Snap.svg text with textpath does not animate as expected - javascript

I'm having an issue animating text using snap.svg. I'm moving text around an arc, from the bottom left of the arc to its apex. I'm using the standard Snap.animate functionality with its built-in setter function.
When I animate a random element (such as the circle I've included in the examples below), the animation behaves as expected. When I animate plain text it also behaves as expected. When I add a textpath attribute to that text, however, the animation functions differently in ways I don't understand.
This text animates as expected:
svg.text(0,200,'Regular Text').attr({'text-anchor': 'middle'});
Example (hover for animation): http://codepen.io/anon/pen/pJbmYW
Whereas this text stops short of its desired destination (also the top of the arc:
var path = 'M0 200 A 200 200, 0, 1, 1, 400 200';
svg.text(0,200,'Arced Text').attr({'text-anchor': 'middle',
'textpath':path});
Example (hover for animation): http://codepen.io/anon/pen/GJqaVp
I suppose I don't understand what adding the textpath is doing to the text object, as it seems I should be able to animate/transform its x and y coordinates as I could before I added the path.
Any insight or suggestions are welcome. Thanks.

It doesn't really make sense to animate x,y for a textPath in this case I think (I may be wrong), as what does that mean in respect to a fluctuating line.
I think what you want is to animate the startOffset. Eg...
Snap.animate(0, arc.getTotalLength()/2,
function(val){
var point = arc.getPointAtLength(val);
circ.attr({cx: point.x,
cy: point.y});
arcText.textPath.attr({ startOffset: val})
},1000,mina.easeinout);
with this bit being the main change ...
arcText.textPath.attr({ startOffset: val})
codepen (hover over)

Related

How to tween a line color in easeljs canvas

I have a series of dots with connected lines that I am animating in an easel.js canvas. The dots move around, and the lines stay connected to them as they move. As the dots move, I'm animating their color, so I want the lines to animate color as well.
I tried calling a color tween on the line, but it requires that I cache the line first.
For a circle, that's easy - I get the radius and, since its registration is in the center, its x and y coordinates and width and height are easy to calculate (for a circle with r=100 at 50,50, its cache would be cache(0,0,100,100). But for a line, I'm not sure how to reference the right coordinates for the cache statement, especially since the line start position, end position, and length are always changing.
Anyone have a way to do this?
I'm using greensock's timelinemax / tweenlite with the easeljs plugin to handle all the animations, if that's helpful.
If TweenLite handles color tweens, then you should just be able to update the "style" of your line any time:
var shape = new createjs.Shape();
var colorCommand = shape.graphics.beginStroke("#000000").command;
shape.graphics.moveTo(0,0).lineTo(100,100); // Draw the line
// Any time
colorCommand.style = "#ff0000";
// So in a tween:
TweenLite.to(colorCommand, 20, {style:"#00ffff"});
If you are using EaselJS, you can also use TweenJS, which has a ColorPlugin. Using similar code:
createjs.Tween.get(colorCommand).to({style:"#00fffff"}, 20000);
Here is a fiddle I made tweening the color of a line with TweenJS https://jsfiddle.net/lannymcnie/5zxpb944/
Cheers.

Circular canvas corners clickable in Chrome

I have two canvases. I have made them circular using border-radius. The 2nd is positioned inside the first one (using absolute position).
I have click events on both circles. If you click on inside canvas, the color at the point of the click is loaded in the outside canvas with opacity varying from white to the picked color and finally to black. If you click on outer canvas the exact color value at that point is loaded in the text-box at the bottom
I am unable to click in red zones (as shown in figure below) of the outer canvas when using chrome. I tried z-idex, arcs but nothing is helping me. But In Firefox everything is working fine.
Note: You can drag the picker object in the outer circle. But if you leave it in red zones, you would not be able to click it again in Chrome. Clicking in green zone will get you its control again
Code in this JSFiddle
Edit
I excluded all irrelevant code to make it easy. Now there is only a container having two canvas.
Filled simply with two distinct colors. Open following fiddle link in both chrome and firefox. Click on both cirles in different zones and see difference in chrome and firefox. I want them to behave in chrome as they do in firefox
Note I will ultimately draw an image in inner canvas.
Updated Fiddle Link
-
Your problem is because canvases currently are always rectangular, even if they don't look rectangular. Border radius makes the edges except the circle transparent, but it still doesn't stop events in Chrome on the corner areas. This is why you cannot click the bottom circle in those areas
I even tried putting it inside of a container that had a border-radius instead but the click event still goes through
With that being said, you have two options. You could either change your code to only use one canvas with the same type of layout, just drawing the background circle before the other each time. Essentially you'd draw a circle, draw your black to color to white gradient, use the xor operation to combine the two into one circle, then do the same with the rainbox gradient. You must draw the background circle first because canvas paints over the old layers every time
or
You could use javascript to only detect clicks in the circular area which takes just a little bit of math (: This solution is featured in edit below
In the future, CSS Shapes may allow canvases to be non-rectangular elements to be used, I'm actually not sure, but we don't have that capability yet at least
Edit
Alright, so after going through your code a bit it seems there are some things I should cover before I offer a solution
Setup all your finite variables outside of the functions that run every time. This means you don't put them (like radiuses, offsets, etc.) in the click function or something that runs often since they don't change
Your "radius"es are actually "diameter"s. The format of .rect goes .rect(x, y, width (diameter of circle), height (diameter of circle))
Almost always when overlaying canvases like you are you want to make them equal dimensions and starting position to prevent calculation error. In the end it makes it easier, doing all relative positioning with javascript instead of mixing it with CSS. In this case, however, since you're using border-radius instead of arc to make a circle, keep it like it is but position it using javascript ....
jQuery isn't needed for something this simple. If you're worried about any load speed I'd recommend doing it in vanilla javascript, essentially just changing the .click() functions into .onclick functions, but I left jQuery for now
You can declare multiple variables in a row without declaring var each time by using the following format:
var name1 = value1,
name2 = value2;
Variables with the same value you can declare like so:
var name1 = name2 = sameValue;
When children have position:absolute and you want it to be positioned relative to the parent, the parent can have position:relative, position:fixed, or position:absolute. I would think you'd want position:relative in this case
When you don't declare var for a variable it becomes global (unlessed chained with a comma like above). For more on that read this question
Now, onto the solution.
After talking with a friend I realized I could sort do the math calculation a lot easier than I originally thought. We can just calculate the center of the circles and use their radiuses and some if statements to make sure the clicks are in the bounds.
Here's the demo
After everything is set up correctly, you can use the following to detect whether or not it's in the bounds of each
function clickHandler(e, r) {
var ex = e.pageX,
ey = e.pageY,
// Distance from click to center
l = Math.sqrt(Math.pow(cx - ex, 2) + Math.pow(cy - ey, 2));
if(l > r) { // If the distance is greater than the radius
if(r === LARGE_RADIUS) { // Outside of the large
// Do nothing
} else { // The corner area you were having a problem with
clickHandler(e, LARGE_RADIUS);
}
} else {
if(r === LARGE_RADIUS) { // Inside the large cirle
alert('Outer canvas clicked x:' + ex + ',y:' + ey);
} else { // Inside the small circle
alert('Inner canvas clicked x:' + ex + ',y:' + ey);
}
}
}
// Just call the function with the appropriate radius on click
$(img_canvas).click(function(e) { clickHandler(e, SMALL_RADIUS); });
$(wheel_canvas).click(function(e) { clickHandler(e, LARGE_RADIUS); });
Hopefully the comments above and code make enough sense, I tried to clean it up as best as I could. If you have any questions don't hesitate to ask!

Raphael inner glow?

I am looking for a way to achieve only an inner glow or shadow on a raphael path. Unfortunately, you can only do radial gradients on an ellipse or a circle.
One idea may be to create a series of paths which are slightly smaller and fit inside the original path and then to give them different stroke colors, but I have no idea how I would approach that. Some function that takes the path and subtracts or adds values to the numbers depending on where they are... Anyway, if anyone has any ideas, or maybe another javascript library that does this, that would be great.
Ok here is how you can achieve that. It is pretty straightforward I think. I know it is hard to manually create a shadow path from your original. But there is a trick called scale() function. Steps to how you can get inner shadow or inner glow effect:
Create your path
Clone it into another path
Set the scale() of cloned path to be 0.9*original
Then hide the cloned path, but apply glow() function on it
The code:
var paper = Raphael("notepad", 500, 500);
var path = paper.path("M 50 200 L 120 100 200 190 80 250z");
var shadow = path.clone().scale(0.9).hide();
shadow.glow();
path.attr({stroke: "darkred"});
Look at the DEMO, this is not perfect but with minor changes, yo can get what you want.
Also as a side note:
glow() function has attributes like offsetx, offsety, opacity... Changing those attributes will give you your preferred shadow/glow.
UPDATED CODE http://jsfiddle.net/jUTFm/41/
Look here. You could try animating the width of the path and darkening the color gradually to give some kinda glowing effect.
check out the bottom part
brain = paper.add(brain);
brain.attr('stroke', '#ff0');
brain.transform('s 0.5, 0.5 0 0');
glow = brain.glow({
color: '#ff0',
width: 5
});
anim = Raphael.animation({
"stroke-width": 15,
opacity: 1
}, 500);
anim = anim.repeat(Infinity);
glow.animate(anim);

Raphael Rectangle Border

When I draw a simple rectangle using the following code the bottom and right edge borders are thicker that the top and left edge borders. Why is this and can I stop it?
var paper = Raphael(10, 50, 500, 500);
var rect = paper.rect(100, 100, 100, 100);
Your rectangle's top and left borders, which are using the default 1 pixel stroke-width, are falling exactly on the top and left borders of your SVG element (as represented by a Raphael paper object. As opposed to pixel based drawing solutions, this means the line is essentially straddling the element's border, resulting in 0.5 pixels of your border stroke being clipped.
To solve, you simply need to shift your drawing over or shift the beginning offset of your SVG element's coordinates.
Here's a fiddle that shows one solution.
The square looks fine to me: http://jsfiddle.net/cMXBC/2/
Could you have some rogue css somewhere that is modifying the stroke of the rect? Try right-clicking the square and inspecting the rectangle in Firebug or with the Chrome inspector to see if there is any style that has been added.

Canvas coordinates in Fabric.js have offset

I just started with fabric.js and I have a (probably beginner) error:
I am using fabric with jquery with the following code:
$(document).ready(function () {
canvas = new fabric.StaticCanvas('scroller');
canvas.add(
new fabric.Rect({ top: 0, left: 0, width: 140, height: 100, fill: '#f55' })
);
});
This code should draw a 140x100 Rectangle on the canvas.
Sadly, only a quarter of the Rectangle appears.
If I change the top and left values to higher numbers, more of the Rectangle appears on the canvas.
So it seems, that the canvas origin is not at 0/0, but at sth. higher.
Does someone know how to fix this or what I am doing wrong?
Thanks in advance,
McFarlane
Here is a jsfiddle link with some examples http://jsfiddle.net/pukster/sdQ7U/2/
My guess is that fabric.js calculates everything from the origin (middle point) since it is drawing exactly one quarter of a rectangle even with a canvas 10 times the size of the rectangle. My guess is that top and left actually refer to the origin and not the top and left sides of the imaginary bounding box. Trouble is there is very little documentation on fabricjs. Is there any reason you are using fabricjs and not easeljs
EDIT Here's the same fiddle but with squares instead of rectangles (it is more clear) http://jsfiddle.net/pukster/sdQ7U/3/
EDIT OK I am now almost absolutely certain that fabric.js uses the center as the top/left. I ripped their example off of their site and overlayed it with the transparent couterpart to those shapes had they been coded in pure canvas http://jsfiddle.net/pukster/uathZ/2/ (blue border is the limit of the canvas element).
What you see is that the boxes are exactly offset by half but the circle (I only drew a semi circle otherwise it would not have been discernable) is perfectly overlapped. This is b/c in HTML Canvas, the circle coordinates (x,y) refer to the origin and not the top left. I did not bother with the triangle b/c my trigonometry is a bit rusty. I personally think it's misleading to use the terms top and left, when x and y would have been more representative and shorter.
Yes, this is highly unexpected and even more undocumented.
Workaround:
Set
originX: "left"
originY: "top"
for each created object.
edit: or use kangax simpler solution in the comment below.
I want to comment but lack the reputation to do so. So anyway, here is what happens when I do the following:
fabric.Object.prototype.originX = "left";
fabric.Object.prototype.originY = "top";
The shape gets rendered fine but when I select it for resizing or moving, it gets offset to a different location. The best approach seems to be to set the coordinates for every object separately using the set() method.

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