Mastering PowerBuilder

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Drag-n-Drop Events

Can I drag any PowerBuilder object? No. All descendent objects to the "DragObject" are draggable. Objects that are inherited from "Draw" object, such as line, circle, rectangle, etc, do not have drag-n-drop functionality. All draggable objects have the following events:

DragEnter: This event gets fired in the target object, as soon as dragged object enters the target object boundaries. What you can do in this event? You can write code to check the object type & class that is being dropped and change the icon to stop icon if the dragged object is not allowed to drop.

DragWithIn: As long as the user keeps dragging the dragged object within the target object boundaries, this event keep firing in the target object. The need of writing code in this event is very rare.

DragDrop: When the dragged object is dropped on the target object, this event fires in the target object. As soon as the user drops the object, drag-n-drop cycle ends. Most of the coding in the drag-n-drop functionality, you need to write here. First thing in the code you need to do after checking for the object type & class name is to change the drag icon to normal mouse pointer, so that user knows drop part is done from his side. If you are doing any heavy duty processing in this event, change the mouse pointer to "HourGlass" and set it to normal when the processing is done.

DragLeave: If the user drags the dragged object out of the target object boundaries without dropping, this event fires in the target object. Typical coding in this event is, changing the icon to the one which it was while entering into target object boundaries.

BeginDrag, BeginRightDrag: These two events are available only for ListView and TreeView objects. These events occur when the user presses the mouse button and drags. All the above mentioned drag related events are fired only when the dragging is enabled (we will explain about enabling drag functionality in a moment). But, these two events are fired whether or not dragging is enabled.

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	DragEnter: This event gets fired in the target object, as soon as dragged object enters the target object boundaries. What you can do in this event? You can write code to check the object type & class that is being dropped and change the icon to stop icon if the dragged object is not allowed to drop.
	DragWithIn: As long as the user keeps dragging the dragged object within the target object boundaries, this event keep firing in the target object. The need of writing code in this event is very rare.
	DragDrop: When the dragged object is dropped on the target object, this event fires in the target object. As soon as the user drops the object, drag-n-drop cycle ends. Most of the coding in the drag-n-drop functionality, you need to write here. First thing in the code you need to do after checking for the object type & class name is to change the drag icon to normal mouse pointer, so that user knows drop part is done from his side. If you are doing any heavy duty processing in this event, change the mouse pointer to "HourGlass" and set it to normal when the processing is done.
	DragLeave: If the user drags the dragged object out of the target object boundaries without dropping, this event fires in the target object. Typical coding in this event is, changing the icon to the one which it was while entering into target object boundaries.
	BeginDrag, BeginRightDrag: These two events are available only for ListView and TreeView objects. These events occur when the user presses the mouse button and drags. All the above mentioned drag related events are fired only when the dragging is enabled (we will explain about enabling drag functionality in a moment). But, these two events are fired whether or not dragging is enabled.