This is a WEB APP not a native app. Please no Objective-C NS commands.
So I need to detect 'pinch' events on iOS. Problem is every plugin or method I see for doing gestures or multi-touch events, is (usually) with jQuery and is a whole additional pluggin for every gesture under the sun. My application is huge, and I am very sensitive to deadwood in my code. All I need is to detect a pinch, and using something like jGesture is just way to bloated for my simple needs.
Additionally, I have a limited understanding of how to detect a pinch manually. I can get the position of both fingers, can't seem to get the mix right to detect this. Does anyone have a simple snippet that JUST detects pinch?
Think about what a pinch event is: two fingers on an element, moving toward or away from each other.
Gesture events are, to my knowledge, a fairly new standard, so probably the safest way to go about this is to use touch events like so:
(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;
}
To get the distance between the two fingers, use the hypot function:
var dist = Math.hypot(
e.touches[0].pageX - e.touches[1].pageX,
e.touches[0].pageY - e.touches[1].pageY);
You want to use the gesturestart, gesturechange, and gestureend events. These get triggered any time 2 or more fingers touch the screen.
Depending on what you need to do with the pinch gesture, your approach will need to be adjusted. The scale multiplier can be examined to determine how dramatic the user's pinch gesture was. See Apple's TouchEvent documentation for details about how the scale property will behave.
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);
You could also intercept the gesturechange event to detect a pinch as it happens if you need it to make your app feel more responsive.
Hammer.js all the way! It handles "transforms" (pinches).
http://eightmedia.github.com/hammer.js/
But if you wish to implement it youself, i think that Jeffrey's answer is pretty solid.
Unfortunately, detecting pinch gestures across browsers is a not as simple as one would hope, but HammerJS makes it a lot easier!
Check out the Pinch Zoom and Pan with HammerJS demo. This example has been tested on Android, iOS and Windows Phone.
You can find the source code at Pinch Zoom and Pan with HammerJS.
For your convenience, here is the source code:
<!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>
detect two fingers pinch zoom on any element, easy and w/o hassle with 3rd party libs like Hammer.js (beware, hammer has issues with scrolling!)
function onScale(el, callback) {
let hypo = undefined;
el.addEventListener('touchmove', function(event) {
if (event.targetTouches.length === 2) {
let hypo1 = Math.hypot((event.targetTouches[0].pageX - event.targetTouches[1].pageX),
(event.targetTouches[0].pageY - event.targetTouches[1].pageY));
if (hypo === undefined) {
hypo = hypo1;
}
callback(hypo1/hypo);
}
}, false);
el.addEventListener('touchend', function(event) {
hypo = undefined;
}, false);
}
The simplest way is to respond to the 'wheel' event.
You need to call ev.preventDefault() to prevent the browser from doing a full screen zoom.
Browsers synthesize the 'wheel' event for pinches on a trackpad, and as a bonus you also handle mouse wheel events. This is the way mapping applications handle it.
More details in my example:
let element = document.getElementById('el');
let scale = 1.0;
element.addEventListener('wheel', (ev) => {
// This is crucial. Without it, the browser will do a full page zoom
ev.preventDefault();
// This is an empirically determined heuristic.
// Unfortunately I don't know of any way to do this better.
// Typical deltaY values from a trackpad pinch are under 1.0
// Typical deltaY values from a mouse wheel are more than 100.
let isPinch = Math.abs(ev.deltaY) < 50;
if (isPinch) {
// This is a pinch on a trackpad
let factor = 1 - 0.01 * ev.deltaY;
scale *= factor;
element.innerText = `Pinch: scale is ${scale}`;
} else {
// This is a mouse wheel
let strength = 1.4;
let factor = ev.deltaY < 0 ? strength : 1.0 / strength;
scale *= factor;
element.innerText = `Mouse: scale is ${scale}`;
}
});
<div id='el' style='width:400px; height:300px; background:#ffa'>
Scale: 1.0
</div>
None of these answers achieved what I was looking for, so I wound up writing something myself. I wanted to pinch-zoom an image on my website using my MacBookPro trackpad. The following code (which requires jQuery) seems to work in Chrome and Edge, at least. Maybe this will be of use to someone else.
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'
});
}
}
}
});
}
My answer is inspired by Jeffrey's answer. Where that answer gives a more abstract solution, I try to provide more concrete steps on how to potentially implement it. This is simply a guide, one that can be implemented more elegantly. For a more detailed example check out this tutorial by MDN web docs.
HTML:
<div id="zoom_here">....</div>
JS
<script>
var dist1=0;
function start(ev) {
if (ev.targetTouches.length == 2) {//check if two fingers touched screen
dist1 = Math.hypot( //get rough estimate of distance between two fingers
ev.touches[0].pageX - ev.touches[1].pageX,
ev.touches[0].pageY - ev.touches[1].pageY);
}
}
function move(ev) {
if (ev.targetTouches.length == 2 && ev.changedTouches.length == 2) {
// Check if the two target touches are the same ones that started
var dist2 = Math.hypot(//get rough estimate of new distance between fingers
ev.touches[0].pageX - ev.touches[1].pageX,
ev.touches[0].pageY - ev.touches[1].pageY);
//alert(dist);
if(dist1>dist2) {//if fingers are closer now than when they first touched screen, they are pinching
alert('zoom out');
}
if(dist1<dist2) {//if fingers are further apart than when they first touched the screen, they are making the zoomin gesture
alert('zoom in');
}
}
}
document.getElementById ('zoom_here').addEventListener ('touchstart', start, false);
document.getElementById('zoom_here').addEventListener('touchmove', move, false);
</script>
Its same as commented by Jeffrey Sweeney, Full example to how to implement in your class.
this.touch.isPinch = false;
this.touc.pinchStart = 0;
this.touch.onTouchStart = (e) => {
if (e.touches.length === 2) {
this.touch.pinchStart = Math.hypot(e.touches[0].pageX - e.touches[1].pageX, e.touches[0].pageY - e.touches[1].pageY);
this.touch.isScaling = true;
}
}
this.touch.onTouchMove = (e) => {
if (this.touch.isScaling) {
const distance = Math.hypot(e.touches[0].pageX - e.touches[1].pageX, e.touches[0].pageY - e.touches[1].pageY);
if (this.touch.pinchStart >= 200 && distance <= 90) this.touchPichOut(); //call function for pinchOut
if (this.touch.pinchStart <= 100 && distance >= 280) this.touchPichIn(); //call function for pinchIn
}
}
this.touch.onTouchCancel = (e) => {
this.touch.isScaling = false;
}
this.touch.onTouchEnd = (e) => {
if (this.touch.isScaling) this.touch.isScaling = false;
}
Regards
Related
if the mouse goes out of canvas and mouse move in -x -y axis , I want disable pan.
how can i disable viewpoint -x -y axis.
this is my code.
var panning = false;
canvas.on('mouse:up', function (e) {
if (isPaningMode) {
panning = false;
}
});
canvas.on('mouse:out', function (e) {
if (isPaningMode) {
panning = false;
}
});
canvas.on('mouse:down', function (e) {
if (isPaningMode) {
panning = true;
}
});
canvas.on('mouse:move', function (e) {
canvas.selection = !isPaningMode;
if (isPaningMode && e && e.e && panning) {
var units = 10;
var delta = new fabric.Point(e.e.movementX, e.e.movementY);
canvas.relativePan(delta);
}
});
Thank you, sorry i cant speak english well. :(
Edit
my canvas is size : 800x800
I just want to use the red striped area. I do not want to use sections with X. I do not want them to be shown by scrolling in these fields. I did what I said for the objects. But I could not do it for panning. In short, I want to panning only in the direction of the arrow.
Make sure you're using the latest version of FabricJS, they are continually improving it. I noticed in the past that canvas.on('mouse:out') was targeting objects and not the canvas.
Here's a working JSFiddle, https://jsfiddle.net/rekrah/bvgLvd3u/.
I'm assuming this was the issue because you were already disabling panning on mouse-out of the canvas.
canvas.on('mouse:out', function(e) {
if (isPaningMode) {
panning = false;
}
});
Let me know if I miss understood your English - which is very good, by-the-way!
After Your Edit
Bulk of the change is in the mouse-move event. In summary: Keeping track of the distance moved so we know where we started from, to get back to (with a tweak, if needed) - hope that makes sense???
var deltaX = 0;
var deltaY = 0;
canvas.on('mouse:move', function(e) {
if (isPaningMode && e && e.e && panning) {
moveX = e.e.movementX;
if (deltaX >= 0) {
deltaX -= moveX;
if (deltaX < 0) {
moveX = deltaX + moveX;
deltaX = 0;
}
}
moveY = e.e.movementY;
if (deltaY >= 0) {
deltaY -= moveY;
if (deltaY < 0) {
moveY = deltaY + moveY;
deltaY = 0;
}
}
if (deltaX >= 0 && deltaY >= 0) {
canvas.relativePan(new fabric.Point(moveX, moveY));
}
}
});
Here's a new, updated, and working :) JSFiddle, https://jsfiddle.net/rekrah/r3gm3uh9/.
I've written a function in Javascript to make images draggable within a container. Even if the image is enlarged it can be dragged all over the screen without disappearing from it. My function relies heaving on using style.top and style.left. Now I've heard that using translate3d might provide better performance. This is interesting because I changed my image scale function, which uses a slider, to scale3d and the scaling is clearly smoother, no doubt. So could anyone help me convert this function I've written to use translate3d? I've tried and tried but have kept failing. Many Thanks:
EDIT: I put up a jsfiddle
https://jsfiddle.net/bx4073tr/
Please note that imgRect is the parent div while img is the image itself (it's in an img tag contained in the div).
function makeImageDraggable(event) {
// Make an image draggable but within bounds of container
let overflow_vertical = false;
let overflow_horizontal = false;
// bounding rectangles to hold image and imageContainer
let imgRect = img.getBoundingClientRect();
let imgContainerRect = imageContainer.getBoundingClientRect();
// find out if image overflows it's container div
// check for vertical overflow, getBoundingClientRect().height will get the real height after the image is scaled
if ( imgRect.height > imageContainer.offsetHeight ) {
overflow_vertical = true;
}
// check for horizontal overflow
if ( imgRect.width > imageContainer.offsetWidth ) {
overflow_horizontal = true;
}
// if there is no overflow, either horizontal or vertical, then do absolutely nothing
if (!overflow_horizontal && !overflow_vertical) {
// nothing to do
} else {
// otherwise make image draggable
event = event || window.event;
// get initial mouse position
let startX = event.clientX;
let startY = event.clientY;
// get position of image to be dragged
let offsetX = pixelToFloat(img.style.left);
let offsetY = pixelToFloat(img.style.top);
// add onmousemove event now we are sure user has initiated a mousedown event
window.onmousemove = function(mousemove_event) {
if (mousemove_event == null) {
mousemove_event = window.event;
}
// calculate bounds so that image does not go off the page
// if there is an overflow, the image will be bigger than the container
// so we need to find the maximum distance we can go upwards, downwards and sideways
// using img.getBoundingClientRect, we can get the width of the scaled image, we also get the width of the container
// divide it by 2 so we can move the same number of pixels in either direction
// max right and left
let max_right = -1 * ( ((imgRect.right - imgRect.left) - (imgContainerRect.right - imgContainerRect.left))/2 );
// should be a positive number
let max_left = -1 * (max_right);
// max bottom and top
let max_bottom = -1 * ( ((imgRect.bottom - imgRect.top) - (imgContainerRect.bottom - imgContainerRect.top))/2 );
// should be a positive number
let max_top = -1 * (max_bottom);
// Dragging image left and right
if (!overflow_horizontal) {
} else {
let scrollX = (offsetX + mousemove_event.clientX - startX);
// img.style.left will keep increasing or decreasing, check if it approaches max_left or max_right
if (scrollX >= max_left || scrollX <= max_right) {
//return false;imageContainer.style.webkitTransform = 'translate3d(' + newX + 'px,' + newY + 'px, 0)';
} else {
if (scrollX < max_left) { img.style.left = min(scrollX, max_left) + 'px'; }
if (scrollX > max_right) { img.style.left = max(scrollX, max_right) + 'px'; }
}
}
// Dragging image top to bottom
if (!overflow_vertical) {
} else {
let scrollY = (offsetY + mousemove_event.clientY - startY);
// as an expanded image is pulled downwards, img.style.top keeps increasing to approach max_top
// if it reaches max top, simply do nothing, else keep increasing
// check for both conditions, approaching max_top and approaching max_bottom
if (scrollY >= max_top || scrollY <= max_bottom) {
// return false;
} else {
if (scrollY < max_top) { img.style.top = min(scrollY, max_top) + 'px'; }
if (scrollY > max_bottom) { img.style.top = max(scrollY, max_bottom) + 'px'; }
}
}
// return
return false;
}
}
// cancel mousemove event on mouseup
window.onmouseup = function(mouseup_event) {
window.onmousemove = null;
// Should not return false as it will interfere with range slider
}
// return false
return false;
}
Works now.
See makeDraggable method in the fiddle below:
https://jsfiddle.net/daibatzu/0u74faz6/6/
All you have to do is add this function to the event listener for the image like:
var img = document.getElementById('myImage');
img.addEventListener('mousedown', function(event) { makeDraggable(event); });
Code
function makeDraggable(event) {
// get bounding rectangle
let imgRect = img.getBoundingClientRect();
let parentRect = parent.getBoundingClientRect();
// check overflow
let overflow_horizontal = (imgRect.width > parent.offsetWidth ? true : false);
let overflow_vertical = (imgRect.height > parent.offsetHeight ? true : false);
// get start position
let startX = event.pageX - translateX, startY = event.pageY - translateY;
let max_left = parentRect.left - imgRect.left;
let max_top = parentRect.top - imgRect.top;
window.onmousemove = function(evt) {
// set event object
if (evt == null) { evt = window.event; }
// Say max_left is 160px, this means we can only translate from 160px to -160px to keep the image visible
// so we check if the image moves beyond abs(160), if it does, set it to 160 or -160 depending on direction, else, let it continue
translateX = (Math.abs(evt.pageX - startX) >= max_left ? (max_left * Math.sign(evt.pageX - startX)) : (evt.pageX - startX));
translateY = (Math.abs(evt.pageY - startY) >= max_top ? (max_top * Math.sign(evt.pageY - startY)) : (evt.pageY - startY));
// check if scaled image width is greater than it's container. if it isn't set translateX to zero and so on
translateX = overflow_horizontal ? translateX : 0, translateY = overflow_vertical ? translateY : 0;
// translate parent div
parent.style['-webkit-transform'] = 'translate(' + translateX + 'px, ' + translateY + 'px)';
// return
return false;
}
window.onmouseup = function(evt) {
// set mousemove event to null
window.onmousemove = null;
}
return false;
};
I'm playing a bit with AMI Medical Imaging (AMI) JS ToolKit. Is there a way to move the windowing to a mouse event like right click & move?
I know that it's possible to change window/level with the menus on the examples, but I would like to change the controller to do it moving the mouse.
Thanks!
To control the window/level by moving the mouse you will have to listen to the mousemouve event then update the stackHelper -> slice -> windowWidth/Center as you wish.
You could enable window/level if the user press shift:
var drag = {
x: null,
y: null
}
var shiftDown = false;
function onKeyPressed(event){
shiftDown = event.shiftKey;
if(!shiftDown){
drag.x = null;
drag.y = null;
}
}
container.addEventListener('keydown', onKeyPressed);
container.addEventListener('keyup', onKeyPressed);
Then update the window/level on mouse move:
function onMouseMove(event){
if(!shiftDown || !stack || !stackHelper){
return;
}
if(drag.x === null){
drag.x = event.offsetX;
drag.y = event.offsetY;
}
var threshold = 15;
var dynamicRange = stack.minMax[1] - stack.minMax[0];
dynamicRange /= container.clientWidth;
if(Math.abs(event.offsetX - drag.x) > threshold){
// window width
stackHelper.slice.windowWidth += dynamicRange * (event.offsetX - drag.x);
drag.x = event.offsetX;
}
if(Math.abs(event.offsetY - drag.y) > threshold){
// window center
stackHelper.slice.windowCenter -= dynamicRange * (event.offsetY - drag.y);
drag.y = event.offsetY;
}
}
container.addEventListener('mousemove', onMouseMove);
See a live demo at (shift + mouse move to control the window level):
http://jsfiddle.net/vabL3qo0/41/
I'm looking to make something exactly like Facebook's Android app's UX for swiping between News Feed, Friend Requests, Messages, and Notifications. You should be able to "peek" at the next view by panning to the right of left, and it should snap to the next page when released if some threshold has been passed or when swiped.
Every scroll snap solution I've seen only snaps after the scrolling stops, whereas I only ever want to scroll one page at a time.
EDIT: Here's what I have so far. It seems to work fine when emulating an Android device in Google Chrome, but doesn't work when I run it on my Galaxy S4 running 4.4.2. Looking into it a bit more, it looks like touchcancel is being fired right after the first touchmove event which seems like a bug. Is there any way to get around this?
var width = parseInt($(document.body).width());
var panThreshold = 0.15;
var currentViewPage = 0;
$('.listContent').on('touchstart', function(e) {
console.log("touchstart");
currentViewPage = Math.round(this.scrollLeft / width);
});
$('.listContent').on('touchend', function(e) {
console.log("touchend");
var delta = currentViewPage * width - this.scrollLeft;
if (Math.abs(delta) > width * panThreshold) {
if (delta < 0) {
currentViewPage++;
} else {
currentViewPage--;
}
}
$(this).animate({
scrollLeft: currentViewPage * width
}, 100);
});
In case anyone wants to do this in the future, the only way I found to actually do this was to manually control all touch events and then re-implement the normally-native vertical scrolling.
It might not be the prettiest, but here's a fiddle to what I ended up doing (edited to use mouse events instead of touch events): http://jsfiddle.net/xtwzcjhL/
$(function () {
var width = parseInt($(document.body).width());
var panThreshold = 0.15;
var currentViewPage = 0;
var start; // Screen position of touchstart event
var isHorizontalScroll = false; // Locks the scrolling as horizontal
var target; // Target of the first touch event
var isFirst; // Is the first touchmove event
var beginScrollTop; // Beginning scrollTop of ul
var atanFactor = 0.6; // atan(0.6) = ~31 degrees (or less) from horizontal to be considered a horizontal scroll
var isMove = false;
$('body').on('mousedown', '.listContent', function (e) {
isMove = true;
isFirst = true;
isHorizontalScroll = false;
target = $(this);
currentViewPage = Math.round(target.scrollLeft() / width);
beginScrollTop = target.closest('ul').scrollTop();
start = {
x: e.originalEvent.screenX,
y: e.originalEvent.screenY
}
}).on('mousemove', '.listContent', function (e) {
if (!isMove) {
return false;
}
e.preventDefault();
var delta = {
x: start.x - e.originalEvent.screenX,
y: start.y - e.originalEvent.screenY
}
// If already horizontally scrolling or the first touchmove is within the atanFactor, horizontally scroll, otherwise it's a vertical scroll of the ul
if (isHorizontalScroll || (isFirst && Math.abs(delta.x * atanFactor) > Math.abs(delta.y))) {
isHorizontalScroll = true;
target.scrollLeft(currentViewPage * width + delta.x);
} else {
target.closest('ul').scrollTop(beginScrollTop + delta.y);
}
isFirst = false;
}).on('mouseup mouseout', '.listContent', function (e) {
isMove = false;
isFirst = false;
if (isHorizontalScroll) {
var delta = currentViewPage * width - target.scrollLeft();
if (Math.abs(delta) > width * panThreshold) {
if (delta < 0) {
currentViewPage++;
} else {
currentViewPage--;
}
}
$(this).animate({
scrollLeft: currentViewPage * width
}, 100);
}
});
});
I am using JavaScript and trying to make a skew effect on a div.
First, take a look at this video: http://www.youtube.com/watch?v=ny5Uy81smpE (0:40-0:60 should be enough). The video shows some nice transformations (skew) when you move the window. What I want to do is the same thing: to skew a div when I move it.
Currently I just have a plain simple div:
<div id="a" style="background: #0f0; position: absolute; left: 0px; top: 0px;"></div>
I have done a simple skew transformation using the CSS3's transform property, but my implementation is buggy. Are there good tutorials or maths sites or resources that describe the logic behind this? I know JavaScript and CSS well enough to implement, if I just knew the logic and maths. I tried reading FreeWins source code, but I am not good in C.
I am accepting any resourceful answers or pseudo code. My dragging system is part of a bigger system, thus, now that I post some real code, it does not work without giving you the entire system (that I can not do at this point). So, you can't run this code as is. The code I use is this (slightly modified though) to demonstrate my idea:
/**
* The draggable object.
*/
Draggable = function(targetElement, options) {
this.targetElement = targetElement;
// Initialize drag data.
this.dragData = {
startX: null,
startY: null,
lastX: null,
lastY: null,
offsetX: null,
offsetY: null,
lastTime: null,
occuring: false
};
// Set the cursor style.
targetElement.style.cursor = 'move';
// The element to move.
this.applyTo = options.applyTo || targetElement;
// Event methods for "mouse down", "up" and "move".
// Mouse up and move are binded to window.
// We can attach and deattach "move" and "up" events as needed.
var me = this;
targetElement.addEventListener('mousedown', function(event) {
me.onMouseDown.call(me, event);
}, false);
this.mouseUp = function(event) {
me.onMouseUp.call(me, event);
};
this.mouseMove = function(event) {
me.onMouseMove.call(me, event);
};
};
/**
* The mouse down event.
* #param {Object} event
*/
Draggable.prototype.onMouseDown = function(event) {
// New drag event.
if (this.dragData.occuring === false) {
this.dragData.occuring = true;
this.dragData.startX = this.dragData.lastX = event.clientX;
this.dragData.startY = this.dragData.lastY = event.clientY;
this.dragData.offsetX = parseInt(this.applyTo.style.left, 10) - event.clientX;
this.dragData.offsetY = parseInt(this.applyTo.style.top, 10) - event.clientY;
this.dragData.lastTime = (new Date()).getTime();
// Mouse up and move events.
var me = this;
window.addEventListener('mousemove', this.mouseMove, false);
window.addEventListener('mouseup', this.mouseUp, false);
}
};
/**
* The mouse movement event.
* #param {Object} event
*/
Draggable.prototype.onMouseMove = function(event) {
if (this.dragData.occuring === true) {
// He is dragging me now, we move if there is need for that.
var moved = (this.dragData.lastX !== event.clientX || this.dragData.lastY !== event.clientY);
if (moved === true) {
var element = this.applyTo;
// The skew animation. :)
var skew = (this.dragData.lastX - event.clientX) * 1;
var limit = 25;
if (Math.abs(skew) > limit) {
skew = limit * (skew > 0 ? 1 : -1);
}
var transform = 'translateX(' + (event.clientX + this.dragData.offsetX - parseInt(element.style.left, 10)) + 'px)';
transform += 'translateY(' + (event.clientY + this.dragData.offsetY - parseInt(element.style.top, 10)) + 'px)';
transform += 'skew(' + skew + 'deg)';
element.style.MozTransform = transform;
element.style.webkitTransform = transform;
this.dragData.lastX = event.clientX;
this.dragData.lastY = event.clientY;
this.dragData.lastTime = (new Date()).getTime();
}
}
};
/**
* The mouse up event.
* #param {Object} event
*/
Draggable.prototype.onMouseUp = function(event) {
this.dragData.occuring = false;
var element = this.applyTo;
// Reset transformations.
element.style.MozTransform = '';
element.style.webkitTransform = '';
// Save the new position.
element.style.left = (this.dragData.lastX + this.dragData.offsetX) + 'px';
element.style.top = (this.dragData.lastY + this.dragData.offsetY) + 'px';
// Remove useless events.
window.removeEventListener('mousemove', this.mouseMove, false);
window.removeEventListener('mousemove', this.mouseUp, false);
};
Currently my dragging system is buggy and simple. I need more information on the logic that I should be applying.
Wow, the idea rocks. :) I've cleaned your code a bit, and solved the problems with initialization. Now it works fine for me on Firefox and Chrome (even though you said it shouldn't).
A few notes:
you need to grab the starting top and left positions during initialization (getBoundingClientRect)
store references like this.dragData and element.style for shortness and faster execution
dragData can be initialized as an empty object. It's fine in javascript. You can add properties later.
options should be conditionally initialized as an empty object, so that you can take zero options
moved and dragData.occuring were totally useless because of the event management
preventDefault is needed in order not to select text during dragging
you may want to keep track of z-indexes to be the active element always visible
Have fun!
Code [See it in action]
/**
* The draggable object.
*/
Draggable = function(targetElement, options) {
this.targetElement = targetElement;
// we can take zero options
options = options || {};
// Initialize drag data.
// #props: startX, startY, lastX, lastY,
// offsetX, offsetY, lastTime, occuring
this.dragData = {};
// Set the cursor style.
targetElement.style.cursor = 'move';
// The element to move.
var el = this.applyTo = options.applyTo || targetElement;
// Event methods for "mouse down", "up" and "move".
// Mouse up and move are binded to window.
// We can attach and deattach "move" and "up" events as needed.
var me = this;
targetElement.addEventListener('mousedown', function(event) {
me.onMouseDown.call(me, event);
}, false);
this.mouseUp = function(event) {
me.onMouseUp.call(me, event);
};
this.mouseMove = function(event) {
me.onMouseMove.call(me, event);
};
// initialize position, so it will
// be smooth even on the first drag
var position = el.getBoundingClientRect();
el.style.left = position.left + "px";
el.style.top = position.top + "px";
el.style.position = "absolute";
if (el.style.zIndex > Draggable.zindex)
Draggable.zindex = el.style.zIndex + 1;
};
Draggable.zindex = 0;
/**
* Sets the skew and saves the position
* #param {Number} skew
*/
Draggable.prototype.setSkew = function(skew) {
var data = this.dragData;
var style = this.applyTo.style;
// Set skew transformations.
data.skew = skew;
style.MozTransform = skew ? 'skew(' + skew + 'deg)' : '';
style.webkitTransform = skew ? 'skew(' + skew + 'deg)' : '';
// Save the new position.
style.left = (data.lastX + data.offsetX) + 'px';
style.top = (data.lastY + data.offsetY) + 'px';
}
/**
* The mouse down event.
* #param {Object} event
*/
Draggable.prototype.onMouseDown = function(event) {
var data = this.dragData;
// New drag event.
var style = this.applyTo.style;
data.startX = data.lastX = event.clientX;
data.startY = data.lastY = event.clientY;
data.offsetX = parseInt(style.left, 10) - event.clientX;
data.offsetY = parseInt(style.top, 10) - event.clientY;
style.zIndex = Draggable.zindex++;
data.lastTime = (new Date()).getTime();
// Mouse up and move events.
window.addEventListener('mousemove', this.mouseMove, false);
window.addEventListener('mouseup', this.mouseUp, false);
event.preventDefault(); // prevent text selection
};
/**
* The mouse movement event.
* #param {Object} event
*/
Draggable.prototype.onMouseMove = function(event) {
// He is dragging me now
var me = this;
var data = me.dragData;
var element = me.applyTo;
var clientX = event.clientX;
var clientY = event.clientY;
data.moving = true;
// The skew animation. :)
var skew = (data.lastX - clientX) * 1;
var limit = 25;
if (Math.abs(skew) > limit) {
skew = limit * (skew > 0 ? 1 : -1);
}
var style = element.style;
var left = parseInt(style.left, 10);
var top = parseInt(style.top, 10);
var transform =
'translateX(' + (clientX + data.offsetX - left) + 'px)' +
'translateY(' + (clientY + data.offsetY - top) + 'px)' +
'skew(' + skew + 'deg)';
style.MozTransform = transform;
style.webkitTransform = transform;
data.lastX = clientX;
data.lastY = clientY;
data.lastTime = (new Date()).getTime();
// here is the cooldown part in order
// not to stay in disorted state
var pre = skew > 0 ? 1 : -1;
clearInterval(data.timer);
data.timer = setInterval(function() {
var skew = data.skew - (pre * 10);
skew = pre * skew < 0 ? 0 : skew;
me.setSkew(skew);
if (data.moving || skew === 0)
clearInterval(data.timer);
}, 20);
data.moving = false;
};
/**
* The mouse up event.
* #param {Object} event
*/
Draggable.prototype.onMouseUp = function(event) {
this.setSkew('');
// Remove useless events.
window.removeEventListener('mousemove', this.mouseMove, false);
window.removeEventListener('mousemove', this.mouseUp, false);
};