Question

可以使用CSS scale和translate函数来放大元素。

以2x2网格中的4个方框为例。

HTML：

<div id="container">
  <div id="zoom-container">
    <div class="box red">A</div>
    <div class="box blue">B</div>
    <div class="box green">C</div>
    <div class="box black">D</div>
  </div>
</div>

CSS：

* { margin: 0; }

body, html { height: 100%; }

#container {
  height: 100%;
  width: 50%;
  margin: 0 auto;
}

#zoom-container {
  height: 100%;
  width: 100%;
  transition: all 0.2s ease-in-out;
}

.box {
  float: left;
  width: 50%;
  height: 50%;
  color: white;
  text-align: center;
  display: block;
}

.red { background: red; }
.blue { background: blue; }
.green { background: green; }
.black { background: black; }

JavaScript的：

window.zoomedIn = false;

$(".box").click(function(event) {
  var el = this;
  var zoomContainer = $("#zoom-container");

  if (window.zoomedIn) {
    console.log("resetting zoom");
    zoomContainer.css("transform", "");
    $("#container").css("overflow", "auto");
    window.zoomedIn = false;
  } else {
    console.log("applying zoom");
    var top = el.offsetTop;
    var left = el.offsetLeft - 0.25*zoomContainer[0].clientWidth;

    var translateY = 0.5*zoomContainer[0].clientHeight - top;
    var translateX = 0.5*zoomContainer[0].clientWidth - left;

    $("#container").css("overflow", "scroll");
    zoomContainer.css("transform", "translate(" + 2 * translateX + "px, " + 2 * translateY + "px) scale(2)");
    window.zoomedIn = true;
  }
});

通过控制translateX和translateY的值，您可以更改缩放的工作方式。

初始渲染视图如下所示：

单击A框将适当放大您的位置：

（请注意，在末尾单击D只是通过缩小显示重置。）

问题是：缩放到框D将缩放缩放容器，使得滚动到顶部和左边不起作用，因为内容溢出。当缩放到方框B（左半部分被裁剪）和C（上半部分被裁剪）时也会发生同样的情况。仅使用A，内容不会溢出容器外。

在与缩放相关的类似情况下（请参阅CSS3 Transform Scale and Container with Overflow），一种可能的解决方案是指定transform-origin: top left（或0 0）。由于缩放相对于左上角的工作方式，滚动功能保持不变。但这似乎并不适用于此，因为这意味着您不再重新定位要关注点击框（A，B，C或D）的内容。

另一种可能的解决方案是向缩放容器添加margin-left和margin-top，这会增加足够的空间来弥补溢出的内容。但同样：翻译价值不再排列。

那么：有没有办法两个放大一个给定的元素，和溢出滚动，这样内容就不会被裁剪？

更新：通过设置scrollTop和scrollLeft动画来实现粗略的解决方案，类似于https://stackoverflow.com/a/31406704/528044（请参阅the jsfiddle example），但它不是一个合适的解决方案，因为它首先放大到左上角，而不是预定的目标。我开始怀疑这实际上是不可能的，因为它可能等同于要求scrollLeft为负面。

Answer 1

为什么不将TransformOrigin重新定位到0 0并在动画后使用正确的scrollTop/scrollLeft ？

~~https://jsfiddle.net/b8vLg0ny/7/~~

已更新： https://jsfiddle.net/b8vLg0ny/13/

如果您不需要动画，TransformOrigin可以始终保持0 0，并且仅使用滚动来显示该框。

为了使动画不那么跳跃，只使用transform属性的过渡，否则transform-origin也会被动画化。我已使用4x4元素编辑了示例，但我认为将一个框完全缩放到视图中是有意义的，这就是我更改缩放级别的原因。但是，如果你继续使用缩放级别2和网格大小15x15，那么使用这种方法应该为变换计算真正精确的原点，然后还要正确滚动。

无论如何，如果你发现这种方法很有用，我也不知道。

Stack snippet

＆＃13;
＆＃13;
var zoomedIn = false; var zoomContainer = $("#zoom-container"); $(".box").click(function(event) { var el = this; if (zoomedIn) { zoomContainer.css({ transform: "scale(1)", transformOrigin: "0 0" }); zoomContainer.parent().scrollTop(0).scrollLeft(0); zoomedIn = false; return; } zoomedIn = true; var $el = $(el); animate($el); zoomContainer.on('transitionend', function(){ zoomContainer.off('transitionend'); reposition($el); }) }); var COLS = 4, ROWS = 4, COLS_STEP = 100 / (COLS - 1), ROWS_STEP = 100 / (ROWS - 1), ZOOM = 4; function animate($box) { var cell = getCell($box); var col = cell.col * COLS_STEP + '%', row = cell.row * ROWS_STEP + '%'; zoomContainer.parent().css('overflow', 'hidden'); zoomContainer.css({ transition: 'transform 0.2s ease-in-out', transform: "scale(" + ZOOM + ")", transformOrigin: col + " " + row }); } function reposition($box) { zoomContainer.css({ transition: 'none', transform: "scale(" + ZOOM + ")", transformOrigin: '0 0' }); zoomContainer.parent().css('overflow', 'auto'); $box.get(0).scrollIntoView(); } function getCell ($box) { var idx = $box.index(); var col = idx % COLS, row = (idx / ROWS) | 0; return { col: col, row: row }; }
＆＃13;
* { margin: 0; } body, html { height: 100%; } #container { height: 100%; width: 50%; margin: 0 auto; overflow: hidden; } #zoom-container { height: 100%; width: 100%; will-change: transform; } .box { float: left; width: 25%; height: 25%; color: white; text-align: center; } .red { background: red; } .blue { background: blue; } .green { background: green; } .black { background: black; } .l { opacity: .3 }
＆＃13;
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script> <div id="container"> <div id="zoom-container"> <div class="box red">A</div> <div class="box blue">B</div> <div class="box green">C</div> <div class="box black">D</div> <div class="box red l">E</div> <div class="box blue l">F</div> <div class="box green l">G</div> <div class="box black l">H</div> <div class="box red">I</div> <div class="box blue">J</div> <div class="box green">K</div> <div class="box black">L</div> <div class="box red l">M</div> <div class="box blue l">N</div> <div class="box green l">O</div> <div class="box black l">P</div> </div> </div>
＆＃13;
＆＃13;
＆＃13;

Answer 2

更新

我卡在滚动条上并没有一直显示，所以我需要调查那部分，以便代码被注释掉，而我使用延迟将点击的框移动到视图中。

这是我用来玩的my fiddle demo，以找出如何解决滚动条问题。

旁注：在@AVAVT发表的评论中，我想链接到his post here，因为这可能对其他人有所帮助，在某些情况下我觉得这是一个有趣的选择。

＆＃13;

(function(zoomed) {
  
  $(".box").click(function(event) {
    
    var el = this, elp = el.parentElement;
    
    if (zoomed) {
      zoomed = false;
      $("#zoom-container").css({'transform': ''});
      
    } else {
      zoomed = true;
      /*  this zooms correct but show 1 or none scroll for B,C,D so need to figure out why
      
      var tro = (Math.abs(elp.offsetTop - el.offsetTop) > 0) ? 'bottom' : 'top';
      tro += (Math.abs(elp.offsetLeft - el.offsetLeft) > 0) ? ' right' : ' left';
      $("#zoom-container").css({'transform-origin': tro, 'transform': 'scale(2)'});
      */
      
      $("#zoom-container").css({'transform-origin': '0 0', 'transform': 'scale(2)'});
      /* delay needed before scroll into view */      
      setTimeout(function() {
        el.scrollIntoView();
      },250);
    }    
  });
})();

＆＃13;

* { margin: 0; }

body, html { height: 100%; }

#container {
  height: 100%;
  width: 50%;
  overflow: auto;
  margin: 0 auto;
}

#zoom-container {
  height: 100%;
  width: 100%;
  transition: all 0.2s ease-in-out;
}

.box {
  float: left;
  width: 50%;
  height: 50%;
  color: white;
  text-align: center;
  display: block;
}

.red {
  background: red; 
}
.blue {
  background: blue;
}
.green {
  background: green;
}
.black {
  background: black;
}

＆＃13;

<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
<div id="container">
  <div id="zoom-container">
    <div class="box red">A</div>
    <div class="box blue">B</div>
    <div class="box green">C</div>
    <div class="box black">D</div>
  </div>
</div>

＆＃13;

Answer 3

我正在回答我自己的问题，因为我相信它实际上不可能满足给定的要求。至少并非没有一些会在视觉上引起问题的hackery，例如，在将scrollTop切换为transform-origin之后通过动画0, 0进行跳跃式滚动（通过将所有内容放回容器中来移除裁剪）。

我喜欢某人证明我错了，但这似乎等同于scrollLeft = -10，MDN will tell you is not possible。（“如果设置为小于0 [...]的值，则scrollLeft设置为0.”）

但是，如果将UI从滚动，缩放和拖动/平移更改为可接受，则可以实现：https://jsfiddle.net/jegn4x0f/5/

这是与原始问题具有相同背景的解决方案：

HTML：

<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>

<button id="zoom-out">Zoom out</button>

<div id="container">
  <div id="inner-container">
    <div id="zoom-container">
      <div class="box red">A</div>
      <div class="box blue">B</div>
      <div class="box green">C</div>
      <div class="box black">D</div>
    </div>
  </div>
</div>

JavaScript的：

//
// credit for the approach goes to
//
//   https://stackoverflow.com/questions/35252249/move-drag-pan-and-zoom-object-image-or-div-in-pure-js#comment58224460_35253567
//
// and the corresponding example:
//
//  https://jsfiddle.net/j8kLz6wm/1/
//

// in a real-world setting, you
// wouldn't keep this information
// on window. this is just for
// the demonstration.
window.zoomedIn = false;

// stores the initial translate values after clicking on a box
window.translateY = null;
window.translateX = null;

// stores the incremental translate values based on
// applying the initial translate values + delta
window.lastTranslateY = null;
window.lastTranslateX = null;

// cursor position relative to the container, at
// the time the drag started
window.dragStartX = null;
window.dragStartY = null;

var handleDragStart = function(element, xCursor, yCursor) {
  window.dragStartX = xCursor - element.offsetLeft;
  window.dragStartY = yCursor - element.offsetTop;

  // disable transition animations, since we're starting a drag
  $("#zoom-container").css("transition", "none");
};

var handleDragEnd = function() {
  window.dragStartX = null;
  window.dragStartY = null;
  // remove the individual element's styling for transitions
  // which brings back the stylesheet's default of animating.
  $("#zoom-container").css("transition", "");

  // keep track of the translate values we arrived at
  window.translateY = window.lastTranslateY;
  window.translateX = window.lastTranslateX;
};

var handleDragMove = function(xCursor, yCursor) {
  var deltaX = xCursor - window.dragStartX;
  var deltaY = yCursor - window.dragStartY;

  var translateY = window.translateY + (deltaY / 2);
  // the subtracted value here is to keep the letter in the center
  var translateX = window.translateX + (deltaX / 2) - (0.25 * $("#inner-container")[0].clientWidth);

  // fudge factor, probably because of percentage
  // width/height problems. couldn't really trace down
  // the underlying cause. hopefully the general approach
  // is clear, though.
  translateY -= 9;
  translateX -= 4;

  var innerContainer = $("#inner-container")[0];

  // cap all values to prevent infinity scrolling off the page
  if (translateY > 0.5 * innerContainer.clientHeight) {
    translateY = 0.5 * innerContainer.clientHeight;
  }

  if (translateX > 0.5 * innerContainer.clientWidth) {
    translateX = 0.5 * innerContainer.clientWidth;
  }

  if (translateY < -0.5 * innerContainer.clientHeight) {
    translateY = -0.5 * innerContainer.clientHeight;
  }

  if (translateX < -0.5 * innerContainer.clientWidth) {
    translateX = -0.5 * innerContainer.clientWidth;
  }

  // update the zoom container's translate values
  // based on the original + delta, capped to the
  // container's width and height.
  $("#zoom-container").css("transform", "translate(" + (2*translateX) + "px, " + (2*translateY) + "px) scale(2)");

  // keep track of the updated values for the next
  // touchmove event.
  window.lastTranslateX = translateX;
  window.lastTranslateY = translateY;
};

// Drag start -- touch version
$("#container").on("touchstart", function(event) {
  if (!window.zoomedIn) {
    return true;
  }

  var xCursor = event.originalEvent.changedTouches[0].clientX;
  var yCursor = event.originalEvent.changedTouches[0].clientY;

  handleDragStart(this, xCursor, yCursor);
});

// Drag start -- mouse version
$("#container").on("mousedown", function(event) {
  if (!window.zoomedIn) {
    return true;
  }

  var xCursor = event.clientX;
  var yCursor = event.clientY;

  handleDragStart(this, xCursor, yCursor);
});

// Drag end -- touch version
$("#inner-container").on("touchend", function(event) {
  if (!window.zoomedIn) {
    return true;
  }

  handleDragEnd();
});

// Drag end -- mouse version
$("#inner-container").on("mouseup", function(event) {
  if (!window.zoomedIn) {
    return true;
  }

  handleDragEnd();
});

// Drag move -- touch version
$("#inner-container").on("touchmove", function(event) {
  // prevent pull-to-refresh. could be smarter by checking
  // if the page's scroll y-offset is 0, and even smarter
  // by checking if we're pulling down, not up.
  event.preventDefault();

  if (!window.zoomedIn) {
    return true;
  }

  var xCursor = event.originalEvent.changedTouches[0].clientX;
  var yCursor = event.originalEvent.changedTouches[0].clientY;

  handleDragMove(xCursor, yCursor);
});

// Drag move -- click version
$("#inner-container").on("mousemove", function(event) {
  // prevent pull-to-refresh. could be smarter by checking
  // if the page's scroll y-offset is 0, and even smarter
  // by checking if we're pulling down, not up.
  event.preventDefault();

  // if we aren't dragging from anywhere, don't move
  if (!window.zoomedIn || !window.dragStartX) {
    return true;
  }

  var xCursor = event.clientX;
  var yCursor = event.clientY;

  handleDragMove(xCursor, yCursor);
});

var zoomInTo = function(element) {
  console.log("applying zoom");

  var top = element.offsetTop;
  // the subtracted value here is to keep the letter in the center
  var left = element.offsetLeft - (0.25 * $("#inner-container")[0].clientWidth);

  var translateY = 0.5 * $("#zoom-container")[0].clientHeight - top;
  var translateX = 0.5 * $("#zoom-container")[0].clientWidth - left;

  $("#container").css("overflow", "scroll");
  $("#zoom-container").css("transform", "translate(" + (2*translateX) + "px, " + (2*translateY) + "px) scale(2)");
  window.translateY = translateY;
  window.translateX = translateX;

  window.zoomedIn = true;
}

var zoomOut = function() {
  console.log("resetting zoom");

  window.zoomedIn = false;
  $("#zoom-container").css("transform", "");
  $("#zoom-container").css("transition", "");
  window.dragStartX = null;
  window.dragStartY = null;
  window.dragMoveJustHappened = null;
  window.translateY = window.lastTranslateY;
  window.translateX = window.lastTranslateX;
  window.lastTranslateX = null;
  window.lastTranslateY = null;
}

$(".box").click(function(event) {
  var element = this;
  var zoomContainer = $("#zoom-container");

  if (!window.zoomedIn) {
    zoomInTo(element);
  }
});

$("#zoom-out").click(function(event) {
  zoomOut();
});

CSS：

* {
  margin: 0;
}

body,
html {
  height: 100%;
}

#container {
  height: 100%;
  width: 50%;
  margin: 0 auto;
}

#inner-container {
  width: 100%;
  height: 100%;
}

#zoom-container {
  height: 100%;
  width: 100%;
  transition: transform 0.2s ease-in-out;
}

.box {
  float: left;
  width: 50%;
  height: 50%;
  color: white;
  text-align: center;
  display: block;
}

.red {
  background: red;
}

.blue {
  background: blue;
}

.green {
  background: green;
}

.black {
  background: black;
}

我将其与另一个问题（Move (drag/pan) and zoom object (image or div) in pure js）拼凑在一起，其中width和height正在被更改。这在我的情况下并不完全适用，因为我需要放大页面上的特定元素（有很多框而不是2x2网格）。该问题的解决方案（https://jsfiddle.net/j8kLz6wm/1/）显示了纯JavaScript中的基本方法。如果你有jQuery，你可以使用jquery.panzoom。

使用CSS transform scale（）放大元素而不进行裁剪，保持滚动

3 个答案: