La forma más sencilla de detectar un pellizco
Esta es una APLICACIÓN WEB no una aplicación nativa. Por favor, no hay comandos Objective-C NS.
Así que necesito detectar eventos 'pellizcar' en iOS. El problema es que cada plugin o método que veo para hacer gestos o eventos multi-touch, es (generalmente) con jQuery y es un complemento adicional para cada gesto bajo el sol. Mi aplicación es enorme, y soy muy sensible a deadwood en mi código. Todo lo que necesito es detectar un pellizco, y usar algo como jGesture es solo una forma de hincharse para mi simple requiere.
Además, tengo una comprensión limitada de cómo detectar un pellizco manualmente. Puedo conseguir la posición de ambos dedos, parece que no puedo conseguir la mezcla correcta para detectar esto. ¿Alguien tiene un fragmento simple que solo detecta pinch?
6 answers
Desea utilizar el gesturestart, gesturechange, y gestureend los eventos. Estos se activan cada vez que 2 o más dedos tocan la pantalla.
Dependiendo de lo que tenga que hacer con el gesto de pellizco, su enfoque tendrá que ser ajustado. El multiplicador scale se puede examinar para determinar qué tan dramático fue el gesto de pellizco del usuario. Consulte La documentación de TouchEvent de Apple para obtener detalles sobre cómo se comportará la propiedad scale.
node.addEventListener('gestureend', function(e) {
if (e.scale < 1.0) {
// User moved fingers closer together
} else if (e.scale > 1.0) {
// User moved fingers further apart
}
}, false);
También podrías interceptar el evento gesturechange para detectar un pellizco a medida que sucede si lo necesita para que su aplicación se sienta más receptiva.
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2017-01-04 18:20:36
Piense en lo que es un evento pinch: dos dedos sobre un elemento, moviéndose hacia o lejos uno del otro.
Los eventos de gestos son, que yo sepa, un estándar bastante nuevo, por lo que probablemente la forma más segura de hacerlo es usar eventos táctiles como estos:
(ontouchstart event)
if (e.touches.length === 2) {
scaling = true;
pinchStart(e);
}
(ontouchmove event)
if (scaling) {
pinchMove(e);
}
(ontouchend event)
if (scaling) {
pinchEnd(e);
scaling = false;
}
Para obtener la distancia entre los dos dedos, use la función hypot:
var dist = Math.hypot(
e.touches[0].pageX - e.touches[1].pageX,
e.touches[0].pageY - e.touches[1].pageY);
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2018-01-09 00:13:33
Martillo.js todo el camino! Maneja "transformaciones" (pellizcos). http://eightmedia.github.com/hammer.js /
Pero si desea implementarlo usted mismo, creo que la respuesta de Jeffrey es bastante sólida.
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2012-06-25 03:57:37
Desafortunadamente, detectar gestos de pellizco en los navegadores no es tan simple como uno esperaría, pero HammerJS lo hace mucho más fácil!
Echa un vistazo a la Pellizcar Zoom y Pan con HammerJS demo. Este ejemplo ha sido probado en Android, iOS y Windows Phone.
Puede encontrar el código fuente en Pinch Zoom y Pan con HammerJS.
Para su comodidad, aquí está el código fuente:
<!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>
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2016-07-22 16:12:33
Ninguna de estas respuestas logró lo que estaba buscando, así que terminé escribiendo algo yo mismo. Quería pellizcar-zoom una imagen en mi sitio web utilizando mi trackpad MacBookPro. El siguiente código (que requiere jQuery) parece funcionar en Chrome y Edge, al menos. Tal vez esto sea de utilidad para alguien más.
function setupImageEnlargement(el)
{
// "el" represents the image element, such as the results of document.getElementByd('image-id')
var img = $(el);
$(window, 'html', 'body').bind('scroll touchmove mousewheel', function(e)
{
//TODO: need to limit this to when the mouse is over the image in question
//TODO: behavior not the same in Safari and FF, but seems to work in Edge and Chrome
if (typeof e.originalEvent != 'undefined' && e.originalEvent != null
&& e.originalEvent.wheelDelta != 'undefined' && e.originalEvent.wheelDelta != null)
{
e.preventDefault();
e.stopPropagation();
console.log(e);
if (e.originalEvent.wheelDelta > 0)
{
// zooming
var newW = 1.1 * parseFloat(img.width());
var newH = 1.1 * parseFloat(img.height());
if (newW < el.naturalWidth && newH < el.naturalHeight)
{
// Go ahead and zoom the image
//console.log('zooming the image');
img.css(
{
"width": newW + 'px',
"height": newH + 'px',
"max-width": newW + 'px',
"max-height": newH + 'px'
});
}
else
{
// Make image as big as it gets
//console.log('making it as big as it gets');
img.css(
{
"width": el.naturalWidth + 'px',
"height": el.naturalHeight + 'px',
"max-width": el.naturalWidth + 'px',
"max-height": el.naturalHeight + 'px'
});
}
}
else if (e.originalEvent.wheelDelta < 0)
{
// shrinking
var newW = 0.9 * parseFloat(img.width());
var newH = 0.9 * parseFloat(img.height());
//TODO: I had added these data-attributes to the image onload.
// They represent the original width and height of the image on the screen.
// If your image is normally 100% width, you may need to change these values on resize.
var origW = parseFloat(img.attr('data-startwidth'));
var origH = parseFloat(img.attr('data-startheight'));
if (newW > origW && newH > origH)
{
// Go ahead and shrink the image
//console.log('shrinking the image');
img.css(
{
"width": newW + 'px',
"height": newH + 'px',
"max-width": newW + 'px',
"max-height": newH + 'px'
});
}
else
{
// Make image as small as it gets
//console.log('making it as small as it gets');
// This restores the image to its original size. You may want
//to do this differently, like by removing the css instead of defining it.
img.css(
{
"width": origW + 'px',
"height": origH + 'px',
"max-width": origW + 'px',
"max-height": origH + 'px'
});
}
}
}
});
}
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2017-10-13 15:19:12
Por si acaso, he estado trabajando en un mvp completo para este escenario, aquí es de código abierto :
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2017-06-30 22:16:04