Re: Question concerning mouseDragged events.
Re: Question concerning mouseDragged events.
- Subject: Re: Question concerning mouseDragged events.
- From: Graham Cox <email@hidden>
- Date: Wed, 28 May 2008 13:46:33 +1000
On 28 May 2008, at 1:38 pm, Graham Reitz wrote:
What is the typical information that people get from a mouse dragged
event?
Generally, the current mouse point and sometimes the modifier flags.
There may be other useful stuff in there but I haven't used much else.
I tried getting the tracking area but ended up with an assertion
error during runtime.
Do folks somehow get the direction of the drag, size of the
rectangle, starting x,y, and etc.?
What rectangle?
If you want to use the mouseDragged: event to drag a rectangle, you
need to record the anchor point on the mouseDown: event. Then the
other corner is given in the mouseDragged: event (you also need to
form the rectangle from these two points in a sensible way, I use this
utility method:
NSRect NSRectFromTwoPoints( const NSPoint a, const NSPoint b)
{
NSRect r;
r.size.width = ABS( b.x - a.x );
r.size.height = ABS( b.y - a.y );
r.origin.x = MIN( a.x, b.x );
r.origin.y = MIN( a.y, b.y );
return r;
}
If the direction of the drag is important, you need to record each
coordinate in an ivar and compare it with the next one received by
subtraction.
Not sure what tracking rect you mean though - the cursor tracking area?
hth,
Graham
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