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Added drift-zooming effect after pinch gesture

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Apply a subtle animated zoom after a pinch gesture completes. Lots of magic numbers involved. Avoid drifting when the pinch is near-static, and when the scale factor would go below the minimum. There is more resistance to pinching outward than pinching inward, because it’s far easier to lose your place when you accidentally zoom out. Disabled two-finger pan, which is typically reserved for changing pitch; otherwise, it’s easy to accidentally pan while intending to pinch.
This commit is contained in:
Minh Nguyễn
2015-04-18 19:47:52 -07:00
parent 4c6987b20e
commit 41d28e7203
1 changed files with 49 additions and 5 deletions
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54
platform/ios/MGLMapView.mm
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@@ -327,6 +327,7 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
//
_pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];
_pan.delegate = self;
_pan.maximumNumberOfTouches = 1;
[self addGestureRecognizer:_pan];
_scrollEnabled = YES;
@@ -747,17 +748,60 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
if (log2(newScale) < mbglMap->getMinZoom()) return;
double scale = mbglMap->getScale();
mbglMap->scaleBy(newScale / scale, [pinch locationInView:pinch.view].x, [pinch locationInView:pinch.view].y);
mbglMap->setScale(newScale, [pinch locationInView:pinch.view].x, [pinch locationInView:pinch.view].y);
}
else if (pinch.state == UIGestureRecognizerStateEnded || pinch.state == UIGestureRecognizerStateCancelled)
{
CGFloat velocity = pinch.velocity;
if (velocity > -0.5 && velocity < 3)
{
velocity = 0;
}
CGFloat duration = velocity > 0 ? 1 : 0.25;
CGFloat scale = self.scale * pinch.scale;
CGFloat newScale = scale;
if (velocity >= 0)
{
newScale += scale * velocity * duration * 0.1;
}
else
{
newScale += scale / (velocity * duration) * 0.1;
}
if (newScale <= 0 || log2(newScale) < mbglMap->getMinZoom())
{
velocity = 0;
}
if (velocity)
{
CGPoint pinchCenter = [pinch locationInView:pinch.view];
mbglMap->setScale(newScale, pinchCenter.x, pinchCenter.y, secondsAsDuration(duration));
}
mbglMap->setGestureInProgress(false);
[self unrotateIfNeededAnimated:YES];
if (velocity)
{
self.animatingGesture = YES;
[self notifyMapChange:@(mbgl::MapChangeRegionDidChange)];
__weak MGLMapView *weakSelf = self;
[self animateWithDelay:duration animations:^
{
weakSelf.animatingGesture = NO;
[weakSelf notifyMapChange:@(mbgl::MapChangeRegionDidChangeAnimated)];
}];
}
else
{
[self notifyMapChange:@(mbgl::MapChangeRegionDidChange)];
}
}
}