代码之家 › 专栏 › 技术社区 › RameshVel

缩放UIViews组但保持其位置

scale transform uiview objective-c ios

RameshVel · 技术社区 · 7 年前

假设我有三个这样堆叠的视图

----------------------------------------------
|                                            |
|    -------                      --------   |   
|    |     |                      |      |   |
|    |  V1 |   ---------------    |      |   |
|    |     | X |     v2      |  Y |   v3 |   |
|    -------   ---------------    |      |   |
|                                 --------   |
---------------------------------------------

在pinch上,我通过使用scale属性计算转换来缩放3个视图中的每一个

CGAffineTransform v1Transform =  CGAffineTransformScale( v1.transform,recognizer.scale, recognizer.scale);
v1.transform = v1Transform
CGAffineTransform v2Transform =  CGAffineTransformScale( v2.transform,recognizer.scale, recognizer.scale);
v2.transform = v2Transform
CGAffineTransform v3Transform =  CGAffineTransformScale( v3.transform,recognizer.scale, recognizer.scale);
v3.transform = v3Transform

并使用当前比例更改每个视图的中心,如下所示

   CGPoint v1Center = CGPointMake(v1.center.x * recognizer.scale,  node.imgView.center.y * recognizer.scale);
   CGPoint v2Center = CGPointMake(v2.center.x * recognizer.scale,  node.imgView.center.y * recognizer.scale);
   CGPoint v3Center = CGPointMake(v3.center.x * recognizer.scale,  node.imgView.center.y * recognizer.scale);
  v1.cente = v1Center;
  v2.center = v2Center;
  v3.center = v3Center;

虽然这三个视图的比例是一致的,但我觉得中心点太偏了,比例看起来更奇怪。请检查以下问题的屏幕截图

有办法吗?非常感谢您的帮助

3 回复 | 直到 7 年前

EmilioPelaez 7 年前

如果我理解正确,您需要在缩放一组元素时的常规行为,这是为了让它们从所有选定元素的中心进行缩放。

我以前做过,它在Swift中,它使用了我创建的一个名为 CGMath *,但它应该足够好作为伪代码:

let scale = recognizer.scale
//  Reset the scale of the recognizer. We'll scale the views by the change in the last tick.
recognizer.scale = 1
//  Get the center of all selected views as a CGPoint
let center = views.map { $0.center }.reduce(CGPoint.zero, +) / CGFloat(views.count)
views.forEach {
    //  Scale the view
    $0.scale *= scale
    //  Get the distance from this view to the center of all views, this is a CGPoint
    let distance = $0.center - center
    //  Multiply the distance by the scale and add it to the center of all views. Set that as the view's center.
    $0.center = center + (distance * scale)
}

drekka 7 年前

发生的事情是,你也在缩放视图的x和y位置,相对于0,0,屏幕的一角。你需要根据屏幕的中心或者你捏的姿势的中心来做。我记不起来了,但我认为有一种方法可以指定刻度的定位点,如果没有,你就必须手动计算位置调整。

RameshVel 7 年前

@埃米利奥佩雷斯的回答工作正常。这是他的伪代码的obj-c版本

CGPoint newCenter =CGPointZero;
for(UIView *node in self.selectedNodes){
    newCenter = CGPointMake(newCenter.x + node.center.x, newCenter.y + node.center.y);
}

newCenter = CGPointMake(newCenter.x/self.selectedNodes.count, newCenter.y/self.selectedNodes.count);
for(UIview *node in self.selectedNodes){
    CGAffineTransform newTransform =  CGAffineTransformScale( node.transform,recognizer.scale, recognizer.scale);
    node.transform = newTransform;
    CGPoint distance = CGPointMake(node.center.x - newCenter.x, node.center.y - newCenter.y);
    CGPoint delta= CGPointMake(distance.x * recognizer.scale, distance.y * recognizer.scale);
    node.center =CGPointMake(newCenter.x + delta.x, newCenter.y + delta.y);
}