Geek Answers Handbook

Moving an image from A to B using JavaScript

Its my first time here, and I don’t know how to backtrack this sorry: /

I have an image of a van, and I'm trying to move it around the screen as if it were driving. Once this is done, I scale the image as if it is moving away (and getting smaller).

I need this to be done in standard javascript without any packages (like jQuery).

I have a van, which for some reason I can’t break, is moving in two ways instead of one. Also moving in the wrong direction (it should move along the path y = -25x, so that every 25 pixels move to the right, it should move 1 pixel up).

To illustrate what I'm trying to achieve, see this image: http://i.stack.imgur.com/9WIfr.jpg

This is my javascript file:

var viewWidth = 800;        
var viewHeight = 480;        
var fps = 30;        
var delay = getFrame(fps);        
var vanWidth, vanHeight, vanObj;   

function initVan() {        
  vanObj = document.getElementById("van");        
  vanObj.style.position = "absolute";        
  vanObj.src = "pics/delivery/van.png";        
  vanWidth = 413;        
  vanHeight = 241;        
  var startX = 0-vanWidth;        
  var startY = viewHeight-vanHeight;        
  setPosition(startX,startY);        
  transition(startX,startY,3000);        
}

function transition(startX,startY,time) {        
  //the intention of this is to follow a path y=-25x in mathematical terms
  var endX = viewWidth;        
  var endY = startY-(endX/-25);        
  //note that this is the velocity per millisecond
  var velocityX = (endX-startX)/time;        
  var velocityY = (endY-startY)/time;        
  alert(endY+", "+startY);        
  move(velocityX,velocityY,endX,endY);        
}

function move(vX,vY,eX,eY) {        
  var posX = getX();        
  var posY = getY();        
  if (posX<=eX || posY<=eY) {        
    //velocityX (in milliseconds) * delay = the amount of pixels moved in one frame @fps=30
    var moveX = vX*delay;        
    var moveY = vY*delay;        
    var newX = posX+moveX;        
    var newY = posY+moveY;        
    setPosition(newX,newY);        
    setTimeout(function() {        
        move(vX,vY,eX,eY);        
    }, delay);        
  }        
} 


function getX() {        
  return vanObj.offsetLeft;        
}    

function getY() {        
  return vanObj.offsetTop;        
}  

function setPosition(newX,newY) {        
  vanObj.style.left = newY + "px";        
  vanObj.style.top = newX + "px";        
}        

function setSize(scaleX,scaleY) {        
  vanWidth *= scaleX;        
  vanHeight *= scaleY;        
  vanObj.width = vanWidth;        
  vanObj.height = vanHeight;        
}      

function getFrame(fps) {        
  return Math.floor(1000/fps);        
}

This is my HTML file:

<script type="text/javascript" src="delivery.js"> </script>
<body onLoad="initVan();">
<img id="van" width=413 height=241/>

+5
source share
2 answers

If you do not have a requirement for non-libraries or, in particular, you like to reinvent the wheel, I would solve this using the jQuery effects library, and in particular .animate: http://api.jquery.com/animate/ . See the first example on this page.

$(document).ready(function() {
  $('#van')
    .attr({
      width: 413,
      height: 241  //etc.
    })
    .animate({
      width: "70%",
      height: "70%"  //etc.
  }, 3000);
});

Less code means less maintenance. Means a happy customer.

+5
source

Even if you already accepted the answer, this is the way to do it without jQuery.

Not finished, but the concept works.

   window.onload = function () {
    updateVan(0);
    function updateVan(i)
    {
        var t = setTimeout(function () {
            document.getElementById("van").style.marginLeft = i + "px";
            document.getElementById("van").style.marginTop = (i/10) + "px";
            document.getElementById("van").style.height = (100-(i/10)) + "px";
            document.getElementById("van").style.width = (100-(i/10)) + "px";
            if (i < 300) updateVan(i+1);
        },30);
    }
}

: http://webbies.dk/tmp/tmp.html

+2

More articles:


All Articles