Dom编程艺术4--动画

1.元素移动

function moveElement(elementID,final_x,final_y,interval) {
  if (!document.getElementById) return false;
  if (!document.getElementById(elementID)) return false;
  var elem = document.getElementById(elementID);
  var xpos = parseInt(elem.style.left);
  var ypos = parseInt(elem.style.top);
  if (xpos == final_x && ypos == final_y) {
    return true;
  }
  if (xpos < final_x) {
    xpos++;
  }
  if (xpos > final_x) {
    xpos--;
  }
  if (ypos < final_y) {
    ypos++;
  }
  if (ypos > final_y) {
    ypos--;
  }
  elem.style.left = xpos + "px";
  elem.style.top = ypos + "px";
  var repeat = "moveElement('"+elementID+"',"+final_x+","+final_y+","+interval+")";
  movement = setTimeout(repeat,interval);
}

function positionMessage() {
  if (!document.getElementById) return false;
  if (!document.getElementById("message")) return false;
  var elem = document.getElementById("message");
  elem.style.position = "absolute";
  elem.style.left = "50px";
  elem.style.top = "100px";
  moveElement("message",125,25,20);
  if (!document.getElementById("message2")) return false;
  var elem = document.getElementById("message2");
  elem.style.position = "absolute";
  elem.style.left = "50px";
  elem.style.top = "50px";
  moveElement("message2",125,75,20);
}
addLoadEvent(positionMessage);

<body>
  <p id="message">Whee!</p>
  <p id="message2">Whoa!</p>
</body>

2.图片滑动

function prepareSlideshow() {
// Make sure the browser understands the DOM methods
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
// Make sure the elements exist
  if (!document.getElementById("linklist")) return false;
  if (!document.getElementById("preview")) return false;
// Apply styles to the preview image
  var preview = document.getElementById("preview");
  preview.style.position = "absolute";
  preview.style.left = "0px";
  preview.style.top = "0px";
// Get all the links in the list
  var list = document.getElementById("linklist");
  var links = list.getElementsByTagName("a");
// Attach the animation behavior to the mouseover event
  links[0].onmouseover = function() {
    moveElement("preview",-100,0,10);
  }
  links[1].onmouseover = function() {
    moveElement("preview",-200,0,10);
  }
  links[2].onmouseover = function() {
    moveElement("preview",-300,0,10);
  }
}
addLoadEvent(prepareSlideshow);
function moveElement(elementID,final_x,final_y,interval) {
  if (!document.getElementById) return false;
  if (!document.getElementById(elementID)) return false;
  var elem = document.getElementById(elementID);
  //在动画之前清除之前的动画
  if (elem.movement) {
    clearTimeout(elem.movement);
  }
  var xpos = parseInt(elem.style.left);
  var ypos = parseInt(elem.style.top);

  if (xpos == final_x && ypos == final_y) {
    return true;
  }
  if (xpos < final_x) {
    xpos++;
  }
  if (xpos > final_x) {
    xpos--;
  }
  if (ypos < final_y) {
    ypos++;
  }
  if (ypos > final_y) {
    ypos--;
  }
  elem.style.left = xpos + "px";
  elem.style.top = ypos + "px";
  var repeat = "moveElement('"+elementID+"',"+final_x+","+final_y+","+interval+")";
  elem.movement = setTimeout(repeat,interval);
}

<body>
  <h1>Web Design</h1>
  <p>These are the things you should know.</p>
  <ol id="linklist">
    <li>
      <a href="structure.html">Structure</a>
    </li>
    <li>
      <a href="presentation.html">Presentation</a>
    </li>
    <li>
      <a href="behavior.html">Behavior</a>
    </li>
  </ol>
  <div id="slideshow">
    <img src="topics.gif" alt="building blocks of web design" id="preview" />
  </div>
</body>

Paste_Image.png

Dom编程艺术4--动画

1.元素移动

2.图片滑动

推荐阅读更多精彩内容