I'm trying to have a user manually color in certain parts of an image. As an example, here's a cat https://techflourish.com/images/3-cat-clipart-9.png. The user should be able to color in the foot of the cat if they choose to. I want them to only color inside the cat body image portion of the canvas (not the background portion of the image or whitespace of canvas, but I guess I could just manually trim the image).
What I've attempted so far is below. Basically I check the color of the pixel at my position and draw only if it isn't that background color. This sort of works, but I'm able to bleed out really easily because something is off. I was wondering if it was possibly to set a specific clip area, but wasn't able to figure it out.
`
var canvas = document.getElementById("space");
var ctx = canvas.getContext("2d");
var pos = { x: 0, y: 0 };
// new position from mouse events
function setPosition(e) {
pos.x = e.clientX;
pos.y = e.clientY;
}
function rgbToHex(r, g, b) {
if (r > 255 || g > 255 || b > 255)
throw "Invalid color component";
return ((r << 16) | (g << 8) | b).toString(16);
}
function draw(e) {
if (e.buttons !== 1) return; // if mouse is pressed.....
var color = "#cb3594";
ctx.beginPath(); // begin the drawing path
ctx.lineWidth = 5; // width of line
ctx.lineCap = "round"; // rounded end cap
ctx.strokeStyle = color; // hex color of line
var p = ctx.getImageData(pos.x, pos.y, 1, 1).data;
var sourceColor = rgbToHex(p[0], p[1], p[2]);
if(sourceColor != "BACKGROUNDHEX" && sourceColor != color) {
ctx.moveTo(pos.x, pos.y); // from position
setPosition(e);
p = ctx.getImageData(pos.x, pos.y, 1, 1).data;
targetColor = rgbToHex(p[0], p[1], p[2]);
if(targetColor != "BACKGROUNDHEX" && targetColor != color) {
ctx.lineTo(pos.x, pos.y); // to position
ctx.stroke(); // draw it!
}
}
}
var outlineImage = new Image();
outlineImage.onload = function() {
ctx.drawImage(outlineImage, 0, 0, 704, 720);
}
outlineImage.src = "IMAGE.png";
space.addEventListener("mousemove", draw);
space.addEventListener("mousedown", setPosition);
space.addEventListener("mouseenter", setPosition);
</script>
`
(related edit: the bleeding is caused by my "sourceColor != color" being wrong, but the question is still relevant as this still doesn't feel like a great solution)
Since the parts of the image you don't want to color are transparent, you can set the context's globalCompositeOperation to 'source-atop'. After that, any pixels you draw to the canvas will automatically take on the overwritten pixels' opacity, and you don't have to mess with getImageData:
var canvas = document.getElementById("space");
var ctx = canvas.getContext("2d");
var pos = {
x: 0,
y: 0
};
// new position from mouse events
function setPosition(e) {
// offsetX/Y gives the correct coordinates within the canvas
// assuming it has no padding
pos.x = e.offsetX;
pos.y = e.offsetY;
}
function draw(e) {
if (e.buttons !== 1) return; // if mouse is pressed.....
var color = "#cb3594";
ctx.beginPath(); // begin the drawing path
ctx.lineWidth = 5; // width of line
ctx.lineCap = "round"; // rounded end cap
ctx.strokeStyle = color; // hex color of line
ctx.moveTo(pos.x, pos.y); // from position
setPosition(e);
ctx.lineTo(pos.x, pos.y); // to position
ctx.stroke(); // draw it!
}
var outlineImage = new Image();
outlineImage.onload = function() {
// the default, set explicitly because we're changing it elsewhere
ctx.globalCompositeOperation = 'source-over';
ctx.drawImage(outlineImage, 0, 0);
// don't draw over the transparent parts of the canvas
ctx.globalCompositeOperation = 'source-atop';
// wait until the stencil is loaded before handing out crayons
space.addEventListener("mousemove", draw);
space.addEventListener("mousedown", setPosition);
space.addEventListener("mouseenter", setPosition);
}
outlineImage.src = "https://i.stack.imgur.com/so095.png";
<canvas id="space" width="610" height="733"></canvas>
Only want shadows to animate and keep the fillText from animating due to letters pixelating from getting ran over and over.
var canvas = document.getElementById('canvas')
var ctx = this.canvas.getContext('2d')
var width = canvas.width = canvas.scrollWidth
var height = canvas.height = canvas.scrollHeight
var start;
var j=0;
var makeText = function(){
j+=1
ctx.shadowColor= 'red';
ctx.shadowOffsetX = j; //animate
ctx.shadowOffsetY = j; //animate
ctx.globalAlpha=0.5;
ctx.font = "48px serif";
ctx.fillStyle = "black";
ctx.fillText('hey you', width/2, height / 2); //Only ran once so letters
//don't pixelate!
}
function animateText(timestamp){
var runtime = timestamp - start;
var progress = Math.min(runtime / 1400, 1);
makeText(progress)
if(progress < 1){
requestAnimationFrame(animateText)
}else {
return;
}
}
requestAnimationFrame(function(timestamp){
start = timestamp;
animateText(timestamp)
})
<canvas id="canvas" width=500px height=500px></canvas>
My outcome of the process would only have shadows animate and keeping letters where they are
Just draw your own shadows, here is an example:
var canvas = document.getElementById('canvas')
var ctx = this.canvas.getContext('2d')
ctx.font = "68px serif";
var base = {text: 'hey you', x: 10, y: 60 }
var inc = 2;
var j = 30;
var makeText = function() {
ctx.globalAlpha = 1;
ctx.fillStyle = "black";
ctx.fillText(base.text, base.x, base.y);
}
var makeshadow = function(offset) {
ctx.fillStyle = "red";
for (var i = 0; i < offset; i++) {
ctx.globalAlpha = 1/i;
ctx.fillText(base.text, base.x + i, base.y + i);
}
}
function animateText() {
ctx.clearRect(0, 0, 999, 999)
makeshadow(j);
makeText();
j += inc;
if (j > 35 || j < 3) inc *= -1
}
setInterval(animateText, 50)
<canvas id="canvas" width=300px height=170px></canvas>
And if you add some math in the mix you can get some cool effects:
var canvas = document.getElementById('canvas')
var ctx = this.canvas.getContext('2d')
ctx.font = "68px serif";
var base = {text: '123456', x: 30, y: 80 }
var inc = 5;
var j = 0;
var makeText = function() {
ctx.globalAlpha = 1;
ctx.fillStyle = "black";
ctx.fillText(base.text, base.x, base.y);
}
var makeshadow = function(offset) {
ctx.globalAlpha = 0.05;
ctx.fillStyle = "red";
for (var i = 0; i < offset; i++)
ctx.fillText(base.text, base.x + Math.sin(i/5)*10, base.y + Math.cos(i/5)*15);
}
function animateText() {
ctx.clearRect(0, 0, 999, 999)
makeshadow(j);
makeText();
j += inc;
if (j > 120 || j < 0) inc *= -1
}
setInterval(animateText, 50)
<canvas id="canvas" width=300px height=170px></canvas>
Your main issue (the text pixelisation) is due to you not clearing the canvas between every frames, and drawing again and again over the same position. semi-transparent pixels created by antialiasing mix up to more and more opaque pixels.
But in your situation, it seems that you actually want at-least the shadow to mix up like this.
To do it, one way would be to draw only once your normal text, and to be able to draw only the shadow, behind the current drawing.
Drawing only the shadow of a shape.
One trick to draw only the shadows of your shape is to draw your shape out of the visible viewPort, with shadowOffsets set to the inverse of this position.
var text = 'foo bar';
var ctx = canvas.getContext('2d');
var original_x = 20; // the position it would have been
ctx.font = '30px sans-serif';
var targetPosition = ctx.measureText(text).width + original_x + 2;
// default shadow settings
ctx.shadowColor = 'red';
ctx.shadowBlur = 3;
// just to show what happens
var x = 0;
anim();
function anim() {
if(++x >= targetPosition) {
x=0;
return;
}
// if we weren't to show the anim, we would use 'targetPosition'
// instead of 'x'
ctx.shadowOffsetX = x;
ctx.clearRect(0,0,canvas.width,canvas.height);
ctx.fillText(text, -x + original_x, 30);
requestAnimationFrame(anim);
}
// restart the anim on click
onclick = function() {
if(x===0)anim();
};
<canvas id="canvas"></canvas>
Once we have this clear shadow, without our shape drawn on it, we can redraw it as we wish.
Drawing behind the current pixels
The "destination-over" compositing option does just that.
So if we put these together, we can draw behind the normal text, and only draw our shadow behind it at each frame, avoiding antialiasing mix-up.
(Note that we can also keep the clean shadow on an offscreen canvas for performances, since shadow is a really slow operation.)
var text = 'foo bar';
var ctx = canvas.getContext('2d');
ctx.font = '48px sans-serif';
var x = 20;
var y = 40;
var shadow = generateTextShadow(ctx, text, x, y, 'red', 5);
ctx.globalAlpha = 0.5;
ctx.fillText(text, x, y);
// from now on we'll draw behind current content
ctx.globalCompositeOperation = 'destination-over';
var shadow_pos = 0;
anim();
// in the anim, we just draw the shadow at a different offset every frame
function anim() {
if(shadow_pos++ > 65) return;
ctx.drawImage(shadow, shadow_pos, shadow_pos);
requestAnimationFrame(anim);
}
// returns a canvas where only the shadow of the text provided is drawn
function generateTextShadow(original_ctx, text, x, y, color, blur, offsetX, offsetY) {
var canvas = original_ctx.canvas.cloneNode();
var ctx = canvas.getContext('2d');
ctx.font = original_ctx.font;
var targetPosition = ctx.measureText(text).width + 2;
// default shadow settings
ctx.shadowColor = color || 'black';
ctx.shadowBlur = blur || 0;
ctx.shadowOffsetX = targetPosition + x +(offsetX ||0);
ctx.shadowOffsetY = (offsetY || 0);
ctx.fillText(text, -targetPosition, y);
return canvas;
}
<canvas id="canvas"></canvas>
Currently, I have a canvas which is the width and height of your browser. Using this code:
var requestAnimationFrame = window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.msRequestAnimationFrame;
var canvas = document.getElementById("canvas");
var width = window.innerWidth;
var height = window.innerHeight;
var circle = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
for(var i = 0; i < numofcirc; i++)
{
name = "circleno" + i;
var name = new Array(3);
name = [height, rndwidth, rndradius, vel]
circles[i] = name;
}
var vel = 2;
var circles = [];
var numofcirc = 1;
var name;
function DrawCircle()
{
rndwidth = Math.floor((Math.random() * width) + 1);
height = height - 13;
rndradius = Math.floor((Math.random() * 15) + 5);
circle.beginPath();
circle.arc(rndwidth, height, rndradius, 0, 2*Math.PI);
circle.fillStyle = "white";
circle.fill();
circle.translate(0,6);
}
function Move()
{
circle.translate(0,6);
requestAnimationFrame(Move);
}
Move();
DrawCircle();
I am able to create a circle placed randomly at the bottom of your screen. The bit of the code that isn't working is this:
function Move()
{
circle.translate(0,6);
requestAnimationFrame(Move);
}
Fireworks();
When DrawCircle(); is called, the circle is drawn on the canvas. Then Move(); is called. Becuase it uses requestAnimationFrame the function Move(); repeats over and over again. I want this code to move that circle drawn ealier up by 6, so it looks like the circle moving up.
If I add the circle.translate(0,6); to the DrawCircle(); function and change the DrawCircle(); function to this:
function DrawCircle()
{
rndwidth = Math.floor((Math.random() * width) + 1);
height = height - 13;
rndradius = Math.floor((Math.random() * 15) + 5);
circle.beginPath();
circle.arc(rndwidth, height, rndradius, 0, 2*Math.PI);
circle.fillStyle = "white";
circle.fill();
circle.translate(0,6);
requestAnimationFrame(Move);
}
DrawCircle();
then it keeps on drawing rows of circles across the screen which are all separated by 6.
Is there any way I can just make one single circle move up on your screen when it is drawn?
Thank you for you help #HelderSepu !
You should look at examples and build from that...
Here is one simple case:
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
canvas.width = canvas.height = 170;
var circles = []
circles.push({color:"red", x:120, y:120, r:15, speed:{x: 0, y: -0.5}})
circles.push({color:"blue", x:80, y:120, r:20, speed:{x: -0.5, y: -2.5}})
circles.push({color:"green", x:40, y:120, r:5, speed:{x: -1.5, y: -1.0}})
function DrawCircle() {
context.clearRect(0, 0, canvas.width, canvas.height);
circles.forEach(function(c) {
c.x += c.speed.x;
c.y += c.speed.y;
context.beginPath();
context.arc(c.x, c.y, c.r, 0, 2 * Math.PI);
context.fillStyle = c.color;
context.fill();
if (c.x + c.r < 0) c.x = canvas.width + c.r
if (c.y + c.r < 0) c.y = canvas.height + c.r
});
window.requestAnimationFrame(DrawCircle);
}
DrawCircle();
<canvas id="canvas"></canvas>
But if you are going to do a lot more animations you should consider using a game engine, there are a lot of great open source ones:
https://github.com/collections/javascript-game-engines
Since you're getting a sequence of circles, it looks like you're not clearing the canvas when a frame is drawn. Simply draw a white rectangle that fills the canvas whenever a new frame is requested, then draw your circle.
The method you provide as an argument to requestAnimationFrame is responsible for drawing a complete image on the canvas which replaces whatever was there during the previous frame.
I am trying to divide my whole canvas in 20 equal columns and animate them individually on the y-axis. The goal is to create a similar wave scroll animation like here. First I tried to create the wave scroll effect with php generated images with the text on it and tried to animate them in single divs with the images as background-images. It technically worked but the performance and page load time was extremely bad. Now I want to create it with canvas: I already have the content with all the images and text in it and tried to animate it. I tried to save the whole content in columns (rectangles) with getImageData() then I created created rectangles with the ImageData and re-draw them in a loop but again the performance was terrible, especially on mobile devices. The animation loop looked as followed:
var animate = function(index, y) {
// The calculations required for the step function
var start = new Date().getTime();
var end = start + duration;
var current = rectangles[index].y;
var distance = y - current;
var step = function() {
// get our current progress
var timestamp = new Date().getTime();
var progress = Math.min((duration - (end - timestamp)) / duration, 1);
context.clearRect(rectangles[index].x, rectangles[index].y, columnWidth, canvas.height);
// update the rectangles y property
rectangles[index].y = current + (distance * progress);
context.putImageData(rectangles[index].imgData, rectangles[index].x, rectangles[index].y);
// if animation hasn't finished, repeat the step.
if (progress < 1)
requestAnimationFrame(step);
};
// start the animation
return step();
};
Now the question: How can I divide the whole canvas in equal columns and animate them on the y-axis with a good performance? Any suggestions? Maybe with the help of Pixi.js / Greensock? Thanks in advance!
Do not use getImageData and setImageData to do animation. The canvas is an image and can be rendered just like any image.
To do what you want
Create a second copy of the canvas and use that canvas a source for the strips you want to render.
Example.
const slices = 20;
var widthStep;
var canvas = document.createElement("canvas");
var canvas1 = document.createElement("canvas");
canvas.style.position = "absolute";
canvas.style.top = canvas.style.left = "0px";
var ctx = canvas.getContext("2d");
var ctx1 = canvas1.getContext("2d");
var w = canvas.width;
var h = canvas.height;
function resize(){
canvas.width = canvas1.width = innerWidth;
canvas.height = canvas1.height = innerHeight;
w = canvas.width;
h = canvas.height;
ctx1.font = "64px arial black";
ctx1.textAlign = "center"
ctx1.textBaseLine = "middle";
ctx1.fillStyle = "blue";
ctx1.fillRect(0,0,w,h);
ctx1.fillStyle = "red";
ctx1.fillRect(50,50,w-100,h-100);
ctx1.fillStyle = "black";
ctx1.strokeStyle = "white";
ctx1.lineWidth = 5;
ctx1.lineJoin = "round";
ctx1.strokeText("Waves and canvas",w / 2, h / 2);
ctx1.fillText("Waves and canvas",w / 2, h / 2);
widthStep = Math.ceil(w / slices);
}
resize();
window.addEventListener("resize",resize);
document.body.appendChild(canvas);
function update(time){
var y;
var x = 0;
ctx.clearRect(0,0,canvas.width,canvas.height);
for(var i = 0; i < slices; i ++){
y = Math.sin(time / 500 + i / 5) * (w / 8);
y += Math.sin(time / 700 + i / 7) * (w / 13);
y += Math.sin(time / 300 + i / 3) * (w / 17);
ctx.drawImage(canvas1,x,0,widthStep,h,x,y,widthStep,h);
x += widthStep;
}
requestAnimationFrame(update);
}
requestAnimationFrame(update);
I'm fairly new to Canvas. I've been trying to get the images reversed in this EaselJS Alpha Mask example so that the initial image is clear, and what you paint is blurry; basically, the reverse of the demo.
I've been playing around with it for hours, applying filters to the bitmap var and removing them from the blur var. Everything I do just doesn't work. Seems like it would be an easy fix of just switching things around but that doesn't seem to be the case. Not for me anyway.
Does anybody have an example of this, or know what to do? I could provide code examples of what I did, but it's basically just playing around with stuff like a monkey on a typewriter.
Here's the code on Github
Here's the relevant code from their example.
<script id="editable">
var stage;
var isDrawing;
var drawingCanvas;
var oldPt;
var oldMidPt;
var displayCanvas;
var image;
var bitmap;
var maskFilter;
var cursor;
var text;
var blur;
function init() {
examples.showDistractor();
image = new Image();
image.onload = handleComplete;
image.src = "../_assets/art/flowers.jpg";
stage = new createjs.Stage("testCanvas");
//text = new createjs.Text("Loading...", "20px Arial", "#FFF");
//text.set({x: stage.canvas.width / 2, y: stage.canvas.height - 40});
//text.textAlign = "center";
}
function handleComplete() {
examples.hideDistractor();
createjs.Touch.enable(stage);
stage.enableMouseOver();
stage.addEventListener("stagemousedown", handleMouseDown);
stage.addEventListener("stagemouseup", handleMouseUp);
stage.addEventListener("stagemousemove", handleMouseMove);
drawingCanvas = new createjs.Shape();
bitmap = new createjs.Bitmap(image);
blur = new createjs.Bitmap(image);
blur.filters = [new createjs.BlurFilter(24, 24, 2), new createjs.ColorMatrixFilter(new createjs.ColorMatrix(60))];
blur.cache(0, 0, 960, 400);
//text.text = "Click and Drag to Reveal the Image.";
stage.addChild(blur, text, bitmap);
updateCacheImage(false);
cursor = new createjs.Shape(new createjs.Graphics().beginFill("#FFFFFF").drawCircle(0, 0, 25));
cursor.cursor = "pointer";
stage.addChild(cursor);
}
function handleMouseDown(event) {
oldPt = new createjs.Point(stage.mouseX, stage.mouseY);
oldMidPt = oldPt;
isDrawing = true;
}
function handleMouseMove(event) {
cursor.x = stage.mouseX;
cursor.y = stage.mouseY;
if (!isDrawing) {
stage.update();
return;
}
var midPoint = new createjs.Point(oldPt.x + stage.mouseX >> 1, oldPt.y + stage.mouseY >> 1);
drawingCanvas.graphics.setStrokeStyle(40, "round", "round")
.beginStroke("rgba(0,0,0,0.2)")
.moveTo(midPoint.x, midPoint.y)
.curveTo(oldPt.x, oldPt.y, oldMidPt.x, oldMidPt.y);
oldPt.x = stage.mouseX;
oldPt.y = stage.mouseY;
oldMidPt.x = midPoint.x;
oldMidPt.y = midPoint.y;
updateCacheImage(true);
}
function handleMouseUp(event) {
updateCacheImage(true);
isDrawing = false;
}
function updateCacheImage(update) {
if (update) {
drawingCanvas.updateCache();
} else {
drawingCanvas.cache(0, 0, image.width, image.height);
}
maskFilter = new createjs.AlphaMaskFilter(drawingCanvas.cacheCanvas);
bitmap.filters = [maskFilter];
if (update) {
bitmap.updateCache(0, 0, image.width, image.height);
} else {
bitmap.cache(0, 0, image.width, image.height);
}
stage.update();
}
</script>
The pure Javascript way using the Canvas 2D context API.
You will need to create a canvas, load the image, create a mask image, and a blur image. I have blurred the image already as I did not want to write a blur.
The following functions in the object imageTools create the canvas/images, and loads images. Note that the canvas and images are interchangeable. The canvas does not have a src, and an image can not be drawn on appart from that they are the same. I convert all images to canvas and attach the context to them. I also call them images.
/** ImageTools.js begin **/
var imageTools = (function () {
var tools = {
canvas : function (width, height) { // create a blank image (canvas)
var c = document.createElement("canvas");
c.width = width;
c.height = height;
return c;
},
createImage : function (width, height) {
var image = this.canvas(width, height);
image.ctx = image.getContext("2d");
return image;
},
loadImage : function (url, callback) {
var image = new Image();
image.src = url;
image.addEventListener('load', callback);
image.addEventListener('error', callback);
return image;
}
};
return tools;
})();
Then I use imageTools to load the images I need and create a mask, when I have the image size as I am matching the mask resolution to the image resolution
// load the images and create the mask
var imageLoadedCount = 0;
var error = false;
var maskImage;
var flowerImage = imageTools.loadImage("http://www.createjs.com/demos/_assets/art/flowers.jpg", function (event) {
if (event.type === "load") {
imageLoadedCount += 1;
} else {
error = true;
}
});
var flowerImageBlur = imageTools.loadImage("http://i.stack.imgur.com/3S5m8.jpg", function () {
if (event.type === "load") {
maskImage = imageTools.createImage(this.width, this.height);
imageLoadedCount += 1;
} else {
error = true;
}
});
I use requestAnimationFrame to create a 60FPS canvas drawing function that waits for the images to load and then displays the 3 layers onto the canvas
// ctx is the main canvas context.
// drawImageCentered scales the image to fit. See Demo for code.
// draw the unblured image that will appear at the top
ctx.globalCompositeOperation = "source-over";
drawImageCentered(ctx, flowerImage, cw, ch);
drawText(ctx, "Click drag to blur the image via mask", 40 + Math.sin(time / 100), cw, ch - 30, "White");
// Mask out the parts when the mask image has pixels
ctx.globalCompositeOperation = "destination-out";
drawImageCentered(ctx, maskImage, cw, ch);
// draw the blured image only where the destination has been masked
ctx.globalCompositeOperation = "destination-atop";
drawImageCentered(ctx, flowerImageBlur, cw, ch);
It first draws the image that appears if no masked pixels are visible. Then it draw some text for instructions.
Next comes the mask that uses destination-out. This means that for pixels in the mask that have an alpha > 0 remove from the destination that amount of alpha. So if a mask pixel has an alpha of 50 and the destination (canvas) has an alpha of 255 then the result of that pixel after rendering the mask with destination-out will be 255 - 50 = 205. This effectively has put holes on the canvas where ever there are pixels on the mask.
Now we can fill the holes with the blurred image and render it using destination-atop which means only draw pixels from the source (blurred image) where the destination alpha is less that 255
That is the layered masking done, all we need is to draw on the mask. For that we just listen to the mouse events and if the button is down draw a circle on the mask where the mouse is. My example has scaled the images so there is a little extra work there but the basics are as follows,
// draws circle with gradient
function drawCircle(ctx, x, y, r) {
var gr = ctx.createRadialGradient(x, y, 0, x, y, r)
gr.addColorStop(1, "rgba(0,0,0,0)")
gr.addColorStop(0.5, "rgba(0,0,0,0.08)")
gr.addColorStop(0, "rgba(0,0,0,0.1)")
ctx.fillStyle = gr;
ctx.beginPath();
ctx.arc(x, y, r, 0, Math.PI * 2);
ctx.fill();
}
// draw a circle on the mask where the mouse is.
drawCircle(maskImage.ctx, mouse.x, mouse.y, 20);
For the demo there is a little more code to make it all work nicely but you can pick out the bits you need.
var imageLoadedCount = 0;
var error = false;
var maskImage;
var flowerImage;
var flowerImageBlur;
/** ImageTools.js begin **/
var imageTools = (function () {
var tools = {
canvas : function (width, height) { // create a blank image (canvas)
var c = document.createElement("canvas");
c.width = width;
c.height = height;
return c;
},
createImage : function (width, height) {
var image = this.canvas(width, height);
image.ctx = image.getContext("2d");
return image;
},
loadImage : function (url, callback) {
var image = new Image();
image.src = url;
image.addEventListener('load', callback);
image.addEventListener('error', callback);
return image;
}
};
return tools;
})();
var mouse;
var demo = function(){
/** fullScreenCanvas.js begin **/
var canvas = (function(){
var canvas = document.getElementById("canv");
if(canvas !== null){
document.body.removeChild(canvas);
}
// creates a blank image with 2d context
canvas = document.createElement("canvas");
canvas.id = "canv";
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
canvas.style.position = "absolute";
canvas.style.top = "0px";
canvas.style.left = "0px";
canvas.style.zIndex = 1000;
canvas.ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
return canvas;
})();
var ctx = canvas.ctx;
/** fullScreenCanvas.js end **/
/** MouseFull.js begin **/
if(typeof mouse !== "undefined"){ // if the mouse exists
if( mouse.removeMouse !== undefined){
mouse.removeMouse(); // remove previouse events
}
}else{
var mouse;
}
var canvasMouseCallBack = undefined; // if needed
mouse = (function(){
var mouse = {
x : 0, y : 0, w : 0, alt : false, shift : false, ctrl : false,
interfaceId : 0, buttonLastRaw : 0, buttonRaw : 0,
over : false, // mouse is over the element
bm : [1, 2, 4, 6, 5, 3], // masks for setting and clearing button raw bits;
getInterfaceId : function () { return this.interfaceId++; }, // For UI functions
startMouse:undefined,
mouseEvents : "mousemove,mousedown,mouseup,mouseout,mouseover,mousewheel,DOMMouseScroll".split(",")
};
function mouseMove(e) {
var t = e.type, m = mouse;
m.x = e.offsetX; m.y = e.offsetY;
if (m.x === undefined) { m.x = e.clientX; m.y = e.clientY; }
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 (canvasMouseCallBack) { canvasMouseCallBack(mouse); }
e.preventDefault();
}
function startMouse(element){
if(element === undefined){
element = document;
}
mouse.element = element;
mouse.mouseEvents.forEach(
function(n){
element.addEventListener(n, mouseMove);
}
);
element.addEventListener("contextmenu", function (e) {e.preventDefault();}, false);
}
mouse.removeMouse = function(){
if(mouse.element !== undefined){
mouse.mouseEvents.forEach(
function(n){
mouse.element.removeEventListener(n, mouseMove);
}
);
canvasMouseCallBack = undefined;
}
}
mouse.mouseStart = startMouse;
return mouse;
})();
if(typeof canvas !== "undefined"){
mouse.mouseStart(canvas);
}else{
mouse.mouseStart();
}
/** MouseFull.js end **/
// load the images and create the mask
if(imageLoadedCount === 0){
imageLoadedCount = 0;
error = false;
maskImage;
flowerImage = imageTools.loadImage("http://www.createjs.com/demos/_assets/art/flowers.jpg", function (event) {
if (event.type === "load") {
imageLoadedCount += 1;
} else {
error = true;
}
})
flowerImageBlur = imageTools.loadImage("http://i.stack.imgur.com/3S5m8.jpg", function () {
if (event.type === "load") {
maskImage = imageTools.createImage(this.width, this.height);
imageLoadedCount += 1;
} else {
error = true;
}
})
}
// set up the canvas
var w = canvas.width;
var h = canvas.height;
var cw = w / 2;
var ch = h / 2;
// calculate time to download image using the MS algorithum. As this code is a highly gaurded secret I have obsficated it for your personal safty.
var calculateTimeToGo= (function(){var b="# SecondQMinuteQHourQDayQWeekQMonthQMomentQTick#.,Some time soon,Maybe Tomorrow.".replace(/Q/g,"#.,# ").split(","),r=Math.random,f=Math.floor,lc=0,pc=0,lt=0,lp=0;var cttg=function(a){if(lc===0){lc=100+r(r()*60);lt=f(r()*40);if(pc===0||r()<(lp/b.length)-0.2){lp=f(r()*b.length);pc=1+f(r()*10)}else{pc-=1}}else{lc-=1}a=lt;if(lp===0){a=lt;if(r()<0.01){lt-=1}}var s=b[lp].replace("#",a);if(a===1){s=s.replace("#","")}else{s=s.replace("#","s")}return s};return cttg})();
// draws circle with gradient
function drawCircle(ctx, x, y, r) {
var gr = ctx.createRadialGradient(x, y, 0, x, y, r)
gr.addColorStop(1, "rgba(0,0,0,0)")
gr.addColorStop(0.5, "rgba(0,0,0,0.08)")
gr.addColorStop(0, "rgba(0,0,0,0.1)")
ctx.fillStyle = gr;
ctx.beginPath();
ctx.arc(x, y, r, 0, Math.PI * 2);
ctx.fill();
}
// draw text
function drawText(ctx, text, size, x, y, c) {
ctx.fillStyle = c;
ctx.strokeStyle = "black";
ctx.lineWidth = 5;
ctx.lineJoin = "round";
ctx.font = size + "px Arial Black";
ctx.textAlign = "center";
ctx.textBaseline = "middle";
if (c !== "black") {
ctx.strokeText(text, x, y + 1);
}
ctx.fillText(text, x, y);
}
// draw the image to fit the current canvas size
function drawImageCentered(ctx, image, x, y) {
var scale = Math.min(w / image.width, h / image.height);
ctx.setTransform(scale, 0, 0, scale, cw, ch);
ctx.drawImage(image, -image.width / 2, -image.height / 2);
ctx.setTransform(1, 0, 0, 1, 0, 0);
}
// points for filling gaps between mouse moves.
var lastMX,lastMY;
// update function will try 60fps but setting will slow this down.
function update(time){
ctx.setTransform(1, 0, 0, 1, 0, 0); // restore transform
ctx.clearRect(0, 0, w, h); // clear rhe canvas
// have the images loaded???
if (imageLoadedCount === 2) {
// draw the unblured image that will appear at the top
ctx.globalCompositeOperation = "source-over";
drawImageCentered(ctx, flowerImage, cw, ch);
drawText(ctx, "Click drag to blur the image via mask", 20 + Math.sin(time / 100), cw, ch - 30, "White");
// Mask out the parts when the mask image has pixels
ctx.globalCompositeOperation = "destination-out";
drawImageCentered(ctx, maskImage, cw, ch);
// draw the blured image only where the destination has been masked
ctx.globalCompositeOperation = "destination-atop";
drawImageCentered(ctx, flowerImageBlur, cw, ch);
// is the mouse down
if (mouse.buttonRaw === 1) {
// because image has been scaled need to get mouse coords on image
var scale = Math.min(w / flowerImage.width, h / flowerImage.height);
var x = (mouse.x - (cw - (maskImage.width / 2) * scale)) / scale;
var y = (mouse.y - (ch - (maskImage.height / 2) * scale)) / scale;
// draw circle on mask
drawCircle(maskImage.ctx, x, y, 20);
// if mouse is draging then draw some points between to fill the gaps
if (lastMX !== undefined) {
drawCircle(maskImage.ctx, ((x + lastMX) / 2 + x) / 2, ((y + lastMY) / 2 + y) / 2, 20);
drawCircle(maskImage.ctx, (x + lastMX) / 2, (y + lastMY) / 2, 20);
drawCircle(maskImage.ctx, ((x + lastMX) / 2 + lastMX) / 2, ((y + lastMY) / 2 + lastMY) / 2, 20);
}
// save las mouse pos on image
lastMX = x;
lastMY = y;
} else {
// undefined last mouse pos
lastMX = undefined;
}
} else {
// Laoding images so please wait.
drawText(ctx, "Please wait.", 40 + Math.sin(time / 100), cw, ch - 30, "White");
drawText(ctx, "loading images... ", 12, cw, ch, "black")
drawText(ctx, "ETA " + calculateTimeToGo(time), 14, cw, ch + 20, "black")
}
// if not restart the request animation frame
if(!STOP){
requestAnimationFrame(update);
}else{
var can = document.getElementById("canv");
if(can !== null){
document.body.removeChild(can);
}
STOP = false;
}
}
update();
}
var STOP = false; // flag to tell demo app to stop
function resizeEvent() {
var waitForStopped = function () {
if (!STOP) { // wait for stop to return to false
demo();
return;
}
setTimeout(waitForStopped, 200);
}
STOP = true;
setTimeout(waitForStopped, 100);
}
window.addEventListener("resize", resizeEvent);
demo();
/** FrameUpdate.js end **/
There are a few steps to do this. Most of them you have probably already done:
1) Change the order you add the items to stage. Since you want to reveal the blur instead, add them in the reverse order. This puts the blur on top.
stage.addChild(bitmap, text, blur);
2) Change what is cached or updateCached in the updateCacheImage method:
if (update) {
blur.updateCache(0, 0, image.width, image.height);
} else {
blur.cache(0, 0, image.width, image.height);
}
This is where you probably got tripped up. If you set the filters on the blurImage to just the maskFilter, it will not appear to work. The maskFilter IS working, but will have removed the blur and color filters that were applied. To add the maskFilter, you have to put it in the array with the current filters. This is my approach, which ensures the original 2 filters are intact, and the maskFilter is just added once:
blur.filters.length = 2; // Truncate the array to 2
blur.filters.push(maskFilter); // add the new filter
In my opinion, this effect isn't as obvious - so you might want to increase the opacity of the brush:
drawingCanvas.graphics.setStrokeStyle(40, "round", "round")
.beginStroke("rgba(0,0,0,0.5)"); // From 0.2
I was the author of the original AlphaMaskFilter demo in EaselJS - glad you found it useful and/or interesting!