如何让UIScrollView（pagingEnabled）每次移动1.2页？ [英] How can I let UIScrollView (pagingEnabled) to move 1.2 page each time?

问题描述

确定。这是故事：

我有一个全屏的UIWebView，宽度= 768

I have a UIWebView in full screen, width = 768

它加载了几张图片并且这些图像在一行中，这意味着UIWebView将仅水平滚动。

It loads several images and those images are in one line, which means the UIWebView will scroll only horizontally.

现在，我将UIWebView中的UIScrollView设置为pagingEnabled = YES。因此，UIWebView上的滚动将逐页移动。

Now, I set the UIScrollView inside the UIWebView to pagingEnabled = YES. So the scroll on the UIWebView will move page by page.

问题是每个图像的宽度大约为900.我不会缩小它们，如果我滚动UIWebView，从第2页开始，将始终显示上一张图像的132点。这对我不好。

The problem is that every image's width is about 900. I won't scale them down and if I scroll the UIWebView, from the 2nd page on, always 132points of previous image will show. This is not good for me.

那么如何在UIWebView中操作UIWebView或UIScrollView，以便每个滚动页面移动900点，如果视图的帧宽是768？

约束是：

1. 我无法更改其contentSize

1. I can't change its contentSize

我无法更改其界限或框架

I can't change its bounds or frame

我说这些约束因为UIWebView在加载内容时会根据自己的目的更改它们。

I say these constraints because UIWebView will change them on its own purpose when it loads contents.

有人想加入这个大脑风暴吗？

Anyone would like to join this brain storming?

谢谢

推荐答案

我想你将需要设置一个UIScrollView委托来跟踪开始和结束的触摸。更具体地说，scrollViewDidEndDragging：willDecelerate是我认为你需要使用的，因为它会在用户从设备上抬起手时触发。

I'm thinking you're going to need to set a UIScrollView delegate that tracks touches beginning and ending. More specifically, scrollViewDidEndDragging:willDecelerate is what I'm thinking you'll need to use, as it fires the instant a user lifts their hand from the device.

首先， pagingEnabled = NO似乎很明显，我们将不得不控制自己的分页。其中，我觉得不是太难了。跟踪scrollViewDidScroll：中滚动的方向，以便我们有一些全局集：
BOOL isGoingRight = YES或NO（NO表示最后一次移动在左边）
float PAGESIZE = 900.0;

First, pagingEnabled=NO seems obvious, we're going to have to control our own paging. Which, I don't feel is too tough. Track the direction of the scrolling in scrollViewDidScroll:, so that we have some global set: BOOL isGoingRight = YES or NO (NO means the last movement was to the left) float PAGESIZE = 900.0;

以下是我的scrollview委托方法处理分页的方式。

Here's how my scrollview delegate method would look like that handles paging.

- (void) scrollViewDidEndDragging:(UIScrollView*)_scrollView willDecelerate:(BOOL)willDecelerate {
    float offsetProportion = _scrollView.contentOffset.x/_scrollView.frame.size.width;
    //depending upon our direction, round up or down
    int page = isGoingRight? ceilf(offsetProportion): floorf(offsetProportion);
    //manually finish the scroll
    [_scrollView scrollRectToVisible:CGRectMake(page*PAGESIZE, 0, _scrollView.frame.size.width, _scrollView.frame.size.height) animated:YES];
}

我没有测试过这个，你可能需要也可能不需要禁用触摸在点。

I didn't test this, you may or may not need to disable touches at points.

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