I have a Fabric.js canvas and I want to implement the full-canvas panning that software packages usually do with a "hand" tool. It's when you press one of the mouse buttons, then move over the canvas while holding the mouse button and the visible portion of the canvas changes accordingly.
You can see in this video what I want to achieve.
In order to implement this functionality I wrote the following code:
$(canvas.wrapperEl).on('mousemove', function(evt) {
if (evt.button == 2) { // 2 is the right mouse button
canvas.absolutePan({
x: evt.clientX,
y: evt.clientY
});
}
});
But it doesn't work. You can see in this video what happens.
How can I modify my code in order:
For panning to work like in the first video?
For the event handler to consume the event? It should prevent the context menu from appearing when the user presses or releases the right mouse button.
An easy way to pan a Fabric canvas in response to mouse movement is to calculate the cursor displacement between mouse events and pass it to relativePan.
Observe how we can use the screenX and screenY properties of the previous mouse event to calculate the relative position of the current mouse event:
function startPan(event) {
if (event.button != 2) {
return;
}
var x0 = event.screenX,
y0 = event.screenY;
function continuePan(event) {
var x = event.screenX,
y = event.screenY;
fc.relativePan({ x: x - x0, y: y - y0 });
x0 = x;
y0 = y;
}
function stopPan(event) {
$(window).off('mousemove', continuePan);
$(window).off('mouseup', stopPan);
};
$(window).mousemove(continuePan);
$(window).mouseup(stopPan);
$(window).contextmenu(cancelMenu);
};
function cancelMenu() {
$(window).off('contextmenu', cancelMenu);
return false;
}
$(canvasWrapper).mousedown(startPan);
We start panning on mousedown and continue panning on mousemove. On mouseup, we cancel the panning; we also cancel the mouseup-cancelling function itself.
The right-click menu, also known as the context menu, is cancelled by returning false. The menu-cancelling function also cancels itself. Thus, the context menu will work if you subsequently click outside the canvas wrapper.
Here is a page demonstrating this approach:
http://michaellaszlo.com/so/fabric-pan/
You will see three images on a Fabric canvas (it may take a moment or two for the images to load). You'll be able to use the standard Fabric functionality. You can left-click on the images to move them around, stretch them, and rotate them. But when you right-click within the canvas container, you pan the whole Fabric canvas with the mouse.
I have an example on Github using fabric.js Canvas panning: https://sabatinomasala.github.io/fabric-clipping-demo/
The code responsible for the panning behaviour is the following: https://github.com/SabatinoMasala/fabric-clipping-demo/blob/master/src/classes/Panning.js
It's a simple extension on the fabric.Canvas.prototype, which enables you to toggle 'drag mode' on the canvas as follows:
canvas.toggleDragMode(true); // Start panning
canvas.toggleDragMode(false); // Stop panning
Take a look at the following snippet, documentation is available throughout the code.
const STATE_IDLE = 'idle';
const STATE_PANNING = 'panning';
fabric.Canvas.prototype.toggleDragMode = function(dragMode) {
// Remember the previous X and Y coordinates for delta calculations
let lastClientX;
let lastClientY;
// Keep track of the state
let state = STATE_IDLE;
// We're entering dragmode
if (dragMode) {
// Discard any active object
this.discardActiveObject();
// Set the cursor to 'move'
this.defaultCursor = 'move';
// Loop over all objects and disable events / selectable. We remember its value in a temp variable stored on each object
this.forEachObject(function(object) {
object.prevEvented = object.evented;
object.prevSelectable = object.selectable;
object.evented = false;
object.selectable = false;
});
// Remove selection ability on the canvas
this.selection = false;
// When MouseUp fires, we set the state to idle
this.on('mouse:up', function(e) {
state = STATE_IDLE;
});
// When MouseDown fires, we set the state to panning
this.on('mouse:down', (e) => {
state = STATE_PANNING;
lastClientX = e.e.clientX;
lastClientY = e.e.clientY;
});
// When the mouse moves, and we're panning (mouse down), we continue
this.on('mouse:move', (e) => {
if (state === STATE_PANNING && e && e.e) {
// let delta = new fabric.Point(e.e.movementX, e.e.movementY); // No Safari support for movementX and movementY
// For cross-browser compatibility, I had to manually keep track of the delta
// Calculate deltas
let deltaX = 0;
let deltaY = 0;
if (lastClientX) {
deltaX = e.e.clientX - lastClientX;
}
if (lastClientY) {
deltaY = e.e.clientY - lastClientY;
}
// Update the last X and Y values
lastClientX = e.e.clientX;
lastClientY = e.e.clientY;
let delta = new fabric.Point(deltaX, deltaY);
this.relativePan(delta);
this.trigger('moved');
}
});
} else {
// When we exit dragmode, we restore the previous values on all objects
this.forEachObject(function(object) {
object.evented = (object.prevEvented !== undefined) ? object.prevEvented : object.evented;
object.selectable = (object.prevSelectable !== undefined) ? object.prevSelectable : object.selectable;
});
// Reset the cursor
this.defaultCursor = 'default';
// Remove the event listeners
this.off('mouse:up');
this.off('mouse:down');
this.off('mouse:move');
// Restore selection ability on the canvas
this.selection = true;
}
};
// Create the canvas
let canvas = new fabric.Canvas('fabric')
canvas.backgroundColor = '#f1f1f1';
// Add a couple of rects
let rect = new fabric.Rect({
width: 100,
height: 100,
fill: '#f00'
});
canvas.add(rect)
rect = new fabric.Rect({
width: 200,
height: 200,
top: 200,
left: 200,
fill: '#f00'
});
canvas.add(rect)
// Handle dragmode change
let dragMode = false;
$('#dragmode').change(_ => {
dragMode = !dragMode;
canvas.toggleDragMode(dragMode);
});
<div>
<label for="dragmode">
Enable panning
<input type="checkbox" id="dragmode" name="dragmode" />
</label>
</div>
<canvas width="300" height="300" id="fabric"></canvas>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.15/fabric.min.js"></script>
Not sure about FabricJS, but it could be in such a way:
for it to work like in the first video:
By making use of CSS cursor property, toggling it on mousedown and mouseup events using javascript.
the event handler consume the event (prevent the context menu from appearing, when the user releases the right mouse button):
Using javascript we return false on contextmenu event
CODE: with a little problem ( * )
using jQuery JS Fiddle 1
$('#test').on('mousedown', function(e){
if (e.button == 2) {
// if right-click, set cursor shape to grabbing
$(this).css({'cursor':'grabbing'});
}
}).on('mouseup', function(){
// set cursor shape to default
$(this).css({'cursor':'default'});
}).on('contextmenu', function(){
//disable context menu on right click
return false;
});
Using raw javascript JS Fiddle 2
var test = document.getElementById('test');
test.addEventListener('mousedown', function(e){
if (e.button == 2) {
// if right-click, set cursor shape to grabbing
this.style.cursor = 'grabbing';
}
});
test.addEventListener('mouseup', function(){
// set cursor shape to default
this.style.cursor = 'default';
});
test.oncontextmenu = function(){
//disable context menu on right click
return false;
}
( * ) Problem:
The above snippets works as it should but there's a cross-browser issue, if you check the above fiddles in Firefox - or Opera -you'll see the correct behavior, when checked in Chrome and IE11 - didn't checked it with Edge or Safari - I found that Chrome and IE don't support the grabbing cursor shape, so in the above code snippets, change the cursor lines into this:
jQuery: $(this).css({'cursor':'move'}); JS Fiddle 3
Raw javascript: this.style.cursor = 'move'; JS Fiddle 4
Now we have a working code but without the hand cursor. but there is the following solution:-
SOLUTIONS:
Chrome and Safari support grab and grabbing with the -webkit- prefix like:
$(this).css({'cursor': '-webkit-grabbing'});
but you need to make browser sniffing first, if Firefox then the default and standard code, if Chrome and Safari then with the -webkit- prefix, and this still makes IE out of the game.
Have a look at this example, test it with Chrome, Safari, Firefox, Opera and IE you can see that cursor: url(foo.bar) works and supported in ALL browsers.
Chrome, Safari, Firefox and Opera shows the yellow smile image smiley.gif, but IE shows the red ball cursor url(myBall.cur).
So I think you can make use of this, and a grabbing hand image like this
Or this:
You can use an image like the above, a png or gif format with all browsers except IE which supports .cur, so you need to find a way to convert it into a .cur. Google search shows many result of convert image to cur
Note that, although this cursor:url(smiley.gif),url(myBall.cur),auto; - with fallback support separated by comma, works well in the W3Schools example shown above, I couldn't get it to work the same way in javascript, I tried $(this).css({'cursor': 'grabbing, move'}); but it didn't work.
I also tried doing it as CSS class
.myCursor{ cursor: grabbing, -webkit-grabbing, move; }
Then with jQuery $(this).addClass('myCursor'); but no avail either.
So you still need to make browser sniffing whether you are going the second solution or a hybrid fix of the both solutions, this is my code which I've used couple times to detect browser and it worked well at the time of this post but you porbabely won't need the "Mobile" and "Kindle" parts.
// Detecting browsers
$UA = navigator.userAgent;
if ($UA.match(/firefox/i)) {
$browser = 'Firefox';
} else if ($UA.indexOf('Trident') != -1 && $UA.indexOf('MSIE') == -1) {
$browser = 'MSIE';
} else if ($UA.indexOf('MSIE') != -1) {
$browser = 'MSIE';
} else if ($UA.indexOf('OPR/') != -1) {
$browser = 'Opera';
} else if ($UA.indexOf("Chrome") != -1) {
$browser = 'Chrome';
} else if ($UA.indexOf("Safari")!=-1) {
$browser = 'Safari';
}
if($UA.match(/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Nokia|Mobile|Opera Mini/i)) {
$browser = 'Mobile';
}else if($UA.match(/KFAPWI/i)){
$browser = 'Kindle';
}
console.log($browser);
Resources:
https://developer.mozilla.org/en-US/docs/Web/CSS/cursor
http://www.w3schools.com/cssref/pr_class_cursor.asp
https://css-tricks.com/almanac/properties/c/cursor/
Google images search of grabbing hand cursor
i have made an example on jsfiddle , that we can actually drag the whole canvas with all its objects, into a parent div, like the picture,and i will try to explain it step by step.
First of all i download the drag library jquery.dradscroll.js, you can find it on the net. This is a small js file that with little changes it can helps us complete the task.
download link: http://www.java2s.com/Open-Source/Javascript_Free_Code/jQuery_Scroll/Download_jquery_dragscroll_Free_Java_Code.htm
create the container that holds our canvas.
<div class="content">
<canvas id="c" width="600" height="700" ></canvas>
</div>
little css
.content{
overflow:auto;
width:400px;
height:400px;
}
javascript:
a. create the canvas.
b. make default cursor , when it is over canvas , open hand
canvas.defaultCursor = 'url(" http://maps.gstatic.com/intl/en_us/mapfiles/openhand_8_8.cur") 15 15, crosshair';
c. override the __onMouseDown function , for change to the closedhand cursor( at end).
fabric.Canvas.prototype.__onMouseDown = function(e){
// accept only left clicks
var isLeftClick = 'which' in e ? e.which === 1 : e.button === 1;
if (!isLeftClick && !fabric.isTouchSupported) {
return;
}
if (this.isDrawingMode) {
this._onMouseDownInDrawingMode(e);
return;
}
// ignore if some object is being transformed at this moment
if (this._currentTransform) {
return;
}
var target = this.findTarget(e),
pointer = this.getPointer(e, true);
// save pointer for check in __onMouseUp event
this._previousPointer = pointer;
var shouldRender = this._shouldRender(target, pointer),
shouldGroup = this._shouldGroup(e, target);
if (this._shouldClearSelection(e, target)) {
this._clearSelection(e, target, pointer);
}
else if (shouldGroup) {
this._handleGrouping(e, target);
target = this.getActiveGroup();
}
if (target && target.selectable && !shouldGroup) {
this._beforeTransform(e, target);
this._setupCurrentTransform(e, target);
}
// we must renderAll so that active image is placed on the top canvas
shouldRender && this.renderAll();
this.fire('mouse:down', { target: target, e: e });
target && target.fire('mousedown', { e: e });
if(!canvas.getActiveObject() || !canvas.getActiveGroup()){
flag=true;
//change cursor to closedhand.cur
canvas.defaultCursor = 'url("http://maps.gstatic.com/intl/en_us/mapfiles/closedhand_8_8.cur") 15 15, crosshair';
}//end if
override the __onMouseUp event ,to change back the cursor to openhand.
fabric.Canvas.prototype.__onMouseUp = function(e){
if(flag){
canvas.defaultCursor = 'url(" http://maps.gstatic.com/intl/en_us/mapfiles/openhand_8_8.cur") 15 15, crosshair';
flag=false;
}
};
You initialize the dragScroll() to work on the content that hosts the canvas:
$('.content').dragScroll({});
Some small changes on the jquery.dragScroll.js file, so as to understand when to drag the canvas and when not. On mousedown() event we add an if statement to check whether we have an active object or group.If true ,no canvas drag.
$($scrollArea).mousedown(function (e) {
if (canvas.getActiveObject() || canvas.getActiveGroup()) {
console.log('no drag');return;
} else {
console.log($('body'));
if (typeof options.limitTo == "object") {
for (var i = 0; i < options.limitTo.length; i++) {
if ($(e.target).hasClass(options.limitTo[i])) {
doMousedown(e);
}
}
} else {
doMousedown(e);
}
}
});
on mousedown event we grab the DOM element (.content) and get the top & left position
function doMousedown(e) {
e.preventDefault();
down = true;
x = e.pageX;
y = e.pageY;
top = e.target.parentElement.parentElement.scrollTop; // .content
left = e.target.parentElement.parentElement.scrollLeft;// .content
}
If we dont want to have the scrollbars visible:
.content{
overflow:hidden;
width:400px;
height:400px;
}
There is a small problem though,jsfiddle, accepts only https libraries ,so it blocks fabricjs, except if you add it from 'https://rawgit.com/kangax/fabric.js/master/dist/fabric.js', but again it still blocks it some times (at least on my chrome and mozilla).
jsfiddle example : https://jsfiddle.net/tornado1979/up48rxLs/
you may have better luck ,than me, on your browser , but it would definitelly work on your live app.
Anyway,
i hope helps ,good luck.
I know this has already been answered, but I redid the pen created in this answer using the new version of fabricjs (4.5.0)
Pen: https://codepen.io/201flaviosilva/pen/GROLbQa
In this case, I used the middle button in the mouse to pan :)
// Enable mouse middle button
canvas.fireMiddleClick = true;
// Mouse Up Event
if (e.button === 2) currentState = STATE_IDLE;
// Mouse Down Event
if (e.button === 2) currentState = STATE_PANNING;
:)
I need to create custom gestures for different shapes like square, circle etc. In other words i need to detect when user draws a square or circle on their touch device using javascript.
currently i'm trying to achieve this by using hammer.js custom gestures
so far i can detect whenever user draws something and the code looks like
var obj= {
name: 'draw',
index: 7,
defaults: {
max_draw_dur:200,
min_delta_x:100,
min_delta_y:200
},
centerX:undefined,
centerY:undefined,
changingDir:false,
changeInDir:0,
startangle:0,
currDir:undefined,
currDX:0,
currDY:0,
handler: function(ev, inst) {
if(Hammer.detection.previous!=undefined) {
var prev = Hammer.detection.previous;
var curr = Hammer.detection.current;
switch (ev.eventType) {
case Hammer.EVENT_START:
this.changeInDir=0;
this.startangle=0;
this.centerX=curr.startEvent.center.pageX;
this.centerY=curr.startEvent.center.pageY;
Hammer.detection.current.name = 'draw'
inst.trigger(this.name, ev);
break;
case Hammer.EVENT_MOVE:
if (Math.abs(ev.angle-this.startangle)>=45&&Math.abs(ev.angle-this.startangle)<=180) {
Hammer.detection.current.name = 'draw'
this.startangle=ev.angle;
this.changeInDir++;
}
break;
case Hammer.EVENT_END:
if (curr.name==this.name && this.changeInDir>=2 && this.changeInDir<=7) {
this.changeInDir=0;
this.startangle=0;
inst.trigger(this.name+'Circle', ev);
// trigger gesture event
}
else if (this.changeInDir>=2 && this.changeInDir<=4) {
this.changeInDir=0;
this.startangle=0;
inst.trigger(this.name+'Square', ev);
// trigger gesture event
}
break;
}
}
}
}
Hammer.detection.register(obj);
however i am not able to make accurate gestures like a square using this. (major problem being even a slight change in any axis will trigger an event in that direction)
is there any other plugins that'll be helpful for achieving this? would be great if someone can point me in the right direction..
There is a pure javascript version of the one-dollar single-stroke recognizer. Its open to expansion - u can add your own gestures on their website - and the JS is pretty easy to understand. https://depts.washington.edu/aimgroup/proj/dollar/
Another option is the jquery-based fancy gestures recognizer: http://anantgarg.com/2009/05/21/jquery-fancy-gestures/
I've created several shapes in SVG and added an effect that changes the shapes color when hovered over.
But how can I make the shapes "pop up" slightly when hovered over?
Would appreciate any help.
You can modify the transform of each element. Probably something like this:
function onEnter (e) {
e.target.setAttribute('transform', 'scale(2,2)');
}
function onLeave (e) {
e.target.removeAttribute('transform');
}
But in fact you do not need to take the long slow way using the attributes, instead you can use the transform interface of SVG elements. The documentation therefore is on the page linked above, too. But dealing with this might be a bit »unintuitive« the first time, since each element has a transform list with several transform items.
I think it would be a good Idea to dive in the svg transform interface (and affine transformations in general), since it is very powerful, but it requires a »learning curve« before you are ready to use it.
If you want to short circuit this you can also use a helper framework like: svg.js, snapsvg or raphael which all have common methods to help you dealing with thing like that.
EDIT
The functions above are just examples for one could do it. The onEnter and onLeave methods should be called only if the mouse enters the svg element or when it leaves. So you could add a mousemove listener and check if the target is one of your desired elements:
var firstElement = document.getElementById('<yourelementsid>');
isOverFirstElement = false;
window.addEventListener('mousemove', function (e) {
if (e.target === firstElement && isOverFirstElement == false) {
isOverFirstElement = true;
onEnter(e);
} else if (e.target !== firstElement && isOverFirstElement == true) {
isOverFirstElement = false;
onLeave(e);
}
}, false);
With code like that you can detect a mouse enter or leave and react accordingly.
I've got it to do what I wanted by adding
target.setAttributeNS(null, 'transform', "translate(0 0)");
as such:
function unselectedColour(evt) {
var target = evt.target;
target.setAttributeNS(null, 'fill', 'white');
target.setAttributeNS(null, 'transform', "translate(0 0)");
}
function selectedColourBuilding(evt) {
var target = evt.target;
target.setAttributeNS(null, 'fill', 'purple');
target.setAttributeNS(null, 'transform', "translate(-3 -3)");
}
To make the 'pop out' stable, keeping it at it's current position when scaling, you can compute the center of its bounding box then translate the element's center to the origin, scale it, then translate back to its current location
e.g.
function onEnter(evt)
{
var target=evt.target
var bb=target.getBBox()
var bbx=bb.x
var bby=bb.y
var bbw=bb.width
var bbh=bb.height
var cx=bbx+.5*bbw
var cy=bby+.5*bbh
target.setAttribute("transform","translate("+(cx)+" "+(cy)+")scale(1.2 1.2)translate("+(-cx)+" "+(-cy)+")")
}
function onExit(evt)
{
var target=evt.target
target.removeAttribute("transform")
}
This jsfiddle illustrates my problem best http://jsfiddle.net/sdg9/YYUrm/
circle.addEventListener("mousedown", function (evt) {
if (evt.nativeEvent.button === 0) {
square = new createjs.Shape();
square.graphics.beginFill("blue").drawRect(0, 0, 100, 100);
makeDraggable(square);
stage.addChild(square);
stage.update();
//How do I give focus to drag blue square without having to click again?
}
});
I have one object (red circle) that on mousedown adds another shape (blue square) to the canvas.
The blue square(s) can be dragged around the canvas.
I want to make it so on mousedown of the red circle a blue square is created and is immediately draggable provided I'm still in a mousedown state. Currently I have to manually perform a second mousedown on the blue square to drag it around.
I don't know if I need to give the blue square focus, programatically fire an event, or do something else to get this working. Any guidance would be appreciated.
What you can do is also listen to the "pressmove" event on the circle, but what you will drag is the square you just created :
circle.addEventListener("pressmove", function (evt) {
if (evt.nativeEvent.button === 0) {
evt.target.topObj.x = evt.stageX;
evt.target.topObj.y = evt.stageY ;
stage.update();
}
});
and the topObj object is saved on the "mousedown" event :
circle.addEventListener("mousedown", function (evt) {
if (evt.nativeEvent.button === 0) {
// Create your square
...
// Then save it as the square on top of the circle
evt.target.topObj = square;
}
});
I have a drawButtons function that takes an argument of "nonhover", "hover1" or "hover2" and draws up a new button set to the canvas, and depending on the argument it takes, will draw the buttons different colors. It does work when i call it from setUpGame() but not when I call it from draw(). I want to call it from draw() because draw() is called 80 times a second in setInterval(). That way it can keep checking if the mouse is hovering over the button and draw the appropriate button set.
setUpGame() is called outside of any object or function. draw() is called by setInterval() which is outside of any function or object. setInterval calls draw 80 times a second.
getMouseOver() another function that is the one that should actually be called by draw(), because it says "if mouse is over button one: drawButtons("hover1") and so on. It just doesn't draw the buttons when I call it.
There are no errors in the browser Javascript console. I am using Chrome which works best with my game.
From this we can deduce that there is no problem with drawButtons() as it worked when called from setUpGame().
There is possibly a problem with draw() as drawButtons() doesn't work when I call it from there (but to perplex us more, displayNumbers does display the numbers when I call it from there) and it worked fine when playing the game (here we are not playing the game, we are on a start screen).
There is probably a problem with getMouseOver() because that doesn't work anywhere.
I will show you getMouseOver() for now. My program is getting big and it is overwhelming to show too much right from the start. I intend for this function to be called 80 times a second.
getMouseOver: function() {
window.onload = (function(){
window.onmouseover = function(e) {
// IE doesn't always have e here
e = e || window.event;
// get event location
// change the code so that it gives the relative location
var location = {
x: e.pageX - offset.x,
y: e.pageY - offset.y
};
if (location.x > 103.5 && location.x < 265.5) {
if (location.y > 240 && location.y < 291) {
nonGameContent.drawButtons("hover1");
}
}
if (location.x > 103.5 && location.x < 265.5) {
if (location.y > 160 && location.y < 212) {
nonGameContent.drawButtons("hover2");
}
}
else{
nonGameContent.drawButtons("nonHover");
}
}
})},
In this fiddle you have click() and onmousemove() that are working.
I didn't understand well if you want to display button at the beginning or just when the mouse hovers somewhere on the future place of the button but it's a beginning :
http://jsfiddle.net/Akinaru/3a7g2/57/
Main modification :
canvas.onmousedown = nonGameContent.getMouseClick;
canvas.onmousemove = nonGameContent.getMouseOver;
to change the canvas rectangle color when you mouse over it use onmousemove to find if you are over it, then redraw the canvas with a different color rectangle
getMouseClick: function() {
window.onmousemove = function(e) {