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JavaScript - Drawing On Multiple Canvas Elements
I'm having a problem with the <CANVAS> element in JavaScript.
here's what i'm trying to do: I need 3 different canvas elements for writing a signature to. they must all 3 be visible at the same time My problem that i'm having is that i can't seem to get the code to work which will write to more than one canvas. here's my code: Code: <html>
<head>
<script language="javascript">
function WriteSignature(element, event)
{
document.addEventListener("mousemove", PenHandler, true);
document.addEventListener("mouseup", upHandler, true);
event.stopPropagation();
event.preventDefault();
function PenHandler(event)
{
var x = event.clientX;
var y = event.clientY;
// mouse event goes here
var canvas1 = document.getElementById("Canvas1");
var ctx = canvas1.getContext("2d");
var PenSize = 2;
ctx.fillStyle = "Black";
ctx.fillRect (x, y, PenSize, PenSize);
event.stopPropagation();
}
function upHandler(event)
{
document.removeEventListener("mouseup", upHandler, true);
document.removeEventListener("mousemove", PenHandler, true);
event.stopPropagation();
}
}
</script>
</head>
<body>
<Canvas id="Canvas1" Width="400" Height="100" Style="border:2px solid black" onmousedown="WriteSignature(this, event);"></Canvas><br><br>
<Canvas id="Canvas2" Width="400" Height="100" Style="border:2px solid black" onmousedown="WriteSignature(this, event);"></Canvas><br>
</body>
</html>
Similar TutorialsHello, Codingforums. I have looked on Google for a solution, done a handful of things, and cannot get my script to draw to the page. Code: <html>
<head>
<script type="text/javascript" src="imageFuncs.js"></script>
<script type="text/javascript">
showImages = function() {
var drawingCanvas = document.getElementById("map");
// Check the element is in the DOM and the browser supports canvas
if (drawingCanvas.getContext) {
var ctx = drawingCanvas.getContext("2d");
var imageSources = new Array("map.jpg");
var images = new Array();
images = loadImages(imageSources);
for (var i = 0; i < images.length; i++) {
var img = new Image();
img.src = images[i].src;
img.onload = function(){
ctx.drawImage(img,0,0,screen.width,screen.height);
}
}
}
}
</script>
</head>
<body onload="showImages()">
<canvas id="map">Your browser does not support canvases...</canvas>
</body>
</html>
The problem appears on the ctx.drawImage(img,0,0,screen.width,screen.height); line. I read that the drawImage method will not draw the image if the images are not loaded, which is why I tried an onload event for img. When I run the code the way it is now, I get a attempt to run compile-and-go script on a cleared scope error from Firebug. When I remove the onload event, the script runs without errors. Either way, no image is drawn on the page. Any help? If it helps, this is the loadImages function that I used to get the array of loaded image objects: Code: function loadImages(sources){
var images = new Array();
var loadedImages = 0;
var numImages = 0;
for (var src in sources) {
numImages++;
}
for (var src in sources) {
images[src] = new Image();
images[src].src = sources[src];
}
return images;
}
I am trying to create an Asteroids type game using JavaScript along with html5's canvas element for drawing. I have searched around and have looked at examples but I can't figure out what is wrong with my rendering that I do in the game loop that is run every frame. The problem appears to be only that the canvas is not cleared at the beginning of each frame but I feel there might be something wrong also. The code used and shown below only works in Firefox but not Google Chrome or Safari. Here is a picture of what it renders in Chrome: What is is supposed to look like and is in Firefox: Here is my set up for drawing on the canvas: Code: var canvas = null;
var c2d = null;
//...
window.onload = init;
function init() {
canvas = document.getElementById('canvas');
c2d = canvas.getContext('2d');
setInterval( step, 1000/FPS );
//...
//c2d.setTransform(1,0,0,1,0,0); // reset to identity <--Do I need this?
}
Below is the game loop function. Am I clearing the canvas correctly because it does not clear the screen? Also am I using the save and restore functions correctly? Each asteroid and player drawn is at a different of position and rotation so am I doing it correct to draw them? Code: function step() {
//...
canvas.width = canvas.width; //clear canvas PROBLEM
//Things I have tried:
//canvas.height = canvas.height; //clear canvas
//c2d.clearRect(0, 0, canvas.width, canvas.height);
for (u=0;u<asteroids.length;u++) {
c2d.save();
asteroids[u].draw();
c2d.restore();
}
c2d.save();
player.draw();
c2d.restore();
c2d.strokeStyle = "#000000";
c2d.stroke();
}
Below is the Asteroid and Player drawing functions. The Asteroid is a polygon and the Player is a triangle. Both rotate and are draw correctly but should I be passing a reference to the drawing reference? Code: function Asteroid_draw() {
c2d.translate( this.x, this.y );
c2d.rotate(this.angle);
for (i=0;i<this.points_x.length-1;i++) {
c2d.moveTo(this.points_x[i],this.points_y[i]);
c2d.lineTo(this.points_x[i+1],this.points_y[i+1]);
}
c2d.moveTo(this.points_x[0],this.points_y[0]);
c2d.lineTo(this.points_x[this.points_x.length-1],this.points_y[this.points_x.length-1]);
}
function Player_draw() {
c2d.translate( this.x, this.y );
c2d.rotate(this.angle);
//Points {0,-12}{7,5}{-7,5}
c2d.moveTo(0,-12);
c2d.lineTo(7,5);
c2d.moveTo(7,5);
c2d.lineTo(-7,5);
c2d.moveTo(-7,5);
c2d.lineTo(0,-12);
}
Any help is appreciated. I have a Canvas controller Class and a new Sprite Controller class Please note I'm not using GIF sprites these are proper programmable sprites like you get in C game engines So i have a Class that controls my Canvas and the Drawing of my Canvas what i mean by this is if you call a new instance of my Class it will create a new Canvas if you already have a canvas you can get a JSRenderEng Object from your Canvas id Now my problem lies with getting my sprites to draw them self's currently my sprites can only appear in one place in a 100x100 px canvas they load as 98x98 1top 1left so they should be a perfect mathematical square inside the canvas with a 1px border, for some reason its not drawing But here is an explination about the classes The Canvas handles the start of the drawing events by going though the sprites attached to the canvas and then calls there draw method, However i seam to have a problem with this my draw method is being fired but is not rendering on the canvas can any one spot the problem. PHP Code: this.draw = function(){ //this.updateParams(); var context = this._canvas.getContext("2d"); context.beginPath(); context.fillRect( 98, 98, 1, 1 ); context.fillStyle = "#000000"; context.fill(); context.closePath(); } Was putting the width and height and the location in the wrong order (DURRRR) Code:
<html>
<head>
<title>test</title>
</head>
<body>
<script language = "javaScript">
var clouds = [];
var i = 0;
while(i <= 5) {
var cld = new Image();
cld.onload = function()
{
clouds.push(cld);
}
cld.src = "cloud.png";
i++;
}
document.write(clouds.length);
</script>
</body>
</html>
Where am I messing up clouds.length returns 0. Why? I know this is simple, but it will get more complex. I can search for the code, but I would like feedback as to what I'm doing wrong. This is more than likely going to be a multi stage question. More to come... ------ Also, I would like to say that this is my first post. Thanks in advance to those who reply. Is it possible to trigger mouse events with shapes drawn in an HTML5 canvas? I want to create a page with drawn elements that you can mouseover and pop up a dialogue box. I also want the shapes to react with some type of feedback. I'm hoping I can do this with javascript instead of Flash but haven't found a way to do it that's simple enough to make it worth it.
Hi. I'm writing a script that graphs data in different colors and shapes and I'm encountering two problems: (1) I can't specify different colors for the graph I'm rendering. If I use fillStyle="red"; then the entire chart becomes red. It seems to use the last color specified as the color for everything on the chart. (2) The shapes are overlapping in strange ways. The fills are not covering the lines of shapes behind them so it's unclear which shape is in front and which is behind. It's like they aren't being treated as separate shapes but instead one shape where boundaries are unclear. I don't know how else to explain it. I'm hoping there is some way to put each shape in its own layer. Would I have to use DIV IDs for that or is there a way to keep it all in the script so it's more scalable? Hello, I'm in need of some help. I have a form that I want to clone and add up to 5 duplicates with slight changes. The changes a Add a second question and another set of related radio buttons for only the duplicates. Change the title in the Header to increment by 1 ex. Header 1, Header 2... I also would like to make the form elements "id" and "names" unique. Also, continue to use the add and remove button at the bottom. I hope this is doable. Any help will be appreciated. I have included my existing code. NOTE: for a visual, I mocked up the the original form and 1 copy of the fields in the html, not to be used. Code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title></title>
<script type="text/javascript" src="http://tablesorter.com/jquery-latest.js"></script>
</head>
<body>
<script type="text/javascript">
$(document).ready(function() {
$('#btnAdd').click(function() {
var num = $('.clonedInput').length; // how many "duplicatable" input fields we currently have
var newNum = new Number(num + 1); // the numeric ID of the new input field being added
var newElem = $('#section' + num).clone().attr('id', 'section' + newNum);
newElem.children(':first').attr('id', 'first' + newNum).attr('name', 'first' + newNum).val('');
newElem.children(':first').attr('id', 'last' + newNum).attr('name', 'last' + newNum).val('');
newElem.children(':first').attr('id', 'phone' + newNum).attr('name', 'phone' + newNum).val('');
newElem.children(':first').attr('id', 'email' + newNum).attr('name', 'email' + newNum).val('');
newElem.children(':first').attr('id', 'yes' + newNum).attr('name', 'yes' + newNum).val('');
newElem.children(':first').attr('id', 'no' + newNum).attr('name', 'no' + newNum).val('');
$('#section' + num).after(newElem);
$('#btnDel').attr('disabled','');
if (newNum == 5)
$('#btnAdd').attr('disabled','disabled');
});
$('#btnDel').click(function() {
var num = $('.clonedInput').length; // how many "duplicatable" input fields we currently have
$('#section' + num).remove(); // remove the last element
$('#btnAdd').attr('disabled',''); // enable the "add" button
// if only one element remains, disable the "remove" button
if (num-1 == 1)
$('#btnDel').attr('disabled','disabled');
});
$('#btnDel').attr('disabled','disabled');
});
</script>
<form id="myForm">
<div id="section1" style="margin-bottom:4px; border-bottom:1px solid #000; width: 400px;" class="clonedInput"> <br>
<br>
<div style=" font-weight:bold; border: 1px solid #000; padding:4px;background:#CCC; font-size:18px; margin-bottom:5px;">Header</div>
First:
<input type="text" name="first1" id="first1" />
<br>
<br>
Last:
<input type="text" name="last1" id="last1" />
<br>
<br>
<br />
<div style=" font-weight:bold;padding:4px;">Header 2</div>
<div>Show this question and radios on load of page.</div>
<div>
<input type="radio" id="yes1" class="eRad" name="yes1" value="" />
<label class="" for="yes">Yes</label>
<input type="radio" id="no1" class="eRad" name="no1" value="" />
<label class="" for="no">No</label>
</div>
Phone:
<input type="text" name="phone1" id="phone1" />
<br>
<br>
Email:
<input type="text" name="email1" id="email1" />
</div>
<div id="section1" style="margin-bottom:4px; border-bottom:1px solid #000; width: 400px;" class="clonedInput"> <br>
<br>
<div style=" font-weight:bold; border: 1px solid #000; padding:4px;background:#CCC; font-size:18px; margin-bottom:5px;">Header 2 (increment this number)</div>
<div>Show this new question and radios on all copies</div>
<div>
<input type="radio" id="yes_a2" class="eRad" name="yes_a2" value="" />
<label class="" for="yes">Yes</label>
<input type="radio" id="no_a2" class="eRad" name="no_a2" value="" />
<label class="" for="no">No</label>
</div>
First:
<input type="text" name="first2" id="first2" />
<br>
<br>
Last:
<input type="text" name="last2" id="last2" />
<br>
<br>
<br />
<div style=" font-weight:bold;padding:4px;">Sub Header 2 (increment this number)</div>
<div>Show this question and radios on load of page.</div>
<div>
<input type="radio" id="yes_a2" class="eRad" name="yes_a2" value="" />
<label class="" for="yes">Yes</label>
<input type="radio" id="no_a2" class="eRad" name="no_a2" value="" />
<label class="" for="no">No</label>
</div>
Phone:
<input type="text" name="phone2" id="phone2" />
<br>
<br>
Email:
<input type="text" name="email2" id="email2" />
</div>
<div style="margin-top:10px;">
<input type="button" id="btnAdd" value="add another name" />
<input type="button" id="btnDel" value="remove name" />
</div>
</form>
</body>
</html>
-Cheers Normally I would just use document.getElementById to get anything I need but here is my problem: I have a zip code control that I load using AJAX. it has city, state, country, county and zip code. This gets loaded within a business application and at one point you can have both a bill to and ship to address forms on the screen at the same time, loading my zip control with the same fields, same ids and same name. This forced me to now pass in the form name that contains the control. I need to get to divs and spans within this form. Primarily as you type in a city or zip code, I am doing a hot search with a popup div that shows you results you can quickly choose from. The only time this becomes an issue is the situation I mentioned before when the zip code control is on the screen twice. I am not certain how to access the innerHTML of a span or div by way of the form name. Is this possible and if so what is the proper syntax? Here is a very basic example at its simplest form of my problem. Code: <form name="frm_billto" id="frm_billto"> <span id="myspan">Hello</span> </form> <form name="frm_shipto" id="frm_shipto"> <span id="myspan">World</span> </form> In the above example because the control was loaded twice, I now have 2 spans with the same ID. I want the innerHTML of the each span based on the form they are in. We wanted one control that we could use throughout the system that we could update in one place and the entire application be updated. Unfortunately we did not anticipate having it load more than once on the page. Thank you for any help hi, I am now building my website as a final project for my year. I am doing graphic design, so the website is actually some kind of portfolio. The idea of this website (which is not yet online) is this : it is some kind of big pasteboard on which i will display all the work i have done in my academy since a couple of years. The pasteboard is at the moment a background image/color field of given dimension (i figure that was the only way to do what i wanted...see further) Every works/image load on a random place and then can be dragged, and dropped (this part i already figured out). At the moment, every image (for every project), is inside a <div>. What i need help for is this: at the moment, my function successfully load 1 element at random position. I now want this function to work separately, for every <div>, so that every image is randomly placed on load, on the background image (and not the browser window, which is smaller). Here is the code i have for the moment (sorry for the mess, i really am just beginning! and truely, i don't get half of this, i just know it is working at the moment): Code: <head>
<!--// function random start position-->
<script>
var aDOM = 0, ieDOM = 0, nsDOM = 0; var stdDOM = document.getElementById; if (stdDOM) aDOM = 1; else {ieDOM = document.all; if (ieDOM) aDOM = 1; else { var nsDOM = ((navigator.appName.indexOf('Netscape') != -1) && (parseInt(navigator.appVersion) ==4)); if (nsDOM) aDOM = 1;}}
function xDOM(objectId, wS) { if (stdDOM) return wS ? document.getElementById(objectId).style: document.getElementById(objectId); if (ieDOM) return wS ? document.all[objectId].style: document.all[objectId]; if (nsDOM) return document.layers[objectId]; }
// More Object Functions
function setObjVis(objectID,vis) {var objs = xDOM(objectID,1); objs.visibility = vis;}
function moveObjTo(objectID,x,y) {var objs = xDOM(objectID,1); objs.left = x; objs.top = y;}
// Browser Window Size and Position
function pageWidth() {return window.innerWidth != null? window.innerWidth: document.body != null? document.body.clientWidth:null;}
function pageHeight() {return window.innerHeight != null? window.innerHeight: document.body != null? document.body.clientHeight:null;}
function posLeft() {return typeof window.pageXOffset != 'undefined' ? window.pageXOffset:document.documentElement.scrollLeft? document.documentElement.scrollLeft:document.body.scrollLeft? document.body.scrollLeft:0;}
function posTop() {return typeof window.pageYOffset != 'undefined' ? window.pageYOffset:document.documentElement.scrollTop? document.documentElement.scrollTop: document.body.scrollTop?document.body.scrollTop:0;}
// Random Position Script
var xxx = Math.floor(Math.random()* (pageWidth()-230));
var yyy = Math.floor(Math.random()* (pageHeight()-50));
function start()
{var x = (posLeft()+xxx) + 'px';
var y = (posTop()+yyy) + 'px';
moveObjTo('myobj',x,y);
setObjVis('myobj','visible');}
window.onload = start;
window.onscroll = start;// JavaScript Document
</script>
</head>
<body bgcolor="#9A9B95" background="../website/background.jpg">
<div id="myobj" style="position:absolute" >
<img src="oblique strategies holes.jpg" width="595" height="842" style="position:absolute" class="dragme"/>
</div>
<div id="div2">
<img src="oblique strategies choices.jpg" width="842" height="595" style="position:absolute" class="dragme" />
</div>
</body>
now, what i really want is this function to work for every <div> but i know there are also some flaws (that i'm unfortunately unable to fix myself): the integers "230 and 50" in the "random position script" should be replaced byt the width and heigh of the image/div (so i guess i should find a function that can get those numbers, name them "ImgWeidth" and "ImgHeigh" so that those integer can be called in this "random position" function. also, once the div 'myobj' is loaded, randomly, it behaves like if position=fixed (so stays on the spot when i scroll down the window). I think this is because it calculates the position according to the browser window and not my background. this has be fixed, because i don't want all my images to load only in the browser window (but on the whole pasteboard/background image). well, i guess this is already 3 questions in one. so i will let it like that for the moment. Sorry if i'm saying too much/not enough... beginners mistake!:confused: thanks in advance for any help you will give me! How would i draw a line on a page dynamically, like if i were clicking points on a map and i wanted to link them together. How could i do that? i found this, but maybe you know of something better that would not require coordinates Hi, I was wondering - how can I convert something that a user draws inside canvas? Say, they draw a square, how could I convert that to print "You have drawn a square" - this would be posted to a text file. Thanks in advance. Hi Everyone I am trying to write some code to create an object in JS that contains the x,y coords for a shape i wish to draw. I create the shape, and then in a draw function I draw the shape to the screen from the object I created erlier. Trouble it is does not seem to work :S have anyone got and ideas? Code: var myShape = new newShape(200,200);
function init() {
canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d");
return setInterval(draw, 50);
} // init
function newShape(x,y){
this.un_X=x
this.un_Y=y
function drawAll() {
ctx.beginPath();
ctx.arc(un_X,un_Y,30,0,Math.PI*2,true);
ctx.closePath();
ctx.stroke();
} // drawAll
} // newShape
function draw() {
ctx.clearRect(0, 0, WIDTH, HEIGHT);
myShape.drawAll();
} // draw
init();
Thanks in advance I've been reading a lot of tutorials on the canvas tag and seen a lot of people using JavaScript that looks something like: ctx.beginPath(); ctx.moveTo(25,25); ctx.lineTo(105,25); ctx.fill(); I understand that ctx is just the variable name and I can replace that with any variable I define, however, I'm looking for a list of all of the methods such as (moveTo, lineTo, fill etc...), as well as what they do. I hope I'm explaining this or asking this correctly. Thanks! -Mike Hey everyone, I have been practicing using canvas to make designs. My current code below will load the word the user inputs and makes it bounce around the canvas as well as a text spinner. However, whenever the user inputs a second word, the bounce below stops to start a new one and the text spinner messes up. I was wondering if anyone could help me so when the user inputs another word, that it either reloads a new textspinner or adds another one, as well as just add the word to the canvas without stopped the old one. Here's my current script. Thanks already, Joey Code:
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>
var ctx;
var a=0.0;
var as=true;//true a is increasing, false decreasing
var x,y;
var xs = 1;
var ys = 1;
var userWord
var myDiv, t;
var test = 0;
var ds ="";//display string
var sli =0; //spinning letter index;
function init(){
ctx = document.getElementById("myCvs").getContext("2d");
userWord = document.getElementById("userWord").value;
x=Math.floor(Math.random()*801)
y=Math.floor(Math.random()*601);
drawText();
setInterval("onEnterFrame()", 50);
myDiv = document.getElementById("myDiv");
for (i =0; i<=userWord.length;i++){
ds += "*";
}
myDiv.innerHTML =ds;
textSpin();
}
function textSpin(){
myChar = randomChar();
var newString = userWord.slice(0, sli);
newString +=myChar;
newString += ds.slice(sli+1, ds.length-1);
myDiv.innerHTML = newString;
if (myChar == userWord.charAt(sli)){sli++;}
if (sli<userWord.length){
t = setTimeout("textSpin()", 80);
}
}
function randomChar(){
var rc = Math.random()*26 + 97; //random lowercase char code
return String.fromCharCode(rc);
}
function onEnterFrame(){
if(a>1){as = false;}
if(a<0){as = true;}
if(as){
a+=0.01;
}else{
a-=0.01;
}
if(x>800){xs = -1}
if(x<0){xs=1}
if(y>600){ys = -1}
if(y<0){ys=1}
x+=10 *xs;
y+=10 *ys;
drawText();
}
function drawText(){
ctx.font = "20px Times New Roman";
//ctx.fillStyle= "rgb(256,256,256)";
//ctx.fillText("Hello", x, y);
ctx.fillStyle = randomColor();
ctx.fillText(userWord, x,y);
}
function randomColor(){
var r = Math.floor(Math.random()*150)+55;
var g = Math.floor(Math.random()*256)+150;
var b = Math.floor(Math.random()*20)+50;
var a = Math.random();
return "rgba("+ r+ ","+g+","+b+","+ a+")";
}
//function randomFont(){
// var s = Math.floor(Math.random()*100) +100;
// return s; //+ "px Times New Roman";}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css">
body {
background-color:#000;
}
#myDiv {
color:#FFF;
}
</style>
</head>
<body onLoad=""><center>
<input type="text" id="userWord" value=""> </input><br>
<input type="button" id="enterWord" value="Enter Word" onClick="init()" ></input><br><br>
<div id="myDiv" > </div>
<canvas id="myCvs" width="800px" height="600px" /><br>
<br>
</center>
</body>
</html>
Hi there! How should I write this - better than it's now - so that when I rotate a figure, in the next "frame" it would stay rotated? Second thing - if you run this code, and set the angle for, let's say 180 degrees the figure is being drawn in some random location. How do I fix this? Code: Code:
function GenericFigure(context) {
this.states = ["wait", "moving", "rotating", "stop"];
this.state = this.states[0];
this.ctx = context;
this.sqrW = this.sqrH = 20;
this.ctxW = 200;
this.ctxH = 350;
this.colorsO = {
red : "#ee1515",
green : "#45d137",
blue : "#17a3f3",
orange : "#ff910f",
purple : "#680077"
};
this.colorsA = ["#ee1515", "#45d137", "#17a3f3", "#ff910f", "#680077"];
this.pickColor = function() {
var num = Math.floor(Math.random() * 5);
return this.colorsA[num];
}
}
function Rectangle(context) {
this.inheritFrom = GenericFigure;
this.inheritFrom(context);
this.width = this.sqrW;
this.height = this.sqrH * 3;
this.x = this.ctxW / 2;
this.y = 0;
this.rotation = -1;
this.setRotation = function(angle) {
this.rotation = angle;
}
this.rotate = function() {
this.ctx.clearRect(0, 0, this.ctxW, this.ctxH);
this.ctx.translate(this.x + 2 * this.width, this.y - 2 * this.height + 20);
this.ctx.rotate(this.rotation * Math.PI / 180);
this.ctx.fillRect(this.ctxW / 2, 0, this.width, this.height);
this.ctx.restore();
}
this.moveDown = function() {
this.y += 20;
this.ctx.restore();
this.ctx.clearRect(0, 0, this.ctxW, this.ctxH);
this.ctx.fillRect(this.x, this.y, this.width, this.height);
this.ctx.save();
if(this.rotation > -1) {
this.rotate();
}
l("A");
}
this.draw = function() {
this.ctx.fillStyle = this.pickColor();
this.ctx.save();
this.ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
//a tak można wywołać:
var ctx = document.getElementById("game").getContext("2d");
var rect = new Rectangle(ctx);
rect.draw();
var inte = setInterval(function(){if(rect.y >= rect.ctxH - rect.height){clearInterval(inte);return;}if(rect.y == 60) rect.setRotation(90);rect.moveDown();}, 500);
And the third problem: Code: this.ctx.translate(this.x, 0); I thought, that this line should set orientation point to top left corner of my figure, but it seems, that it doesn't - after rotation my figure is being drawn two heights lower. Again - how do I fix it? Any help will be much appreciated . I just cant wrap my mind around canvas. As far as I can tell theres no logical reason as to why the code would not work. Could someone take a look at it and possibly figure out whats wrong? I'm trying to intialize and draw a canvas with a simple image. I have the functions in a custom namespace in javascript. I am also using Jquery Code: var birdr = new Image();
var birdl = new Image();
$(document).ready(function(){
if(Modernizr.canvas){
var c = document.createElement('canvas');
LK.animLoad();
document.getElementById('backg-canvas').appendChild(c);
$('canvas').attr({'width':'500','height':'500','id':'canvas'});
var context = LK.returnCanvas();
context.drawImage(birdl, 400,487,10,10);
}
});
var LK = {
birdx: 400, //unused (lets just get it to draw the image first :\)
birdy: 487, //unused
animLoad: function(){
birdl.src = "images/bird2.png";
birdr.src = "images/bird.png";
//alert(birdl);
//alert(birdr);
},
returnCanvas: function(ca){
var b_canvas = LK.getCanvas();
var b_context = b_canvas.getContext('2d');
return b_context;
},
getCanvas: function(){
var a_canvas = document.getElementById('canvas');
//alert(a_canvas);
return a_canvas;
}
}
Any help would be greatly appreciate thanks. Btw safari web inspector indicates the canvas is getting properly created and appended to the container div. So that all works fine. Anyone got any suggestions on techniques? The main one I find is to use translate to move the canvas around, which just seems odd to me. I don't even fully understand how it works. But the one I was looking at used clearRect. In examples given looked as though it had to redraw the canvas every frame. I'm just mucking around with a simple poker game, figured i'd have the table in one layer and anything that moves on a top layer? By doing that I could only clear each card as it moved around...yes? Anyone know of a better way of doing things? Hello guys! I need your help! I want to create a rectangle with a line in the middle with the canvas object. The problem is that the line in the middle gets bigger than the rest of the rectangle. How do I solve this? I believe it has something to do with shadows. If so, how do I turn them off. My code is: <html> <head> <title></title> </head> <body> <canvas id='chart' width='400' height='200'> <script type="text/javascript"> var canvas = document.getElementById('chart'); var ctx = canvas.getContext('2d'); ctx.lineWidth = 10; ctx.strokeRect(0, 0, 400, 200); ctx.moveTo(0, 100); ctx.lineTo(400, 100); ctx.stroke(); </script> </body> </html> Code: <form>
<input id="a" size=4 name="neg" placeholder="1st Screen size in inch">
<input id="b" size=4 name="hoyr" placeholder="2nd Screen size in inch">
<input type="submit" value="GO!" onclick="getValue()">
</form>
</div>
<canvas id="MyCanvas" width="1000" height="1000"></canvas>
<script type="text/javascript">
function getValue()
{
var x = document.getElementById("a").value;
var y = document.getElementById("b").value;
var aWidth;
var aHeight;
var bWidth;
var bHeight;
var c= document.getElementById("MyCanvas");
var ctx= c.getContext("2d");
ctx.fillStyle="#4AA02C";
ctx.fillRect(0,0,x,y);
}
Here, it draws canvas then disappears immediately. So I've been making a game using html canvas. Here is a link to the game. (Move around with wasd, rotate turret with left and right arrows) http://db.tt/ei3LlR The problem is that the shadow flickers when it is rotated. This does not happen in firefox. The shadow is not an image, but another canvas element, generated dynamically from the image of the tank. So the problem seems to be with webkit drawing rotated canvas elements inside another. Could this possibly be the reason behind this, or is it more likely to be a problem on my end? |
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