I'm working on a user account system for my website. I want users to be able to upload a custom profile picture. Currently, it displays a preview of the uploaded image. But it only works every other time. I can't seem to fix it.
Here is my code:
<img id="pfp-img" src="<?php echo (empty($row["pfp"]) ? "https://www.media.yoo-babobo.com/images/user.png" : $row["pfp"]); ?>" alt="Your profile picture" onclick="$('#pfp').trigger('click');" style="width: 150px; height: auto; border-radius: 100%; cursor: pointer;" />
<input type="file" id="pfp" name="pfp" placeholder="Profile Picture" capture="user" accept="image/*" style="display: none;" />
And here is the javascript:
$("#pfp").on("input change", e => {
var canvas = $('<canvas width="150" height="150" style="display: none;">');
$("body").append(canvas);
var ctx = document.querySelector("canvas").getContext("2d");
var img = new Image();
img.onload = function() {
ctx.drawImage(img, 0, 0, 150, 150);
}
img.src = window.URL.createObjectURL(e.target.files[0] || "<DEFAULT PROFILE PICTURE>");
var data_uri = document.querySelector("canvas").toDataURL("image/png");
document.getElementById("pfp-img").src = data_uri;
canvas.remove();
})
Is there anything I'm doing wrong? And are there any better ways to do this?
Related
I am creating a program where the user will upload an image and the program will display a div above the canvas and solved this problem already. But my problem is when I am trying to save/download the image, it will only save the canvas.
<div id="memePlaceHolder" style="height: 700px; width:700px;background:#BBB;">
<canvas id="c" width="0" height="0">
</canvas>
<div id="myTestDiv" name="myTestDiv">
<h1>#Test Hashtag</h1>
<br/>
<h2>My Test Display</h2>
</div>
</div>
I used this code to save/download the canvas.
e.downloadLink.href = e.c.toDataURL();
Is there a method to save the image together with the div displayed above it?
You can achieve that using a JavaScript library called html2canvas.
ᴅᴇᴍᴏ
let wrapper = document.querySelector('#wrapper');
let title = document.querySelector('#title');
let canvas = document.querySelector('#canvas');
let ctx = canvas.getContext('2d');
let img = new Image();
img.onload = function () {
ctx.drawImage(this, 0, 0, 150, 150);
}
img.crossOrigin = 'anonymous';
img.src = 'https://i.imgur.com/Q6aZlme.jpg';
function save() {
html2canvas(wrapper, {
onrendered: function (canvas) {
let a = document.createElement('a');
a.href = canvas.toDataURL();
a.download = 'myImage.png';
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}
});
}
#title {font: 16px Verdana;color: #07C}#canvas {border: 1px solid #ccc}
<script src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/0.4.1/html2canvas.min.js"></script>
<div id="wrapper">
<div id="title">DreiDreiDrei</div>
<canvas id="canvas" width="150" height="150"></canvas>
</div>
<button onclick="save()">Save as Image</button>
To learn more about the library, refer to the official documentation.
No, you can't save the div with the canvas element,
I'm making a page where I want people to be able to overlapp images and then upload them to my server.
I've built the uploading page and I've put two test images in a canvas. The only issue noe is to be able to hide / show these two images through a button or checkbox.
I've uploaded a test page here: http://kaosmos.no/bokbodentest2/upload.html
This is my code for the canvas:
<input type="checkbox"/>Check to hide img1
<input type="checkbox"/>Check to hide img2
<img class="bilder" id="img1" src="test1.png">
<img class="bilder" id="img2" src="test2.png">
<canvas id="canvas"></canvas>
<script type="text/javascript">
var img1 = document.getElementById('img1');
var img2 = document.getElementById('img2');
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
canvas.width = img1.width;
canvas.height = img1.height;
context.globalAlpha = 1.0;
context.drawImage(img1, 0, 0);
context.globalAlpha = 0.5; //Remove if pngs have alpha
context.drawImage(img2, 0, 0);
</script>
And CSS:
canvas {
border: solid;
overflow: hidden;
}
canvas img {
width: 600px;
position: absolute;
mix-blend-mode: multiply;
}
.bilder {
display: none;
}
The display: none; in the "bilder" class is so that the images won't be visable outside the canvas. How do I make a function to hide / show these images?
Any help is much appreciated!
Since when an image is drawn to the canvas, it is no longer linked to the original element in the DOM, you want to hide it on the canvas, so you'll need to redraw the canvas each time an input is changed, not calling the relevant context.drawImage function. Something along these lines:
<input type="checkbox" onchange="draw()"/>Check to hide img1
<input type="checkbox" onchange="draw()"/>Check to hide img2
<img class="bilder" id="img1" src="test1.png">
<img class="bilder" id="img2" src="test2.png">
<canvas id="canvas"></canvas>
<script type="text/javascript">
var img1 = document.getElementById('img1');
var img2 = document.getElementById('img2');
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var inputs = document.querySelectorAll('input[type="checkbox"]');
canvas.width = img1.width;
canvas.height = img1.height;
function draw(){
context.clearRect(0, 0, canvas.width, canvas.height);
context.globalAlpha = 1.0;
if(inputs[0].checked){
context.drawImage(img1, 0, 0);
}
context.globalAlpha = 0.5; //Remove if pngs have alpha
if(inputs[1].checked){
context.drawImage(img2, 0, 0);
}
}
</script>
I have the following code:
<link rel="stylesheet" href="style.css">
<script src="/static/js/jquery/2.1.4/jquery.min.js"></script>
<script src="http://fengyuanchen.github.io/cropper/js/cropper.min.js"></script>
<form action="" method="post" enctype="multipart/form-data">
<img id="crop" style="width:400px;height:200px;" />
<div id="img2" style="position: relative; overflow: hidden; border: 1px solid #000; background: #fff; width: 100px; height: 100px;"></div>
X: <input type="text" id="crop_x" name="crop_x" /><br />
Y: <input type="text" id="crop_y" name="crop_y" /><br />
Width: <input type="text" id="crop_width" name="crop_width" /><br />
Height: <input type="text" id="crop_height" name="crop_height" /><br />
<input type="file" id="file" name="file" />
<input type="submit" id="submit" name="submit" value="Submit" />
</form>
<script>
var url = null;
$('#file').on('change',function(){
var file = this.files[0];
if(url != null){
URL.revokeObjectURL(url);
}
url = URL.createObjectURL(file);
startCropper();
});
function startCropper(){
$('#crop').removeAttr('src');
$('#crop').attr('src',url);
$('#crop').cropper({
viewMode : 0,
cropBoxResizable : false,
minCropBoxWidth : 100,
minCropBoxHeight : 100,
dragMode : 'none',
preview : $('#img2'),
aspectRatio: 1,
crop : function(e){
$('#crop_x').val(e.x);
$('#crop_y').val(e.y);
}
});
};
</script>
The problem is that when I select a new file, the new image is not showed (the old image is still displayed in the cropper).
As you can see, I check the old url and revoke this. When I don't use $("#crop").cropper({...}) in the startCropper() function, it works.
GitHub: https://github.com/fengyuanchen/cropper/tree/v2.3.0
How can I force the cropper to load the new image?
You need to call
$('#crop').cropper('destroy');
before crop initialization
This code will solve the problem of Image not changing in Cropper.
HTML
<input id="userImage" type="file" name="userImage" accept="image/*">
<div>
<canvas id="canvas" style="display: none;">
Your browser does not support the HTML5 canvas element.
</canvas>
</div>
<div id="imagePreview" style="position: relative; overflow: hidden; border: 1px solid #000; background: #fff; width: 100px; height: 100px;"></div>
CSS
img {max-width: 100%;} /* This rule is very important, please do not ignore this! */
#canvas {
height: auto;
width: 250px; /*Change this value according to your need*/
background-color: #ffffff;
cursor: default;
border: 1px solid #000;
}
JS
var canvas = $("#canvas");
context = canvas.get(0).getContext("2d");
$('#userImage').on( 'change', function(){
if (this.files && this.files[0]) {
if ( this.files[0].type.match(/^image\//) ) {
var reader = new FileReader();
reader.onload = function(evt) {
var img = new Image();
img.onload = function() {
context.canvas.height = img.height;
context.canvas.width = img.width;
context.drawImage(img, 0, 0);
// Destroy the old cropper instance
canvas.cropper('destroy');
// Replace url
canvas.attr('src', this.result);
var cropper = canvas.cropper({
//these options can be changed or modified according to need
viewMode: 0,
cropBoxResizable: false,
minCropBoxWidth: 100,
minCropBoxHeight: 100,
dragMode: 'none',
preview: $('#imagePreview'),
aspectRatio: 1,
crop : function(e){
$('#crop_x').val(e.x);
$('#crop_y').val(e.y);
}
});
};
img.src = evt.target.result;
};
reader.readAsDataURL(this.files[0]);
} else {
alert("Invalid file type! Please select an image file.");
}
} else {
alert('No file(s) selected.');
}
});
For more details and better understanding Visit
Cropper Official Documentation
For cropper JS 1.3.3 it is cropper.destroy(); instead of canvas.cropper('destroy') after the drawing of the canvas.
`
I can show the full content of canvas in an <img> tag using canvas.toDataURL() method.
I can get a part of image from canvas using getImageData() method and draw it in another canvas using putImageData() method.
The problem is, I want to show the part of image getting by getImageData() in an <img> tag as canvas.toDataURL() but I failed.
What I've tried so far is:
var canvas = $('canvas')[0];
var ctx = canvas.getContext("2d");
$('#baseImg').load(function() {
ctx.drawImage(this, 0, 0);
});
$('#full').click(function () {
$('div').html('');
var image = new Image();
image.onload = function() {
$('div').html(this);
};
image.src = canvas.toDataURL();
});
// here i failed
$('#partail').click(function () {
$('div').html('');
var image = new Image();
image.onload = function () {
$('div').html(this);
};
image.src = ctx.getImageData(10, 10, 50, 50);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h3>Canvas</h3>
<canvas id="canvas" width="100" height="100" style="border: 1px solid #000000;"></canvas>
<br/><br/>
<img id="baseImg" style="display: none;" src="data:image/png;base64,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" />
<input id="full" type="button" value="Show Full Image" />
<input id="partail" type="button" value="Show Partial Image" />
<h3>Image from canvas</h3>
<div style="border: 1px solid #000000; height: 100px; width: 100px;"></div>
You can use context.drawImage to draw a partial clipped rectangular part of your full image.
The clipping version of drawImage looks like this:
context.drawImage(imageObject,
XClipFromSource, YClipFromSource, widthToClipFromSource, heightToClipFromSource,
canvasX, canvasY, canvasWidth, canvasHeight
);
Here's example code and a demo:
<<===>>
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var status=1;
var img=document.getElementById('baseImg');
$('#toggle').on('click',function(){
status*=-1;
draw();
});
draw();
//
function draw(){
if(status==1){
canvas.width=img.width;
canvas.height=img.height;
ctx.drawImage(img,0,0);
}else{
canvas.width=50;
canvas.height=50;
ctx.drawImage(img,10,10,50,50,0,0,50,50);
}
}
body{ background-color: ivory; }
#canvas{border:1px solid red; margin:0 auto; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<button id=toggle>Toggle img display</button>
<br>
<canvas id="canvas" width=300 height=300></canvas>
<img id="baseImg" style="display: none;" src="data:image/png;base64,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" />
I have solved my problem with the suggestions of everyone. I've used a temporary canvas to hold the part of main canvas and then get the partial image from it.
And my solution is:
var canvas = $('canvas')[0];
var ctx = canvas.getContext("2d");
$('#baseImg').load(function() {
ctx.drawImage(this, 0, 0);
});
$('#full').click(function() {
$('div').html('');
var image = new Image();
image.onload = function() {
$('div').html(this);
};
image.src = canvas.toDataURL();
});
$('#partail').click(function() {
$('div').html('');
var height = 50, width = 50;
var copyCanvas = $('<canvas id="canvas" width="' + width + '" height="' + height + '"></canvas>')[0];
var copyCtx = copyCanvas.getContext("2d");
copyCtx.putImageData(ctx.getImageData(10, 10, width, height), 0, 0);
var image = new Image();
image.onload = function() {
$('div').html(this);
};
image.src = copyCanvas.toDataURL();
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h3>Canvas</h3>
<canvas id="canvas" width="100" height="100" style="border: 1px solid #000000;"></canvas>
<br /><br />
<img id="baseImg" style="display: none;" 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/>
<input id="full" type="button" value="Show Full Image" />
<input id="partail" type="button" value="Show Partial Image" />
<h3>Image from canvas</h3>
<div style="border: 1px solid #000000; height: 100px; width: 100px;"></div>
I'm creating an application with the image of a christmas tree that is placed in a canvas element , where there is the possibility of drag images over it . After the tree is decorated with the draggable images, the user has to be able to save the entire composition (canvas + images) as a PNG file . The problem is: when I drag the images to the canvas, they are hidden behind the christmas tree. Can you please help me to fix it?
Here's the code:
<html>
<head>
<script>
function allowDrop(e)
{
e.preventDefault();
}
function drag(e)
{
//store the position of the mouse relativly to the image position
e.dataTransfer.setData("mouse_position_x",e.clientX - e.target.offsetLeft );
e.dataTransfer.setData("mouse_position_y",e.clientY - e.target.offsetTop );
e.dataTransfer.setData("image_id",e.target.id);
}
function drop(e)
{
e.preventDefault();
var image = document.getElementById( e.dataTransfer.getData("image_id") );
var mouse_position_x = e.dataTransfer.getData("mouse_position_x");
var mouse_position_y = e.dataTransfer.getData("mouse_position_y");
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var imageObj=new Image();
imageObj.onload=function(){
ctx.save();
ctx.drawImage(this,0,0,canvas.width,canvas.height);
ctx.restore();
}
imageObj.src="bg.png";
// the image is drawn on the canvas at the position of the mouse when we lifted the mouse button
ctx.drawImage( image , e.clientX - canvas.offsetLeft - mouse_position_x , e.clientY - canvas.offsetTop - mouse_position_y );
}
function convertCanvasToImage() {
var canvas = document.getElementById('canvas');
var image_src = canvas.toDataURL("image/png");
window.open(image_src);
}
</script>
<style type="text/css">
body {
text-align: center;
}
#wrapper {
text-align: left;
width: 870px;
height:566px;
margin-left: auto;
margin-right: auto;
}
#options{
width: 70px;
height:566px;
float:left;
}
#options img {
margin-bottom: 15px;
}
#canvas{
width:800px;
height:566px;
float:left;
background-image:url(../images/bg.png);
}
</style>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<div id="options">
<img id="img1" draggable="true" ondragstart="drag(event)" src='estrela.png'>
<img id="img2" draggable="true" ondragstart="drag(event)" src='bola.png'>
<img id="img3" draggable="true" ondragstart="drag(event)" src='sino.png'>
<img id="img4" draggable="true" ondragstart="drag(event)" src='bota.png'>
<img id="img5" draggable="true" ondragstart="drag(event)" src='anjo.png'>
<img id="img6" draggable="true" ondragstart="drag(event)" src='laco.png'>
</div>
<canvas id="canvas" onDrop="drop(event)" onDragOver="allowDrop(event)" width="800" height="566"></canvas>
<input type="button" onClick="convertCanvasToImage()" value="Gerar Imagem" style="float:right"/>
</body>
Thanks!
Check out this post which allows you to drag images from a toolbar and drop them on the canvas:
HTML5 drag and drop images from a toolbar to a canvas
When you're done creating your tree, you can save the canvas as an image by converting it to an image and displaying the image in a new browser tab. The user can then right-click-save that image to their local drive:
$("#save").click(function(){
var html="<p>Right-click on image below and Save-Picture-As</p>";
html+="<img src='"+canvas.toDataURL()+"' alt='image from canvas'/>";
var tab=window.open();
tab.document.write(html);
});
Some browsers (Chrome, Firefox) even allow the user to right-click the canvas element itself and save it as an image.