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我創建了一個可拖動的UIImageView，與iPhone/iPod Touch的「Slide to設備鎖定時解鎖「滑塊。在1軸上拖動UIImageView/UIView而不讓view.center跳轉到觸摸位置（從視圖上的任意位置拖動到在x軸上移動）
我可以通過以下方式使視圖沿着X軸平滑移動：float newCenter = touchPoint.x;
但是這並沒有考慮到觸摸與中心的偏移。它只是將視圖的中心點移動到觸摸點。我試圖通過從UIImageView的x軸上的任何點拖動視圖來移動視圖。
下面，我試着計算TouchesMoved內的newCenter，但它無法順利滑動。
代碼：
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView:self]; // self is a UIView
CGRect sliderRect = sliderView.frame; // sliderView is a UIImageView
if (CGRectContainsPoint(sliderRect, touchPoint)){
float sliderHalfWidth = sliderView.frame.size.width/2;
float leftEdge = sliderView.center.x - sliderHalfWidth;
float distanceToTouchFromEdge = touchPoint.x - leftEdge;
float newCenter = (distanceToTouchFromEdge - sliderHalfWidth) + touchPoint.x; // <--- the math here is probably incorrect. I tried a few other formulas, none of which gave me the results I was looking for.
//float newCenter = touchPoint.x; <--- This slides smoothly but always centers view on touch-point (we want to drag from anywhere)
NSLog(@"--------------");
NSLog(@"sliderHalfWidth: %f", sliderHalfWidth);
NSLog(@"sliderView.center.x: %f", sliderView.center.x);
NSLog(@"leftEdge: %f", leftEdge);
NSLog(@"distanceToTouchFromEdge: %f", distanceToTouchFromEdge);
NSLog(@"touchPoint.x: %f", touchPoint.x);
NSLog(@"newCenter: %f", newCenter);
NSLog(@"--------------");
sliderView.center = CGPointMake(newCenter, sliderView.frame.size.height/2);
}
}
有什麼想法？