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我在我的應用程序中使用UIPinchGestureRecognizer放大視圖(是的,有一個原因,我沒有使用UIScrollView)。當我用手指向外捏時,視圖會按照預期放大,如果我反過來捏而不會將手指從屏幕上移開,它也會放大。但是,如果我通過捏向內啓動縮放,則視圖縮放的速度將顯着變慢。我猜這是因爲UIPinchGestureRecognizer的工作原理 - 當向外捏時UIPinchGestureRecognizer的大小大於1,向內捏時大小爲1。不幸的是,我不知道如何在我的代碼中準確反映這一點。UIPinchGestureRecognizer向內捏「較慢」
- (IBAction)didDetectPinchGesture:(id)sender {
UIPinchGestureRecognizer *gestureRecognizer = (UIPinchGestureRecognizer *)sender;
CGFloat scale = [gestureRecognizer scale];
switch ([gestureRecognizer state]) {
case UIGestureRecognizerStateBegan:
_lastScale = [gestureRecognizer scale];
break;
case UIGestureRecognizerStateChanged:
CGFloat currentScale = [[self.imageView.layer valueForKeyPath:@"transform.scale"] floatValue];
// Constants to adjust the max/min values of zoom
const CGFloat kMaxScale = 5.0;
const CGFloat kMinScale = 1.0;
CGFloat newScale = 1 - (_lastScale - scale); // new scale is in the range (0-1)
newScale = MIN(newScale, kMaxScale/currentScale);
newScale = MAX(newScale, kMinScale/currentScale);
NSLog(@"%f", newScale);
CGAffineTransform transform = CGAffineTransformScale([self.imageView transform], newScale, newScale);
self.imageView.transform = transform;
_lastScale = scale; // Store the previous scale factor for the next pinch gesture call
break;
default:
_lastScale = [gestureRecognizer scale];
break;
}
}
我有同樣的問題。你有沒有想過這個? –
實際上有更簡單的方法來做到這一點。根據比例變化設置變換,然後在完成'gestureRecognizer.scale = 1.f;';)後重置手勢的比例*爲1 – borrrden
我不知道發生了什麼,該值不是隻讀的。我完全按照我描述的方式進行,文檔也說它不是隻讀的。你確定你沒有寫出類似'[gestureRecognizer scale] = 1.f'的東西嗎?這更像是信息的聲音。 @JohnRiselvato – borrrden