935
edits
Changes
Jump to navigation
Jump to search
mLine 1:
Line 1: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Link
The event '''on.grabDown''' is used to handle grabbing motions (cursor press & hold).<br /><br />
This routine is called in these situations:
* When the user presses and holds the Select key on a device
* When the user presses Ctrl + Select on a device
* When the user presses the middle mouse button over an active card on the desktop
The passed coordinated, x and y, are always 0 and 0.
The ''grabDown'' and [[on.grabUp|''grabUp'']] events prevent the generation of a [[on.mouseUp|''mouseUp'']] event in all cases.
They will be preceded by a [[on.mouseDown]] event when generated by pressing and holding the Select key on a device.
== Example ==
Below is an example of a program that handles the grabbing motion to move an object :
<source lang="lua">function Ball:move(x,y)
self.x = x
self.y = y
platform.window:invalidate()
end
function on.grabDown(x,y)
isGrabbing = not isGrabbing -- makes the variable switch from true to false and vice versa
platform.window:invalidate()
end
function on.mouseMove(x,y)
if isGrabbing and (trackedBall and trackedBall.isActive) then -- assuming trackedBall is defined etc.
trackedBall:move(x-trackedBall.r/2,y-trackedBall.r/2)
end
end
</source>
You can see the whole lua example about Ball generation and movements here : [[Balls_Example|Balls Example (Class + Events Handling)]]
== See Also ==
[[on.grabUp]]
[[Category:Events]]
[[Category:Events]]
