[英]Pan Gesture Recognizer reset
我在按鈕上添加了平移手勢,當我在不添加任何其他代碼的情況下移動它時,一切都很好,但是當我添加一些代碼時(在下面的示例中進行了注釋),按鈕開始重置為其原點位置。
為什么會這樣呢? 這是什么原因?
- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer {
switch([recognizer state]){
case UIGestureRecognizerStateBegan: {
UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button setFrame:recognizer.view.frame];
[button setBackgroundColor: [UIColor redColor]];
// [self.view insertSubview:button belowSubview:recognizer.view];
_tempButton = button;
}break;
case UIGestureRecognizerStateChanged: {
CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}break;
}
}
您在UIGestureRecognizerStateChanged情況下添加的代碼,將其移至Action方法的標題中:
CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
之后,您要做的另一件事是在Switch方法中創建另一個Case:
//This checks if you ended the pan gesture (removed finger from object)
case UIGestureRecognizerStateEnded:
{
CGPoint velocity = [recognizer velocityInView:self.view];
CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
CGFloat slideMult = magnitude / 200;
NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);
float slideFactor = 0.1 * slideMult; // Increase for more of a slide
CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor),
recognizer.view.center.y + (velocity.y * slideFactor));
finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);
finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);
[UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
recognizer.view.center = finalPoint;
} completion:nil];
}
因此,我在UIGestureRecognizerStateEnded狀態下所做的就是,我到達了用戶發送圖像的最后一個點。 在那之后,我將圖像的中心設置為等於圖像是最后一刻的點。 因此,現在圖像將不會返回到上一個點,但它將保留在用戶將要拍攝的位置。
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