Getting pixel data on setInterval with canvas - html

I want to build an animated alphabet, made up of particles. Basically, the particles transform from one letter shape to another.
My idea is to fill the letters as text on canvas real quickly (like for a frame), get the pixel data and put the particles to the correct location on setInterval. I have this code for scanning the screen right now:
var ctx = canvas.getContext('2d'),
width = ctx.canvas.width,
height = ctx.canvas.height,
particles = [],
gridX = 8,
gridY = 8;
function Particle(x, y) {
this.x = x;
this.y = y;
}
// fill some text
ctx.font = 'bold 80px sans-serif';
ctx.fillStyle = '#ff0';
ctx.fillText("STACKOVERFLOW", 5, 120);
// now parse bitmap based on grid
var idata = ctx.getImageData(0, 0, width, height);
// use a 32-bit buffer as we are only checking if a pixel is set or not
var buffer32 = new Uint32Array(idata.data.buffer);
// using two loops here, single loop with index-to-x/y is also an option
for(var y = 0; y < height; y += gridY) {
for(var x = 0; x < width; x += gridX) {
//buffer32[] will have a value > 0 (true) if set, if not 0=false
if (buffer32[y * width + x]) {
particles.push(new Particle(x, y));
}
}
}
// render particles
ctx.clearRect(0, 0, width, height);
particles.forEach(function(p) {
ctx.fillRect(p.x - 2, p.y - 2, 4, 4); // just squares here
})
But this way I am only showing one word, without any changes throughout the time. Also, I want to set up initially like 200 particles and reorganise them based on the pixel data, not create them on each scan.. How would you rewrite the code, so on every 1500ms I can pass a different letter and render it with particles?

Hopefully the different parts of this code should be clear enough : There are particles, that can draw and update, fillParticle will spawn particles out of a text string, and spawnChars will get a new part of the text rendered on a regular basis.
It is working quite well, play with the parameters if you wish, they are all at the start of the fiddle.
You might want to make this code cleaner, by avoiding globals and creating classes.
http://jsbin.com/jecarupiri/1/edit?js,output
// --------------------
// parameters
var text = 'STACKOVERFLOW';
var fontHeight = 80;
var gridX = 4,
gridY = 4;
var partSize = 2;
var charDelay = 400; // time between two chars, in ms
var spead = 80; // max distance from start point to final point
var partSpeed = 0.012;
// --------------------
var canvas = document.getElementById('cv'),
ctx = canvas.getContext('2d'),
width = ctx.canvas.width,
height = ctx.canvas.height,
particles = [];
ctx.translate(0.5,0.5);
// --------------------
// Particle class
function Particle(startX, startY, finalX, finalY) {
this.speed = partSpeed*(1+Math.random()*0.5);
this.x = startX;
this.y = startY;
this.startX = startX;
this.startY = startY;
this.finalX =finalX;
this.finalY =finalY;
this.parameter = 0;
this.draw = function() {
ctx.fillRect(this.x - partSize*0.5, this.y - partSize*0.5, partSize, partSize);
};
this.update = function(p) {
if (this.parameter>=1) return;
this.parameter += partSpeed;
if (this.parameter>=1) this.parameter=1;
var par = this.parameter;
this.x = par*this.finalX + (1-par)*this.startX;
this.y = par*this.finalY + (1-par)*this.startY;
};
}
// --------------------
// Text spawner
function fillParticle(text, offx, offy, spread) {
// fill some text
tmpCtx.clearRect(0,0,tmpCtx.canvas.width, tmpCtx.canvas.height);
tmpCtx.font = 'bold ' + fontHeight +'px sans-serif';
tmpCtx.fillStyle = '#A40';
tmpCtx.textBaseline ='top';
tmpCtx.textAlign='left';
tmpCtx.fillText(text, 0, 0);
//
var txtWidth = Math.floor(tmpCtx.measureText(text).width);
// now parse bitmap based on grid
var idata = tmpCtx.getImageData(0, 0, txtWidth, fontHeight);
// use a 32-bit buffer as we are only checking if a pixel is set or not
var buffer32 = new Uint32Array(idata.data.buffer);
// using two loops here, single loop with index-to-x/y is also an option
for(var y = 0; y < fontHeight; y += gridY) {
for(var x = 0; x < txtWidth; x += gridX) {
//buffer32[] will have a value > 0 (true) if set, if not 0=false
if (buffer32[y * txtWidth + x]) {
particles.push(new Particle(offx + x+Math.random()*spread - 0.5*spread,
offy + y+Math.random()*spread - 0.5*spread, offx+x, offy+y));
}
}
}
return txtWidth;
}
var tmpCv = document.createElement('canvas');
// uncomment for debug
//document.body.appendChild(tmpCv);
var tmpCtx = tmpCv.getContext('2d');
// --------------------------------
// spawn the chars of the text one by one
var charIndex = 0;
var lastSpawnDate = -1;
var offX = 30;
var offY = 30;
function spawnChars() {
if (charIndex>= text.length) return;
if (Date.now()-lastSpawnDate < charDelay) return;
offX += fillParticle(text[charIndex], offX, offY, spead);
lastSpawnDate = Date.now();
charIndex++;
}
// --------------------------------
function render() {
// render particles
particles.forEach(function(p) { p.draw();
});
}
function update() {
particles.forEach(function(p) { p.update(); } );
}
// --------------------------------
// animation
function animate(){
requestAnimationFrame(animate);
ctx.clearRect(0, 0, width, height);
render();
update();
//
spawnChars();
}
// launch :
animate();

Related

How to let a user remove an object in canvas 2D from an arbitrary position

I've got some simple barchart making code written which allows a user to add a barchart but I'd also like to allow them to remove a barchart of choice from the canvas. I don't think this should be overly difficult but I'm relatively new to html and I'm quite unsure how to go about it. Any help would be greatly appreciated.
Here's the code I've written.
<html>
<head>
<script>
var barVals = [];
function draw() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// calculate highest bar value (used to scale the rest)
var highest = 0;
for (var b=0; b<barVals.length; b++) {
if (barVals[b]>highest)
highest=barVals[b];
}
// we have 8 horizontal lines so calculate an appropriate scale
var lineSpacing = 1;
var highestLine = 7*lineSpacing;
while (highestLine<highest) {
lineSpacing *= 10;
highestLine = 7*lineSpacing;
}
// grey background
ctx.fillStyle = "rgb(200,200,200)";
ctx.fillRect (0, 0, 600, 450);
// draw and (if we have any data to scale from) label horizontal lines
var lineNum = 0;
ctx.fillStyle="white";
ctx.font="16px sans-serif";
for (y=0; y<=350; y+=50) {
// line
ctx.beginPath();
ctx.moveTo(50,y+50);
ctx.lineTo(550,y+50);
ctx.stroke();
// label (the 6 is an offset to centre the text vertically on the line)
if (barVals.length>0) {
ctx.fillText(lineSpacing*lineNum, 10, 400-y+6);
lineNum++;
}
}
// draw boxes (widths based on how many we have)
var barWidth = 500/barVals.length;
var halfBarWidth = barWidth/2;
for (b=0; b<barVals.length; b++) {
// calculate size of box and draw it
var x = 60+b*barWidth;
var hgt = (barVals[b]/highestLine)*350; // as fraction of highest line
if (b%2==0)
ctx.fillStyle = "red";
else
ctx.fillStyle = "blue";
ctx.fillRect(x,400-hgt,barWidth,hgt);
// calculate position of text and draw it
ctx.fillStyle="white";
var metrics = ctx.measureText(barVals[b]);
var halfTextWidth = metrics.width/2;
x = 60+halfBarWidth+(b*barWidth)-halfTextWidth;
ctx.fillText(barVals[b], x, 420-hgt);
}
}
function addBar() {
var textBoxObj = document.getElementById("barVal");
barVals.push(parseInt(textBoxObj.value)); // add new value to end of array. As an integer not a string!!
draw(); // redraw
textBoxObj.value = 0;
}
</script>
</head>
<body onload="draw();">
<center>
<canvas id="canvas" width="600" height="450"></canvas>
<form>
<BR>
<input type=button value='Add Bar' onclick='addBar();'> <input id='barVal' value=0>
</form>
</body>
</html>
Removing a specific chart isn't much different from adding. In fact you almost have everything you need right in your code yet.
Let's take a look at it. As soon as you click on the "Add Bar" button it will add a value from the associated textbox to the barVal array. For example, if there has been a value of 5 and 12 and you would trace the contents of barVal to the console using
console.log(barVal);
you would see this
Array [ 5, 12 ]
So 5 is stored at the first position and 12 at the second inside the array. With this knowledge in mind, what about adding a function which simply removes a specific element from the array? Here comes the array.splice() function into play. You can pass it an index inside the array and a number of elements it should remove.
e.g. if we want to get rid of the 12, we'd call barVal.splice(1,1);
After the element has been removed it's just a matter of updating your graph by calling draw() again. Now you might wonder why we pass 1 as the index, as we want to remove the second element - that's because indexes start counting from 0.
Here's an example:
var barVals = [];
function draw() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// calculate highest bar value (used to scale the rest)
var highest = 0;
for (var b = 0; b < barVals.length; b++) {
if (barVals[b] > highest)
highest = barVals[b];
}
// we have 8 horizontal lines so calculate an appropriate scale
var lineSpacing = 1;
var highestLine = 7 * lineSpacing;
while (highestLine < highest) {
lineSpacing *= 10;
highestLine = 7 * lineSpacing;
}
// grey background
ctx.fillStyle = "rgb(200,200,200)";
ctx.fillRect(0, 0, 600, 450);
// draw and (if we have any data to scale from) label horizontal lines
var lineNum = 0;
ctx.fillStyle = "white";
ctx.font = "16px sans-serif";
for (y = 0; y <= 350; y += 50) {
// line
ctx.beginPath();
ctx.moveTo(50, y + 50);
ctx.lineTo(550, y + 50);
ctx.stroke();
// label (the 6 is an offset to centre the text vertically on the line)
if (barVals.length > 0) {
ctx.fillText(lineSpacing * lineNum, 10, 400 - y + 6);
lineNum++;
}
}
// draw boxes (widths based on how many we have)
var barWidth = 500 / barVals.length;
var halfBarWidth = barWidth / 2;
for (b = 0; b < barVals.length; b++) {
// calculate size of box and draw it
var x = 60 + b * barWidth;
var hgt = (barVals[b] / highestLine) * 350; // as fraction of highest line
if (b % 2 == 0)
ctx.fillStyle = "red";
else
ctx.fillStyle = "blue";
ctx.fillRect(x, 400 - hgt, barWidth, hgt);
// calculate position of text and draw it
ctx.fillStyle = "white";
var metrics = ctx.measureText(barVals[b]);
var halfTextWidth = metrics.width / 2;
x = 60 + halfBarWidth + (b * barWidth) - halfTextWidth;
ctx.fillText(barVals[b], x, 420 - hgt);
}
}
function addBar() {
var textBoxObj = document.getElementById("barVal");
barVals.push(parseInt(textBoxObj.value)); // add new value to end of array. As an integer not a string!!
draw(); // redraw
textBoxObj.value = 0;
}
function removeBar() {
var textBoxObj = document.getElementById("removeBarVal");
barVals.splice(parseInt(textBoxObj.value), 1);
draw(); // redraw
}
draw();
<center>
<canvas id="canvas" width="600" height="450"></canvas>
<form>
<br>
<input type=button value='Add Bar' onclick='addBar();'> <input id='barVal' value=0>
<input type=button value='Remove Bar' onclick='removeBar();'> <input id='removeBarVal' value=0>
</form>
</center>

Detect Colour Using Action Script 3

So I have made a game in scratch which uses the following code block:
I am trying to remake this game in Adobe Animate using Action Script 3 (for a class project), is there a similar way to do this in animate?
It is possible. The trick to do it is to create a tiny-teeny BitmapData object and to draw a small portion of stage under the mouse pointer into that object so that you can obtain the pixel color value.
// BitmapData object and some service objects.
var BD:BitmapData = new BitmapData(3, 3, true);
var R:Rectangle = new Rectangle(0, 0, 3, 3);
var M:Matrix = new Matrix;
// Let's create a TextField so we can output the pixel color value.
var T:TextField = new TextField;
var TF:TextFormat = new TextFormat("_typewriter", 12, 0x000000, true, false, false, null, null, TextFormatAlign.CENTER);
T.x = 10;
T.y = 10;
T.width = 100;
T.height = 18;
T.border = true;
T.background = true;
T.selectable = false;
T.mouseEnabled = false;
T.defaultTextFormat = TF;
addChild(T);
// Lets add some semi-transparent color circles
// so we have colored things to point the mouse at.
for (var i:int = 0; i < 10; i++)
{
var aColor:uint = 0;
aColor |= int(128 + 128 * Math.random()) << 16; // RED
aColor |= int(128 + 128 * Math.random()) << 8; // GREEN
aColor |= int(128 + 128 * Math.random()); // BLUE
var anX:int = stage.stageWidth / 8 + Math.random() * stage.stageWidth * 3 / 4;
var anY:int = stage.stageHeight / 8 + Math.random() * stage.stageHeight * 3 / 4;
var aRadius:int = 50 + 100 * Math.random();
var anAlpha:Number = 0.5 + 0.5 * Math.random();
graphics.beginFill(aColor, anAlpha);
graphics.drawCircle(anX, anY, aRadius);
graphics.endFill();
}
// Now let's watch the mouse every frame.
addEventListener(Event.ENTER_FRAME, onFrame);
function onFrame(e:Event):void
{
// Get pixel color as an RRGGBB String and print it.
T.text = "#" + addZeroes(getColorUnderMouse());
}
function getColorUnderMouse():uint
{
// Adjust Matrix so that we draw the correct piece of screen.
M.tx = -root.mouseX + 1;
M.ty = -root.mouseY + 1;
// Clear the BitmapData and capture the 3x3 piece under the mouse pointer.
BD.fillRect(R, 0xFFFFFFFF);
BD.draw(root, M, null, null, R);
// Read the pixel color value at the center of 3x3 and return it.
return BD.getPixel(1, 1);
}
// This function fixes the hexabinary value with leading
// zeroes if the color value is too small (like 0 = black).
function addZeroes(value:uint, count:uint = 6):String
{
var result:String = value.toString(16).toUpperCase();
while (result.length < count)
{
result = "0" + result;
}
return result;
}

Merge or Use instance and Native render make no difference with Chrome plus Integrated Graphics Card [duplicate]

I am testing the FPS with my laptop using the Intel(R) Iris(R) Plus Graphics 655 card.
To test the threeJS example with Instance rendering and merge-drawcall rendering.
So I used both the QRCode_buffergeometry.json model and the suzanne_buffergeometry.json model.
for the QRCode_buffergeometry.json: vertex:12852, face: 4284
and for the suzanne_buffergeometry.json: vertex:1515 face: 967
Then the FPS for the suzanne_buffergeometry with 8000 count:
INSTANCE: 36
MERGED: 43
NATIVE: from 23 to 35 by rotation
for the QRCode_buffergeometry model with 8000 count:
INSTANCE: 9
MERGED: 15-17
NATIVE: 17-19
I am very confused with this performance.
1. As far as my understanding, with no matter if i use instance or merge-drawcall, the drawcall is fixed to be 1 and the total face number to draw is same, why merged-drawcall is better than instance? Since the face and vertex number are both same, I suppose what happened in the vertex shader for transform the vertex should be same too, so why merged is faster?
For the QRCode_buffergeometry model, native is almost same as merged, and better than instance, so I guess the CPU is not the bottle neck but the GPU is, however the final drawing data should be same, i mean eventually the face number to be draw should be same, why native is faster?, isn't that the instance is supposed to be the best way? I am pretty sure the camera's far and near is big enough, so there should not be any culling issue.
When I am trying to optimize some big scene, when should I pick merge? when to pick instance? and when maybe no doing anything is better?
Any help?
Thanks a lot~~~
Attached the code for the sample is here
body { margin: 0; }
<div id="container"></div>
<script type="module">
import * as THREE from 'https://cdn.jsdelivr.net/npm/three#0.112.1/build/three.module.js';
import Stats from 'https://cdn.jsdelivr.net/npm/three#0.112.1/examples/jsm/libs/stats.module.js';
import {
GUI
} from 'https://cdn.jsdelivr.net/npm/three#0.112.1/examples/jsm/libs/dat.gui.module.js';
import {
OrbitControls
} from 'https://cdn.jsdelivr.net/npm/three#0.112.1/examples/jsm/controls/OrbitControls.js';
import {
BufferGeometryUtils
} from 'https://cdn.jsdelivr.net/npm/three#0.112.1/examples/jsm/utils/BufferGeometryUtils.js';
var container, stats, gui, guiStatsEl;
var camera, controls, scene, renderer, material;
// gui
var Method = {
INSTANCED: 'INSTANCED',
MERGED: 'MERGED',
NAIVE: 'NAIVE'
};
var api = {
method: Method.INSTANCED,
mesh_number: 1,
count_per_mesh: 1000
};
var modelName = 'suzanne_buffergeometry.json';
var modelScale = (modelName === 'suzanne_buffergeometry.json' ? 1 : 0.01);
var modelVertex = (modelName === 'suzanne_buffergeometry.json' ? 1515 : 12852);
var modelFace = (modelName === 'suzanne_buffergeometry.json' ? 967 : 4284);
//
init();
initMesh();
animate();
//
function clean() {
var meshes = [];
scene.traverse(function(object) {
if (object.isMesh) meshes.push(object);
});
for (var i = 0; i < meshes.length; i++) {
var mesh = meshes[i];
mesh.material.dispose();
mesh.geometry.dispose();
scene.remove(mesh);
}
}
var randomizeMatrix = function() {
var position = new THREE.Vector3();
var rotation = new THREE.Euler();
var quaternion = new THREE.Quaternion();
var scale = new THREE.Vector3();
return function(matrix) {
position.x = Math.random() * 40 - 20;
position.y = Math.random() * 40 - 20;
position.z = Math.random() * 40 - 20;
rotation.x = Math.random() * 2 * Math.PI;
rotation.y = Math.random() * 2 * Math.PI;
rotation.z = Math.random() * 2 * Math.PI;
quaternion.setFromEuler(rotation);
scale.x = scale.y = scale.z = Math.random() * modelScale;
matrix.compose(position, quaternion, scale);
};
}();
function initMesh() {
clean();
console.time(api.method + ' (build)');
for (var i = 0; i < api.mesh_number; i++) {
// make instances
new THREE.BufferGeometryLoader()
.setPath('https://threejs.org/examples/models/json/')
.load(modelName, function(geometry) {
material = new THREE.MeshNormalMaterial();
geometry.computeVertexNormals();
switch (api.method) {
case Method.INSTANCED:
makeInstanced(geometry);
break;
case Method.MERGED:
makeMerged(geometry);
break;
case Method.NAIVE:
makeNaive(geometry);
break;
}
});
}
console.timeEnd(api.method + ' (build)');
var drawCalls = 0;
switch (api.method) {
case Method.INSTANCED:
case Method.MERGED:
drawCalls = api.mesh_number;
break;
case Method.NAIVE:
drawCalls = api.mesh_number * api.count_per_mesh;
break;
}
guiStatsEl.innerHTML = [
'<i>GPU draw calls</i>: ' + drawCalls,
'<i>Face Number</i>: ' + (modelFace * api.mesh_number * api.count_per_mesh),
'<i>Vertex Number</i>: ' + (modelVertex * api.mesh_number * api.count_per_mesh)
].join('<br/>');
}
function makeInstanced(geometry, idx) {
var matrix = new THREE.Matrix4();
var mesh = new THREE.InstancedMesh(geometry, material, api.count_per_mesh);
for (var i = 0; i < api.count_per_mesh; i++) {
randomizeMatrix(matrix);
mesh.setMatrixAt(i, matrix);
}
scene.add(mesh);
}
function makeMerged(geometry, idx) {
var instanceGeometry;
var geometries = [];
var matrix = new THREE.Matrix4();
for (var i = 0; i < api.count_per_mesh; i++) {
randomizeMatrix(matrix);
var instanceGeometry = geometry.clone();
instanceGeometry.applyMatrix(matrix);
geometries.push(instanceGeometry);
}
var mergedGeometry = BufferGeometryUtils.mergeBufferGeometries(geometries);
scene.add(new THREE.Mesh(mergedGeometry, material));
}
function makeNaive(geometry, idx) {
var matrix = new THREE.Matrix4();
for (var i = 0; i < api.count_per_mesh; i++) {
randomizeMatrix(matrix);
var mesh = new THREE.Mesh(geometry, material);
mesh.applyMatrix(matrix);
scene.add(mesh);
}
}
function init() {
var width = window.innerWidth;
var height = window.innerHeight;
// camera
camera = new THREE.PerspectiveCamera(70, width / height, 1, 100);
camera.position.z = 30;
// renderer
renderer = new THREE.WebGLRenderer({
antialias: true
});
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(width, height);
renderer.outputEncoding = THREE.sRGBEncoding;
container = document.getElementById('container');
container.appendChild(renderer.domElement);
// scene
scene = new THREE.Scene();
scene.background = new THREE.Color(0xffffff);
// controls
controls = new OrbitControls(camera, renderer.domElement);
controls.autoRotate = true;
// stats
stats = new Stats();
container.appendChild(stats.dom);
// gui
gui = new GUI();
gui.add(api, 'method', Method).onChange(initMesh);
gui.add(api, 'count_per_mesh', 1, 20000).step(1).onChange(initMesh);
gui.add(api, 'mesh_number', 1, 200).step(1).onChange(initMesh);
var perfFolder = gui.addFolder('Performance');
guiStatsEl = document.createElement('li');
guiStatsEl.classList.add('gui-stats');
perfFolder.__ul.appendChild(guiStatsEl);
perfFolder.open();
// listeners
window.addEventListener('resize', onWindowResize, false);
Object.assign(window, {
scene
});
}
//
function onWindowResize() {
var width = window.innerWidth;
var height = window.innerHeight;
camera.aspect = width / height;
camera.updateProjectionMatrix();
renderer.setSize(width, height);
}
function animate() {
requestAnimationFrame(animate);
controls.update();
stats.update();
render();
}
function render() {
renderer.render(scene, camera);
}
//
function getGeometryByteLength(geometry) {
var total = 0;
if (geometry.index) total += geometry.index.array.byteLength;
for (var name in geometry.attributes) {
total += geometry.attributes[name].array.byteLength;
}
return total;
}
// Source: https://stackoverflow.com/a/18650828/1314762
function formatBytes(bytes, decimals) {
if (bytes === 0) return '0 bytes';
var k = 1024;
var dm = decimals < 0 ? 0 : decimals;
var sizes = ['bytes', 'KB', 'MB'];
var i = Math.floor(Math.log(bytes) / Math.log(k));
return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}
</script>
This is only guesses
Three.js by default culls if things are outside the frustum.
We can turn this off with mesh.frustumCulled = false. I didn't notice a difference and this should show up in the draw count.
Three.js by default sorts opaque objects back to front.
This means everything else being equal, sorted will run faster
than unsorted because of the depth test. If I set the depth test
to always
material.depthFunc = THREE.AlwaysDepth
Then I seem to get slightly faster rendering with instanced vs native. Of course
everything else is not equal.
An issue in Chrome.
If I run in Firefox or Safari I get the expected results. Merged > Instanced > Native
It could be a bug or it could be they're working around a driver or
security issue that the other browsers are not. You'd have to ask.

Html5 canvas scrolling vertically and horizontally

<!DOCTYPE html>
<html>
<head>
<style type="text/css">
#canvasOne
{
border: 1px solid black;
}
</style>
<script src="http://code.jquery.com/jquery-1.10.2.js" type="text/javascript"></script>
</head>
<body>
<div align="center">
<canvas id="canvasOne">
</canvas>
</div>
<script type="text/javascript">
var myCanvas = document.getElementById("canvasOne");
var myContext = myCanvas.getContext("2d");
var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
init();
var numShapes;
var shapes;
var dragIndex;
var dragging;
var mouseX;
var mouseY;
var dragHoldX;
var dragHoldY;
var timer;
var targetX;
var targetY;
var easeAmount;
var bgColor;
var nodes;
var colorArr;
function init()
{
myCanvas.width = $(window).width() - 200;
myCanvas.height = $(window).height() - 200;
shapes = [];
nodes = ["0;Person;24828760;Alok Kumar;Gorakhpur;#F44336;28",
"0;Suspect;04/Dec/2016;4;Suman_Biswas;#3F51B5;20","1;Rule;4;Apparent Means;3 Parameter;#EEFF41;20",
"0;Policy;36QA649749;In-Force;Quarterly;#FF9800;20","3;Product;Pension;Saral Pension;SRPEN;#795548;20","3;Payment;Cheque;Realized;Lucknow;#0091EA;20",
"0;Policy;162348873;Lapsed;Quarterly;#FF9800;20","6;Product;Pension;Life-Long Pension;LLPP;#795548;20","6;Payment;Cheque;Realized;Gorakhpur;#0091EA;20",
"0;Policy;1EQF178639;Lapsed;Monthly;#FF9800;20","9;Product;Life;Shield;SHIELDA;#795548;20","9;Payment;Demand Draft;Realized;Lucknow;#0091EA;20"];
numShapes = nodes.length;
makeShapes();
drawScreen();
myCanvas.addEventListener("mousedown", mouseDownListener, false);
}
//drawing
function makeShapes()
{
var tempX;
var tempY;
for(var i = 0; i < numShapes; i++)
{
var centerX = myCanvas.width/2;
var centerY = myCanvas.height/2;
var nodeColor = nodes[i].split(";")[5];
var nodeRadius = nodes[i].split(";")[6];
var nodeConnect = nodes[i].split(";")[0];
if(i == 0)//center of circle
{
tempX = centerX
tempY = centerY;
}
else
{
//tempX = Math.random() * (myCanvas.width - tempRadius);
//tempY = Math.random() * (myCanvas.height - tempRadius);
//var x = x0 + r * Math.cos(2 * Math.PI * i / items);
//var y = y0 + r * Math.sin(2 * Math.PI * i / items);
//250 is the distance from center node to outside nodes it can be actual radius in degrees
tempX = shapes[nodeConnect].x + 300 * Math.cos(2 * Math.PI * i / numShapes);
tempY = shapes[nodeConnect].y + 300 * Math.sin(2 * Math.PI * i / numShapes);
}
tempShape = {x: tempX, y: tempY, rad: nodeRadius, color: nodeColor, text: nodes[i]};
shapes.push(tempShape);
}
}
//drawing both shape (line and circle) and screen
function drawScreen()
{
myContext.fillStyle = "#ffffff";
myContext.fillRect(0, 0, myCanvas.width, myCanvas.height);
drawShapes();
}
function drawShapes()
{
//line
for(var i = 1; i < numShapes; i++)
{
myContext.beginPath();
myContext.strokeStyle = "#B2B19D";
var nodeConnect = nodes[i].split(";")[0];
myContext.moveTo(shapes[nodeConnect].x, shapes[nodeConnect].y);
myContext.lineTo(shapes[i].x, shapes[i].y);
myContext.stroke();
}
//circle
for(var i = 0; i < numShapes; i++)
{
myContext.fillStyle = shapes[i].color;
myContext.beginPath();
myContext.arc(shapes[i].x, shapes[i].y, shapes[i].rad, 0, 2*Math.PI, false);
myContext.closePath();
myContext.fill();
}
//text
for(var i = 0; i < numShapes; i++)
{
myContext.beginPath();
myContext.font = '10pt Arial';
myContext.fillStyle = 'black';
var textarr = shapes[i].text.split(";");
myContext.fillText(textarr[1], shapes[i].x + 30, shapes[i].y - 24);
/*myContext.fillText(textarr[2], shapes[i].x + 30, shapes[i].y + 1);
myContext.fillText(textarr[3], shapes[i].x + 30, shapes[i].y + 22);
myContext.fillText(textarr[4], shapes[i].x + 30, shapes[i].y + 44);*/
myContext.closePath();
myContext.fill();
}
}
//animation
function mouseDownListener(evt)
{
var highestIndex = -1;
var bRect = myCanvas.getBoundingClientRect();
mouseX = (evt.clientX - bRect.left) * (myCanvas.width/bRect.width);
mouseY = (evt.clientY - bRect.top) * (myCanvas.height/bRect.height);
for(var i = 0; i < numShapes; i++)
{
if(hitTest(shapes[i], mouseX, mouseY))
{
dragging = true;
if(i > highestIndex)
{
dragHoldX = mouseX - shapes[i].x;
dragHoldY = mouseY - shapes[i].y;
highestIndex = i;
dragIndex = i;
}
}
}
if(dragging)
{
window.addEventListener("mousemove", mouseMoveListener, false);
}
myCanvas.removeEventListener("mousedown", mouseDownListener, false);
window.addEventListener("mouseup", mouseUpListener, false);
if(evt.preventDefault)
{
evt.preventDefault;
}
return false;
}
function mouseMoveListener(evt)
{
var shapeRad = shapes[dragIndex].rad;
var minX = shapeRad;
var maxX = myCanvas.width - shapeRad;
var minY = shapeRad;
var maxY = myCanvas.height - shapeRad;
//get mouse position correctly
var bRect = myCanvas.getBoundingClientRect();
mouseX = (evt.clientX - bRect.left)*(myCanvas.width / bRect.width);
mouseY = (evt.clientY - bRect.top)*(myCanvas.height / bRect.height);
//clamp x and y position to prevent object from dragging outside canvas
posX = mouseX - dragHoldX;
posX = (posX < minX) ? minX : ((posX > maxX) ? maxX : posX);
posY = mouseY - dragHoldY;
posY = (posY < minY) ? minY : ((posY > maxY) ? maxY : posY);
shapes[dragIndex].x = posX;
shapes[dragIndex].y = posY;
drawScreen();
}
function mouseUpListener(evt)
{
myCanvas.addEventListener("mousedown", mouseDownListener, false);
window.removeEventListener("mouseup", mouseUpListener, false);
if(dragging)
{
dragging = false;
window.removeEventListener("mousemove", mouseMoveListener, false);
}
}
function hitTest(shape, mx, my)
{
var dx = mx - shape.x;
var dy = my - shape.y;
return(dx * dx + dy * dy < shape.rad * shape.rad);
}
</script>
</body>
</html>
The following canvas animation creates nodes and edges. However due
to space constraint, some of the nodes are not visible due to canvas
height and width. Even adding overflow css to canvas dosen't help as
i am not able to scroll.
<canvas> context doesn't have a built-in scroll method.
You then have multiple ways to circumvent this limitation.
The first one, is as in #markE's answer, to scale your context's matrix so that your drawings fit into the required space. You could also refactor your code so that all coordinates are relative to the canvas size.
This way, you won't need scrollbars and all your drawings will just be scaled appropriately, which is the desirable behavior in most common cases.
But if you really need to have some scrolling feature, here are some ways :
The easiest and most recommended one : let the browser handle it.
You will have to set the size of your canvas to the maximum of your drawings, and wrap it in an other element which will scroll. By setting the overflow:auto css property on the container, our scrollbars appear and we have our scrolling feature.
In following example, the canvas is 5000px wide and the container 200px.
var ctx = canvas.getContext('2d');
ctx.textAlign = 'center';
for (var w = 0; w < canvas.width; w += 100) {
for (var h = 0; h < canvas.height; h += 100) {
ctx.fillText(w + ',' + h, w, h);
}
}
#container {
width: 200px;
height: 200px;
overflow: auto;
border: 1px solid;
}
canvas{
display: block;
}
<div id="container">
<canvas id="canvas" height="5000" width="5000"></canvas>
</div>
Main advantages :
easily implemented.
users are used to these scrollbars.
Main caveats :
You're limited by canvas maximum sizes.
If your canvas is animated, you'll also draw for each frame parts of the canvas that aren't visible.
You have small control on scrollbars look and you'll still have to implement drag-to-scroll feature yourself for desktop browsers.
A second solution, is to implement this feature yourself, using canvas transform methods : particularly translate, transform and setTransform.
Here is an example :
var ctx = canvas.getContext('2d');
var app = {};
// the total area of our drawings, can be very large now
app.WIDTH = 5000;
app.HEIGHT = 5000;
app.draw = function() {
// reset everything (clears the canvas + transform + fillStyle + any other property of the context)
canvas.width = canvas.width;
// move our context by the inverse of our scrollbars' left and top property
ctx.setTransform(1, 0, 0, 1, -app.scrollbars.left, -app.scrollbars.top);
ctx.textAlign = 'center';
// draw only the visible area
var visibleLeft = app.scrollbars.left;
var visibleWidth = visibleLeft + canvas.width;
var visibleTop = app.scrollbars.top
var visibleHeight = visibleTop + canvas.height;
// you probably will have to make other calculations than these ones to get your drawings
// to draw only where required
for (var w = visibleLeft; w < visibleWidth + 50; w += 100) {
for (var h = visibleTop; h < visibleHeight + 50; h += 100) {
var x = Math.round((w) / 100) * 100;
var y = Math.round((h) / 100) * 100;
ctx.fillText(x + ',' + y, x, y);
}
}
// draw our scrollbars on top if needed
app.scrollbars.draw();
}
app.scrollbars = function() {
var scrollbars = {};
// initial position
scrollbars.left = 0;
scrollbars.top = 0;
// a single constructor for both horizontal and vertical
var ScrollBar = function(vertical) {
var that = {
vertical: vertical
};
that.left = vertical ? canvas.width - 10 : 0;
that.top = vertical ? 0 : canvas.height - 10;
that.height = vertical ? canvas.height - 10 : 5;
that.width = vertical ? 5 : canvas.width - 10;
that.fill = '#dedede';
that.cursor = {
radius: 5,
fill: '#bababa'
};
that.cursor.top = vertical ? that.cursor.radius : that.top + that.cursor.radius / 2;
that.cursor.left = vertical ? that.left + that.cursor.radius / 2 : that.cursor.radius;
that.draw = function() {
if (!that.visible) {
return;
}
// remember to reset the matrix
ctx.setTransform(1, 0, 0, 1, 0, 0);
// you can give it any shape you like, all canvas drawings operations are possible
ctx.fillStyle = that.fill;
ctx.fillRect(that.left, that.top, that.width, that.height);
ctx.beginPath();
ctx.arc(that.cursor.left, that.cursor.top, that.cursor.radius, 0, Math.PI * 2);
ctx.fillStyle = that.cursor.fill;
ctx.fill();
};
// check if we're hovered
that.isHover = function(x, y) {
if (x >= that.left - that.cursor.radius && x <= that.left + that.width + that.cursor.radius &&
y >= that.top - that.cursor.radius && y <= that.top + that.height + that.cursor.radius) {
// we are so record the position of the mouse and set ourself as the one hovered
scrollbars.mousePos = vertical ? y : x;
scrollbars.hovered = that;
that.visible = true;
return true;
}
// we were visible last call and no wheel event is happening
else if (that.visible && !scrollbars.willHide) {
that.visible = false;
// the app should be redrawn
return true;
}
}
return that;
};
scrollbars.horizontal = ScrollBar(0);
scrollbars.vertical = ScrollBar(1);
scrollbars.hovered = null;
scrollbars.dragged = null;
scrollbars.mousePos = null;
// check both of our scrollbars
scrollbars.isHover = function(x, y) {
return this.horizontal.isHover(x, y) || this.vertical.isHover(x, y);
};
// draw both of our scrollbars
scrollbars.draw = function() {
this.horizontal.draw();
this.vertical.draw();
};
// check if one of our scrollbars is visible
scrollbars.visible = function() {
return this.horizontal.visible || this.vertical.visible;
};
// hide it...
scrollbars.hide = function() {
// only if we're not using the mousewheel or dragging the cursor
if (this.willHide || this.dragged) {
return;
}
this.horizontal.visible = false;
this.vertical.visible = false;
};
// get the area's coord relative to our scrollbar
var toAreaCoord = function(pos, scrollBar) {
var sbBase = scrollBar.vertical ? scrollBar.top : scrollBar.left;
var sbMax = scrollBar.vertical ? scrollBar.height : scrollBar.width;
var areaMax = scrollBar.vertical ? app.HEIGHT - canvas.height : app.WIDTH - canvas.width;
var ratio = (pos - sbBase) / (sbMax - sbBase);
return areaMax * ratio;
};
// get the scrollbar's coord relative to our total area
var toScrollCoords = function(pos, scrollBar) {
var sbBase = scrollBar.vertical ? scrollBar.top : scrollBar.left;
var sbMax = scrollBar.vertical ? scrollBar.height : scrollBar.width;
var areaMax = scrollBar.vertical ? app.HEIGHT - canvas.height : app.WIDTH - canvas.width;
var ratio = pos / areaMax;
return ((sbMax - sbBase) * ratio) + sbBase;
}
scrollbars.scroll = function() {
// check which one of the scrollbars is active
var vertical = this.hovered.vertical;
// until where our cursor can go
var maxCursorPos = this.hovered[vertical ? 'height' : 'width'];
var pos = vertical ? 'top' : 'left';
// check that we're not out of the bounds
this.hovered.cursor[pos] = this.mousePos < 0 ? 0 :
this.mousePos > maxCursorPos ? maxCursorPos : this.mousePos;
// seems ok so tell the app we scrolled
this[pos] = toAreaCoord(this.hovered.cursor[pos], this.hovered);
// redraw everything
app.draw();
}
// because we will hide it after a small time
scrollbars.willHide;
// called by the wheel event
scrollbars.scrollBy = function(deltaX, deltaY) {
// it's not coming from our scrollbars
this.hovered = null;
// we're moving horizontally
if (deltaX) {
var newLeft = this.left + deltaX;
// make sure we're in the bounds
this.left = newLeft > app.WIDTH - canvas.width ? app.WIDTH - canvas.width : newLeft < 0 ? 0 : newLeft;
// update the horizontal cursor
this.horizontal.cursor.left = toScrollCoords(this.left, this.horizontal);
// show our scrollbar
this.horizontal.visible = true;
}
if (deltaY) {
var newTop = this.top + deltaY;
this.top = newTop > app.HEIGHT - canvas.height ? app.HEIGHT - canvas.height : newTop < 0 ? 0 : newTop;
this.vertical.cursor.top = toScrollCoords(this.top, this.vertical);
this.vertical.visible = true;
}
// if we were called less than the required timeout
clearTimeout(this.willHide);
this.willHide = setTimeout(function() {
scrollbars.willHide = null;
scrollbars.hide();
app.draw();
}, 500);
// redraw everything
app.draw();
};
return scrollbars;
}();
var mousedown = function(e) {
// tell the browser we handle this
e.preventDefault();
// we're over one the scrollbars
if (app.scrollbars.hovered) {
// new promotion ! it becomes the dragged one
app.scrollbars.dragged = app.scrollbars.hovered;
app.scrollbars.scroll();
}
};
var mousemove = function(e) {
// check the coordinates of our canvas in the document
var rect = canvas.getBoundingClientRect();
var x = e.clientX - rect.left;
var y = e.clientY - rect.top;
// we're dragging something
if (app.scrollbars.dragged) {
// update the mouse position
app.scrollbars.mousePos = app.scrollbars.dragged.vertical ? y : x;
app.scrollbars.scroll();
} else if (app.scrollbars.isHover(x, y)) {
// something has changed, redraw to show or hide the scrollbar
app.draw();
}
e.preventDefault();
};
var mouseup = function() {
// we dropped it
app.scrollbars.dragged = null;
};
var mouseout = function() {
// we're out
if (app.scrollbars.visible()) {
app.scrollbars.hide();
app.scrollbars.dragged = false;
app.draw();
}
};
var mouseWheel = function(e) {
e.preventDefault();
app.scrollbars.scrollBy(e.deltaX, e.deltaY);
};
canvas.addEventListener('mousemove', mousemove);
canvas.addEventListener('mousedown', mousedown);
canvas.addEventListener('mouseup', mouseup);
canvas.addEventListener('mouseout', mouseout);
canvas.addEventListener('wheel', mouseWheel);
range.onchange = function() {
app.WIDTH = app.HEIGHT = this.value;
app.scrollbars.left = 0;
app.scrollbars.top = 0;
app.draw();
};
// an initial drawing
app.draw();
canvas {border: 1px solid;}
span{font-size: .8em;}
<canvas id="canvas" width="200" height="150"></canvas>
<span>
change the total area size
<input type="range" min="250" max="5000000" steps="250" value="5000" id="range" />
</span>
Main advantages :
no limitation for the size of your drawing areas.
you can customize your scrollbars as you wish.
you can control when the scrollbars are enable or not.
you can get the visible area quite easily.
Main caveats:
a bit more code than the CSS solution...
no really, that's a lot of code...
A third way I wrote some time ago for an other question took advantage of the ability to draw an other canvas with ctx.drawImage(). It has its own caveats and advantages, so I let you pick the one you need, but this last one also had a drag and slide feature which can be useful.
So your node drawings don't fit on the canvas size?
You can easily "shrink" your content to fit the visible canvas with just 1 command!
The context.scale(horizontalRescale,verticalRescale) command will shrink every following drawing by your specified horizontalRescale & verticalRescale percentages.
An Important note: You must make horizontalRescale,verticalRescale the same value or your content will be distorted.
The nice thing about using context.scale is that you don't have to change any of the code that draws your nodes ... canvas automatically scales all those nodes for you.
For example, this code will shrink your nodes to 80% of their original size:
var downscaleFactor= 0.80;
context.scale( downscaleFactor, downscaleFactor );
Rather than go through your 200+ lines of code, I leave it to you to calculate downscaleFactor.

HTML5 Canvas Challenge

I am creating an HTML5 app that will display a bunch of shapes in different colors. I am having trouble display more than one of any shape.
Here is a JSFiddle link to my project: http://jsfiddle.net/tithos/3uyLc/
Here is one of the things I tried:
$("#go").click(function() {
var number = $("#number option:selected").val();
var shape = $("#shape option:selected").val();
var size = $("#size option:selected").val();
var offset = size;
var i = 0;
var shift = 0;
while(i < number){
switch(shape){
case '1':
console.log(shift);
square((offset+shift), size);
shift = (shift + size);
break;
case '2':
circle(offset, size);
break;
case '3':
triangle(offset, size);
break;
}
i++;
}
});
This, when repeated 16 times, gives me "0121212121212121212121212121212" in the concole. It is concatenating, not adding. Why?
Any help or insights are welcome
Thanks,
Tim
Since .val() returns a string you are using + operator between two strings, which is the concatenation operator. Use parseInt to convert a string to integer.
In the first few lines, you need to parseInt from each of the .val() functions. So:
var number = $("#number option:selected").val();
var shape = $("#shape option:selected").val();
var size = $("#size option:selected").val();
becomes
var number = parseInt($("#number option:selected").val());
var shape = $("#shape option:selected").val();
var size = parseInt($("#size option:selected").val());
but the size and "offset" calculations are all done in the wrong place. they need to be done in the main loop while the drawShape methods each have the task of drawing a given shape in a given location of a specified size. http://jsfiddle.net/3uyLc/39/
Here's the fixed code:
jQuery.noConflict();
(function($) {
$("#clear").click(function() {
console.log("clear!");
var c=document.getElementById("canvas");
var context=c.getContext("2d");
context.clearRect(0, 0, canvas.width, canvas.height);
});
function square(offset, size){
var color = $("#color option:selected").val();
var c=document.getElementById("canvas");
var context=c.getContext("2d");
context.fillStyle = color;
context.fillRect(offset,0,size,size);
}
function circle(offset, size){
var color = $("#color option:selected").val();
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var radius = size / 2;
var x = offset + radius;
var y = radius;
context.beginPath();
context.arc(x, y, radius, 0, 2 * Math.PI, false);
context.lineWidth = 1;
context.fillStyle = color;
context.fill();
//context.fillStyle="#ff0000";
//context.fillRect(x-1, y-1, 2, 2);
}
function triangle(offset, size){
console.log(offset);
var color = $("#color option:selected").val();
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var width = size;
var height = size;
// Draw a path
context.beginPath();
//top of triangle
context.moveTo(offset + width/2, 0);
//top to right
context.lineTo(offset + width, size);
//bottom of triangle
context.lineTo(offset, size);
context.closePath();
// Fill the path
context.fillStyle = color;
context.fill();
}
$("#go").click(function() {
var number = parseInt($("#number option:selected").val());
var shape = $("#shape option:selected").val();
var size = parseInt($("#size option:selected").val()) * 10;
var i = 0;
var position = 0;
var padding = size * 0.5; //leave space between the shapes 1/2 as large as the shape itself
while(i < number){
switch(shape){
case '1':
square(position, size);
break;
case '2':
circle(position, size);
break;
case '3':
triangle(position, size);
break;
}
i++;
// calculate the position of the next shape
position = position + size + padding;
}
});
})(jQuery);​