Asked  7 Months ago    Answers:  5   Viewed   23 times

I've the following sample html, there is a DIV which has 100% width. It contains some elements. While performing windows re-sizing, the inner elements may be re-positioned, and the dimension of the div may change. I'm asking if it is possible to hook the div's dimension change event? and How to do that? I currently bind the callback function to the jQuery resize event on the target DIV, however, no console log is outputted, see below:

Before Resize enter image description here

<html>
<head>
    <script type="text/javascript" language="javascript" src="http://code.jquery.com/jquery-1.6.1.min.js"></script>
    <script type="text/javascript" language="javascript">
            $('#test_div').bind('resize', function(){
                console.log('resized');
            });
    </script>
</head>
<body>
    <div id="test_div" style="width: 100%; min-height: 30px; border: 1px dashed pink;">
        <input type="button" value="button 1" />
        <input type="button" value="button 2" />
        <input type="button" value="button 3" />
    </div>
</body>
</html>

 Answers

29

There is a very efficient method to determine if a element's size has been changed.

http://marcj.github.io/css-element-queries/

This library has a class ResizeSensor which can be used for resize detection.
It uses an event-based approach, so it's damn fast and doesn't waste CPU time.

Example:

new ResizeSensor(jQuery('#divId'), function(){ 
    console.log('content dimension changed');
});

Please do not use the jQuery onresize plugin as it uses setTimeout() in combination with reading the DOM clientHeight/clientWidth properties in a loop to check for changes.
This is incredible slow and inaccurate since it causes layout thrashing.

Disclosure: I am directly associated with this library.

Tuesday, June 1, 2021
 
Francisunoxx
answered 7 Months ago
23

canplaythrough is the event that should fire when enough data has downloaded to play without buffering.

From the Opera teams excellent (although maybe very slightly dated now) resource Everything you need to know about HTML5 video and audio

If the load is successful, whether using the src attribute or using source elements, then as data is being downloaded, progress events are fired. When enough data has been loaded to determine the video's dimensions and duration, a loadedmetadata event is fired. When enough data has been loaded to render a frame, the loadeddata event is fired. When enugh data has been loaded to be able to play a little bit of the video, a canplay event is fired. When the browser determines that it can play through the whole video without stopping for downloading more data, a canplaythrough event is fired; this is also when the video starts playing if it has a autoplay attribute.

'canplaythrough' support matrix available here: https://caniuse.com/mdn-api_htmlmediaelement_canplaythrough_event

You can get around the support limitations by binding the load element to the same function, as it will trigger on those.

Wednesday, July 28, 2021
 
Easen
answered 5 Months ago
71

Depending on what you're doing, you might want to check out the python Natural Language Processing Toolkit (NLTK), which has some support for Bayesian Learning Algorithms.

In general, the letter and word frequencies would probably be the fastest evaluation, but the NLTK (or a bayesian learning algorithm in general) will probably be useful if you need to do anything beyond identification of the language. Bayesian methods will probably be useful also if you discover the first two methods have too high of an error rate.

Monday, August 9, 2021
 
ajay
answered 4 Months ago
46

Here's one way using getImageData to manipulate the hue of each image pixel:

  • Use getImageData to fetch the RGBA color data of each pixel

  • Convert the RGBA color to HSL color. The H in HSL means Hue which is what we normally think of as "color".

  • If the Hue of an original pixel is red-ish (Hue<30 or Hue>300) then shift the hue by the amount specified in your range control. If you want to shift from red to blue, then your slider should shift the color (Hue) from 0 to -.33.

Note: getImageData requires that the image originate on the same domain as the webpage or else you will get a cross-domain security error.

Here's example code and a Demo:

var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;

var imgData,data,originalData;

$myslider=$('#myslider');
$myslider.attr({min:0,max:33}).val(0);
$myslider.on('input change',function(){
  var value=parseInt($(this).val());
  HueShift(30,300,-value/100);
});

var img=new Image();
img.crossOrigin='anonymous';
img.onload=start;
img.src="http://icons.iconarchive.com/icons/iconshow/transport/256/Sportscar-car-icon.png";
function start(){
  cw=canvas.width=img.width;
  ch=canvas.height=img.height;
  ctx.drawImage(img,0,0);

  imgData=ctx.getImageData(0,0,cw,ch);
  data=imgData.data;
  imgData1=ctx.getImageData(0,0,cw,ch);
  originalData=imgData1.data;

}



function HueShift(hue1,hue2,shift){

  for(var i=0;i<data.length;i+=4){
    red=originalData[i+0];
    green=originalData[i+1];
    blue=originalData[i+2];
    alpha=originalData[i+3];

    // skip transparent/semiTransparent pixels
    if(alpha<230){continue;}

    var hsl=rgbToHsl(red,green,blue);
    var hue=hsl.h*360;

    // change redish pixels to the new color
    if(hue<30 || hue>300){


      var newRgb=hslToRgb(hsl.h+shift,hsl.s,hsl.l);
      data[i+0]=newRgb.r;
      data[i+1]=newRgb.g;
      data[i+2]=newRgb.b;
      data[i+3]=255;
    }
  }    
  ctx.putImageData(imgData,0,0);
}






////////////////////////
// Helper functions
//

function rgbToHsl(r, g, b){
  r /= 255, g /= 255, b /= 255;
  var max = Math.max(r, g, b), min = Math.min(r, g, b);
  var h, s, l = (max + min) / 2;
  if(max == min){
    h = s = 0; // achromatic
  }else{
    var d = max - min;
    s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
    switch(max){
      case r: h = (g - b) / d + (g < b ? 6 : 0); break;
      case g: h = (b - r) / d + 2; break;
      case b: h = (r - g) / d + 4; break;
    }
    h /= 6;
  }
  return({ h:h, s:s, l:l });
}

function hslToRgb(h, s, l){
  var r, g, b;
  if(s == 0){
    r = g = b = l; // achromatic
  }else{
    function hue2rgb(p, q, t){
      if(t < 0) t += 1;
      if(t > 1) t -= 1;
      if(t < 1/6) return p + (q - p) * 6 * t;
      if(t < 1/2) return q;
      if(t < 2/3) return p + (q - p) * (2/3 - t) * 6;
      return p;
    }
    var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
    var p = 2 * l - q;
    r = hue2rgb(p, q, h + 1/3);
    g = hue2rgb(p, q, h);
    b = hue2rgb(p, q, h - 1/3);
  }
  return({
    r:Math.round(r * 255),
    g:Math.round(g * 255),
    b:Math.round(b * 255),
  });
}
body{ background-color: ivory; }
#canvas{border:1px solid red;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h4>Change the slider to change the car color</h4>
<input id=myslider type=range min=0 max=100 value=0><br>
<canvas id="canvas" width=300 height=300></canvas>
Tuesday, October 5, 2021
 
LDropl
answered 2 Months ago
49

Don't try to build separate JS and non-JS versions of the site. Build a non-JS version and then enhance it with JS. This makes it easier to reuse code, allows you to use object/feature detection for the entire stack, and makes it less likely that users without JavaScript will be left behind if developers update one branch of the site but not the other.

Thursday, October 21, 2021
 
Ralph
answered 2 Months ago
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