USAGE
void DragGadget(Window, DragInfo)
FUNCTION
This lets you take a normal Intuition BOOLGADGET style Gadget and drag it to
a new location. The Gadget must be rendered with Intuition Image structure,
because it is the Image that will be dragged.
There are several options to dragging the Gadget:
* You can specify a bounding box to move within. Bounding boxes may overlap
since the hit box is only the Gadget itself.
* You can specify that Gadget only be displayed in one window, or that it
can move across windows. This allows the user to select an item in one
window and move it to another. Ofcourse, the Gadget is not suddenly
transferred to the other window's Gadget list, nor is the other window
notified, but the illusion has been created, so now software can back it
up. An example of Gadgets that move from window to window would be the
disk and file icons that Workbench uses.
* You can specify wether the Gadget has a transparent or solid backround.
If transparent, all pen 0 parts of the image are transparent.
* you can specify wether you want the Gadget to move to the new location
once the user lets up the mouse, or that it bounce back to its original
locaiton.
Before calling DragGadget the first time, you must initialise a DragInfo
structure .
The fields that need to be set in the DragInfo structure are:
Gadget This is a pointer to the Gadget you wish to drag:
LeftEdge This is the left edge of the bounding box that describes the
region this Gadget can move within.
TopEdge This is the top edge of the bounding box that describes the
region this Gadget can move within.
RightEdge This is the right edge of the bounding box that describes the
region this Gadget can move within.
BottomEdge This is the bottom edge of the bounding box that describes the
region this Gadget can move within.
Flags There are several flags you can set to influence the behavior of
the Drag Gadget.
DRAG_INWINDOW indicates you wish to have the Gadget displayed
only within the rastport of your window.
DRAG_OUTLINE indicates you'd the pen 0 color in the Gadget
Image to be transparent.
DRAG_MOVEGADGET indicates that you'd like the Gadget to stay
where the user moves it. Be careful. If the
bounding box is outside the window, the user can
move the Gadget out of the window, too.
And then it's somewhat hard to get back.
XPos, YPos These coordinates indicate where the Gadget is now in the window.
You need not set these, but you may need to read them at some
point.
UpdateRoutine You can supply a function that is called every time the Gadget
moves. This function is passed two parameters: The window and the
DragInfo structure (which, in turn, points to the Gadget). If you
don't need to supply a routine, set this to NULL. Such a routine
is particulary useful if you need to provide some sort of real
time update while the Gadget moves.
INPUTS
Window = Pointer to the window this Gadget belongs to.
DragInfo = Initialised DragInfo structure.
RESULT
none (void)