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How to use L.canvas to draw a fluctuating circle

I am a back-end programmer who is using leaflet for the first time. I don’t know much about js animation steps. I want to use L.canvas to draw a dynamic circle, just like the picture below.
Specify the range of the circle or the latitude and longitude of the center of the circle, and the radius will continue to fluctuate and spread outward, similar to water waves (this effect in the picture is made by me using a highly encapsulated animation library)
I hope someone can provide me with an example, or give me a suggestion so that I can smoothly draw a dynamic circle on the map. thanks a lot

You can create mutliple circles and update the radius each millisecond:
var canvasRenderer = L.canvas();
function createWavingCircle(latlng, color, fromRadius, toRadius){
var circle = L.circle(latlng, {radius: fromRadius, color, renderer: canvasRenderer}).addTo(map);
var nextCircle;
var interval = setInterval(()=>{
var radius = circle.getRadius()+1;
if(radius <= toRadius){
circle.setRadius(radius);
if(Math.round((radius / toRadius) * 100) >= 30 && !nextCircle){
nextCircle = createWavingCircle(latlng, color, fromRadius, toRadius);
}
} else {
if(nextCircle && nextCircle.getRadius() >= toRadius){
circle.remove();
clearInterval(interval);
}
}
},1)
return circle;
}
// replace this values with your custom ones
createWavingCircle(map.getCenter(), 'red', 10, 400);
https://plnkr.co/edit/IT5VcxokeCWpkpEx

Create a new L.canvas object and specify the desired options, and use the addTo() method to add the circle to your map.
This will create a circle that is initially drawn with a radius of 10, and will have its radius redrawn with a new random value every second. The circle will continue to fluctuate in size until the setInterval() loop is stopped.
import { L } from 'leaflet';
const circle = L.canvas({
center: [51.505, -0.09],
radius: 10,
color: 'red',
});
circle.addTo(map);
setInterval(() => {
const newRadius = Math.random() * 50;
circle.setRadius(newRadius);
}, 1000);
Hope it works!

// build CircleMarker
createFloatCircle(latLng, color, fromRadius, toRadius){
var _this = this;
var circle = L.circleMarker(latLng,
{radius: fromRadius,
color: color,
renderer: L.canvas({ padding: 0.5 }),
fillColor: color,
fillOpacity: 0.5,
stroke: false,
});
circle.addTo(_this.offMap);
setInterval(() => {
var newRadius = circle.getRadius() + 1;
if(newRadius <= toRadius){
circle.setRadius(newRadius);
} else {
circle.setRadius(fromRadius);
}
circle.setStyle({fillColor: _this.getColor(newRadius, fromRadius, toRadius)});
}, 20);
},
getColor(radius, fromRadius, toRadius){
var _this = this;
var color = 'red';
var percent = (radius - fromRadius) / (toRadius - fromRadius);
var red = Math.round(255 * percent);
var green = Math.round(255 * (1 - percent));
color = 'rgb(' + red + ',' + green + ',0)';
return color;
},
This is my implementation, as the circle expands, the color of the layer gradually deepens

Pixi.js - Draw Rectangle with Gradient Fill

I'm using the Pixi.js v4 graphics library to make a game with JavaScript. I know that I can draw a black + rounded rectangle like so:
const rectangle = new pixi.Graphics();
rectangle.beginFill(0); // Color it black
rectangle.drawRoundedRect(
0,
0,
100, // Make it 100x100
100,
5, // Make the rounded corners have a radius of 5
);
rectangle.endFill();
stage.addChild(rectangle);
How do I draw a rounded rectangle with a gradient from white to black?
How do I draw a rounded rectangle that has gradual opacity such that it fades in from left to right?

It looks like it's not possible to implement what you need with pixi.js without additional code, but we can do some magic to make it happen. Here's the result of what I've got: https://jsfiddle.net/exkf3zfo/21/
The bottom color is a pure red with 0.2 alpha.
I would split the whole process to the next steps:
Drawing the gradient
Masking the gradient with the rounded mask
Here is the code itself:
var app = new PIXI.Application(800, 600, {
antialias: true
});
document.body.appendChild(app.view);
// Functions
// param color is a number (e.g. 255)
// return value is a string (e.g. ff)
var prepareRGBChannelColor = function(channelColor) {
var colorText = channelColor.toString(16);
if (colorText.length < 2) {
while (colorText.length < 2) {
colorText = "0" + colorText;
}
}
return colorText;
}
// Getting RGB channels from a number color
// param color is a number
// return an RGB channels object {red: number, green: number, blue: number}
var getRGBChannels = function(color) {
var colorText = color.toString(16);
if (colorText.length < 6) {
while (colorText.length < 6) {
colorText = "0" + colorText;
}
}
var result = {
red: parseInt(colorText.slice(0, 2), 16),
green: parseInt(colorText.slice(2, 4), 16),
blue: parseInt(colorText.slice(4, 6), 16)
};
return result;
}
// Preparaiton of a color data object
// param color is a number [0-255]
// param alpha is a number [0-1]
// return the color data object {color: number, alpha: number, channels: {red: number, green: number, blue: number}}
var prepareColorData = function(color, alpha) {
return {
color: color,
alpha: alpha,
channels: getRGBChannels(color)
}
}
// Getting the color of a gradient for a very specific gradient coef
// param from is a color data object
// param to is a color data object
// return value is of the same type
var getColorOfGradient = function(from, to, coef) {
if (!from.alpha && from.alpha !== 0) {
from.alpha = 1;
}
if (!from.alpha && from.alpha !== 0) {
to.alpha = 1;
}
var colorRed = Math.floor(from.channels.red + coef * (to.channels.red - from.channels.red));
colorRed = Math.min(colorRed, 255);
var colorGreen = Math.floor(from.channels.green + coef * (to.channels.green - from.channels.green));
colorGreen = Math.min(colorGreen, 255);
var colorBlue = Math.floor(from.channels.blue + coef * (to.channels.blue - from.channels.blue));
colorBlue = Math.min(colorBlue, 255);
var rgb = prepareRGBChannelColor(colorRed) + prepareRGBChannelColor(colorGreen) + prepareRGBChannelColor(colorBlue);
return {
color: parseInt(rgb, 16),
alpha: from.alpha + coef * (to.alpha - from.alpha)
};
}
var startTime = Date.now();
console.log("start: " + startTime);
// Drawing the gradient
//
var gradient = new PIXI.Graphics();
app.stage.addChild(gradient);
//
var rect = {
width: 200,
height: 200
};
var round = 20;
//
var colorFromData = prepareColorData(0xFF00FF, 1);
var colorToData = prepareColorData(0xFF0000, 0.2);
//
var stepCoef;
var stepColor;
var stepAlpha;
var stepsCount = 100;
var stepHeight = rect.height / stepsCount;
for (var stepIndex = 0; stepIndex < stepsCount; stepIndex++) {
stepCoef = stepIndex / stepsCount;
stepColor = getColorOfGradient(colorFromData, colorToData, stepCoef);
gradient.beginFill(stepColor.color, stepColor.alpha);
gradient.drawRect(
0,
rect.height * stepCoef,
rect.width,
stepHeight
);
}
// Applying a mask with round corners to the gradient
var roundMask = new PIXI.Graphics();
roundMask.beginFill(0x000000);
roundMask.drawRoundedRect(0, 0, rect.width, rect.height, round);
app.stage.addChild(roundMask);
gradient.mask = roundMask;
var endTime = Date.now();
console.log("end: " + endTime);
console.log("total: " + (endTime - startTime));
The interesting thing is that it takes only about 2-5 ms for the whole process!
If you wan't to change colors of the gradient to white>black (as described in the question), just change the next params:
var colorFromData = prepareColorData(0xFF00FF, 1);
var colorToData = prepareColorData(0xFF0000, 0.2);
To:
var colorFromData = prepareColorData(0xFFFFFF, 1);
var colorToData = prepareColorData(0x000000, 0.2);

Not full answer but some extra information
As far I know, you can't use gradient for PIXI.Graphics even for sprites you need extra canvas
Just draw the gradient you want to a canvas:
https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/createLinearGradient
Then use that canvas as a texture: Texture.fromCanvas(canvas);
Look at this article.
For gradual opacity, Alpha Mask can help
http://pixijs.io/examples/#/demos/alpha-mask.js
P.S Maybe phaser.js can do more

Did you ever figure this out? I couldn't find a solution online either, so I implemented it myself using a filter. Have a look: https://codepen.io/Lancer611/pen/KodabK.
Some of the pixi code:
function newGradientPoly(poly, fill, fillSize){
var container = new PIXI.Sprite();
app.stage.addChild(container);
var shape = new PIXI.Graphics();
shape.beginFill(0xffffff)
.lineStyle(1, 0x333333)
.drawPolygon(poly);
var mask = new PIXI.Graphics();
mask.beginFill(0xffffff, 1)
.drawPolygon(poly);
container.mask = mask;
container.addChild(shape);
var fshaderCode = document.getElementById("fragShader").innerHTML;
fogShader = new PIXI.Filter(null, fshaderCode);
fogShader.uniforms.resolution = [width, height];
fogShader.uniforms.segments = poly.slice();
fogShader.uniforms.count = poly.length/2;
fogShader.uniforms.gSize = fillSize;
fogShader.uniforms.fill = fill;
shape.filters=[fogShader];
}

I've created a pixi plugin for displaying vector drawings in Pixi. The main limitation is that you need to draw your rectangle in the vector art program Omber first, so you need to know the size of your rectangle beforehand (since everything is vector-based, you could theoretically scale things later, but then the rounded corners would end up being a little uneven). The workflow is similar to using sprites: 1. draw your rectangles in Omber 2. export them to gltf 3. load the gltf files in your Pixi program 4. position the rectangles where you want them.
Another possibility is that you could create the gradient as a separate object, and then you can mask it out with a polygon. Here's an example. In that example, I'm using a vector drawing for the gradient, but since gradients don't become blurry when resized, you could probably use a sprite for that as well. I'm not sure if masks have good performance, but if you just need a few of them, then it's probably fine.

Zooming in D3 v4 on a globe

I'm looking for a way to zoom from place to place on a globe in D3 v4 (v4 is important). What I'm looking for is basically exactly this: https://www.jasondavies.com/maps/zoom/ My problem is that Jason Davies obfuscated his code, so I can't read it, and I can't find a bl.ock containing that project or anything similar to it. I'll provide a link to what I've got here: http://plnkr.co/edit/0mjyR3ovTfkDXB8FTG0j?p=preview
The relevant is probably inside the .tween():
.tween("rotate", function () {
var p = d3.geoCentroid(points[i]),
r = d3.geoInterpolate(projection.rotate(), [-p[0], -p[1]]);
return function (t) {
projection.rotate(r(t));
convertedLongLats = [projection(points[0].coordinates), projection(points[1].coordinates)]
c.clearRect(0, 0, width, height);
c.fillStyle = colorGlobe, c.beginPath(), path(sphere), c.fill();
c.fillStyle = colorLand, c.beginPath(), path(land), c.fill();
for (var j = 0; j < points.length; j++) {
var textCoords = projection(points[j].coordinates);
c.fillStyle = textColors, c.textAlign = "center", c.font = "18px FontAwesome", c.fillText(points[j].icon, textCoords[0], textCoords[1]);
textCoords[0] += 15;
c.textAlign = "left", c.font = " 12px Roboto", c.fillText(points[j].location, textCoords[0], textCoords[1]);
}
c.strokeStyle = textColors, c.lineWidth = 4, c.setLineDash([10, 10]), c.beginPath(), c.moveTo(convertedLongLats[0][0], convertedLongLats[0][1]), c.lineTo(convertedLongLats[1][0], convertedLongLats[1][1]), c.stroke();
};
})
Basically, I want what I've got now but I want it to zoom in, pretty much exactly like it is in the Animated World Zoom example I provided above. I'm not really looking for code, I'd rather someone point me in the right direction with an example or something (it's worth noting that I'm fairly new to d3 and that this project is heavily based on World Tour by mbostock, so it uses canvas). Thank you all in advance!

Based on your plunker and comment, a challenge in zooming out between two points in a transition is that the interpolator will only interpolate between two values. The solution in your plunker relies on two interpolators, one for zooming in and zooming out. This method has added un-needed complexity and somewhere along the line, as you note, it jumps to an incorrect scale. You could simplify this:
Take an interpolator that interpolates between -1 and 1, and weight each scale according to the absolute value of the interpolator. At zero, the zoom should be out all the way, while at -1,1, you should be zoomed in:
var s = d3.interpolate(-1,1);
// get the appropriate scale:
scale = Math.abs(0-s(t))*startEndScale + (1-Mat.abs(0-s(t)))*middleScale
This is a little clunky as it goes from zooming out to zooming in rather abruptly, so you could ease it with a sine type easing:
var s = d3.interpolate(0.0000001,Math.PI);
// get the appropriate scale:
scale = (1-Math.abs(Math.sin(s(t))))*startEndScale + Math.abs(Math.sin(s(t)))*middleScale
I've applied this to your plunker here.
For a simple and minimal example using the example that I suggested and your two points and path (and using your plunkr as a base), stripping out the animated line and icons, I would probably put together something like (plunker, snippet below best viewed on full screen):
var width = 600,
height = 600;
var points = [{
type: "Point",
coordinates: [-74.2582011, 40.7058316],
location: "Your Location",
icon: "\uF015"
}, {
type: "Point",
coordinates: [34.8887969, 32.4406351],
location: "Caribe Royale Orlando",
icon: "\uF236"
}];
var canvas = d3.select("body").append("canvas")
.attr("width", width)
.attr("height", height);
var c = canvas.node().getContext("2d");
var point = points[0].coordinates;
var projection = d3.geoOrthographic()
.translate([width / 2, height / 2])
.scale(width / 2)
.clipAngle(90)
.precision(0.6)
.rotate([-point[0], -point[1]]);
var path = d3.geoPath()
.projection(projection)
.context(c);
var colorLand = "#4d4f51",
colorGlobe = "#2e3133",
textColors = "#fff";
d3.json("https://unpkg.com/world-atlas#1/world/110m.json", function (error, world) {
if (error) throw error;
var sphere = { type: "Sphere" };
var land = topojson.feature(world, world.objects.land);
var i = 0;
var scaleMiddle = width/2;
var scaleStartEnd = width * 2;
loop();
function loop() {
d3.transition()
.tween("rotate",function() {
var flightPath = {
type: 'Feature',
geometry: {
type: "LineString",
coordinates: [points[i++%2].coordinates, points[i%2].coordinates]
}
};
// next point:
var p = points[i%2].coordinates;
// current rotation:
var currentRotation = projection.rotate();
// next rotation:
var nextRotation = projection.rotate([-p[0],-p[1]]).rotate();
// Interpolaters:
var r = d3.geoInterpolate(currentRotation,nextRotation);
var s = d3.interpolate(0.0000001,Math.PI);
return function(t) {
// apply interpolated values
projection.rotate(r(t))
.scale( (1-Math.abs(Math.sin(s(t))))*scaleStartEnd + Math.abs(Math.sin(s(t)))*scaleMiddle ) ;
c.clearRect(0, 0, width, height);
c.fillStyle = colorGlobe, c.beginPath(), path(sphere), c.fill();
c.fillStyle = colorLand, c.beginPath(), path(land), c.fill();
c.beginPath(), path(flightPath), c.globalAlpha = 0.5, c.shadowColor = "#fff", c.shadowBlur = 5, c.lineWidth = 0.5, c.strokeStyle = "#fff", c.stroke(), c.shadowBlur = 0, c.globalAlpha = 1;
}
})
.duration(3000)
.on("end", function() { loop(); })
}
});
<script src="http://d3js.org/d3.v4.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>

How to draw a simple path with animation in Raphaël.js

I am trying to draw a simple path with animation from start to end of a path using the Raphaël.js library at this Demo.
var canvas = Raphael('canvas', 900, 648);
var pathString = "M 200,200 L200,10 L100,10";
$('#start').click(function(e) {
var line = canvas.path(pathString).attr({ stroke: "#000" });
line.animate({ },5000);
});
but not sure how to use the animate() function here. How can I achieve this?

There may be a better way to do this, but here is the best I can find: getSubpath allows retrieving a segment of a path. By implementing a custom property which can be animated, we can control the path based on the value of this property:
var canvas = Raphael('canvas', 900, 648);
var pathString = "M 200,200 L200,10 L100,10";
canvas.customAttributes.subpath = function (from, to) {
from = Math.floor(from);
to = Math.floor(to);
if(to < from)
to = from;
return {path: this.parentPath.getSubpath(from, to)};
};
$('#start').click(function(e) {
canvas.clear();
// Create an invisible full representation of the path
var completeLine = canvas.path(pathString).attr({ 'stroke-opacity': 0 });
var len = completeLine.getTotalLength(pathString);
// Create a partial representation of the path
var line = canvas.path(pathString);
line.parentPath = completeLine;
line.attr({ stroke: "#000", subpath: [0, 0]});
// Animate using our custom subpath attribute from 0 to the length of the full path
line.animate({ subpath: [0, len] }, 5000);
});
https://jsfiddle.net/r40k0kjv/5/

fabricjs How can i keep fixed size on group elements while others scaling?

Hello I use fabricjs to play with the html canvas.
I create the canvas and i add group of objects on it.
On a group of objects, I need to keep fixed width & height for some objects while I scale the object.
I use the 'object:scaling' event to get the active object when it changes size, I read each object of the group and I assign element[i].set({'radius':5}) on the group objects that I want to be unchanged.
But the result is that , all the group object to resize.
I show you the snippet of the object:scaling event :
canvas.on('object:scaling',function(e){
var activeObject1 = e.target;
var elements = e.target._objects;
var count_elements = elements.length;
for(var i = 0; i < count_elements; i++) {
var type = elements[i].typeCircle;
if(type == "parts"){
//elements[i].set({"radius":8,"fill":"#abcde2","stroke":"#367827"});
//elements[i].set('radius',8);
/*elements[i].setWidth(16);
elements[i].setHeight(16);
elements[i].currentWidth = 16;
elements[i].currentHeight = 16;
elements[i].scaleX = 1;
elements[i].scaleY = 1;
console.log(elements[i]);
canvas.renderAll();*/
}
}
});
What should I write into the for loop to keep fixed size on some objects?
everything that I used above, they don't work except for the "fill":"#abcde2","stroke":"#367827"
If anyone has faced something similar on fabricjs, please let me know .

You must use setScaleX() and setScaleY() methods.
Here is an example...
var Rect = new fabric.Rect({
width: 200,
height: 200,
top: 100,
left: 100,
fill: 'rgba(255,0,0,0.5)',
stroke: '#000',
strokeWidth: 1,
});
var Circle = new fabric.Circle({
left: 100,
top: 100,
fill: '#FF00FF',
stroke: 'red',
radius: 100,
opacity: 1,
});
var Group = new fabric.Group([Rect, Circle])
canvas.add(Group)
canvas.on({
'object:scaling': onChange
})
function onChange(obj) {
var circle = obj.target.item(1),
group = obj.target,
scaleX = circle.width / group.getWidth(),
scaleY = circle.height / group.getHeight();
circle.setScaleX(scaleX);
circle.setScaleY(scaleY);
}
JSFIDDLE

Using fabricjs2 to stop scaling of a text item I have modified Rafik Avtoyan's function to work well. I have locked Y scaling for my group so you will have to add this if required.
function handleScalingEvent(obj) {
var text = obj.target.item(1),
group = obj.target,
scaleX = group.width / (group.width * group.scaleX);
text.set('scaleX', scaleX);
}

Best way to make the objects the same size is to divide desired width by object width. For example, if you want all added objects to be 256px the code will look this way:
function selectImage(imagePath){
fabric.Image.fromURL(imagePath, function(oImg) {
canvas.add(oImg);
let zoom = 256 / oImg.width;
oImg.set({ scaleX: zoom, scaleY: zoom, });
oImg.center();
});
}
In the case when the image will be 64px it will scale it by 4 to 256px and in case the image is 512px it will scale it by 0.5 which will make the image smaller to 256px.