I've got a simple page that allows you to take a picture with your phone and then upload it to the server.
To achieve that, I'm using HTML5's input as file, so when I click (or tap on) Choose File two options are displayed:
Use the phone's camera (I'm using an iPhone with iOS8)
Select a picture from the library.
If I select the picture from the library everything works just fine, as for now I'm only displaying it on screen, but if I use the camera, after taking the picture the browser crashes. I haven't been able to debug because it never hits my breakpoints since the debugging session crashes as well.
Here's the code. Any help will be highly appreciated.
<!--Seg:openPage-->
<script>
function resizeImg(img, canvas, ctx){
var MAX_WIDTH = 500;
var MAX_HEIGHT = 300;
var width = img.width;
var height = img.height;
alert(width + " " + height);
if (width > height) {
if (width > MAX_WIDTH) {
height *= MAX_WIDTH / width;
width = MAX_WIDTH;
}
} else {
if (height > MAX_HEIGHT) {
width *= MAX_HEIGHT / height;
height = MAX_HEIGHT;
}
}
canvas.width = width;
canvas.height = height;
//var ctx = canvas.getContext("2d");
//var dataURL = canvas.toDataURL(img, 0.5);
//img.src = dataURL;
ctx.drawImage(img, 0, 0, width, height);
}
function drawOnCanvas(file) {
var reader = new FileReader();
reader.onload = function (e) {
var dataURL = e.target.result;
var c = document.querySelector('canvas');
var ctx = c.getContext('2d');
var img = new Image();
img.src = dataURL;
//****img.onload = function() {
//c.width = 200; //img.width;
//c.height = 200; //img.height;
if (img.complete) {
resizeImg(img, c, ctx);
//ctx.drawImage(img, 0, 0);
} else {
img.onload = function () {
resizeImg(img, c, ctx);
//ctx.drawImage(img, 0, 0);
};
}
//ctx.drawImage(img, 0, 0);
//****};
//****img.src = dataURL;
};
reader.readAsDataURL(file);
}
function upload(file){
var encodedB64 = window.btoa(file);
var reader = new FileReader();
reader.readAsDataURL(file);
reader.onloadend=function(){
if(file){
//reader.readAsDataURL(file);
console.log(reader);
//alert(reader.result);
$('.output').val(reader.result);
}
submit_form('f','GO');
}
}
$(document).ready(function(){
var input = document.querySelector('input[type=file]');
input.onchange = function () {
var file = input.files[0];
//upload(file);
drawOnCanvas(file);
//displayAsImage(file);
};
});
</script>
<style>
/**
#canvas-container {
width: 100%;
height: 100%;
}
#canvas-container #myCanvas{
width: 100%;
}**/
</style>
<div class="container" style="padding-top: 10px;">
<div id="page_content">
<form name="f" method="POST" action="#&PGM " class="sigPad">
<input type="hidden" name="output" class="output">
<!--Add file input-->
<p>Choose a picture from your device or capture one with your camera now:</p>
<input type="file" id="picManager" accept="image/*" capture="camera">
<!--Add canvas-->
<p>Photo:</p>
<div id="canvas-container">
<canvas id="myCanvas"></canvas>
</div>
<button type="submit" class="btn btn-primary">View</button>
</form>
</div>
</div>
<!--End:openPage-->
Related
I'm trying to resize an image in the client side and then send it to my server. But the image is not all the times settled correctly to the canvas used to resize the image.
I already sent the image resize but i need to send it at least 2 times to work.
I put <p> labels in my html to verify the data of the image and i can see the data incomplete the first time i send it.
This is my html
function ResizeImage() {
var filesToUpload = document.getElementById('imageFile').files;
var file = filesToUpload[0];
console.log('Data');
// Create an image
var img = document.createElement("img");
// Create a file reader
var reader = new FileReader();
// Set the image once loaded into file reader
reader.onload = function(e) {
//HERE IN THIS PART, the e.target.result works strange
img.src = e.target.result;
var canvas = document.createElement("canvas");
//var canvas = $("<canvas>", {"id":"testing"})[0];
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
// var MAX_WIDTH = 400;
// var MAX_HEIGHT = 400;
var width = 200;
var height = 200;
if (img.width > img.height) {
if (img.width > width) {
height *= height / img.width;
//width = width;
}
} else {
if (img.height > height) {
width *= height / img.height;
//height = height;
}
}
canvas.width = width;
canvas.height = height;
ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, width, height);
var dataurl = canvas.toDataURL("image/png");
console.log(dataurl);
canvas.toBlob((blob) => {
var fd = new FormData();
fd.append("name", "paul");
fd.append("image", blob);
fd.append("key", "××××××××××××");
var xhr = new XMLHttpRequest();
xhr.open("POST", "http://localhost:5000/2");
xhr.send(fd);
}, "image/png", 1)
document.getElementById('output').src = dataurl;
var para = document.createElement("p");
var node = document.createTextNode(dataurl);
para.appendChild(node);
var element = document.getElementById("contenedor");
element.appendChild(para);
}
// Load files into file reader
reader.readAsDataURL(file);
}
<input type="text" name="fileName">
<input type="file" id="imageFile" name="sampleFile" accept="image/png" />
<input type='button' value='Upload!' onclick="ResizeImage()" />
<img src="" id="output">
<div id="contenedor"></div>
<hr>
I expect it works the first time i send the data to the server.
Img.src is asynchronous.
To verify this, replace 'img.src = e.target.result;' with
img.onload = function () { console.log('done')}
img.src = e.target.result;
console.log('src')
If done runs after src, you know that the image isn't loaded yet when you try to ctx.drawImage.
To fix, simply move all your resizing code into img.onload.
So I am trying to build a Meme-Creator. You already can upload the pics as the background-img from the canvas. Now I am trying to do the Meme font but it isnt really working. However it is creating a big gap in the picture. Thanks for your help and attention! :D
var canvas = document.getElementById("meme-canvas");
var ctx = canvas.getContext("2d");
var width = canvas.width;
var height = canvas.height;
function readImage() {
if (this.files && this.files[0]) {
var FR = new FileReader();
FR.onload = function(e) {
var img = new Image();
img.addEventListener("load", function() {
ctx.clearRect(0, 0, width, height);
canvas.width = img.width;
canvas.height = img.height;
ctx.drawImage(img, 0, 0);
});
img.src = e.target.result;
};
FR.readAsDataURL(this.files[0]);
}
}
function Text() {
ctx.clearRect(0, 0, width, height);
var textT = document.getElementById("top-text").value;
var textB = document.getElementById("bottom-text").value;
ctx.font = "60px Impact";
ctx.lineWidth = 3;
ctx.strokeText(textT, 10, 65);
ctx.strokeText(textB, 10, 400);
}
document.getElementById("image-input").addEventListener("change", readImage, false);
<input type="file" id="image-input" accept="image/*">
<input type="text" id="top-text" oninput="Text()">
<input type="text" id="bottom-text" oninput="Text()">
<canvas style="position: absolute; width: 400px; top: 100px; left: 10px;" id="meme-canvas"></canvas>
I've made a few changes to your script. because you need to draw the image several times I've written a function that draws the image. The canvas is cleared every time one of the 2 text input changes it's value, and every time you have to redraw everything.
Also textT and textB can be declared only once. You don't need to declare them in the Text function.
I need to use the font size (60) more than once, so I've made a variable fontSize = 60
Since you don't know the size of your canvas ( depends on the size of the uploaded image ) you need to calculate the position for the bottom text textB = height - fontSize/2 where height is the height of the canvas: height = canvas.height = img.height;
I hope it's useful.
var canvas = document.getElementById("meme-canvas");
var ctx = canvas.getContext("2d");
var width = (canvas.width = 400);
var height = (canvas.height = 400);
var fontSize = 60;
var img = new Image();
var textT = document.getElementById("top-text");
var textB = document.getElementById("bottom-text");
function readImage() {
if (this.files && this.files[0]) {
var FR = new FileReader();
FR.onload = function(e) {
img.addEventListener("load", function() {
width = canvas.width = img.width;
height = canvas.height = img.height;
drawImage();
});
img.src = e.target.result;
};
FR.readAsDataURL(this.files[0]);
}
}
function drawImage() {
ctx.drawImage(img, 0, 0);
}
function Text() {
ctx.font = fontSize + "px Impact";
ctx.textAlign = "center";
ctx.lineWidth = 3;
ctx.clearRect(0, 0, width, height);
drawImage();
ctx.strokeText(textT.value, width / 2, 65);
ctx.strokeText(textB.value, width / 2, height - fontSize/2);
}
document
.getElementById("image-input")
.addEventListener("change", readImage, false);
textT.addEventListener("input", Text);
textB.addEventListener("input", Text);
canvas{position: absolute; left: 10px; top:60px;border:1px solid #d9d9d9;}
<input type="file" id="image-input" accept="image/*">
<input type="text" id="top-text" />
<input type="text" id="bottom-text" />
<canvas style="" id="meme-canvas"></canvas>
A few of the issues I encountered:
If you change the size of the canvas you should not use the variables, because those wont be correct, or you will need to keep track of them
If you do clearRect you have to be aware what are you clearing and re-draw it.
The font did not look too clear so I added a white shadow for better contrast
The bottom text needed to be relative to the canvas height
Here is the code:
var canvas = document.getElementById("meme-canvas");
var ctx = canvas.getContext("2d");
var img = new Image();
function readImage() {
if (this.files && this.files[0]) {
var FR = new FileReader();
FR.onload = function(e) {
img.addEventListener("load", function() {
canvas.width = img.width;
canvas.height = img.height;
draw();
});
img.src = e.target.result;
};
FR.readAsDataURL(this.files[0]);
}
}
function draw() {
var textT = document.getElementById("top-text").value;
var textB = document.getElementById("bottom-text").value;
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.font = "60px Impact";
ctx.shadowColor = "white"
ctx.shadowOffsetX = ctx.shadowOffsetY = 2
ctx.lineWidth = 3;
if (img) ctx.drawImage(img, 0, 0);
ctx.strokeText(textT, 10, 45);
ctx.strokeText(textB, 10, canvas.height -10);
}
document.getElementById("image-input")
.addEventListener("change", readImage, false);
<input type="file" id="image-input" accept="image/*"><br>
<input type="text" id="top-text" placeholder="Top text" oninput="draw()"><br>
<input type="text" id="bottom-text" placeholder="Bottom text" oninput="draw()"><br>
<canvas id="meme-canvas"></canvas>
I'm newbie in JS and React. I am using React and I have multiple file input in a form, I wish if the user select image the images should be resized and previewed before user click upload. Now the resizing, previewing and uploading are all fine, the problem is when I change a file input, the other file inputs preview and upload are all changed synchronously! any help will be appreciated.
This is the code:
render():
render(){
return(
...
<label>Image1
<input type="file" id="img1" on Change={this.handleChange} />
</label>
<br/>
<img id="img1_preview" src="" height="100" />
<label>Image2
<input type="file" id="img2" on Change={this.handleChange} />
</label>
<img id="img2_preview" src="" height="100" />
...
)
}
function():
...
handleChange(event) {
...
/* handle all image input change */
if (event.target.id.includes('img')) {
var field = event.target.id;
var preview = document.getElementById(field + '_preview');
var file = event.target.files[0];
var reader = new FileReader();
reader.onload = function(readerEvent) {
var image = new Image();
image.onload = function(imageEvent) {
var canvas = document.createElement('canvas');
var max_size = 800; /* max size */
var width = image.width, height = image.height;
if (width > height) {
if (width > max_size) {
height *= max_size / width;
width = max_size;
}
} else {
if (height > max_size) {
width *= max_size / height;
height = max_size;
}
}
canvas.width = width;
canvas.height = height;
canvas.getContext('2d').drawImage(image, 0, 0, width, height);
var dataUrl = canvas.toDataURL('image/jpeg');
/* Utility function to convert a canvas to a BLOB */
var dataURLToBlob = function(dataURL) {
var BASE64_MARKER = ';base64,';
if (dataURL.indexOf(BASE64_MARKER) === -1) {
var parts = dataURL.split(',');
var contentType = parts[0].split(':')[-1];
var raw = parts[1];
return new Blob([raw],{type:contentType});
}
var parts = dataURL.split(BASE64_MARKER);
var contentType = parts[0].split(':')[1];
var raw = window.atob(parts[1]);
var rawLength = raw.length;
var uInt8Array = new Uint8Array(rawLength);
for (var i = 0; i < rawLength; ++i) {
uInt8Array[i] = raw.charCodeAt(i);
}
return new Blob([uInt8Array],{type:contentType});
}
/* End Utility function to convert a canvas to a BLOB */
var resizedImage = dataURLToBlob(dataUrl);
$.event.trigger({
type: "imageResized",
blob: resizedImage,
url: dataUrl
});
}
image.src = readerEvent.target.result;
}
reader.readAsDataURL(file);
$(document).on("imageResized",function(event1){
if (event1.blob && event1.url) {
var blob = event1.blob, url = event1.url;
# set state, later will be submit to server
this.setState({[field]:blob});
/* preview */
var reader1 = new FileReader();
reader1.addEventListener("load",function(){
preview.src = url;
}, false);
reader1.readAsDataURL(blob);
/* end preview */
}
})
}
the page:
the page image
thanks #Kaiido, according to his advise, the problem has been solved(although I don't know the exact reason).
this is the working code:
...
handleChange(event) {
...
/* handle all image input change */
if (event.target.id.includes('img')) {
var field = event.target.id;
var preview = document.getElementById(field + '_preview');
var file = event.target.files[0];
var reader = new FileReader();
reader.onload = function(readerEvent) {
var image = new Image();
image.onload = function(imageEvent) {
var canvas = document.createElement('canvas');
var max_size = 800; /* max size */
var width = image.width, height = image.height;
if (width > height) {
if (width > max_size) {
height *= max_size / width;
width = max_size;
}
} else {
if (height > max_size) {
width *= max_size / height;
height = max_size;
}
}
canvas.width = width;
canvas.height = height;
canvas.getContext('2d').drawImage(image, 0, 0, width, height);
var dataUrl = canvas.toDataURL('image/jpeg');
/* changed code */
canvas.toBlob(function(blob){
this.setState({[field]:blob});
var reader1 = new FileReader();
reader1.addEventListener("load",function(){
preview.src = dataUrl;
}, false);
reader1.readAsDataURL(blob);
});
/* end changed */
}
image.src = readerEvent.target.result;
}
reader.readAsDataURL(file);
}
I have created a image select and resize (Client side) and upload to server. What I am asking for help is with image preview in iframe(resized) but cannot figure out. I will be only using Chrome desktop for this application. Qusetion is please help me with displaying resized image within my iframe here are my scripts below
HTML
<input type="file" input id="input" onchange="ClientSideResize()" name="Image" value="%%%img%%%"/>
HTML iframe
<img src="" id="image">
<iframe name="my_iframe" src="" id="my_iframe" style="visibility: hidden;"></iframe>
SCRIPT
<script>
function ClientSideResize(){
var dataurl = null;
var uniq = 'id' + (new Date()).getTime();
var filesToUpload = document.getElementById('input').files;
var file = filesToUpload[0];
// Create an image
var img = document.createElement("img");
// Create a file reader
var reader = new FileReader();
// Set the image once loaded into file reader
reader.onload = function(e)
{
img.src = e.target.result;
img.onload = function () {
canvas = document.createElement("canvas");
ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
var MAX_WIDTH = 200;
var MAX_HEIGHT = 400;
var width = img.width;
var height = img.height;
if (width > height) {
if (width > MAX_WIDTH) {
height *= MAX_WIDTH / width;
width = MAX_WIDTH;
}
} else {
if (height > MAX_HEIGHT) {
width *= MAX_HEIGHT / height;
height = MAX_HEIGHT;
}
}
canvas.width = width;
canvas.height = height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, width, height);
dataurl = canvas.toDataURL("image/jpeg",100);
var blobBin = atob(dataurl.split(',')[1]);
var array = [];
for(var i = 0; i < blobBin.length; i++) {
array.push(blobBin.charCodeAt(i));
}
files = new Blob([new Uint8Array(array)], {type: 'image/jpg', name: "Sample"});
} // img.onload
}
// Load files into file reader
reader.readAsDataURL(file);
}
</script>
Giving you a few other tips along the way... filereader is not the preferred way. and the way you build your blob afterwards is no good, use canvas#toBlob directly instead.
function ClientSideResize () {
// var uniq = 'id' + Date.now() // never used
var filesToUpload = document.getElementById('input').files
var file = filesToUpload[0]
// Create an image
var img = new Image
img.onload = () => {
const MAX_WIDTH = 200
const MAX_HEIGHT = 400
var canvas = document.createElement('canvas')
var ctx = canvas.getContext('2d')
var width = img.width
var height = img.height
// figure out new width and hight while keeping proportionally
if (width > height) {
if (width > MAX_WIDTH) {
height *= MAX_WIDTH / width
width = MAX_WIDTH
}
} else {
if (height > MAX_HEIGHT) {
width *= MAX_HEIGHT / height
height = MAX_HEIGHT
}
}
// set diminsion
canvas.width = width
canvas.height = height
// draw resized image
ctx.drawImage(img, 0, 0, width, height)
// get it as a blob
canvas.toBlob(blob => {
// Do something with blob
// let file = new File([blob], 'filename.png', {type: blob.type})
let iframe = document.querySelector('iframe')
iframe.contentWindow.postMessage(blob, '*')
}, 'image/jpeg', 100)
} // img.onload
img.src = URL.createObjectURL(file)
}
// on iframe
window.onmessage = event => {
console.log(event) // will contain your blob object
}
I'm trying to make an image upload from where, when user browse an image from disk, the scaled image shows as a preview on the canvas. to get the scaled image from the canvas the dataurl image only shows half image. when I try to right click and view image from the canvas, i get the complete image url.
here's my code.
<html>
<head>
<title></title>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script>
$('#fileupload').change(function(){
var MAX_WIDTH = 180;
var MAX_HEIGHT = 120;
var file = this.files[0];
var canvas = document.getElementById('canvas');
var img = document.createElement("img");
var reader = new FileReader();
reader.onload = function(e) {
img.src = e.target.result;
}
img.onload = function(){
var width = img.width;
var height = img.height;
if (width > height) {
if (width > MAX_WIDTH) {
height *= MAX_WIDTH / width;
width = MAX_WIDTH;
}
} else {
if (height > MAX_HEIGHT) {
width *= MAX_HEIGHT / height;
height = MAX_HEIGHT;
}
}
canvas.width = width;
canvas.height = height;
var ctx = canvas.getContext("2d");
ctx.scale(1,1);
ctx.drawImage(img, 0, 0, width, height);
dataurl = canvas.toDataURL("image/png");
alert(dataurl); //this path shows imcomplete image.
}
reader.readAsDataURL(file);
</script>
</head>
<body>
<input id="fileupload" type="file">
<canvas width="180" height="120" id="canvas"></canvas>
</body>
</html>