Get viewport height when soft keyboard is on

问题

I've been trying to make this work for days now, with no luck, so I thought I'd share info and maybe someone comes up with a solution.

I want to get the exact viewport size when the soft keyboard is up. I am currently using the following code on the header in order for the site to be responsive:

<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no"/>

What I realized is that when the soft keyboard comes up, it uses the device height as the viewport height and pushes the rest of the site upwards - which makes me assume that it's getting it's height from the width=device-width option.

Using the following code after initiating the soft keyboard:

setTimeout(function() {  
    viewport = document.querySelector("meta[name=viewport]");
    viewport.setAttribute('content', 'height=auto');
}, 300)

And then getting the height using jquery shows CORRECT results on Android - aka the visible viewport size WITHOUT the virtual keyboard, but not on iOS. I am getting a random number, which I assume stems from the rest of the meta tag not existing, so I am getting a zoomed-in version of the website along with a number like 75 or 100 (on iphone 4s)

I also tried creating a fixed element after bringing the keyboard up, making it use the viewport height with top:0; and bottom:0; attributes, but I still get the original height.

What comes closer to this, is setting the viewport meta tag height to a fixed value, that can be picked up by jquery's $(window).height(), which means that the meta tag actually makes a difference after initiating the keyboard, but there is no true value for a fixed height.

I've seen lots of topics around this, but none with a solution. Anyone that has a solution for this?

回答1:

The viewport dimensions come from the size of the UIWebView element.

As mentioned in the previous answer there are two ways to handle adapting to the on screen keyboard. You can resize the view or adjust the content insets.

The dimensions of the viewport on iOS are reporting the size of the view so resizing would adjust the viewport. Safari adjusts the insets and keeps the view the same size so the viewport does not change.

If you were to make assumptions that touch devices generally utilize on screen input rather than external keyboards you can programmatically adjust the size on your own by taking the device height or width depending on orientation and factor in a multiplier for portion of the screen consumed by the on screen keyboard.

I utilize a viewport class to act as a proxy to give me most likely real viewport dimensions rather than browser reported and binds to input elements to track state of input elements and orientation changes to dynamically modify the multiplier applied when requesting the viewport dimensions.

回答2:

In the view I wanted to take the height of the remaining screen after the virtual keyboard was on, I was using an absolutely overflown element that covered the whole screen using screen height and the content of the whole page was inside of it. As a result, the virtual keyboard was opening on TOP of the overflown element, without changing its dimensions.

To fix the specific problem, all I had was change the position of this element to static and remove the overflow when the virtual keyboard was opened - actually ios changes to THIS behaviour by default when issuing he virtual keyboard (changes elements to static position) and this is why the fixed elements become static.

I hope this helps.

回答3:

I've found myself with the same problem and after a while mixing CSS and a little bit of javascript, I found a solution.

Notes:

I used jQuery and SCSS
I preferred to hide the element instead of changing its position (simple and effective)
The element is shown if the virtual keyboard is closed but the input is still on focus. For this I wrapped the css rule in a media query @media screen and (min-aspect-ratio: 11/16). 11/16 because it's less than the common 9/16 ratio (the presence of the virtual keyboard increases this ratio then the rule is applied)

The solution:

First, the script (using jQuery):

$(document).on('focus', 'input, textarea', function(){
    $('body').addClass("fixfixed");
});

$(document).on('blur', 'input, textarea', function(){
    $('body').removeClass("fixfixed");
});

So, while the user focuses on a text input and the virtual keyboard is open, the body has a 'fixfixed' class.

Then, the CSS (I'm using SCSS):

.fixfixed{
  @media screen and (min-aspect-ratio: 11/16) {
    .bottomThingToHideWhenVirtualKeyboardIsShown{
      opacity: 0;
      pointer-events: none;
    }
  }
}

And that's it!

Hope it helps someone!

回答4:

Just to give you an idea, when the keyboard appears on iOS by default it does nothing on the underlying scrollview.

If your content is shown in a custom UIWebView, it is up to the programmer to either:

Resize the scrollview to avoid getting unreachable content under the keyboard.
Adjust the scrollview's content insets (recommended). The scrollview size stays the same but a "border" is added to the bottom so the user can scroll all to all the contents.

I am not sure how either solution affects the viewport, but your could try both.

If your web content is being presented by Safari however, Apple adjusts the insets for you.

回答5:

This solution is a bit convoluted, but it might work...

Detect whether or not the keyboard is active.
Grab the viewport width/height
Subtract the height of the keyboard.

回答6:

I came up with this hack:

var storedWidth = 0;
var storedHheight = 0;

function onResize() {

  var windowWidth = $(window).width();
  var windowHeight = $(window).height();
  var screenWidth = screen.width || windowWidth;
  var screenHeight = screen.height || windowHeight;
  var width, height;

  if(screenWidth < screenHeight) {
    if(windowWidth > storedWidth) storedWidth = windowWidth;
    if(windowHeight > storedHeight) storedHeight = windowHeight;
    width = storedWidth;
    height = storedHeight;
  }else {
    width = windowWidth;
    height = windowHeight;
  }

  //use width and height from here

}

Now this would fail in two cases:

screen.width/screen.height not being supported; it would fallback to the erroneous jquery dimensions. In my case, the soft keyboard made the height smaller than the width while in portrait mode, so the jQuery dimensions resulted in a false landscape mode and thus showing the 'rotate your device' message.
the page is opened with the soft keyboard opened, which I think is moot. Also after hiding it, the largest height is stored so things will be fixed after that.

Note:

window.innerWidth/window.innerHeight could be used to ditch the jQuery dependency
above code is to fix the keyboard issue in portrait mode, but same solution could be used for landscape mode

回答7:

Piece attempts to return approximate window.innerWidth, window.innerHeight values at ios6 ua; jquery utilized for selectors and .on(). Not certain about detecting ios device keyboard events portion; see resources links

Try

css

html {
    height : 100vh;
    width : 100vw;
}

$(function() {    
    if (/ipad|iphone/gi.test(window.navigator.userAgent)) {
    var events = "abort blur focus input scroll submit touchstart touchmove";
    $("form, input").on(events, function(e) {
      return (function(window, elem, w, h) {
               var vh = window.getComputedStyle(elem,null).getPropertyValue(h);
               var vw = window.getComputedStyle(elem,null).getPropertyValue(w);
               var vwh = { 
                           "documentWidth": vw, 
                           "documentHeight": vh, 
                           "windowInnerWidth": window.innerWidth, 
                           "windowInnerHeight": window.innerHeight
                         };
               console.log(vwh);
               var _vwh = document.getElementById("vwh");
               _vwh.innerHTML = JSON.stringify(vwh)
               return vwh 
              }(window, document.documentElement, "width", "height"));
    }).focus();
    };
})

jsfiddle http://jsfiddle.net/guest271314/Pv3N2/

resources

https://developer.mozilla.org/en-US/docs/Web/API/Window.innerHeight

http://www.w3.org/TR/2013/CR-css3-values-20130730/#vh-unit

how to handle key events in iphone

https://coderwall.com/p/xuawww Responding to Keyboard Events on iOS

http://looksok.wordpress.com/2013/02/02/ios-tutorial-hide-keyboard-after-return-done-key-press-in-uitextfield/ iOS tutorial: hide keyboard after return / done key press in UITextField

https://developer.apple.com/library/safari/documentation/InternetWeb/Conceptual/SafariVisualEffectsProgGuide/InteractiveControl/InteractiveControl.html#//apple_ref/doc/uid/TP40008032-CH16

http://www.quirksmode.org/mobile/viewports2.html

来源：https://stackoverflow.com/questions/23023549/get-viewport-height-when-soft-keyboard-is-on

标签

jquery

ios

css

viewport