在我的 iPad 应用程序中,我希望用户能够调整UIView
通过从边缘拖动视图。我将使用 iOS 5 SDK,那么最简洁的方法是什么?有没有其他方法可以在不处理touchesBegan、touchesMoved等的情况下实现这一目标?
您可以通过检查触摸起点来完成此操作。如果它击中了四个角之一,您可以根据触摸起始点和当前触摸点之间的距离调整大小。 (如果触摸起点没有到达角落,我们只需移动视图而不是调整大小。)
定义可拖动角的大小。
CGFloat kResizeThumbSize = 45.0f;
将这些实例变量添加到您的类中以跟踪触摸状态以及我们调整大小的方式。
@interface MY_CLASS_NAME : UIView {
BOOL isResizingLR;
BOOL isResizingUL;
BOOL isResizingUR;
BOOL isResizingLL;
CGPoint touchStart;
}
处理触摸启动/更改事件。
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
touchStart = [[touches anyObject] locationInView:self];
isResizingLR = (self.bounds.size.width - touchStart.x < kResizeThumbSize && self.bounds.size.height - touchStart.y < kResizeThumbSize);
isResizingUL = (touchStart.x <kResizeThumbSize && touchStart.y <kResizeThumbSize);
isResizingUR = (self.bounds.size.width-touchStart.x < kResizeThumbSize && touchStart.y<kResizeThumbSize);
isResizingLL = (touchStart.x <kResizeThumbSize && self.bounds.size.height -touchStart.y <kResizeThumbSize);
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
CGPoint touchPoint = [[touches anyObject] locationInView:self];
CGPoint previous = [[touches anyObject] previousLocationInView:self];
CGFloat deltaWidth = touchPoint.x - previous.x;
CGFloat deltaHeight = touchPoint.y - previous.y;
// get the frame values so we can calculate changes below
CGFloat x = self.frame.origin.x;
CGFloat y = self.frame.origin.y;
CGFloat width = self.frame.size.width;
CGFloat height = self.frame.size.height;
if (isResizingLR) {
self.frame = CGRectMake(x, y, touchPoint.x+deltaWidth, touchPoint.y+deltaWidth);
} else if (isResizingUL) {
self.frame = CGRectMake(x+deltaWidth, y+deltaHeight, width-deltaWidth, height-deltaHeight);
} else if (isResizingUR) {
self.frame = CGRectMake(x, y+deltaHeight, width+deltaWidth, height-deltaHeight);
} else if (isResizingLL) {
self.frame = CGRectMake(x+deltaWidth, y, width-deltaWidth, height+deltaHeight);
} else {
// not dragging from a corner -- move the view
self.center = CGPointMake(self.center.x + touchPoint.x - touchStart.x,
self.center.y + touchPoint.y - touchStart.y);
}
}
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