Related
what exactly I want to achieve is
to draw objects on canvas and
on mouseover display relevant data in tooltip.
here you can view the code.
var canvasBack;
var canvasLabel;
var canvasDraw;
var ctxBack;
var ctxLabel;
var ctxDraw;
var last_mousex = 0;
var last_mousey = 0;
var mousex = 0;
var mousey = 0;
var canWidth;
var canHeight;
var scaleParameter;
var radius;
var xVertex;
var yVertex;
var hotspots = [];
// initialization on loading of canvas
$('canvas').ready(function() {
init();
});
// initialization function used for binding events, and inital logic implemented.
function init() {
scaleParameter = 1;
canvasBack = document.getElementById('backSpace');
canvasLabel = document.getElementById('layerCanvas');
canvasDraw = document.getElementById('drawSpace');
ctxBack = canvasBack.getContext('2d');
ctxLabel = canvasLabel.getContext('2d');
ctxDraw = canvasDraw.getContext('2d');
canWidth = parseInt($(canvasBack).attr('width'));
canHeight = parseInt($(canvasBack).attr('height'));
var canvasx = $(canvasBack).offset().left;
var canvasy = $(canvasBack).offset().top
var mousedown = false;
//Mousedown
$('canvas').on('mousedown', function(e) {
$('#drawSpace').css('display', 'block');
last_mousex = mousex = parseInt(e.clientX - canvasx);
last_mousey = mousey = parseInt(e.clientY - canvasy);
mousedown = true;
});
//Mouseup
$('canvas').on('mouseup', function(e) {
hotspots.push({
x: xVertex,
y: yVertex,
radius: radius,
tip: 'You are over ' + mousex + ',' + mousey
});
let cw = canvasBack.width;
let ch = canvasBack.height;
ctxBack.drawImage(canvasDraw, 0, 0, cw, ch);
$('#drawSpace').css('display', 'none');
mousedown = false;
});
//Mousemove
$('canvas').on('mousemove', function(e) {
mousex = parseInt(e.clientX - canvasx);
mousey = parseInt(e.clientY - canvasy);
if (mousedown) {
// draw(mousedown);
drawEllipse(last_mousex, last_mousey, mousex, mousey);
} else {
hoverTooltip();
}
});
}
function drawEllipse(x1, y1, x2, y2) {
var leftScroll = $("#scrollParent").scrollLeft();
var topScroll = $("#scrollParent").scrollTop();
let cw = canvasBack.width;
let ch = canvasBack.height;
ctxDraw.clearRect(0, 0, cw, ch);
var radiusX = x2 - x1,
radiusY = y2 - y1,
centerX = x1 + radiusX,
centerY = y1 + radiusY,
step = 0.01,
a = step,
pi2 = Math.PI * 2 - step;
radius = Math.sqrt(radiusX * radiusX + radiusY * radiusY) / 2;
ctxDraw.beginPath();
ctxDraw.arc(centerX, centerY, radius, 0, 2 * Math.PI, true);
ctxDraw.closePath();
ctxDraw.fillStyle = 'green';
ctxDraw.fill();
ctxDraw.strokeStyle = '#000';
ctxDraw.stroke();
xVertex = centerX;
yVertex = centerY;
}
// tooltip show on hover over objects
function hoverTooltip() {
var leftScroll = $("#scrollParent").scrollLeft();
var topScroll = $("#scrollParent").scrollTop();
let cw = canvasBack.width;
let ch = canvasBack.height;
for (var i = 0; i < hotspots.length; i++) {
var h = hotspots[i];
var dx = mousex - h.x;
var dy = mousey - h.y;
if (dx * dx + dy * dy < h.radius * h.radius) {
$('#console').text(h.tip);
ctxLabel.clearRect(0, 0, cw, ch);
ctxLabel.fillText(h.tip, mousex + leftScroll, mousey + topScroll);
} else {
ctxLabel.clearRect(0, 0, cw, ch);
}
}
}
#scrollParent {
width: 644px;
height: 364px;
overflow: auto;
position: relative;
}
#scrollParent>canvas {
position: absolute;
left: 0;
top: 0;
border: 1px solid #ababab;
}
#backSpace {
z-index: 0;
}
#drawSpace {
display: none;
z-index: 1;
}
#layerCanvas {
z-index: 2;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="scrollParent">
<!-- actual canvas that is visible -->
<canvas width="640" height="360" id="backSpace"></canvas>
<!-- canvas used for drawing new objects -->
<canvas width="640" height="360" id="drawSpace"></canvas>
<!-- canvas used to display tooltip -->
<canvas width="640" height="360" id="layerCanvas"></canvas>
</div>
<div id="console"></div>
</div>
actual problem is in the bellow image, tooltip worked fine when the 1st object was drawn, but once the second object was drawn tooltip worked only for the second one, not for previously drawn objects.
what is causing this issue, and how to fix it ?
Removing else will not remove the label when leaving the elipse.
You need to exit the loop once you found the correct elipse from the array using break.
function hoverTooltip() {
var leftScroll = $("#scrollParent").scrollLeft();
var topScroll = $("#scrollParent").scrollTop();
let cw = canvasBack.width;
let ch = canvasBack.height;
for (var i = 0; i < hotspots.length; i++) {
var h = hotspots[i];
var dx = mousex - h.x;
var dy = mousey - h.y;
if (dx * dx + dy * dy < h.radius * h.radius) {
$('#console').text(h.tip);
ctxLabel.clearRect(0, 0, cw, ch);
ctxLabel.fillText(h.tip, mousex + leftScroll, mousey + topScroll);
break; // exit the loop
} else {
ctxLabel.clearRect(0, 0, cw, ch);
}
}
}
UPDATE
I figured that if you draw two objects over each other, it will behave poorly. Try this instead. It will display information of the latest drawn spot.
function hoverTooltip() {
var leftScroll = $("#scrollParent").scrollLeft();
var topScroll = $("#scrollParent").scrollTop();
let cw = canvasBack.width;
let ch = canvasBack.height;
var spots = hotspots.filter((h) => {
var dx = mousex - h.x;
var dy = mousey - h.y;
return (dx * dx + dy * dy < h.radius * h.radius);
})
if (spots.length > 0) {
var h = spots[spots.length - 1]; // latest drawn spot
$('#console').text(h.tip);
ctxLabel.clearRect(0, 0, cw, ch);
ctxLabel.fillText(h.tip, mousex + leftScroll, mousey + topScroll);
}
else
{
ctxLabel.clearRect(0, 0, cw, ch);
}
}
I see there are already a few answers. This is mine:
In order to be able to show the label for every circle on hover you need to save all your circles in am array: the circles array. I'm using the ctx.isPointInPath() method to know if the mouse is over the circle, and if it is I paint the label.
const canvas = document.querySelector("canvas");
const ctx = canvas.getContext("2d");
let cw = canvas.width = 640;
let ch = canvas.height = 360;
let found = false;//is a circle found?
const cText = document.querySelector("#text");
const ctxText = cText.getContext("2d");
cText.width = 640;
cText.height = 360;
ctxText.font="1em Verdana";
let drawing = false;
let circles = []
class Circle{
constructor(x,y){
this.x = x;
this.y = y;
this.r = 0;
}
updateR(m) {
this.r = dist(this,m);
}
draw(){
ctx.beginPath();
ctx.arc(this.x,this.y,this.r,0,2*Math.PI);
}
paint(){
ctx.fillStyle = "green";
ctx.strokeStyle = "black";
this.draw();
ctx.stroke();
ctx.fill();
}
label(m){
this.draw();
if (ctx.isPointInPath(m.x, m.y)) {
ctx.beginPath();
ctx.arc(this.x, this.y, 4, 0, 2 * Math.PI);
ctxText.fillStyle = "black";
ctxText.fillText(`you are over ${this.x},${this.y}`,m.x,m.y)
found = true;
}
}
}
let m = {}// mouse
cText.addEventListener("mousedown",(e)=>{
drawing = true;
m = oMousePos(canvas, e);
let circle = new Circle(m.x,m.y)
circles.push(circle);
})
cText.addEventListener("mouseup",(e)=>{
drawing = false;
})
cText.addEventListener("mousemove",(e)=>{
m = oMousePos(canvas, e);
found = false;
if(drawing){
let circle = circles[circles.length-1];//the last circle in the circles arrey
circle.updateR(m);
}
ctx.clearRect(0,0, cw,ch);
ctxText.clearRect(0,0,cw,ch)
circles.map((c) => {c.paint();});
for(let i = circles.length-1; i >=0 ; i--){
circles[i].label(m);
if(found){break;}
}
})
function oMousePos(canvas, evt) {
var ClientRect = canvas.getBoundingClientRect();
return { //objeto
x: Math.round(evt.clientX - ClientRect.left),
y: Math.round(evt.clientY - ClientRect.top)
}
}
function dist(p1, p2) {
let dx = p2.x - p1.x;
let dy = p2.y - p1.y;
return Math.sqrt(dx * dx + dy * dy);
}
canvas{border:1px solid;position:absolute; top:0; left:0;}
#scrollParent{position:relative;}
<div id="scrollParent">
<!-- actual canvas that is visible -->
<canvas width="640" height="360"></canvas>
<canvas width="640" height="360" id="text"></canvas>
</div>
I've updated the code in base of the comment of #HelderSepu
A SECOND UPDATE in base of a second message from #HelderSepu. He wants to see "multiple message but avoid overlapping the messages"
const canvas = document.querySelector("canvas");
const ctx = canvas.getContext("2d");
let cw = canvas.width = 640;
let ch = canvas.height = 360;
let text = "";
const cText = document.querySelector("#text");
const ctxText = cText.getContext("2d");
cText.width = 640;
cText.height = 360;
ctxText.font="1em Verdana";
let drawing = false;
let circles = []
class Circle{
constructor(x,y){
this.x = x;
this.y = y;
this.r = 0;
}
updateR(m) {
this.r = dist(this,m);
}
draw(){
ctx.beginPath();
ctx.arc(this.x,this.y,this.r,0,2*Math.PI);
}
paint(){
ctx.fillStyle = "green";
ctx.strokeStyle = "black";
this.draw();
ctx.stroke();
ctx.fill();
}
label(m){
this.draw();
if (ctx.isPointInPath(m.x, m.y)) {
this.text = `[${this.x},${this.y}]`
}else{
this.text = "";
}
}
}
let m = {}// mouse
cText.addEventListener("mousedown",(e)=>{
drawing = true;
m = oMousePos(canvas, e);
let circle = new Circle(m.x,m.y)
circles.push(circle);
})
cText.addEventListener("mouseup",(e)=>{
drawing = false;
})
cText.addEventListener("mousemove",(e)=>{
m = oMousePos(canvas, e);
if(drawing){
let circle = circles[circles.length-1];//the last circle in the circles arrey
circle.updateR(m);
}
ctx.clearRect(0,0, cw,ch);
ctxText.clearRect(0,0,cw,ch);
text="";
circles.map((c) => {c.paint();c.label(m);});
circles.map((c) => {text += c.text;});
ctxText.fillStyle = "black";
ctxText.fillText(text,m.x,m.y)
})
function oMousePos(canvas, evt) {
var ClientRect = canvas.getBoundingClientRect();
return { //objeto
x: Math.round(evt.clientX - ClientRect.left),
y: Math.round(evt.clientY - ClientRect.top)
}
}
function dist(p1, p2) {
let dx = p2.x - p1.x;
let dy = p2.y - p1.y;
return Math.sqrt(dx * dx + dy * dy);
}
canvas{border:1px solid;position:absolute; top:0; left:0;}
#scrollParent{position:relati
<div id="scrollParent">
<!-- actual canvas that is visible -->
<canvas width="640" height="360"></canvas>
<canvas width="640" height="360" id="text"></canvas>
<div id="console"></div>
</div>
How do I shoot bullets from my Player X and Y towards the mouse x and y?
I can find the angle of the mouse X and Y but I have no idea how to create a bullet which will fly towards the mouse.
The code for the mouse coordinates are (dx, dy).
Also, if you could explain the logic behind what you did and how you did it, I would be greatful.
Thanks!
Fiddle
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var pressingDown = false;
var pressingUp = false;
var pressingLeft = false;
var pressingRight = false;
var mouseX, mouseY;
function Player(x, y) {
this.x = x;
this.y = y;
this.angle;
}
Player.prototype.draw = function() {
context.save();
context.translate(this.x, this.y);
context.rotate(this.angle);
context.beginPath();
context.fillStyle = "green";
context.arc(0, 0, 30, 0, 2 * Math.PI);
context.fill();
context.fillStyle = "red";
context.fillRect(0, -10, 50, 20);
context.restore();
}
Player.prototype.update = function(mouseX, mouseY) {
var dx = mouseX - this.x;
var dy = mouseY - this.y;
this.angle = Math.atan2(dy, dx);
}
canvas.addEventListener('mousemove', mouseMove);
function mouseMove(evt) {
mouseX = evt.x;
mouseY = evt.y;
}
var player = new Player(350, 250);
function updatePlayer() {
context.clearRect(0, 0, canvas.width, canvas.height);
player.draw();
player.update(mouseX, mouseY);
updatePlayerPosition();
}
document.onkeydown = function(event) {
if (event.keyCode === 83) //s
pressingDown = true;
else if (event.keyCode === 87) //w
pressingUp = true;
else if (event.keyCode === 65) //a
pressingLeft = true;
else if (event.keyCode === 68) //d
pressingRight = true;
}
document.onkeyup = function(event) {
if (event.keyCode === 83) //s
pressingDown = false;
else if (event.keyCode === 87) //w
pressingUp = false;
else if (event.keyCode === 65) //a
pressingLeft = false;
else if (event.keyCode === 68) //d
pressingRight = false;
}
updatePlayerPosition = function() {
if (pressingRight)
player.x += 1;
if (pressingLeft)
player.x -= 1;
if (pressingDown)
player.y += 1;
if (pressingUp)
player.y -= 1;
}
function update() {
updatePlayer();
}
setInterval(update, 0)
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<style>
body {
background-color: black;
}
canvas {
position: absolute;
margin: auto;
left: 0;
right: 0;
border: solid 1px white;
border-radius: 10px;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script type="application/javascript">
(function() {
"use strict";
var canvasWidth = 180;
var canvasHeight = 160;
var canvas = null;
var bounds = null;
var ctx = null;
var mouseX = 0.0;
var mouseY = 0.0;
var player = {
x: (canvasWidth * 0.5) | 0,
y: (canvasHeight * 0.5) | 0,
dx: 0.0,
dy: 0.0,
angle: 0.0,
radius: 17.5,
tick: function() {
this.angle = Math.atan2(mouseY - this.y,mouseX - this.x);
},
render: function() {
ctx.fillStyle = "darkred";
ctx.strokeStyle = "black";
ctx.translate(this.x,this.y);
ctx.rotate(this.angle);
ctx.beginPath();
ctx.moveTo(this.radius,0.0);
ctx.lineTo(-0.5 * this.radius,0.5 * this.radius);
ctx.lineTo(-0.5 * this.radius,-0.5 * this.radius);
ctx.lineTo(this.radius,0.0);
ctx.fill();
ctx.stroke();
ctx.rotate(-this.angle);
ctx.translate(-this.x,-this.y);
}
};
var bullet = {
x: (canvasWidth * 0.5) | 0,
y: (canvasHeight * 0.5) | 0,
dx: 0.0,
dy: 0.0,
radius: 5.0,
tick: function() {
this.x += this.dx;
this.y += this.dy;
if (this.x + this.radius < 0.0
|| this.x - this.radius > canvasWidth
|| this.y + this.radius < 0.0
|| this.y - this.radius > canvasHeight)
{
this.dx = 0.0;
this.dy = 0.0;
}
},
render: function() {
ctx.fillStyle = "darkcyan";
ctx.strokeStyle = "white";
ctx.beginPath();
ctx.arc(this.x,this.y,this.radius,0.0,2.0*Math.PI,false);
ctx.fill();
ctx.stroke();
}
};
function loop() {
// Tick
bullet.tick();
player.tick();
// Render
ctx.fillStyle = "gray";
ctx.fillRect(0,0,canvasWidth,canvasHeight);
bullet.render();
player.render();
//
requestAnimationFrame(loop);
}
window.onmousedown = function(e) {
// The mouse pos - the player pos gives a vector
// that points from the player toward the mouse
var x = mouseX - player.x;
var y = mouseY - player.y;
// Using pythagoras' theorm to find the distance (the length of the vector)
var l = Math.sqrt(x * x + y * y);
// Dividing by the distance gives a normalized vector whose length is 1
x = x / l;
y = y / l;
// Reset bullet position
bullet.x = player.x;
bullet.y = player.y;
// Get the bullet to travel towards the mouse pos with a new speed of 10.0 (you can change this)
bullet.dx = x * 10.0;
bullet.dy = y * 10.0;
}
window.onmousemove = function(e) {
mouseX = e.clientX - bounds.left;
mouseY = e.clientY - bounds.top;
}
window.onload = function() {
canvas = document.getElementById("canvas");
canvas.width = canvasWidth;
canvas.height = canvasHeight;
bounds = canvas.getBoundingClientRect();
ctx = canvas.getContext("2d");
loop();
}
})();
</script>
</body>
</html>
Moving from point to point.
Given two points p1 and p2, each point as a coordinate (x,y) and a speed value that is the number of pixels per step, there are two methods you can use to move between them.
Cartesian
Calculate the vector from p1 to p2
var vx = p2.x - p1.x;
var vy = p2.y - p1.y;
Then calculate the delta by getting the length of the vector, normalise it (make the vector 1 pixel long) then multiply by the speed
var dist = Math.sqrt(vx * vx + vy * vy);
var dx = vx / dist;
var dy = vy / dist;
dx *= speed;
dy *= speed;
This can be optimized a little by scaling the speed with the distance.
var scale = speed / Math.sqrt(vx * vx + vy * vy);
var dx = vx / dist;
var dy = vy / dist;
Polar
The other way is to get the direction from p1 to p2 and use that create the deltas
var dir = Math.atan2(p2.y - p1.y, p2.x - p1.x);
var dx = Math.cos(dir) * speed;
var dx = Math.sin(dir) * speed;
Animate
Once you have the delta you just need to update the position via addition.
const bullet = {x : p1.x, y : p1.y}; // set the bullet start pos
// then each frame add the delta
bullet.x += dx;
bullet.y += dy;
// draw the bullet
I would like to draw a spring in a HTML5 canvas, and show if that spring is at its rest length or not.
My spring is attached to a rectangular shape to some X-Y coordinates and defined as follows:
function Spring(restLenght, width, numRounds){
this.x1 = 0;
this.y1 = 0;
this.x2 = 0;
this.y2 = 0;
this.restLenght = restLenght;
this.width = width;
this.numRounds = numRounds;
this.color = "green";
this.lineWidth = 6;
}
The parameters are explained in the picture below:
When the spring is at its rest length, the lines shall be parallel to each other, otherwise this means the spring is stretched or compressed. Then it will be immediately clear what state the spring is.
I'm stuck now with the bezierCurveTo() Method:
Here is my Fiddle: https://jsfiddle.net/df3mm8kz/1/
var cv = document.getElementById('cv'),
ctx = cv.getContext('2d'),
mouse = capture(cv),
box = new Box(120, 80, 0, 16),
spring = new Spring(160, 20, 2, 0.03, 0.9),
vx = 0,
vy = 0;
function Spring(restLenght, width, numRounds, k, f){
this.x1 = 0;
this.y1 = 0;
this.x2 = 0;
this.y2 = 0;
this.restLenght = restLenght;
this.width = width;
this.numRounds = numRounds;
this.k = k;
this.f = f;
this.color = "green";
this.lineWidth = 6;
}
Spring.prototype.draw = function(ctx) {
var sPX, sPY, cP1X, cP1Y, cP2X, cP2Y, ePX, ePY;
ctx.save();
ctx.translate(this.x, this.y);
ctx.rotate(this.rotation);
ctx.lineWidth = this.lineWidth;
ctx.strokeStyle = this.color;
ctx.fillStyle = this.color;
ctx.beginPath();
ctx.moveTo(this.x1, this.y1);
// length of one spring's round
var l = this.restLenght/(this.numRounds + 2);
// Initial segment, from spring anchor point to the first round
sPX = this.x1+l; sPY = this.y2;
ctx.lineTo(sPX, sPY);
// half width of spring's rounds
var hw = 0.5*this.width;
// half length of one spring's round
var hl = 0.5*l;
for(var i=0, n=this.numRounds; i<n; i++) {
cP1X = sPX + hl*i; cP1Y = sPY + hw;
cP2X = sPX + l*i; cp2Y = sPY + hw;
ePX = sPX + l*i; ePY = sPY;
ctx.bezierCurveTo(cP1X,cP1Y,cP2X,cp2Y,ePX,ePY);
cP1X = sPX + hl*i; cP1Y = sPY - hw;
cP2X = sPX + l*i; cp2Y = sPY - hw;
ePX = sPX + l*i; ePY = sPY;
ctx.bezierCurveTo(cP1X,cP1Y,cP2X,cp2Y,ePX,ePY);
}
// Final segment, from last springs round to the center of mass
ctx.lineTo(this.x2, this.y2);
ctx.closePath();
ctx.fill();
ctx.stroke();
ctx.restore();
};
function Box(w, h, mx, my) {
this.x = 0;
this.y = 0;
this.w = w;
this.h = h;
this.mx = mx;
this.my = my;
this.vx = 0;
this.vy = 0;
this.rotation = 0;
this.color = "red";
this.lineWidth = 1;
}
Box.prototype.draw = function(ctx) {
ctx.save();
ctx.translate(this.x, this.y);
ctx.rotate(this.rotation);
ctx.lineWidth = this.lineWidth;
ctx.strokeStyle = "black";
ctx.fillStyle = this.color;
ctx.beginPath();
ctx.rect(-0.5*this.w, -0.5*this.h, this.w, this.h);
ctx.closePath();
ctx.fill();
ctx.stroke();
ctx.beginPath();
ctx.strokeStyle = "yellow";
ctx.fillStyle = "yellow";
ctx.arc(this.mx, 0.5*this.h-this.my, 6, 0, 2 * Math.PI, false);
ctx.stroke();
ctx.closePath();
ctx.fill();
ctx.restore();
};
window.requestAnimFrame = (
function(callback) {
return window.setTimeout(callback, 1000/30);
});
(function drawFrame() {
window.requestAnimFrame(drawFrame, cv);
ctx.clearRect(0, 0, cv.width, cv.height);
var dx = box.x - mouse.x,
dy = box.y - mouse.y,
angle = Math.atan2(dy, dx),
boxAngle = angle + 0.5*Math.PI,
targetX = mouse.x + Math.cos(angle) * spring.restLenght,
targetY = mouse.y + Math.sin(angle) * spring.restLenght;
vx += (targetX - box.x) * spring.k;
vy += (targetY - box.y) * spring.k;
vx *= spring.f;
vy *= spring.f;
box.rotation = boxAngle;
box.x += vx;
box.y += vy;
box.draw(ctx);
spring.x1 = mouse.x;
spring.y1 = mouse.y;
spring.x2 = box.x;
spring.y2 = box.y;
spring.draw(ctx);
}());
function capture(element) {
var mouse = {
x: 0,
y: 0,
event: null
},
body_scrollLeft = document.body.scrollLeft,
element_scrollLeft = document.documentElement.scrollLeft,
body_scrollTop = document.body.scrollTop,
element_scrollTop = document.documentElement.scrollTop,
offsetLeft = element.offsetLeft,
offsetTop = element.offsetTop;
element.addEventListener('mousemove', function(event) {
var x, y;
if (event.pageX || event.pageY) {
x = event.pageX;
y = event.pageY;
} else {
x = event.clientX + body_scrollLeft + element_scrollLeft;
y = event.clientY + body_scrollTop + element_scrollTop;
}
x -= offsetLeft;
y -= offsetTop;
mouse.x = x;
mouse.y = y;
mouse.event = event;
}, false);
return mouse;
}
<canvas id="cv" width="600" height="400"></canvas>
Drawing a spring
Rather than use bezier curves which do not actually fit the curve of a spring (but close) I just use a simple path and use trig functions to draw each winding. the function has a start x1,y1 and end x2, y2, windings (should be an integer), width of spring, the offset (bits at ends), Dark colour, and light colour, and the stroke width (width of the wire).
The demo draws an extra highlight to give the spring a little more depth. It can easily be removed.
The code came from this answer that has a simpler version of the same function
function drawSpring(x1, y1, x2, y2, windings, width, offset, col1, col2, lineWidth){
var x = x2 - x1;
var y = y2 - y1;
var dist = Math.sqrt(x * x + y * y);
var nx = x / dist;
var ny = y / dist;
ctx.strokeStyle = col1
ctx.lineWidth = lineWidth;
ctx.lineJoin = "round";
ctx.lineCap = "round";
ctx.beginPath();
ctx.moveTo(x1,y1);
x1 += nx * offset;
y1 += ny * offset;
x2 -= nx * offset;
y2 -= ny * offset;
var x = x2 - x1;
var y = y2 - y1;
var step = 1 / (windings);
for(var i = 0; i <= 1-step; i += step){ // for each winding
for(var j = 0; j < 1; j += 0.05){
var xx = x1 + x * (i + j * step);
var yy = y1 + y * (i + j * step);
xx -= Math.sin(j * Math.PI * 2) * ny * width;
yy += Math.sin(j * Math.PI * 2) * nx * width;
ctx.lineTo(xx,yy);
}
}
ctx.lineTo(x2, y2);
ctx.lineTo(x2 + nx * offset, y2 + ny * offset)
ctx.stroke();
ctx.strokeStyle = col2
ctx.lineWidth = lineWidth - 4;
var step = 1 / (windings);
ctx.beginPath();
ctx.moveTo(x1 - nx * offset, y1 - ny * offset);
ctx.lineTo(x1, y1);
ctx.moveTo(x2, y2);
ctx.lineTo(x2 + nx * offset, y2 + ny * offset)
for(var i = 0; i <= 1-step; i += step){ // for each winding
for(var j = 0.25; j <= 0.76; j += 0.05){
var xx = x1 + x * (i + j * step);
var yy = y1 + y * (i + j * step);
xx -= Math.sin(j * Math.PI * 2) * ny * width;
yy += Math.sin(j * Math.PI * 2) * nx * width;
if(j === 0.25){
ctx.moveTo(xx,yy);
}else{
ctx.lineTo(xx,yy);
}
}
}
ctx.stroke();
}
function display() {
ctx.setTransform(1, 0, 0, 1, 0, 0); // reset transform
ctx.globalAlpha = 1; // reset alpha
ctx.clearRect(0, 0, w, h);
ctx.lineWidth = 8;
drawSpring(canvas.width / 2,10, mouse.x,mouse.y,8,100,40,"green","#0C0",15);
}
// Boiler plate code from here down and not part of the answer
var w, h, cw, ch, canvas, ctx, mouse, globalTime = 0, firstRun = true;
;(function(){
const RESIZE_DEBOUNCE_TIME = 100;
var createCanvas, resizeCanvas, setGlobals, resizeCount = 0;
createCanvas = function () {
var c,
cs;
cs = (c = document.createElement("canvas")).style;
cs.position = "absolute";
cs.top = cs.left = "0px";
cs.zIndex = 1000;
document.body.appendChild(c);
return c;
}
resizeCanvas = function () {
if (canvas === undefined) {
canvas = createCanvas();
}
canvas.width = innerWidth;
canvas.height = innerHeight;
ctx = canvas.getContext("2d");
if (typeof setGlobals === "function") {
setGlobals();
}
if (typeof onResize === "function") {
if(firstRun){
onResize();
firstRun = false;
}else{
resizeCount += 1;
setTimeout(debounceResize, RESIZE_DEBOUNCE_TIME);
}
}
}
function debounceResize() {
resizeCount -= 1;
if (resizeCount <= 0) {
onResize();
}
}
setGlobals = function () {
cw = (w = canvas.width) / 2;
ch = (h = canvas.height) / 2;
}
mouse = (function () {
function preventDefault(e) {
e.preventDefault();
}
var mouse = {
x : 0,
y : 0,
w : 0,
alt : false,
shift : false,
ctrl : false,
buttonRaw : 0,
over : false,
bm : [1, 2, 4, 6, 5, 3],
active : false,
bounds : null,
crashRecover : null,
mouseEvents : "mousemove,mousedown,mouseup,mouseout,mouseover,mousewheel,DOMMouseScroll".split(",")
};
var m = mouse;
function mouseMove(e) {
var t = e.type;
m.bounds = m.element.getBoundingClientRect();
m.x = e.pageX - m.bounds.left;
m.y = e.pageY - m.bounds.top;
m.alt = e.altKey;
m.shift = e.shiftKey;
m.ctrl = e.ctrlKey;
if (t === "mousedown") {
m.buttonRaw |= m.bm[e.which - 1];
} else if (t === "mouseup") {
m.buttonRaw &= m.bm[e.which + 2];
} else if (t === "mouseout") {
m.buttonRaw = 0;
m.over = false;
} else if (t === "mouseover") {
m.over = true;
} else if (t === "mousewheel") {
m.w = e.wheelDelta;
} else if (t === "DOMMouseScroll") {
m.w = -e.detail;
}
if (m.callbacks) {
m.callbacks.forEach(c => c(e));
}
if ((m.buttonRaw & 2) && m.crashRecover !== null) {
if (typeof m.crashRecover === "function") {
setTimeout(m.crashRecover, 0);
}
}
e.preventDefault();
}
m.addCallback = function (callback) {
if (typeof callback === "function") {
if (m.callbacks === undefined) {
m.callbacks = [callback];
} else {
m.callbacks.push(callback);
}
}
}
m.start = function (element) {
if (m.element !== undefined) {
m.removeMouse();
}
m.element = element === undefined ? document : element;
m.mouseEvents.forEach(n => {
m.element.addEventListener(n, mouseMove);
});
m.element.addEventListener("contextmenu", preventDefault, false);
m.active = true;
}
m.remove = function () {
if (m.element !== undefined) {
m.mouseEvents.forEach(n => {
m.element.removeEventListener(n, mouseMove);
});
m.element.removeEventListener("contextmenu", preventDefault);
m.element = m.callbacks = undefined;
m.active = false;
}
}
return mouse;
})();
// Clean up. Used where the IDE is on the same page.
var done = function () {
window.removeEventListener("resize", resizeCanvas)
mouse.remove();
document.body.removeChild(canvas);
canvas = ctx = mouse = undefined;
}
function update(timer) { // Main update loop
if(ctx === undefined){
return;
}
globalTime = timer;
display(); // call demo code
if (!(mouse.buttonRaw & 2)) {
requestAnimationFrame(update);
} else {
done();
}
}
setTimeout(function(){
resizeCanvas();
mouse.start(canvas, true);
mouse.crashRecover = done;
window.addEventListener("resize", resizeCanvas);
requestAnimationFrame(update);
},0);
})();
/** SimpleFullCanvasMouse.js end **/
To make drawing easier, use .translate() and .rotate() to move into an aligned coordinate system.
ctx.translate(this.x1, this.y1);
ctx.rotate(Math.atan2(this.y2 - this.y1, this.x2 - this.x1));
You can then draw the spring along the local x-axis, and it will appear in the correct place and rotation.
Your spacing of the segments were wrong. hl*i is half the distance from the spring's starting point, not the segment's starting point.
var cv = document.getElementById('cv'),
ctx = cv.getContext('2d'),
mouse = capture(cv),
box = new Box(120, 80, 0, 16),
spring = new Spring(160, 50, 2, 0.03, 0.9),
vx = 0,
vy = 0;
function Spring(restLenght, width, numRounds, k, f) {
this.x1 = 0;
this.y1 = 0;
this.x2 = 0;
this.y2 = 0;
this.restLenght = restLenght;
this.width = width;
this.numRounds = numRounds;
this.k = k;
this.f = f;
this.color = "green";
this.lineWidth = 6;
}
Spring.prototype.draw = function(ctx) {
var sPX, sPY, cP1X, cP1Y, cP2X, cP2Y, ePX, ePY;
ctx.save();
ctx.lineWidth = this.lineWidth;
ctx.strokeStyle = this.color;
ctx.fillStyle = this.color;
var vx = this.x2 - this.x1;
var vy = this.y2 - this.y1;
var vm = Math.sqrt(vx * vx + vy * vy);
ctx.translate(this.x1, this.y1);
ctx.rotate(Math.atan2(vy, vx));
ctx.beginPath();
ctx.moveTo(0, 0);
// length of one spring's round
var l = vm / (this.numRounds + 2);
// Initial segment, from spring anchor point to the first round
sPX = l;
sPY = 0;
ctx.lineTo(sPX, sPY);
// half width of spring's rounds
var hw = 0.5 * this.width;
for (var i = 0, n = this.numRounds; i < n; i++) {
cP1X = sPX + l * (i + 0.0);
cP1Y = sPY + hw;
cP2X = sPX + l * (i + 0.5);
cp2Y = sPY + hw;
ePX = sPX + l * (i + 0.5);
ePY = sPY;
ctx.bezierCurveTo(cP1X, cP1Y, cP2X, cp2Y, ePX, ePY);
cP1X = sPX + l * (i + 0.5);
cP1Y = sPY - hw;
cP2X = sPX + l * (i + 1.0);
cp2Y = sPY - hw;
ePX = sPX + l * (i + 1.0);
ePY = sPY;
ctx.bezierCurveTo(cP1X, cP1Y, cP2X, cp2Y, ePX, ePY);
}
// Final segment, from last springs round to the center of mass
ctx.lineTo(vm, 0);
//ctx.closePath();
//ctx.fill();
ctx.stroke();
ctx.restore();
};
function Box(w, h, mx, my) {
this.x = 0;
this.y = 0;
this.w = w;
this.h = h;
this.mx = mx;
this.my = my;
this.vx = 0;
this.vy = 0;
this.rotation = 0;
this.color = "red";
this.lineWidth = 1;
}
Box.prototype.draw = function(ctx) {
ctx.save();
ctx.translate(this.x, this.y);
ctx.rotate(this.rotation);
ctx.lineWidth = this.lineWidth;
ctx.strokeStyle = "black";
ctx.fillStyle = this.color;
ctx.beginPath();
ctx.rect(-0.5 * this.w, -0.5 * this.h, this.w, this.h);
ctx.closePath();
ctx.fill();
ctx.stroke();
ctx.beginPath();
ctx.strokeStyle = "yellow";
ctx.fillStyle = "yellow";
ctx.arc(this.mx, 0.5 * this.h - this.my, 6, 0, 2 * Math.PI, false);
ctx.stroke();
ctx.closePath();
ctx.fill();
ctx.restore();
};
window.requestAnimFrame = (
function(callback) {
return window.setTimeout(callback, 1000 / 30);
});
(function drawFrame() {
window.requestAnimFrame(drawFrame, cv);
ctx.clearRect(0, 0, cv.width, cv.height);
var dx = box.x - mouse.x,
dy = box.y - mouse.y,
angle = Math.atan2(dy, dx),
boxAngle = angle + 0.5 * Math.PI,
targetX = mouse.x + Math.cos(angle) * spring.restLenght,
targetY = mouse.y + Math.sin(angle) * spring.restLenght;
vx += (targetX - box.x) * spring.k;
vy += (targetY - box.y) * spring.k;
vx *= spring.f;
vy *= spring.f;
box.rotation = boxAngle;
box.x += vx;
box.y += vy;
box.draw(ctx);
spring.x1 = mouse.x;
spring.y1 = mouse.y;
spring.x2 = box.x;
spring.y2 = box.y;
spring.draw(ctx);
}());
function capture(element) {
var mouse = {
x: 0,
y: 0,
event: null
},
body_scrollLeft = document.body.scrollLeft,
element_scrollLeft = document.documentElement.scrollLeft,
body_scrollTop = document.body.scrollTop,
element_scrollTop = document.documentElement.scrollTop,
offsetLeft = element.offsetLeft,
offsetTop = element.offsetTop;
element.addEventListener('mousemove', function(event) {
var x, y;
if (event.pageX || event.pageY) {
x = event.pageX;
y = event.pageY;
} else {
x = event.clientX + body_scrollLeft + element_scrollLeft;
y = event.clientY + body_scrollTop + element_scrollTop;
}
x -= offsetLeft;
y -= offsetTop;
mouse.x = x;
mouse.y = y;
mouse.event = event;
}, false);
return mouse;
}
<canvas id="cv" width="600" height="400"></canvas>
Hi I try to create an animation with a circle. The function drawRandom(drawFunctions) should pic one of the three drawcircle functions and should bring it on the canvas. Now the problem is that this function become executed every second (main loop) and the circle change his colour. How can I fix that?
window.onload = window.onresize = function() {
var C = 1; // canvas width to viewport width ratio
var el = document.getElementById("myCanvas");
var viewportWidth = window.innerWidth;
var viewportHeight = window.innerHeight;
var canvasWidth = viewportWidth * C;
var canvasHeight = viewportHeight;
el.style.position = "fixed";
el.setAttribute("width", canvasWidth);
el.setAttribute("height", canvasHeight);
var x = canvasWidth / 100;
var y = canvasHeight / 100;
var ballx = canvasWidth / 100;
var n;
window.ctx = el.getContext("2d");
ctx.clearRect(0, 0, canvasWidth, canvasHeight);
// draw triangles
function init() {
ballx;
return setInterval(main_loop, 1000);
}
function drawcircle1()
{
var radius = x * 5;
ctx.beginPath();
ctx.arc(ballx * 108, canvasHeight / 2, radius, 0, 2 * Math.PI, false);
ctx.fillStyle = 'yellow';
ctx.fill();
}
function drawcircle2()
{
var radius = x * 5;
ctx.beginPath();
ctx.arc(ballx * 108, canvasHeight / 2, radius, 0, 2 * Math.PI, false);
ctx.fillStyle = 'blue';
ctx.fill();
}
function drawcircle3()
{
var radius = x * 5;
ctx.beginPath();
ctx.arc(ballx * 105, canvasHeight / 2, radius, 0, 2 * Math.PI, false);
ctx.fillStyle = 'orange';
ctx.fill();
}
function draw() {
var counterClockwise = false;
ctx.clearRect(0, 0, canvasWidth, canvasHeight);
//first halfarc
ctx.beginPath();
ctx.arc(x * 80, y * 80, y * 10, 0 * Math.PI, 1 * Math.PI, counterClockwise);
ctx.lineWidth = y * 1;
ctx.strokeStyle = 'black';
ctx.stroke();
// draw stop button
ctx.beginPath();
ctx.moveTo(x * 87, y * 2);
ctx.lineTo(x * 87, y * 10);
ctx.lineWidth = x;
ctx.stroke();
ctx.beginPath();
ctx.moveTo(x * 95, y * 2);
ctx.lineTo(x * 95, y * 10);
ctx.lineWidth = x;
ctx.stroke();
function drawRandom(drawFunctions){
//generate a random index
var randomIndex = Math.floor(Math.random() * drawFunctions.length);
//call the function
drawFunctions[randomIndex]();
}
drawRandom([drawcircle1, drawcircle2, drawcircle3]);
}
function update() {
ballx -= 0.1;
if (ballx < 0) {
ballx = -radius;
}
}
function main_loop() {
draw();
update();
collisiondetection();
}
init();
function initi() {
console.log('init');
// Get a reference to our touch-sensitive element
var touchzone = document.getElementById("myCanvas");
// Add an event handler for the touchstart event
touchzone.addEventListener("mousedown", touchHandler, false);
}
function touchHandler(event) {
// Get a reference to our coordinates div
var can = document.getElementById("myCanvas");
// Write the coordinates of the touch to the div
if (event.pageX < x * 50 && event.pageY > y * 10) {
ballx += 1;
} else if (event.pageX > x * 50 && event.pageY > y * 10 ) {
ballx -= 1;
}
console.log(event, x, ballx);
draw();
}
initi();
draw();
}
Take a look at my code that I wrote:
var lastTime = 0;
function requestMyAnimationFrame(callback, time)
{
var t = time || 16;
var currTime = new Date().getTime();
var timeToCall = Math.max(0, t - (currTime - lastTime));
var id = window.setTimeout(function(){ callback(currTime + timeToCall); }, timeToCall);
lastTime = currTime + timeToCall;
return id;
}
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
canvas.width = window.innerWidth - 20;
canvas.height = window.innerHeight - 20;
canvas.style.width = canvas.width + "px";
canvas.style.height = canvas.height + "px";
var circles = [];
var mouse =
{
x: 0,
y: 0
}
function getCoordinates(x, y)
{
return "(" + x + ", " + y + ")";
}
function getRatio(n, d)
{
// prevent division by 0
if (d === 0 || n === 0)
{
return 0;
}
else
{
return n/d;
}
}
function Circle(x,y,d,b,s,c)
{
this.x = x;
this.y = y;
this.diameter = Math.round(d);
this.radius = Math.round(d/2);
this.bounciness = b;
this.speed = s;
this.color = c;
this.deltaX = 0;
this.deltaY = 0;
this.drawnPosition = "";
this.fill = function()
{
context.beginPath();
context.arc(this.x+this.radius,this.y+this.radius,this.radius,0,Math.PI*2,false);
context.closePath();
context.fill();
}
this.clear = function()
{
context.fillStyle = "#ffffff";
this.fill();
}
this.draw = function()
{
if (this.drawnPosition !== getCoordinates(this.x, this.y))
{
context.fillStyle = this.color;
// if commented, the circle will be drawn if it is in the same position
//this.drawnPosition = getCoordinates(this.x, this.y);
this.fill();
}
}
this.keepInBounds = function()
{
if (this.x < 0)
{
this.x = 0;
this.deltaX *= -1 * this.bounciness;
}
else if (this.x + this.diameter > canvas.width)
{
this.x = canvas.width - this.diameter;
this.deltaX *= -1 * this.bounciness;
}
if (this.y < 0)
{
this.y = 0;
this.deltaY *= -1 * this.bounciness;
}
else if (this.y+this.diameter > canvas.height)
{
this.y = canvas.height - this.diameter;
this.deltaY *= -1 * this.bounciness;
}
}
this.followMouse = function()
{
// deltaX/deltaY will currently cause the circles to "orbit" around the cursor forever unless it hits a wall
var centerX = Math.round(this.x + this.radius);
var centerY = Math.round(this.y + this.radius);
if (centerX < mouse.x)
{
// circle is to the left of the mouse, so move the circle to the right
this.deltaX += this.speed;
}
else if (centerX > mouse.x)
{
// circle is to the right of the mouse, so move the circle to the left
this.deltaX -= this.speed;
}
else
{
//this.deltaX = 0;
}
if (centerY < mouse.y)
{
// circle is above the mouse, so move the circle downwards
this.deltaY += this.speed;
}
else if (centerY > mouse.y)
{
// circle is under the mouse, so move the circle upwards
this.deltaY -= this.speed;
}
else
{
//this.deltaY = 0;
}
this.x += this.deltaX;
this.y += this.deltaY;
this.x = Math.round(this.x);
this.y = Math.round(this.y);
}
}
function getRandomDecimal(min, max)
{
return Math.random() * (max-min) + min;
}
function getRoundedNum(min, max)
{
return Math.round(getRandomDecimal(min, max));
}
function getRandomColor()
{
// array of three colors
var colors = [];
// go through loop and add three integers between 0 and 255 (min and max color values)
for (var i = 0; i < 3; i++)
{
colors[i] = getRoundedNum(0, 255);
}
// return rgb value (RED, GREEN, BLUE)
return "rgb(" + colors[0] + "," + colors[1] + ", " + colors[2] + ")";
}
function createCircle(i)
{
// diameter of circle
var minDiameter = 25;
var maxDiameter = 50;
// bounciness of circle (changes speed if it hits a wall)
var minBounciness = 0.2;
var maxBounciness = 0.65;
// speed of circle (how fast it moves)
var minSpeed = 0.3;
var maxSpeed = 0.45;
// getRoundedNum returns a random integer and getRandomDecimal returns a random decimal
var x = getRoundedNum(0, canvas.width);
var y = getRoundedNum(0, canvas.height);
var d = getRoundedNum(minDiameter, maxDiameter);
var c = getRandomColor();
var b = getRandomDecimal(minBounciness, maxBounciness);
var s = getRandomDecimal(minSpeed, maxSpeed);
// create the circle with x, y, diameter, bounciness, speed, and color
circles[i] = new Circle(x,y,d,b,s,c);
}
function makeCircles()
{
var maxCircles = getRoundedNum(2, 5);
for (var i = 0; i < maxCircles; i++)
{
createCircle(i);
}
}
function drawCircles()
{
var ii = 0;
for (var i = 0; ii < circles.length; i++)
{
if (circles[i])
{
circles[i].draw();
ii++;
}
}
}
function clearCircles()
{
var ii = 0;
for (var i = 0; ii < circles.length; i++)
{
if (circles[i])
{
circles[i].clear();
ii++;
}
}
}
function updateCircles()
{
var ii = 0;
for (var i = 0; ii < circles.length; i++)
{
if (circles[i])
{
circles[i].keepInBounds();
circles[i].followMouse();
ii++;
}
}
}
function update()
{
requestMyAnimationFrame(update,10);
updateCircles();
}
function draw()
{
requestMyAnimationFrame(draw,1000/60);
context.clearRect(0,0,canvas.width,canvas.height);
drawCircles();
}
window.addEventListener("load", function()
{
window.addEventListener("mousemove", function(e)
{
mouse.x = e.layerX || e.offsetX;
mouse.y = e.layerY || e.offsetY;
});
makeCircles();
update();
draw();
});
I have using scaling and rotation of images using mouse dragging separately. but i need to combine both the operations.
Please refer jsfiddle files for your understanding.
Scaling - http://jsfiddle.net/QqwKR/74/
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var canvasOffset = $("#canvas").offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var startX;
var startY;
var isDown = false;
var pi2 = Math.PI * 2;
var resizerRadius = 8;
var rr = resizerRadius * resizerRadius;
var draggingResizer = {
x: 0,
y: 0
};
var imageX = 50;
var imageY = 50;
var imageWidth, imageHeight, imageRight, imageBottom;
var draggingImage = false;
var startX;
var startY;
var img = new Image();
img.onload = function (){
imageWidth = img.width;
imageHeight = img.height;
imageRight = imageX + imageWidth;
imageBottom = imageY + imageHeight;
draw(true, false);}
img.src = "https://dl.dropboxusercontent.com/u/139992952/stackoverflow/facesSmall.png";
function draw(withAnchors, withBorders) {
// clear the canvas
ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw the image
ctx.drawImage(img, 0, 0, img.width, img.height, imageX, imageY, imageWidth, imageHeight);
// optionally draw the draggable anchors
if (withAnchors) {
drawDragAnchor(imageX, imageY);
drawDragAnchor(imageRight, imageY);
drawDragAnchor(imageRight, imageBottom);
drawDragAnchor(imageX, imageBottom);
}
// optionally draw the connecting anchor lines
if (withBorders) {
ctx.beginPath();
ctx.moveTo(imageX, imageY);
ctx.lineTo(imageRight, imageY);
ctx.lineTo(imageRight, imageBottom);
ctx.lineTo(imageX, imageBottom);
ctx.closePath();
ctx.stroke();
}
}
function drawDragAnchor(x, y) {
ctx.beginPath();
ctx.arc(x, y, resizerRadius, 0, pi2, false);
ctx.closePath();
ctx.fill();
}
function anchorHitTest(x, y) {
var dx, dy;
// top-left
dx = x - imageX;
dy = y - imageY;
if (dx * dx + dy * dy <= rr) {
return (0);
}
// top-right
dx = x - imageRight;
dy = y - imageY;
if (dx * dx + dy * dy <= rr) {
return (1);
}
// bottom-right
dx = x - imageRight;
dy = y - imageBottom;
if (dx * dx + dy * dy <= rr) {
return (2);
}
// bottom-left
dx = x - imageX;
dy = y - imageBottom;
if (dx * dx + dy * dy <= rr) {
return (3);
}
return (-1);
}
function hitImage(x, y) {
return (x > imageX && x < imageX + imageWidth && y > imageY && y < imageY + imageHeight);
}
function handleMouseDown(e) {
startX = parseInt(e.clientX - offsetX);
startY = parseInt(e.clientY - offsetY);
draggingResizer = anchorHitTest(startX, startY);
draggingImage = draggingResizer < 0 && hitImage(startX, startY);
}
function handleMouseUp(e) {
draggingResizer = -1;
draggingImage = false;
draw(true, false);
}
function handleMouseOut(e) {
handleMouseUp(e);
}
function handleMouseMove(e) {
if (draggingResizer > -1) {
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// resize the image
switch (draggingResizer) {
case 0:
//top-left
imageX = mouseX;
imageWidth = imageRight - mouseX;
imageY = mouseY;
imageHeight = imageBottom - mouseY;
break;
case 1:
//top-right
imageY = mouseY;
imageWidth = mouseX - imageX;
imageHeight = imageBottom - mouseY;
break;
case 2:
//bottom-right
imageWidth = mouseX - imageX;
imageHeight = mouseY - imageY;
break;
case 3:
//bottom-left
imageX = mouseX;
imageWidth = imageRight - mouseX;
imageHeight = mouseY - imageY;
break;
}
// enforce minimum dimensions of 25x25
if (imageWidth < 25) {
imageWidth = 25;
}
if (imageHeight < 25) {
imageHeight = 25;
}
// set the image right and bottom
imageRight = imageX + imageWidth;
imageBottom = imageY + imageHeight;
// redraw the image with resizing anchors
draw(true, true);
} else if (draggingImage) {
imageClick = false;
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// move the image by the amount of the latest drag
var dx = mouseX - startX;
var dy = mouseY - startY;
imageX += dx;
imageY += dy;
imageRight += dx;
imageBottom += dy;
// reset the startXY for next time
startX = mouseX;
startY = mouseY;
// redraw the image with border
draw(false, true);
}
}
$("#canvas").mousedown(function (e) {
handleMouseDown(e);
});
$("#canvas").mousemove(function (e) {
handleMouseMove(e);
});
$("#canvas").mouseup(function (e) {
handleMouseUp(e);
});
$("#canvas").mouseout(function (e) {
handleMouseOut(e);
});
Rotating - http://jsfiddle.net/m1erickson/QqwKR/
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var canvasOffset = $("#canvas").offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var startX;
var startY;
var isDown = false;
var cx = canvas.width / 2;
var cy = canvas.height / 2;
var w;
var h;
var r = 0;
var img = new Image();
img.onload = function () {
w = img.width / 2;
h = img.height / 2;
draw();
}
img.src = "https://dl.dropboxusercontent.com/u/139992952/stackoverflow/facesSmall.png";
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawRotationHandle(true);
drawRect();
}
function drawRect() {
ctx.save();
ctx.translate(cx, cy);
ctx.rotate(r);
ctx.drawImage(img, 0, 0, img.width, img.height, -w / 2, -h / 2, w, h);
// ctx.fillStyle="yellow";
// ctx.fillRect(-w/2,-h/2,w,h);
ctx.restore();
}
function drawRotationHandle(withFill) {
ctx.save();
ctx.translate(cx, cy);
ctx.rotate(r);
ctx.beginPath();
ctx.moveTo(0, -1);
ctx.lineTo(w / 2 + 20, -1);
ctx.lineTo(w / 2 + 20, -7);
ctx.lineTo(w / 2 + 30, -7);
ctx.lineTo(w / 2 + 30, 7);
ctx.lineTo(w / 2 + 20, 7);
ctx.lineTo(w / 2 + 20, 1);
ctx.lineTo(0, 1);
ctx.closePath();
if (withFill) {
ctx.fillStyle = "blue";
ctx.fill();
}
ctx.restore();
}
function handleMouseDown(e) {
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
drawRotationHandle(false);
isDown = ctx.isPointInPath(mouseX, mouseY);
console.log(isDown);
}
function handleMouseUp(e) {
isDown = false;
}
function handleMouseOut(e) {
isDown = false;
}
function handleMouseMove(e) {
if (!isDown) {
return;
}
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
var dx = mouseX - cx;
var dy = mouseY - cy;
var angle = Math.atan2(dy, dx);
r = angle;
draw();
}
$("#canvas").mousedown(function (e) {
handleMouseDown(e);
});
$("#canvas").mousemove(function (e) {
handleMouseMove(e);
});
$("#canvas").mouseup(function (e) {
handleMouseUp(e);
});
$("#canvas").mouseout(function (e) {
handleMouseOut(e);
})
;
I need to work scaling with rotation of image. ie) Four anchor points with rotating handle