AYUDA EN LÍNEA
 WINDEV, WEBDEV Y WINDEV MOBILE
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Ayuda / WLanguage / Funciones WLanguage / Controles, páginas y ventanas / Funciones de arrastrar y soltar
  • Overview
  • Example of Drag and Drop between a List Box and Button control
  • Example of Drag and Drop between a TreeView control and a TreeView Table control
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Otros
Procedimientos almacenados
Overview
This help page presents two examples of programmed Drag and Drop performed in a WINDEV application:
Example of Drag and Drop between a List Box and Button control
The following code is used to delete the data found in a List Box control by Drag and Drop to a graphic button containing a recycle bin. Only the move (cut/paste) is allowed. The move cursor is displayed during the move (cut/paste) between the List Box control and the "Bin" button.
  1. Source definition: the List Box control
    //- - Initialize the List Box control
LIST_List.DndSource = dndProgram
  2. Target definition: the BTN_Poubelle button. In the button initialization code, the Drag and Drop management procedures are also called using DnDEvent.
    In this example:
    • the dndDragOver event is used to change the mouse cursor ("Rollover" procedure).
    • the dndDrop event is used to program the process for managing the drop. In our case, this process corresponds to the deletion of element from the List Box control ("OnDrop" procedure).
    //- - Initializing the BTN_Bin button
BTN_Bin.DndTarget = dndProgram

// Call the OnDrop procedure when the left mouse button 
// is released on the BTN_Bin button
DnDEvent("OnDrop", BTN_Bin, dndDrop)

// Call the OnDragOver procedure when the mouse cursor 
// moves between the source list and the BTN_Bin button
DnDEvent("OnDragOver", BTN_Bin, dndDragOver)
  3. Defining the procedures: 
    PROCEDURE OnDragOver()
// Cursor indicating the move
DnDCursor(dndMove)

    PROCEDURE OnDrop()
// Only the move is allowed (not the copy)
DnDAccept(dndMove)
// Delete the element from the source control
ListDelete(_DND.SourceControl)
Example of Drag and Drop between a TreeView control and a TreeView Table control
The window contains:
  • a TreeView control populated programmatically.
  • a TreeView Table control populated programmatically.
The following example is used to move a Treeview control element (or a branch and its children) into a TreeView Table control. The two methods of programmed Drag and Drop are presented.
Method 1: Full program mode
  1. Definition of the source field: the TreeView control: 
    // -- Initialization code of TREE_MENU control 
TreeAdd(TREE_MENU, "STARTERS")
TreeAdd(TREE_MENU, "STARTERS" + TAB + "Salad")
TreeAdd(TREE_MENU, "STARTERS" + TAB + "Cooked meat")
TreeAdd(TREE_MENU, "STARTERS" + TAB + "Prawn cocktail")
TreeAdd(TREE_MENU, "MAIN COURSES")
TreeAdd(TREE_MENU, "MAIN COURSES" + TAB + "Chicken stew")
TreeAdd(TREE_MENU, "MAIN COURSES" + TAB + "Fish and chips")
TreeAdd(TREE_MENU, "MAIN COURSES" + TAB + "Pasta with salmon")
TreeAdd(TREE_MENU, "MAIN COURSES" + TAB + "Pasta alla carbonara")
TreeAdd(TREE_MENU, "MAIN COURSES" + TAB + "Pork ribs")
TreeAdd(TREE_MENU, "DESSERTS")
TreeAdd(TREE_MENU, "DESSERTS" + TAB + "Caramel custard")
TreeAdd(TREE_MENU, "DESSERTS" + TAB + "Chocolate cream")
TreeAdd(TREE_MENU, "DESSERTS" + TAB + "Tiramisu")
TreeAdd(TREE_MENU, "DESSERTS" + TAB + "Ice cream")
TreeAdd(TREE_MENU, "DESSERTS" + TAB + "Apple pie")

// Enable the programmed Drag and Drop
TREE_MENU.DndSource = dndProgram
  2. Target definition: the TreeView Table control field. In the initialization code of TreeView Table control, the procedures for managing Drag and Drop are also called by DnDEvent.
    In this example:
    • the dndDragOver event is used to change the mouse cursor ("pRollover" procedure).
    • the dndDrop event is used to program the process for managing the drop. In our case, this process corresponds to the copy of the elements found in the Table control into the TreeView Table control ("pDrop" procedure).
      // -- Initializing the TreeView Table control 
TVT_MENU.DndTarget = dndProgram

DnDEvent(pRollover, TVT_MENU, dndDragOver)
DnDEvent(pDrop, TVT_MENU, dndDrop)
  3. Defining the procedures: 
    PROCEDURE pRollover()

// Cursor indicating the move
DnDCursor(dndMove)

    PROCEDURE pDrop()

// Only the move is allowed (not the copy)
DnDAccept(dndMove)

sRoot is string
sLeaf is string
sElement is string
sChild is string

sElement = TreeSelect(TREE_MENU)
sRoot = ExtractString(sElement, 1, TAB, FromBeginning)
sLeaf = ExtractString(sElement, 1, TAB, FromEnd)

IF sLeaf = sRoot THEN
	IF TableSearchChild(COL_TREE, sRoot) = -1 THEN 
		TableAddChild(TVT_MENU, 0, sRoot)
	END

	sChild = TreeGiveChild(TREE_MENU, sRoot, tvFirst)
	WHILE sChild <> ""
		TableAddChild(TVT_MENU, sRoot, sChild)
		sChild = TreeGiveChild(TREE_MENU, sRoot, tvNext)
	END
ELSE
	IF TableSearchChild(COL_TREE, sRoot) = -1 THEN
		TableAddChild(TVT_MENU, 0, sRoot)
	END
	TableAddChild(TVT_MENU, sRoot, sLeaf)
END
Method 2: Simplified program mode
  1. Definition of the source field: the TreeView control field. 
    TreeAdd(TREE_MENU1, "STARTERS")
TreeAdd(TREE_MENU1, "STARTERS" + TAB + "Salad")
TreeAdd(TREE_MENU1, "STARTERS" + TAB + "Cooked meat")
TreeAdd(TREE_MENU1, "STARTERS" + TAB + "Prawn cocktail")
TreeAdd(TREE_MENU1, "MAIN COURSES")
TreeAdd(TREE_MENU1, "MAIN COURSES" + TAB + "Chicken stew")
TreeAdd(TREE_MENU1, "MAIN COURSES" + TAB + "Fish and chips")
TreeAdd(TREE_MENU1, "MAIN COURSES" + TAB + "Pasta with salmon")
TreeAdd(TREE_MENU1, "MAIN COURSES" + TAB + "Pasta alla carbonara")
TreeAdd(TREE_MENU1, "MAIN COURSES" + TAB + "Pork ribs")
TreeAdd(TREE_MENU1, "DESSERTS")
TreeAdd(TREE_MENU1, "DESSERTS" + TAB + "Caramel custard")
TreeAdd(TREE_MENU1, "DESSERTS" + TAB + "Chocolate cream")
TreeAdd(TREE_MENU1, "DESSERTS" + TAB + "Tiramisu")
TreeAdd(TREE_MENU1, "DESSERTS" + TAB + "Ice cream")
TreeAdd(TREE_MENU1, "DESSERTS" + TAB + "Apple pie")
// Enable the programmed Drag and Drop
TREE_MENU1..DndSource = dndProgram
  2. Target definition: Hierarchical table
    // -- Initializing the TreeView Table control
TVT_MENU1.DndTarget = dndProgram
  3. Adding EVENTS specific to Drag and Drop into the code of the target control (code of TreeView Table control).
    • Open the events of the TreeView Table control (select "Code" in the control context menu).
    • Display the optional events window: click on the "Add other events" link at the end of the field events.
    • In our example, the events to add are:
      • Rollover in target Drag/Drop (dndDragOver).
      • Drop in target Drag/Drop (dndDrop).
  4. Enter the code corresponding to the actions to perform:
    • Event for Drop in target Drag/Drop (dndDrop)
      // Only the move is allowed (not the copy)
DnDAccept(dndMove)

sRoot is string
sLeaf is string
sElement is string
sChild is string

sElement = TreeSelect(TREE_MENU1)
sRoot = ExtractString(sElement, 1, TAB, FromBeginning)
sLeaf = ExtractString(sElement, 1, TAB, FromEnd)

IF sLeaf = sRoot THEN
	IF TableSearchChild(COL_TREE1, sRoot) = -1 THEN
		TableAddChild(TVT_MENU1, 0, sRoot)
	END

	sChild = TreeGiveChild(TREE_MENU1, sRoot, tvFirst)
	WHILE sChild <> ""
		TableAddChild(TVT_MENU1, sRoot, sChild)
		sChild = TreeGiveChild(TREE_MENU1, sRoot, tvNext)
	END
ELSE
	IF TableSearchChild(COL_TREE1, sRoot) = -1 THEN
		TableAddChild(TVT_MENU1, 0, sRoot)
	END
	TableAddChild(TVT_MENU1, sRoot, sLeaf)
END
    • Event for Rollover in target Drag/Drop (dndDragOver)
      // Cursor indicating the move 
DnDCursor(dndMove)
Ver también
Versión mínima requerida
  • Versión 17
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Última modificación: 25/03/2025

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