I am trying to make a racing game using canvas, and a png file with transparent background for the car.
I have a problem when I hold down on one of the arrows. In the opposite way of the movement it appears like a white shadow the old position of the car.
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
var canvas;
var ctx;
var car = new Image();
var x = 0;
var y = 0;
function startUp(){
canvas = document.getElementById('myCanvas');
ctx = canvas.getContext('2d');
loadImages();
startGameLoop();
}
function startGameLoop() {
setInterval(function() {
drawScreen();
drawCar();
}, 16);
window.addEventListener('keydown', whatKey, true);
}
function drawScreen(){
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = '#aaaaaa';
ctx.rect(0, 0, canvas.width, canvas.height);
ctx.fill();
}
function drawCar(){
ctx.drawImage(car, x ,y, 200, 103);
}
function whatKey(evt) {
switch (evt.keyCode) {
// Left arrow.
case 37: {
x -= 15;
}
break;
// Right arrow.
case 39:{
x += 15;
}
break;
// Down arrow
case 40:{
y += 15;
}
break;
// Up arrow
case 38: {
y -= 15;
}
break;
}
}
function loadImages() {
car.src = 'http://sammywasem.com/images/f3-top.png';
}
</script>
</head>
<body onload="startUp()">
<canvas id="myCanvas" width="1050" height="620">
</canvas>
</body>
</html>
The car move is in fact the right way.
Say you press the right key : the event is sent to the window, and trapped by your code : the car goes right. But the event is also handled by the whole window, where it is understood as : move the window to the right.
So what you see in the end, since the window move more than the car, is a move to the left of the car.
What you need to do is to prevent the key event from bubbling further once you handled it : it is done with
event.preventDefault();
and
event.stopPropagation();
look mdn to see the specifications of preventDefault or stopPropagation .
i've done a fiddle out of your code, and updated it :
http://jsbin.com/joboxuvu/1/edit?js,output
Related
i got this code looking around this forum but, I'm not being able to make it work on mobile devices with touchscreen. Problem is I need it to work as simple as this, not calling any library, because it's not for an app but for a simple Wordpress that's using an html widget. Is this even posible?
Thank you all!
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="400" height="200" style="background: #ffffff; margin-left: 0px;">Your browser does not support the HTML5 canvas tag.</canvas>
<script>
const c = document.getElementById("myCanvas");
// c.addEventListener("click", penTool); // fires after mouse left btn is released
c.addEventListener("mousedown", setLastCoords); // fires before mouse left btn is released
c.addEventListener("mousemove", freeForm);
const ctx = c.getContext("2d");
function setLastCoords(e) {
const {x, y} = c.getBoundingClientRect();
lastX = e.clientX - x;
lastY = e.clientY - y;
}
function freeForm(e) {
if (e.buttons !== 1) return; // left button is not pushed yet
penTool(e);
}
function penTool(e) {
const {x, y} = c.getBoundingClientRect();
const newX = e.clientX - x;
const newY = e.clientY - y;
ctx.beginPath();
ctx.lineWidth = 5;
ctx.moveTo(lastX, lastY);
ctx.lineTo(newX, newY);
ctx.strokeStyle = 'black';
ctx.stroke();
ctx.closePath();
lastX = newX;
lastY = newY;
}
let lastX = 0;
let lastY = 0;
</script>
</body>
</html>
Came up with this for mobile version only, still not working :(
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="400" height="200" style="background: #ffffff; margin-left: 0px;">Your browser does not support the HTML5 canvas tag.</canvas>
<script>
const c = document.getElementById("myCanvas");
// c.addEventListener("click", penTool); // fires after mouse left btn is released
c.addEventListener("touchstart", setLastCoords); // fires before mouse left btn is released
c.addEventListener("touchmove", freeForm);
const ctx = c.getContext("2d");
function setLastCoords(e) {
const {x, y} = c.getBoundingClientRect();
lastX = e.touches[0].clientX - x;
lastY = e.touches[0].clientY - y;
}
function freeForm(e) {
if (e.touches !== 1) return; // left button is not pushed yet
penTool(e);
}
function penTool(e) {
const {x, y} = c.getBoundingClientRect();
const newX = e.touches[0].clientX;
const newY = e.touches[0].clientY;
ctx.beginPath();
ctx.lineWidth = 5;
ctx.moveTo(lastX, lastY);
ctx.lineTo(newX, newY);
ctx.strokeStyle = 'black';
ctx.stroke();
ctx.closePath();
lastX = newX;
lastY = newY;
}
let lastX = 0;
let lastY = 0;
</script>
</body>
</html>
I also tried this script (credits to Zipso, great article on that)
<head>
<title>Sketchpad</title>
<script type="text/javascript">
// Variables for referencing the canvas and 2dcanvas context
var canvas,ctx;
// Variables to keep track of the mouse position and left-button status
var mouseX,mouseY,mouseDown=0;
// Variables to keep track of the touch position
var touchX,touchY;
// Keep track of the old/last position when drawing a line
// We set it to -1 at the start to indicate that we don't have a good value for it yet
var lastX,lastY=-1;
// Draws a line between the specified position on the supplied canvas name
// Parameters are: A canvas context, the x position, the y position, the size of the dot
function drawLine(ctx,x,y,size) {
// If lastX is not set, set lastX and lastY to the current position
if (lastX==-1) {
lastX=x;
lastY=y;
}
// Let's use black by setting RGB values to 0, and 255 alpha (completely opaque)
r=0; g=0; b=0; a=255;
// Select a fill style
ctx.strokeStyle = "rgba("+r+","+g+","+b+","+(a/255)+")";
// Set the line "cap" style to round, so lines at different angles can join into each other
ctx.lineCap = "round";
//ctx.lineJoin = "round";
// Draw a filled line
ctx.beginPath();
// First, move to the old (previous) position
ctx.moveTo(lastX,lastY);
// Now draw a line to the current touch/pointer position
ctx.lineTo(x,y);
// Set the line thickness and draw the line
ctx.lineWidth = size;
ctx.stroke();
ctx.closePath();
// Update the last position to reference the current position
lastX=x;
lastY=y;
}
// Clear the canvas context using the canvas width and height
function clearCanvas(canvas,ctx) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
// Keep track of the mouse button being pressed and draw a dot at current location
function sketchpad_mouseDown() {
mouseDown=1;
drawLine(ctx,mouseX,mouseY,12);
}
// Keep track of the mouse button being released
function sketchpad_mouseUp() {
mouseDown=0;
// Reset lastX and lastY to -1 to indicate that they are now invalid, since we have lifted the "pen"
lastX=-1;
lastY=-1;
}
// Keep track of the mouse position and draw a dot if mouse button is currently pressed
function sketchpad_mouseMove(e) {
// Update the mouse co-ordinates when moved
getMousePos(e);
// Draw a dot if the mouse button is currently being pressed
if (mouseDown==1) {
drawLine(ctx,mouseX,mouseY,12);
}
}
// Get the current mouse position relative to the top-left of the canvas
function getMousePos(e) {
if (!e)
var e = event;
if (e.offsetX) {
mouseX = e.offsetX;
mouseY = e.offsetY;
}
else if (e.layerX) {
mouseX = e.layerX;
mouseY = e.layerY;
}
}
// Draw something when a touch start is detected
function sketchpad_touchStart() {
// Update the touch co-ordinates
getTouchPos();
drawLine(ctx,touchX,touchY,12);
// Prevents an additional mousedown event being triggered
event.preventDefault();
}
function sketchpad_touchEnd() {
// Reset lastX and lastY to -1 to indicate that they are now invalid, since we have lifted the "pen"
lastX=-1;
lastY=-1;
}
// Draw something and prevent the default scrolling when touch movement is detected
function sketchpad_touchMove(e) {
// Update the touch co-ordinates
getTouchPos(e);
// During a touchmove event, unlike a mousemove event, we don't need to check if the touch is engaged, since there will always be contact with the screen by definition.
drawLine(ctx,touchX,touchY,12);
// Prevent a scrolling action as a result of this touchmove triggering.
event.preventDefault();
}
// Get the touch position relative to the top-left of the canvas
// When we get the raw values of pageX and pageY below, they take into account the scrolling on the page
// but not the position relative to our target div. We'll adjust them using "target.offsetLeft" and
// "target.offsetTop" to get the correct values in relation to the top left of the canvas.
function getTouchPos(e) {
if (!e)
var e = event;
if(e.touches) {
if (e.touches.length == 1) { // Only deal with one finger
var touch = e.touches[0]; // Get the information for finger #1
touchX=touch.pageX-touch.target.offsetLeft;
touchY=touch.pageY-touch.target.offsetTop;
}
}
}
// Set-up the canvas and add our event handlers after the page has loaded
function init() {
// Get the specific canvas element from the HTML document
canvas = document.getElementById('sketchpad');
// If the browser supports the canvas tag, get the 2d drawing context for this canvas
if (canvas.getContext)
ctx = canvas.getContext('2d');
// Check that we have a valid context to draw on/with before adding event handlers
if (ctx) {
// React to mouse events on the canvas, and mouseup on the entire document
canvas.addEventListener('mousedown', sketchpad_mouseDown, false);
canvas.addEventListener('mousemove', sketchpad_mouseMove, false);
window.addEventListener('mouseup', sketchpad_mouseUp, false);
// React to touch events on the canvas
canvas.addEventListener('touchstart', sketchpad_touchStart, false);
canvas.addEventListener('touchend', sketchpad_touchEnd, false);
canvas.addEventListener('touchmove', sketchpad_touchMove, false);
}
}
</script>
<style>
/* Some CSS styling */
#sketchpadapp {
/* Prevent nearby text being highlighted when accidentally dragging mouse outside confines of the canvas */
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
.leftside {
float:left;
width:220px;
height:285px;
background-color:#def;
padding:10px;
border-radius:4px;
}
.rightside {
float:left;
margin-left:10px;
}
#sketchpad {
float:left;
height:300px;
width:400px;
border:2px solid #888;
border-radius:4px;
position:relative; /* Necessary for correct mouse co-ords in Firefox */
}
#clearbutton {
font-size: 15px;
padding: 10px;
-webkit-appearance: none;
background: #eee;
border: 1px solid #888;
}
</style>
</head>
<body onload="init()">
<div id="sketchpadapp">
<div class="leftside">
Touchscreen and mouse support HTML5 canvas sketchpad.<br/><br/>
Draw something by tapping or dragging.<br/><br/>
Works on iOS, Android and desktop/laptop touchscreens using Chrome/Firefox/Safari.<br/><br/>
<input type="submit" value="Clear Sketchpad" id="clearbutton" onclick="clearCanvas(canvas,ctx);">
</div>
<div class="rightside">
<canvas id="sketchpad" height="300" width="400">
</canvas>
</div>
</div>
</body>
</html>
But I can't manage to make it work on my mobile, as it only draws the first dot when touching!
I am a very beginner web designer and I have two questions about this code.
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
#canvas1{border: #666 3px solid;}
</style>
<script type="application/javascript" language="javascript">
function draw (x,y){
var canvas = document.getElementById('canvas1');
var ctx = canvas.getContext('2d');
ctx.save();
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillstyle = "rgb (0,200, 0)";
ctx.fillRect(x, 20, 50, 50);
ctx.restore();
x += 5;
var loop = setTimeout('draw('+x+', '+y+')', 100);
}
</script>
</head>
<body>
<button onclick="draw(0,0)">Start</button>
<canvas id="canvas1" width="400" height="400"</canvas>
</body>
</html>
Why does the block always turn out black? and Why if I try to press start again, the clearRect function doesn’t work?
When you click start you are starting a new loop that runs parallel to the one already started and depending on which one executes first your canvas would be cleared and filled twice (or as many times you started the loop - the more the more pronounced the flicker will be).
You need a mechanism to prevent the loop from starting several times. One way is to use a flag. I would also suggest you refactor the code a bit separating the loop and the drawing:
Live demo here
/// put these outside, no need to re-allocate them each time
var canvas = document.getElementById('canvas1');
var ctx = canvas.getContext('2d');
var w = canvas.width;
var h = canvas.height;
var x = 0;
var isRunning = false;
/// all loop-related here:
function loop() {
/// call draw from inside the loop instead
draw(x, 0); /// you are never using y so I just set 0 here...
x += 5;
if (isRunning && x <= w) {
requestAnimationFrame(loop); /// this is a better alternative
//setTimeout(loop, 100); /// optionally, but not recommended
} else {
isRunning = false; /// box is outside visible area so we'll stop..
}
}
/// keep draw() "clean", no loop code in here:
function draw(x, y) {
/// no need for save/restore here...
ctx.clearRect(0, 0, w, h);
ctx.fillStyle = "rgb(0, 200, 0)";
ctx.fillRect(x, 20, 50, 50);
}
Your fillStyle was typed wrong, your rgb(... must be without space (as mentioned in the other answer - but it would only result in the fill style being black in this case), in addition you're missing a closing bracket for your canvas tag in the html.
To check for button clicks this is a more recommended way instead of inlining the JS in the html:
/// check for button clicks (start):
document.getElementById('start').addEventListener('click', function() {
if (!isRunning) { /// are we running? if not start loop
isRunning = true; /// set flag so we can prevent multiple clicks
x = 0; /// reset x
loop(); /// now we start the *loop*
}
}, false);
And in your html:
<button id="start">Start</button>
Now you can easily make a pause button:
<button id="stop">Stop</button>
and add this to the script:
document.getElementById('stop').addEventListener('click', function() {
isRunning = false;
}, false);
Because you need to use:
ctx.fillStyle = "rgb(0,200,0)";
with a capital 'S' and no space between 'rgb' and the opening bracket: http://jsfiddle.net/dtHjf/
Then, in terms of why pressing 'Start' multiple times causes the square to flicker, that's because each time you press it you're starting another animation loop, but without cancelling the old one, so that you've got multiple loops fighting with each other. If you make sure to cancel any pre-existing loop before you start a new one, you should be fine:
http://jsfiddle.net/dtHjf/2/
HTML:
<button id="startAnim">Start</button><br />
<canvas id="canvas1" width="400" height="400"></canvas>
JS:
var canvas = document.getElementById('canvas1'),
ctx = canvas.getContext('2d'),
loop;
function draw(x, y) {
ctx.save();
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "rgb(0,200,0)";
ctx.fillRect(x, 20, 50, 50);
ctx.restore();
x += 5;
loop = setTimeout(function(){draw(x,y)}, 100);
}
document.getElementById('startAnim').onclick = function(){
clearTimeout(loop);
draw(0,0);
};
Also, this is unrelated to your problem, but you might want to take a look at requestAnimationFrame:
https://developer.mozilla.org/en-US/docs/Web/API/window.requestAnimationFrame
http://www.paulirish.com/2011/requestanimationframe-for-smart-animating/
<script>
function hum() {
var width = 280,
height = 210,
frames = 3,
currentFrame = 0,
hump = document.getElementById("Canvas2").getContext('2d');
humpImage = new Image()
humpImage.src = 'images/hum.png';
var draw = function () {
hump.clearRect(0, 0, width, height);
hump.drawImage(humpImage, 0, height * currentFrame, width, height, 0, 0, width, height);
if (currentFrame == frames) {
currentFrame = 0;
} else {
currentFrame++;
}
}
setInterval(draw, 150);
}
</script>
The above is a canvas animation javascript code . Here it loops automatically.. I want to make to cancel the loop and to play the canvas only on click how to do it.
Please spot light on this
Saravan, theres a number of different ways you could go about this. Best practise, I believe is to use the RequestAnimationFrame function, though I don't seem to find any old source code here in which I've used it.
I notice in your code, each time around the draw-loop, you call setInterval. Unless I'm mistaken, the correct function to use there is actually setTimeOut. As you can see from my code, (and js help) the function setInterval only needs to be called once.
When you call it, it gives you a unique identifier which can be used later to remove the interval handler. That's the method I've used. When the button is clicked, the interval is set and it's handle saved. Then, when the canvas is clicked, I simply remove the interval handler.
It's late and I'm tired. This should give you plenty to go on.
EDIT: new code.
<!DOCTYPE html>
<html>
<head>
<script>
function byId(e){return document.getElementById(e);}
function newEl(tag){return document.createElement(tag);}
window.addEventListener('load', mInit, false);
var drawIntervalHandle;
var hump, humpImage, isRunning = false;
var width = 44,height = 128,frames = 3,currentFrame = 0;
var myImageSource = 'thermometer.png';
function mInit()
{
byId('Canvas2').addEventListener('click', onCanvasClick, false);
initAndStartAnim();
}
function onCanvasClick()
{
if (isRunning)
{
clearInterval(drawIntervalHandle);
isRunning = false;
byId('status').innerHTML = "Stopped, frame: " + currentFrame;
}
else
{
drawIntervalHandle = setInterval(draw, 150);
isRunning = true;
}
}
function draw()
{
hump.clearRect(0, 0, width, height);
hump.drawImage(humpImage, 0, height * currentFrame, width, height, 0, 0, width, height);
if (currentFrame == frames)
currentFrame = 0;
else
currentFrame++;
byId('status').innerHTML = "Running, frame: " + currentFrame;
}
function initAndStartAnim()
{
var can = document.getElementById("Canvas2");
can.width = width;
can.height = height;
hump = can.getContext('2d');
humpImage = new Image()
humpImage.src = myImageSource;
drawIntervalHandle = setInterval(draw, 150);
isRunning = true;
}
</script>
<style>
</style>
</head>
<body>
<canvas id='Canvas2'>Canvas not supported if you see this. :(</canvas>
<br>
<div id='status'></div>
</body>
</html>
Basically, a user uploads a picture and then can paint on it, and save the result. Another user can then view the photo and if they click in the same area as painted, something happens.
So user 1 can make an area click-able for user 2 by drawing on the photo.
now the upload bit is fine, and painting with help from a tutorial and example I've got sussed out. But defining what area is click-able is a bit harder. For something like a rectangle its easy enough, I made an example.
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var button = new Object();
button.x = 50;
button.y = 50;
button.width = 50;
button.height = 50;
button.rgb = "rgb(0, 0, 255)";
function drawbutton(buttonobject)
{
context.fillStyle = buttonobject.rgb;
context.fillRect (buttonobject.x, buttonobject.y, buttonobject.width, buttonobject.height);
context.strokeRect(buttonobject.x, buttonobject.y, buttonobject.width, buttonobject.height);
}
drawbutton(button);
function checkIfInsideButtonCoordinates(buttonObj, mouseX, mouseY)
{
if(((mouseX > buttonObj.x) && (mouseX < (buttonObj.x + buttonObj.width))) && ((mouseY > buttonObj.y) && (mouseY < (buttonObj.y + buttonObj.height))))
return true;
else
return false;
}
$("#myCanvas").click(function(eventObject) {
mouseX = eventObject.pageX - this.offsetLeft;
mouseY = eventObject.pageY - this.offsetTop;
if(checkIfInsideButtonCoordinates(button, mouseX, mouseY))
{
button.rgb = "rgb(0, 255, 0)";
drawbutton(button);
} else {
button.rgb = "rgb(255, 0, 0)";
drawbutton(button);
}
});
but when it comes to other shapes like circles, or just someone smothering the page, how would you go about detecting that ?
one thought I had was using the edited layer, making it hidden, and detecting a pixel color of say blue, from here but that limits the color use of the photo and im not entirely sure how to implement it. any other ideas ?
EDIT:
I figured out circles after some tinkering, using Pythagoras theorem to see if mouse coordinates are smaller than the radius, but this assumes circle center of 0,0, so then offset mouse by circles actual center. example
function checkIfInsideButtonCoordinates(buttonObj, mouseX, mouseY) {
actualX = mouseX - buttonObj.x
actualY = mouseY - buttonObj.y
mousesqX = actualX * actualX
mousesqY = actualY * actualY
sqR = buttonObj.r * buttonObj.r
sqC = mousesqX + mousesqY
if (sqC < sqR) return true;
else return false;
}
Here’s how to test whether user#2 is inside user#1’s paintings
Create a second canvas used to hit-test whether user#2 is inside of user#1’s paintings.
The hit-test canvas is the same size as the drawing canvas, but it only contains user#1’s paintings…not the image.
When user#1 is painting, also draw their paintings on the hit canvas.
When user#1 is done painting, save all their paintings from the hit canvas.
You have at least 2 ways to save user#1’s paintings from the hit canvas:
Serialize all the canvas commands needed to recreate the shapes/paths that user#1 paints.
Save the hit canvas as an image using canvas.toDataURL.
When user#2 clicks, check if the corresponding pixel on the hit canvas is filled or is transparent (alpha>0).
// getImageData for the hit-test canvas (this canvas just contains user#1's paintings)
imageDataData=hitCtx.getImageData(0,0,hit.width,hit.height).data;
// look at the pixel under user#2's mouse
// return true if that pixel is filled (not transparent)
function isHit(x,y){
var pixPos=(x+y*hitWidth)*4+3;
return( imageDataData[pixPos]>10)
}
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/etA5a/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; padding:15px; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var hit=document.getElementById("hit");
var hitCtx=hit.getContext("2d");
var user2=document.getElementById("user2");
var ctx2=user2.getContext("2d");
var canvasOffset=$("#user2").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var imageDataData;
var hitWidth=hit.width;
var img=document.createElement("img");
img.onload=function(){
// left canvas: image+user#1 paintings
ctx.globalAlpha=.25;
ctx.drawImage(img,0,0);
ctx.globalAlpha=1.00;
scribble(ctx,"black");
// mid canvas: just user#1 paintings (used for hittests)
scribble(hitCtx,"black");
// right canvas: user#2
ctx2.drawImage(img,0,0);
imageDataData=hitCtx.getImageData(0,0,hit.width,hit.height).data;
}
img.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/colorhouse.png";
function scribble(context,color){
context.beginPath();
context.moveTo(70,2);
context.lineTo(139,41);
context.lineTo(70,41);
context.closePath();
context.rect(39,54,22,30);
context.arc(73,115,3,0,Math.PI*2,false);
context.fillStyle=color;
context.fill();
}
function handleMouseMove(e){
var mouseX=parseInt(e.clientX-offsetX);
var mouseY=parseInt(e.clientY-offsetY);
// If user#2 has a hit on user#1's painting, mid-canvas turns red
var color="black";
if(isHit(mouseX,mouseY)){ color="red"; }
scribble(hitCtx,color);
}
function isHit(x,y){
var pixPos=(x+y*hitWidth)*4+3;
return( imageDataData[pixPos]>10)
}
$("#user2").mousemove(function(e){handleMouseMove(e);});
}); // end $(function(){});
</script>
</head>
<body>
<p>Left: original image with user#1 painting</p>
<p>Mid: user#1 painting only (used for hit-testing)</p>
<p>Right: user#2 (move mouse over hit areas)</p>
<canvas id="canvas" width=140 height=140></canvas>
<canvas id="hit" width=140 height=140></canvas>
<canvas id="user2" width=140 height=140></canvas><br>
</body>
</html>
I have tried many different ways of trying to get mouse coordinates in HTML5 canvas in compliment with video and none have seemed too work very well in either Chrome or Safari.
At the moment I am using:
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Test</title>
<script src="modernizr-1.6.min.js"></script>
<script type="text/javascript">
window.addEventListener('load', eventWindowLoaded,false);
var videoElement;
var VideoDiv;
var Object1;
var Mouse = {
x:0
x:y}
function eventWindowLoaded(){
videoElement = document.createElement("video");
videoDiv = document.createElement('div');
document.body.appendChild(videoDiv);
videoDiv.appendChild(videoElement);
videoDiv.setAttribute("style", "display:none;");
var videoType = supportedVideoFormat(videoElement);
if (videoType == ""){
alert("no video support");
return;
}
videoElement.setAttribute("src", "different_movement>" + videoType);
videoElement.addEventListener("canplaythrough", videoLoaded, false);
}
function supportedVideoFormat(video){
var returnExtension= "";
if(video.canPlayType("video/webm") =="probably" || video.canPlayType("video/webm") == "maybe"){
returnExtension = "webm";
} else if (video.canPlayType("video/mp4") == "probably" || video.canPlayType("video/mp4") == "maybe"){
returnExtension = "mp4";
}else if(video.canPlayType("video/ogg") == "probably" || video.canPlayType("video/ogg") == "maybe"){
returnExtension = "ogv";
}
return returnExtension;
}
function videoLoaded(event){
canvasApp();
}
canvasOne.onmousemove = function (event){
Mouse={
x: event.offsetX,
y: event.offsetY}
}
}
function canvasApp(){
function drawScreen(){
context.drawImage(videoElement, 0, 0);
context.fillStyle = '#ffffff';
context.fillText(Mouse.x, 280, 280);
context.fillText(Mouse.y, 280, 300);
}
var theCanvas = document.getElementByID('canvasOne');
var context = theCanvas.getContext('2d');
videoElement.play();
setinterval(drawScreen, 33);
}
</script>
</head>
<body>
<canvas id="canvasOne" width="640" height="480">
Your browser does not support HTML5 Canvas.
</canvas>
</div>
</body>
</html>
The result of this is the 0,0 will be shown on the video from the initial variable set at 0,0 but then instead of changing as the mouse is moved around the screen, it stays 0,0. This leads me to believe that it is the part of the code that is finding the mouse coordinates that is not working.
I have tried various other attempts at finding mouse coordinates including:
Mouse={
x: event.pageX,
y: event.pageX}
,
if (e.pageY) {
posy = e.pageY;
} else if (e.clientY) {
posy = e.clientY + document.body.scrollTop
+ document.documentElement.scrollTop;
}
,
var mouseX;
var mouseY;
var pieceX;
var pieceY;
if (e.pageX || e.pageY) {
mouseX = e.pageX;
mouseX = e.pageY;
} else {
mouseX = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
mouseY = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
}
My end product is supposed to be a video that has mouse interactions that will play sounds when certain parts on the video are clicked (thus the part of video). I have tried not using canvas at all for this, and instead positioning a image on top of the canvas which has image mapping on it, but it doesn't seem to work.
Another issue I am going to run into when I figure out mouse coordinates is what I will test collisions with the mouse coordinates to initiate it to play the sounds.
EDIT:
Completely rewrote the code using e.offset, seems to work.
I used <iframe> to set an html page with a canvas element positioned top left of document. Then when I get clientX-Y it's origin is the top left of the canvas document, that's in the iframe, that you can have positioned anywhere on the canvas-containing document. It's easy as pie.
<iframe scrolling="no" height="100%" width="100%" src="canvas.html"></iframe>
also, I got the canvas to scale when it is scaled by style sheet. I added this to my canvas program.
c = canvas element, ctx = canvas context;
ctx.scale(c.width/630,c.height/800); // I originally intended it to be 630x800
(note: I am not sure if this answers your problem, but it is how I find coordinates without having to offset.)