CGRectInset的使用

来源：互联网发布：windows 10 iso bt 编辑：程序博客网时间：2024/04/28 21:44

在IntroduceToTextKitDemo中，在添加textView视图时使用了CGRectInset来定义其框架：

CGRect newTextViewRect = CGRectInset(self.view.bounds, 8., 0.);UITextView *newTextView = [[UITextView alloc] initWithFrame:newTextViewRect textContainer:container];

这是sdk包中的定义：

/* Inset `rect' by `(dx, dy)' -- i.e., offset its origin by `(dx, dy)', and   decrease its size by `(2*dx, 2*dy)'. */CG_EXTERN CGRect CGRectInset(CGRect rect, CGFloat dx, CGFloat dy)  CG_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

随后我写了一个Demo来试用一下，代码如下

- (void)viewDidLoad{    [super viewDidLoad];    CGRect rect = CGRectInset(self.view.bounds, 8., 0.);    UIView *greenView = [[UIView alloc] initWithFrame:rect];    greenView.backgroundColor = [UIColor greenColor];    NSLog(@"greenView location:");    NSLog(@"x = %f", greenView.frame.origin.x);    NSLog(@"y = %f", greenView.frame.origin.y);    NSLog(@"width = %f", greenView.frame.size.width);    NSLog(@"height = %f", greenView.frame.size.height);    CGRect newRect0 = CGRectInset(greenView.frame, 0., 100.0);    UIView *blueView = [[UIView alloc] initWithFrame:newRect0];    blueView.backgroundColor = [UIColor blueColor];    NSLog(@"blueView location:");    NSLog(@"x = %f", blueView.frame.origin.x);    NSLog(@"y = %f", blueView.frame.origin.y);    NSLog(@"width = %f", blueView.frame.size.width);    NSLog(@"height = %f", blueView.frame.size.height);    [greenView addSubview:blueView]; // 以greenView为参考坐标系添加blueView    CGRect newRect = CGRectInset(greenView.bounds, 0., 200.0);    UIView *blackView = [[UIView alloc] initWithFrame:newRect];    blackView.backgroundColor = [UIColor blackColor];    NSLog(@"blackView location:");    NSLog(@"x = %f", blackView.frame.origin.x);    NSLog(@"y = %f", blackView.frame.origin.y);    NSLog(@"width = %f", blackView.frame.size.width);    NSLog(@"height = %f", blackView.frame.size.height);    [greenView addSubview:blackView];    [self.view addSubview:greenView];}

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