为可调整大小的 UIView 设置最小和最大宽度和高度

Posted 2023-03-13

【中文标题】为可调整大小的 UIView 设置最小和最大宽度和高度

【英文标题】：Setting the Min and Max width and height for resizable UIView

【发布时间】：2015-02-16 11:29:46

【问题描述】：

我想使用角落的触摸来制作一个可调整大小的 UIView，我找到了这个答案 here 并且效果很好。但是，例如，当宽度/高度为 200 时，如何添加停止调整大小的功能？

这是代码：

CGFloat kResizeThumbSize = 45.0f;

@interface MY_CLASS_NAME : UIView 
BOOL isResizingLR;
BOOL isResizingUL;
BOOL isResizingUR;
BOOL isResizingLL;
CGPoint touchStart;

还有..

- (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);

 

谢谢

【参考方案1】：

if (isResizingLR) 
   if(touchPoint.x+deltaWidth < 200 && touchPoint.y+deltaWidth < 200)
     self.frame = CGRectMake(x, y, touchPoint.x+deltaWidth, touchPoint.y+deltaWidth);
 else if (isResizingUL) 
   if(width-deltaWidth < 200 && height-deltaHeight < 200)
     self.frame = CGRectMake(x+deltaWidth, y+deltaHeight, width-deltaWidth, height-deltaHeight);
 else if (isResizingUR) 
   if(width+deltaWidth < 200 && height-deltaHeight < 200)
     self.frame = CGRectMake(x, y+deltaHeight, width+deltaWidth, height-deltaHeight);      
 else if (isResizingLL) 
   if(width-deltaWidth < 200 && height+deltaHeight < 200)
      self.frame = CGRectMake(x+deltaWidth, y, width-deltaWidth, height+deltaHeight);   

这应该可行。

【参考方案2】：

@property(nonatomic) CGRect frame

描述框架矩形，描述视图在其父视图坐标系中的位置和大小。

在使用 CGRect 设置 self.frame 之前，检查宽度和高度！

CGRect CGRectMake(CGFloat x, CGFloat y, CGFloat width, CGFloat height);

使用宽度和高度作为实际尺寸，使用增量进行变换。