Contact US

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Canvas Profile Picture Edit

Canvas Profile Picture Edit

Canvas Profile Picture Edit

I built a web based canvas Profile Picture Editor. It has zooming and panning capabilities. After that I am trying to take a portion of the context and export it via toDataUrl((). There by allowing users to save the image. What I get is the same part of the picture exported to the img regardless of any zooming or panning.
Please comment. Thank you.

$(document).ready( function() {
var myEditCanvas = document.getElementById("myEditCanvas");
var context = myEditCanvas.getContext("2d");
var scale = 2;
var originx = 0;
var originy = 0;
var imageObj = new Image();
imageObj.src = document.getElementById("photoId").src;

var mouse={x:0,y:0}; //make an object to hold mouse position
var isDown = false;
var startCoords = [];
var last = [0, 0];

function draw(){
// From: http://goo.gl/jypct
// Store the current transformation matrix


// Use the identity matrix while clearing the canvas
context.setTransform(1, 0, 0, 1, 0, 0);
context.clearRect(0, 0, myEditCanvas.width, myEditCanvas.height);

// Restore the transform

// Draw on transformed context
context.drawImage(imageObj, mouse.x, mouse.y, 300, 300);

var mousewheelevt=(/Firefox/i.test(navigator.userAgent))? "DOMMouseScroll" : "mousewheel" //FF doesn't recognize mousewheel as of FF3.x

if (myEditCanvas.attachEvent) //if IE (and Opera depending on user setting)

myEditCanvas.attachEvent("on"+mousewheelevt, scrollOnYou)

else if (myEditCanvas.addEventListener) //WC3 browsers

myEditCanvas.addEventListener(mousewheelevt, scrollOnYou, false)

function scrollOnYou(event){

var mousex = event.clientX - myEditCanvas.offsetLeft;
var mousey = event.clientY - myEditCanvas.offsetTop;
var wheel = event.detail? event.detail / 120 : event.wheelDelta

//according to Chris comment
var zoom = Math.pow(1 + Math.abs(wheel)/2 , wheel > 0 ? 1 : -1);

-( mousex / scale + originx - mousex / ( scale * zoom ) ),
-( mousey / scale + originy - mousey / ( scale * zoom ) )

originx = ( mousex / scale + originx - mousex / ( scale * zoom ) );
originy = ( mousey / scale + originy - mousey / ( scale * zoom ) );
scale *= zoom;

isDown = true;

if(isDown == true){
mouse={x:e.pageX-this.offsetLeft - (myEditCanvas.width / 2) , y:e.pageY-this.offsetTop - (myEditCanvas.height / 2)};

isDown = false;
//alert("mouse up");

function getResults() {

var temp_ctx, temp_canvas;
temp_canvas = document.createElement('canvas');
temp_ctx = temp_canvas.getContext('2d');
temp_ctx.drawImage(imageObj, 200, 200, 300, 300, 0, 0, 100, 100);
var vData = temp_canvas.toDataURL();
document.getElementById("saveimg").src = vData;
} );

<div id="map">
<canvas id="myEditCanvas" width="300" height="300"></canvas>
<div style="display:none">
<img src="" id="photoId"></img > <!-- sorry cant give out path info security reasons -->
<img src="" id="saveimg"></img>

RE: Canvas Profile Picture Edit

I would suggest forum216: Javascript


Indifference will be the downfall of mankind, but who cares?
Time flies like an arrow, however, fruit flies like a banana.
Webmaster Forum

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close