WM_NOTIFY message, with further information, ; that tells you, that it is #LVN_BEGINDRAG. If Message = #WM_NOTIFY ; The lparam paramenter contains a pointer to a NMHDR structure. There is ; the information about the Message *nmhdr.NMHDR = lParam ; The 'hwndfrom' member tells you, which Gadget actually sent the message ; This must be always checked to be sure, it is the right gadget. ; We allow only our 2 Gadgets: If *nmhdr\hwndfrom = GadgetID(#ListIcon1) Or *nmhdr\hwndfrom = GadgetID(#ListIcon2) ; The 'code' member contains the real message, in our case #LVN_BEGINDRAG If *nmhdr\code = #LVN_BEGINDRAG ; Let's find out, which of our Gadgets is the source, we will need this later. ; If you have more than 2 Gadgets with drag&drop, you have to add more checks ; here: If *nmhdr\hwndfrom = GadgetID(#ListIcon1) SourceGadget = #ListIcon1 Else ; must be #ListIcon2, as we have allready checked, that it is only one of the 2 SourceGadget = #ListIcon2 EndIf ; Ok, for the #LVN_BEGINDRAG notification message, lParam is a pointer to a ; NMLISTVIEW Structure. You might think that this can't be, as lParam allready ; pointed to a NMHDR structure, but this is correct, as NMLISTVIEW has a ; NMHDR structure inside, it only adds more members to it. *nmv.NMLISTVIEW = lParam ; The 'iItem' member contains the index of the source item, which we will need ; later. SourceItem = *nmv\iItem ; By sending a #LVM_CREATEDRAGIMAGE message to the gadget, we create an ImageList ; that contains just one image, the drag&drop image. We will need the Imagelist WinAPI ; commands to work with that one later. This message also expects a POINT structure ; as parameter that contains the hot-spot in the image. As we set this to (0|0), we ; don't even need to initialize this variable. DragImageList = SendMessage_(GadgetID(SourceGadget), #LVM_CREATEDRAGIMAGE, SourceItem, @UpperLeft.POINT) ; It is important to check the result, as it would lock the mouse, if ; we continue without this one working. If DragImageList ; This begins the drag&drop operation by displaying the image If ImageList_BeginDrag_(DragImageList , 0, 0, 0) ; this command shows or hides the drag&drop image. Or course, ; we want to see it now :) ImageList_DragShowNolock_(#TRUE) ; this causes windows to send all mouse messages to our window, ; even if the mouse is outside of our window. This is neccesary, ; because we need to detect the mouseup event to abort the ; operation, even if the mouse is outside our window. SetCapture_(GetParent_(GadgetID(SourceGadget))) ; hide the standart cursor ShowCursor_(#FALSE) ; When processing the other events, we need to know whether something ; is being draged or not. IsDraging = #TRUE EndIf ; check for ImageList_BeginDrag_() EndIf ; check for DragImageList EndIf ; check for #LVN_BEGINDRAG EndIf ; check for right gadget ; The next message we need is #WM_MOUSEMOVE, to update the mouse. ; But only if IsDraging is #TRUE. ElseIf Message = #WM_MOUSEMOVE And IsDraging ; this moves the drag Image. It requires Screen coordinates. ImageList_DragMove_(WindowMouseX()+WindowX(), WindowMouseY()+WindowY()) ; now we hide the image to avoid redraw problems. ImageList_DragShowNolock_(#FALSE) ; the next thing we do is hilighting the target item in the target gadget. ; for this, we need mouse coordinates relative to the client area of our ; window. WindowMouseX() and WindowMouseY() include the window borders, so ; we can't use them. When #EM_MOUSEMOVE is sent, the lParam parameter contains ; the x coordinate in the low-word and the y coordinate in the high-word, so we ; just use them here: MouseX = lParam & $FFFF MouseY = lParam >> 16 ; first, we unhilight the previous target, if there was one: If TargetGadget <> -1 ; We send a #LNM_SETITEM message for that, but we only need to change the ; item state, so #LVIF_STATE is enough for the mask. pitem.LV_ITEM pitem\mask = #LVIF_STATE pitem\iItem = TargetItem ; 'stateMask' determines, what will be changed, and 'state' sets the actual value, ; so here, we set the #LVIS_DROPHILITED state flag to 0. pitem\state = 0 pitem\stateMask = #LVIS_DROPHILITED SendMessage_(GadgetID(TargetGAdget), #LVM_SETITEM, 0, @pitem) ; a redraw is neccesary here to avoid problems. RedrawWindow_(GadgetID(TargetGadget), 0, 0, #RDW_UPDATENOW) EndIf ; now we need to find out, which Gadget is currently the target one. ; with ChildWindowFromPoint_() we can get it's handle. TargetGadgetID = ChildWindowFromPoint_(Window, MouseX, MouseY) ; find out the PB numeric ID for the Gadget ; again, for more Gadgets, more checks are needed. If TargetGadgetID = GadgetID(#ListIcon1) TargetGadget = #ListIcon1 ElseIf TargetGadgetID = GadgetID(#ListIcon2) TargetGadget = #ListIcon2 Else TargetGadget = -1 EndIf If TargetGadget <> -1 ; What we need next is the Item, that is currently under the mouse cursor. ; the #LVM_HITTEST message does that test for us. ; here, we need coordinates relative to the top/left corner of our target ; Gadget, so we substract the Gadget position from our window coordinates. hittestinfo.LV_HITTESTINFO hittestinfo\pt\x = MouseX - GadgetX(TargetGadget) hittestinfo\pt\y = MouseY - GadgetY(TargetGadget) ; find the item, if none is under the cursor, we get -1, and the next ; SendMessage won't work, and nothing is hilighted. TargetItem = SendMessage_(GadgetID(TargetGadget), #LVM_HITTEST, 0, @hittestinfo) ; same as before, this time we set the #LVIS_DROPHILITED flag to #LVIS_DROPHILITED. pitem.LV_ITEM pitem\mask = #LVIF_STATE pitem\iItem = TargetItem pitem\state = #LVIS_DROPHILITED pitem\stateMask = #LVIS_DROPHILITED SendMessage_(GadgetID(TargetGadget), #LVM_SETITEM, 0, @pitem) RedrawWindow_(GadgetID(TargetGadget), 0, 0, #RDW_UPDATENOW) ; again a redraw EndIf ; now we can show the drag image again: ImageList_DragShowNolock_(#TRUE) ; that's all to do while moving the mouse. Of course, there can be more checks added, ; and for example, a different cursor displayed, if you don't want the source to ; be draged to the current target and so on, but i think this is enough for a basic ; example. ; next is the end of the drag&drop operation... when the user releases the mouse. ElseIf Message = #WM_LBUTTONUP And IsDraging ; first, we release all we did, to unlock the mouse. ; mouse messages will be sent to other windows again ReleaseCapture_() ; and drag&drop (remove the image) ImageList_EndDrag_() ; free the image list ImageList_Destroy_(DragImageList) ; show cursor again ShowCursor_(#TRUE) ; no draging in progress now. IsDraging = #FALSE ; next, we unhilight the last target item, just like before: If TargetGadget <> -1 pitem.LV_ITEM pitem\mask = #LVIF_STATE pitem\iItem = TargetItem pitem\state = 0 pitem\stateMask = #LVIS_DROPHILITED SendMessage_(GadgetID(TargetGAdget), #LVM_SETITEM, 0, @pitem) RedrawWindow_(GadgetID(TargetGadget), 0, 0, #RDW_UPDATENOW) EndIf ; there is no need to check, which is the target, because this was allready ; done on the last mouse move. ; just check, if the mouse is over one of our target gadgets: If TargetGadget <> -1 ; at this point, every thing is complete, and we know, that the ; drag&drop was successfull, from one gadget to another. ; We can now take the action on this operation. ; Note: TargetItem might be -1, if the item was draged into the ; empty area of the target gadget. The TargetItem doesn't have to ; be a valid item. ; for the example, we just remove the source, and add the target. ItemText$ = GetGadgetItemText(SourceGadget, SourceItem, 0) RemoveGadgetItem(SourceGadget, SourceItem) AddGadgetItem(TargetGadget, TargetItem, ItemText$) EndIf ; check TargetGadget EndIf ; check Message ProcedureReturn Result EndProcedure ; ------------------------------------------------------------------ ; ; That's all for this example. If you have more questions, feel free ; to post them at http://purebasic.myforums.net/, or send me a mail ; at freak@betriebsdirektor.de ; ; ------------------------------------------------------------------