fireonmac/index.html

## index.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport"
        content="user-scalable=no, width=device-width, initial-scale=1, maximum-scale=1">
  <title>Pinch Zoom</title>
</head>

<body>

  <div>

    <div style="height:150px;background-color:#eeeeee">
      Ignore this area. Space is needed to test on the iPhone simulator as pinch simulation on the
      iPhone simulator requires the target to be near the middle of the screen and we only respect
      touch events in the image area. This space is not needed in production.
    </div>

    <style>

      .pinch-zoom-container {
        overflow: hidden;
        height: 300px;
      }

      .pinch-zoom-image {
        width: 100%;
      }

    </style>

    <script src="https://hammerjs.github.io/dist/hammer.js"></script>

    <script>

      var MIN_SCALE = 1; // 1=scaling when first loaded
      var MAX_SCALE = 64;

      // HammerJS fires "pinch" and "pan" events that are cumulative in nature and not
      // deltas. Therefore, we need to store the "last" values of scale, x and y so that we can
      // adjust the UI accordingly. It isn't until the "pinchend" and "panend" events are received
      // that we can set the "last" values.

      // Our "raw" coordinates are not scaled. This allows us to only have to modify our stored
      // coordinates when the UI is updated. It also simplifies our calculations as these
      // coordinates are without respect to the current scale.

      var imgWidth = null;
      var imgHeight = null;
      var viewportWidth = null;
      var viewportHeight = null;
      var scale = null;
      var lastScale = null;
      var container = null;
      var img = null;
      var x = 0;
      var lastX = 0;
      var y = 0;
      var lastY = 0;
      var pinchCenter = null;

      // We need to disable the following event handlers so that the browser doesn't try to
      // automatically handle our image drag gestures.
      var disableImgEventHandlers = function () {
        var events = ['onclick', 'onmousedown', 'onmousemove', 'onmouseout', 'onmouseover',
                      'onmouseup', 'ondblclick', 'onfocus', 'onblur'];

        events.forEach(function (event) {
          img[event] = function () {
            return false;
          };
        });
      };

      // Traverse the DOM to calculate the absolute position of an element
      var absolutePosition = function (el) {
        var x = 0,
          y = 0;

        while (el !== null) {
          x += el.offsetLeft;
          y += el.offsetTop;
          el = el.offsetParent;
        }

        return { x: x, y: y };
      };

      var restrictScale = function (scale) {
        if (scale < MIN_SCALE) {
          scale = MIN_SCALE;
        } else if (scale > MAX_SCALE) {
          scale = MAX_SCALE;
        }
        return scale;
      };

      var restrictRawPos = function (pos, viewportDim, imgDim) {
        if (pos < viewportDim/scale - imgDim) { // too far left/up?
          pos = viewportDim/scale - imgDim;
        } else if (pos > 0) { // too far right/down?
          pos = 0;
        }
        return pos;
      };

      var updateLastPos = function (deltaX, deltaY) {
        lastX = x;
        lastY = y;
      };

      var translate = function (deltaX, deltaY) {
        // We restrict to the min of the viewport width/height or current width/height as the
        // current width/height may be smaller than the viewport width/height

        var newX = restrictRawPos(lastX + deltaX/scale,
                                  Math.min(viewportWidth, curWidth), imgWidth);
        x = newX;
        img.style.marginLeft = Math.ceil(newX*scale) + 'px';

        var newY = restrictRawPos(lastY + deltaY/scale,
                                  Math.min(viewportHeight, curHeight), imgHeight);
        y = newY;
        img.style.marginTop = Math.ceil(newY*scale) + 'px';
      };

      var zoom = function (scaleBy) {
        scale = restrictScale(lastScale*scaleBy);

        curWidth = imgWidth*scale;
        curHeight = imgHeight*scale;

        img.style.width = Math.ceil(curWidth) + 'px';
        img.style.height = Math.ceil(curHeight) + 'px';

        // Adjust margins to make sure that we aren't out of bounds
        translate(0, 0);
      };

      var rawCenter = function (e) {
        var pos = absolutePosition(container);

        // We need to account for the scroll position
        var scrollLeft = window.pageXOffset ? window.pageXOffset : document.body.scrollLeft;
        var scrollTop = window.pageYOffset ? window.pageYOffset : document.body.scrollTop;

        var zoomX = -x + (e.center.x - pos.x + scrollLeft)/scale;
        var zoomY = -y + (e.center.y - pos.y + scrollTop)/scale;

        return { x: zoomX, y: zoomY };
      };

      var updateLastScale = function () {
        lastScale = scale;
      };

      var zoomAround = function (scaleBy, rawZoomX, rawZoomY, doNotUpdateLast) {
        // Zoom
        zoom(scaleBy);

        // New raw center of viewport
        var rawCenterX = -x + Math.min(viewportWidth, curWidth)/2/scale;
        var rawCenterY = -y + Math.min(viewportHeight, curHeight)/2/scale;

        // Delta
        var deltaX = (rawCenterX - rawZoomX)*scale;
        var deltaY = (rawCenterY - rawZoomY)*scale;

        // Translate back to zoom center
        translate(deltaX, deltaY);

        if (!doNotUpdateLast) {
          updateLastScale();
          updateLastPos();
        }
      };

      var zoomCenter = function (scaleBy) {
        // Center of viewport
        var zoomX = -x + Math.min(viewportWidth, curWidth)/2/scale;
        var zoomY = -y + Math.min(viewportHeight, curHeight)/2/scale;

        zoomAround(scaleBy, zoomX, zoomY);
      };

      var zoomIn = function () {
        zoomCenter(2);
      };

      var zoomOut = function () {
        zoomCenter(1/2);
      };

      var onLoad = function () {

        img = document.getElementById('pinch-zoom-image-id');
        container = img.parentElement;

        disableImgEventHandlers();

        imgWidth = img.width;
        imgHeight = img.height;
        viewportWidth = img.offsetWidth;
        scale = viewportWidth/imgWidth;
        lastScale = scale;
        viewportHeight = img.parentElement.offsetHeight;
        curWidth = imgWidth*scale;
        curHeight = imgHeight*scale;

        var hammer = new Hammer(container, {
          domEvents: true
        });

        hammer.get('pinch').set({
          enable: true
        });

        hammer.on('pan', function (e) {
          translate(e.deltaX, e.deltaY);
        });

        hammer.on('panend', function (e) {
          updateLastPos();
        });

        hammer.on('pinch', function (e) {

          // We only calculate the pinch center on the first pinch event as we want the center to
          // stay consistent during the entire pinch
          if (pinchCenter === null) {
            pinchCenter = rawCenter(e);
            var offsetX = pinchCenter.x*scale - (-x*scale + Math.min(viewportWidth, curWidth)/2);
            var offsetY = pinchCenter.y*scale - (-y*scale + Math.min(viewportHeight, curHeight)/2);
            pinchCenterOffset = { x: offsetX, y: offsetY };
          }

          // When the user pinch zooms, she/he expects the pinch center to remain in the same
          // relative location of the screen. To achieve this, the raw zoom center is calculated by
          // first storing the pinch center and the scaled offset to the current center of the
          // image. The new scale is then used to calculate the zoom center. This has the effect of
          // actually translating the zoom center on each pinch zoom event.
          var newScale = restrictScale(scale*e.scale);
          var zoomX = pinchCenter.x*newScale - pinchCenterOffset.x;
          var zoomY = pinchCenter.y*newScale - pinchCenterOffset.y;
          var zoomCenter = { x: zoomX/newScale, y: zoomY/newScale };

          zoomAround(e.scale, zoomCenter.x, zoomCenter.y, true);
        });

        hammer.on('pinchend', function (e) {
          updateLastScale();
          updateLastPos();
          pinchCenter = null;
        });

        hammer.on('doubletap', function (e) {
          var c = rawCenter(e);
          zoomAround(2, c.x, c.y);
        });

      };

    </script>

    <button onclick="zoomIn()">Zoom In</button>
    <button onclick="zoomOut()">Zoom Out</button>

    <div class="pinch-zoom-container">
      <img id="pinch-zoom-image-id" class="pinch-zoom-image" onload="onLoad()"
           src="https://hammerjs.github.io/assets/img/pano-1.jpg">
    </div>


  </div>

</body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<meta name="viewport"
	content="user-scalable=no, width=device-width, initial-scale=1, maximum-scale=1">
	<title>Pinch Zoom</title>
	</head>

	<body>

	<div>

	<div style="height:150px;background-color:#eeeeee">
	Ignore this area. Space is needed to test on the iPhone simulator as pinch simulation on the
	iPhone simulator requires the target to be near the middle of the screen and we only respect
	touch events in the image area. This space is not needed in production.
	</div>

	<style>

	.pinch-zoom-container {
	overflow: hidden;
	height: 300px;
	}

	.pinch-zoom-image {
	width: 100%;
	}

	</style>

	<script src="https://hammerjs.github.io/dist/hammer.js"></script>

	<script>

	var MIN_SCALE = 1; // 1=scaling when first loaded
	var MAX_SCALE = 64;

	// HammerJS fires "pinch" and "pan" events that are cumulative in nature and not
	// deltas. Therefore, we need to store the "last" values of scale, x and y so that we can
	// adjust the UI accordingly. It isn't until the "pinchend" and "panend" events are received
	// that we can set the "last" values.

	// Our "raw" coordinates are not scaled. This allows us to only have to modify our stored
	// coordinates when the UI is updated. It also simplifies our calculations as these
	// coordinates are without respect to the current scale.

	var imgWidth = null;
	var imgHeight = null;
	var viewportWidth = null;
	var viewportHeight = null;
	var scale = null;
	var lastScale = null;
	var container = null;
	var img = null;
	var x = 0;
	var lastX = 0;
	var y = 0;
	var lastY = 0;
	var pinchCenter = null;

	// We need to disable the following event handlers so that the browser doesn't try to
	// automatically handle our image drag gestures.
	var disableImgEventHandlers = function () {
	var events = ['onclick', 'onmousedown', 'onmousemove', 'onmouseout', 'onmouseover',
	'onmouseup', 'ondblclick', 'onfocus', 'onblur'];

	events.forEach(function (event) {
	img[event] = function () {
	return false;
	};
	});
	};

	// Traverse the DOM to calculate the absolute position of an element
	var absolutePosition = function (el) {
	var x = 0,
	y = 0;

	while (el !== null) {
	x += el.offsetLeft;
	y += el.offsetTop;
	el = el.offsetParent;
	}

	return { x: x, y: y };
	};

	var restrictScale = function (scale) {
	if (scale < MIN_SCALE) {
	scale = MIN_SCALE;
	} else if (scale > MAX_SCALE) {
	scale = MAX_SCALE;
	}
	return scale;
	};

	var restrictRawPos = function (pos, viewportDim, imgDim) {
	if (pos < viewportDim/scale - imgDim) { // too far left/up?
	pos = viewportDim/scale - imgDim;
	} else if (pos > 0) { // too far right/down?
	pos = 0;
	}
	return pos;
	};

	var updateLastPos = function (deltaX, deltaY) {
	lastX = x;
	lastY = y;
	};

	var translate = function (deltaX, deltaY) {
	// We restrict to the min of the viewport width/height or current width/height as the
	// current width/height may be smaller than the viewport width/height

	var newX = restrictRawPos(lastX + deltaX/scale,
	Math.min(viewportWidth, curWidth), imgWidth);
	x = newX;
	img.style.marginLeft = Math.ceil(newX*scale) + 'px';

	var newY = restrictRawPos(lastY + deltaY/scale,
	Math.min(viewportHeight, curHeight), imgHeight);
	y = newY;
	img.style.marginTop = Math.ceil(newY*scale) + 'px';
	};

	var zoom = function (scaleBy) {
	scale = restrictScale(lastScale*scaleBy);

	curWidth = imgWidth*scale;
	curHeight = imgHeight*scale;

	img.style.width = Math.ceil(curWidth) + 'px';
	img.style.height = Math.ceil(curHeight) + 'px';

	// Adjust margins to make sure that we aren't out of bounds
	translate(0, 0);
	};

	var rawCenter = function (e) {
	var pos = absolutePosition(container);

	// We need to account for the scroll position
	var scrollLeft = window.pageXOffset ? window.pageXOffset : document.body.scrollLeft;
	var scrollTop = window.pageYOffset ? window.pageYOffset : document.body.scrollTop;

	var zoomX = -x + (e.center.x - pos.x + scrollLeft)/scale;
	var zoomY = -y + (e.center.y - pos.y + scrollTop)/scale;

	return { x: zoomX, y: zoomY };
	};

	var updateLastScale = function () {
	lastScale = scale;
	};

	var zoomAround = function (scaleBy, rawZoomX, rawZoomY, doNotUpdateLast) {
	// Zoom
	zoom(scaleBy);

	// New raw center of viewport
	var rawCenterX = -x + Math.min(viewportWidth, curWidth)/2/scale;
	var rawCenterY = -y + Math.min(viewportHeight, curHeight)/2/scale;

	// Delta
	var deltaX = (rawCenterX - rawZoomX)*scale;
	var deltaY = (rawCenterY - rawZoomY)*scale;

	// Translate back to zoom center
	translate(deltaX, deltaY);

	if (!doNotUpdateLast) {
	updateLastScale();
	updateLastPos();
	}
	};

	var zoomCenter = function (scaleBy) {
	// Center of viewport
	var zoomX = -x + Math.min(viewportWidth, curWidth)/2/scale;
	var zoomY = -y + Math.min(viewportHeight, curHeight)/2/scale;

	zoomAround(scaleBy, zoomX, zoomY);
	};

	var zoomIn = function () {
	zoomCenter(2);
	};

	var zoomOut = function () {
	zoomCenter(1/2);
	};

	var onLoad = function () {

	img = document.getElementById('pinch-zoom-image-id');
	container = img.parentElement;

	disableImgEventHandlers();

	imgWidth = img.width;
	imgHeight = img.height;
	viewportWidth = img.offsetWidth;
	scale = viewportWidth/imgWidth;
	lastScale = scale;
	viewportHeight = img.parentElement.offsetHeight;
	curWidth = imgWidth*scale;
	curHeight = imgHeight*scale;

	var hammer = new Hammer(container, {
	domEvents: true
	});

	hammer.get('pinch').set({
	enable: true
	});

	hammer.on('pan', function (e) {
	translate(e.deltaX, e.deltaY);
	});

	hammer.on('panend', function (e) {
	updateLastPos();
	});

	hammer.on('pinch', function (e) {

	// We only calculate the pinch center on the first pinch event as we want the center to
	// stay consistent during the entire pinch
	if (pinchCenter === null) {
	pinchCenter = rawCenter(e);
	var offsetX = pinchCenter.xscale - (-xscale + Math.min(viewportWidth, curWidth)/2);
	var offsetY = pinchCenter.yscale - (-yscale + Math.min(viewportHeight, curHeight)/2);
	pinchCenterOffset = { x: offsetX, y: offsetY };
	}

	// When the user pinch zooms, she/he expects the pinch center to remain in the same
	// relative location of the screen. To achieve this, the raw zoom center is calculated by
	// first storing the pinch center and the scaled offset to the current center of the
	// image. The new scale is then used to calculate the zoom center. This has the effect of
	// actually translating the zoom center on each pinch zoom event.
	var newScale = restrictScale(scale*e.scale);
	var zoomX = pinchCenter.x*newScale - pinchCenterOffset.x;
	var zoomY = pinchCenter.y*newScale - pinchCenterOffset.y;
	var zoomCenter = { x: zoomX/newScale, y: zoomY/newScale };

	zoomAround(e.scale, zoomCenter.x, zoomCenter.y, true);
	});

	hammer.on('pinchend', function (e) {
	updateLastScale();
	updateLastPos();
	pinchCenter = null;
	});

	hammer.on('doubletap', function (e) {
	var c = rawCenter(e);
	zoomAround(2, c.x, c.y);
	});

	};

	</script>

	<button onclick="zoomIn()">Zoom In</button>
	<button onclick="zoomOut()">Zoom Out</button>

	<div class="pinch-zoom-container">
	<img id="pinch-zoom-image-id" class="pinch-zoom-image" onload="onLoad()"
	src="https://hammerjs.github.io/assets/img/pano-1.jpg">
	</div>


	</div>

	</body>
	</html>