| id | title | brief | sdk | |||||
|---|---|---|---|---|---|---|---|---|
4538054F-6C77-40CC-9DBB-7285053E4029 |
Zoom a Collection View |
This recipe shows how to use a gesture recognizer to allow the user to zoom in a Collection View. |
|
To allow a user to zoom in a Collection View, you first need to add a gesture recognizer to your View:
public override void ViewDidLoad ()
{
base.ViewDidLoad ();
UIPinchGestureRecognizer pinch = new UIPinchGestureRecognizer (handlePinchGesture);
this.CollectionView.AddGestureRecognizer (pinch);
}
Then add a handler method to respond to the gesture:
public void handlePinchGesture (UIPinchGestureRecognizer gesture)
{
if (gesture.State == UIGestureRecognizerState.Began)
{
scaleStart = this.scale;
}
else if (gesture.State == UIGestureRecognizerState.Changed)
{
this.scale = scaleStart * gesture.Scale;
this.CollectionView.CollectionViewLayout.InvalidateLayout ();
}
}
Finally, in the Collection View's delegate, you will need to override the GetSizeForItem() method to apply the zoom's scale factor to the size of each item:
public override System.Drawing.CGSize GetSizeForItem (UICollectionView collectionView, UICollectionViewLayout layout, NSIndexPath indexPath)
{
return new System.Drawing.CGSize (50 * parent.scale, 50 * parent.scale);
}