I am working about draggable objects on Konva stage. I want to the canvas object layer turn to PDF. I use toDataURL. Like this;
var stage = new Konva.Stage({
container: 'container',
width: width,
height: height,
id: 'stage',
});
var grid_layer = new Konva.Layer();
var object_layer = new Konva.Layer();
stage.add(grid_layer);
stage.add(object_layer);
function updateScreen() {
object_layer.batchDraw()
}
function downloadURI(uri, name) {
var link = document.createElement('a');
link.download = name;
link.href = uri;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
delete link;
}
document.getElementById('save').addEventListener(
'click',
function() {
var dataURL = stage.toDataURL({ pixelRatio: 3 });
downloadURI(dataURL, 'stage.png');
},
false
);
Save button work without objects and save canvas image. But when i run the code with objects on stage, the page reloads and the button doesn't work. doesn't save canvas image
I would strongly recommend to doing it like shown in the Konva Wiki.
// Code form KonvaJS wiki
var pdf = new jsPDF('l', 'px', [stage.width(), stage.height()]);
pdf.setTextColor('#000000');
// first add texts
stage.find('Text').forEach((text) => {
const size = text.fontSize() / 0.75; // convert pixels to points
pdf.setFontSize(size);
pdf.text(text.text(), text.x(), text.y(), {
baseline: 'top',
angle: -text.getAbsoluteRotation(),
});
});
// then put image on top of texts (so texts are not visible)
pdf.addImage(
stage.toDataURL({ pixelRatio: 2 }),
0,
0,
stage.width(),
stage.height()
);
pdf.save('canvas.pdf');
This should add all text and other objects to a pdf.
From the comments, I can conclude that you don't host the images using the server you use for the konva stuff. You can't access the images from your website as they are not from the same origin. This helps secure the files on your computer from the access of websites like yours. So you would have to move the images to the server and access them from there.
I'm currently working on web app for photo editing using FabricJS and one of features I need to implement is something like Clipping masks from Photoshop.
For example I have this assets: frame, mask and image. I need to insert image inside frame and clip it with mask. Most tricky part is in requirements:
User should be able to modify image inside frame, e.g. move, rotate, skew... Frame itself also can be moved inside canvas.
Number of layers is not limited so user can add objects under or above masked image.
Masks, frames and images is not predefined, user should be able to upload and use new assets.
My current solution is this:
Load assets
Set globalCompositeOperation of image to source-out
Set clipTo function for image.
Add assets on canvas as a group
In this solution clipTo function preserve image inside rectangular area of frame and with help of globalCompositeOperation I'm clipping image to actual mask. At first sight it works fine but if I add new layer above this newly added group it will be cutted off because of globalCompositeOperation="source-out" rule. I've created JSFiddle to show this.
So, that else could I try? I've seen some posts on StackOverflow with advices to use SVGs for clipping mask, but if I understand it correctly SVG must contain only one path. This could be a problem because of third requirement of my app.
Any advice in right direction will help, because right now I'm totally stuck with this problem.
You can do this by using ClipPath property of Img Object which you want to mask. With this, you can Mask Any Type of Object. and also you need to add some Ctx Configuration in ClipTo function of Img Object.
check this link https://jsfiddle.net/naimsajjad/8w7hye2v/8/
(function() {
var img01URL = 'http://fabricjs.com/assets/printio.png';
var img02URL = 'http://fabricjs.com/lib/pug.jpg';
var img03URL = 'http://fabricjs.com/assets/ladybug.png';
var img03URL = 'http://fabricjs.com/assets/ladybug.png';
var canvas = new fabric.Canvas('c');
canvas.backgroundColor = "red";
canvas.setHeight(500);
canvas.setWidth(500);
canvas.setZoom(1)
var circle = new fabric.Circle({radius: 40, top: 50, left: 50, fixed: true, fill: '', stroke: '1' });
canvas.add(circle);
canvas.renderAll();
fabric.Image.fromURL(img01URL, function(oImg) {
oImg.scale(.25);
oImg.left = 10;
oImg.top = 10;
oImg.clipPath = circle;
oImg.clipTo = function(ctx) {
clipObject(this,ctx)
}
canvas.add(oImg);
canvas.renderAll();
});
var bili = new fabric.Path('M85.6,606.2c-13.2,54.5-3.9,95.7,23.3,130.7c27.2,35-3.1,55.2-25.7,66.1C60.7,814,52.2,821,50.6,836.5c-1.6,15.6,19.5,76.3,29.6,86.4c10.1,10.1,32.7,31.9,47.5,54.5c14.8,22.6,34.2,7.8,34.2,7.8c14,10.9,28,0,28,0c24.9,11.7,39.7-4.7,39.7-4.7c12.4-14.8-14-30.3-14-30.3c-16.3-28.8-28.8-5.4-33.5-11.7s-8.6-7-33.5-35.8c-24.9-28.8,39.7-19.5,62.2-24.9c22.6-5.4,65.4-34.2,65.4-34.2c0,34.2,11.7,28.8,28.8,46.7c17.1,17.9,24.9,29.6,47.5,38.9c22.6,9.3,33.5,7.8,53.7,21c20.2,13.2,62.2,10.9,62.2,10.9c18.7,6.2,36.6,0,36.6,0c45.1,0,26.5-15.6,10.1-36.6c-16.3-21-49-3.1-63.8-13.2c-14.8-10.1-51.4-25.7-70-36.6c-18.7-10.9,0-30.3,0-48.2c0-17.9,14-31.9,14-31.9h72.4c0,0,56-3.9,70.8,26.5c14.8,30.3,37.3,36.6,38.1,52.9c0.8,16.3-13.2,17.9-13.2,17.9c-31.1-8.6-31.9,41.2-31.9,41.2c38.1,50.6,112-21,112-21c85.6-7.8,79.4-133.8,79.4-133.8c17.1-12.4,44.4-45.1,62.2-74.7c17.9-29.6,68.5-52.1,113.6-30.3c45.1,21.8,52.9-14.8,52.9-14.8c15.6,2.3,20.2-17.9,20.2-17.9c20.2-22.6-15.6-28-16.3-84c-0.8-56-47.5-66.1-45.1-82.5c2.3-16.3,49.8-68.5,38.1-63.8c-10.2,4.1-53,25.3-63.7,30.7c-0.4-1.4-1.1-3.4-2.5-6.6c-6.2-14-74.7,30.3-74.7,30.3s-108.5,64.2-129.6,68.9c-21,4.7-18.7-9.3-44.3-7c-25.7,2.3-38.5,4.7-154.1-44.4c-115.6-49-326,29.8-326,29.8s-168.1-267.9-28-383.4C265.8,13,78.4-83.3,32.9,168.8C-12.6,420.9,98.9,551.7,85.6,606.2z',{top: 0, left: 180, fixed: true, fill: 'white', stroke: '', scaleX: 0.2, scaleY: 0.2 });
canvas.add(bili);
canvas.renderAll();
fabric.Image.fromURL(img02URL, function(oImg) {
oImg.scale(0.5);
oImg.left = 180;
oImg.top = 0;
oImg.clipPath = bili;
oImg.clipTo = function(ctx) {
clipObject(this,ctx)
}
canvas.add(oImg);
canvas.renderAll();
});
function clipObject(thisObj,ctx)
{
if (thisObj.clipPath) {
ctx.save();
if (thisObj.clipPath.fixed) {
var retina = thisObj.canvas.getRetinaScaling();
ctx.setTransform(retina, 0, 0, retina, 0, 0);
// to handle zoom
ctx.transform.apply(ctx, thisObj.canvas.viewportTransform);
thisObj.clipPath.transform(ctx);
}
thisObj.clipPath._render(ctx);
ctx.restore();
ctx.clip();
var x = -thisObj.width / 2, y = -thisObj.height / 2, elementToDraw;
if (thisObj.isMoving === false && thisObj.resizeFilter && thisObj._needsResize()) {
thisObj._lastScaleX = thisObj.scaleX;
thisObj._lastScaleY = thisObj.scaleY;
thisObj.applyResizeFilters();
}
elementToDraw = thisObj._element;
elementToDraw && ctx.drawImage(elementToDraw,
0, 0, thisObj.width, thisObj.height,
x, y, thisObj.width, thisObj.height);
thisObj._stroke(ctx);
thisObj._renderStroke(ctx);
}
}
})();
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.3/fabric.min.js"></script>
<canvas id="c" width="400" height="400"></canvas>
Not sure what you want.
If you want the last image loaded (named img2), the one you send to the back to not effect the layers above do the following.
You have mask,frame,img, and img2;
Put them in the following order and with the following comp settings.
img2, source-over
img, source-over
mask, destination-out
frame, source-over
If you want something else you will have to explain it in more detail.
Personally when I provide masking to the client I give them full access to all the composite methods and allow them to work out what they need to do to achieve a desired effect. Providing a UI that allows you to change the comp setting, and layer order makes it a lot easier to sort out the sometimes confusing canvas composite rules.
I'd suggest looking at this solution.
Multiple clipping areas on Fabric.js canvas
You end up with a shape layer that is used to define the mask shape. That shape then gets applied as a clipTo to your image.
The one limitation I can think off though that you might run into is when you start to rotate various shapes. I know I have it working great with a rectangle and a circle, however ran into some issues with polygons from what I recall... This was all setup under and older version of FabricJS however, so there may have been some improvements there that I'm not experienced with.
The other issue I ran into was drop shadows didn't render correctly when passed to a NodeJS server running FabricJS.
I have a page which allows you to browse in an image, then draw on it and save both the original and the annotated version. I am leveraging megapix-image.js and exif.js to help in rendering images from multiple mobile devices properly. It works great, except in certain orientations. For example, a vertical photo taken on an iPhone4s is considered orientation 6 by exif and gets flipped accordingly by megapix-image so it's rendered nicely on the canvas. For some reason, when I draw on it afterward, it seems like the drawing is reversed. Mouse and touch both behave the same way. The coordinates look right to me (meaning they match a working horizontal pic and a non-working vertical pic), as does the canvas height and width when megapix-image.js flips it. This leads me to believe it has something to do with the context, but honestly, I am not really sure. I have a JS fiddle of the part of my work that shows the behavior. Just browse in a vertically taken pic from a mobile device or take a pic in vertical format on a mobile device and use it. I think all will show this same behavior.
The final rendering is done like this:
function RenderImage(file2) {
if (typeof file2[0].files[0] != 'undefined') {
EXIF.getData(file2[0].files[0], function () {
orientation = EXIF.getTag(this, "Orientation");
var file = file2[0].files[0];
var mpImg = new MegaPixImage(file);
var resCanvas1 = document.getElementById('annoCanvas');
mpImg.render(resCanvas1, {
maxWidth: 700,
maxHeight: 700,
orientation: orientation
});
});
}
}
But the full jsfiddle is here:
http://jsfiddle.net/awebster28/Tq3qU/6/
Does anyone have any clues for me?
If you look at the lib you are using there is a transformCoordinate function that is used to set the right transform before drawing.
And they don't save/restore the canvas (boooo!!!) so it remains with this transform after-wise.
Solution for you is to do what the lib should do : save the context before the render and restore it after :
function RenderImage(file2) {
// ... same code ...
var mpImg = new MegaPixImage(file);
var eData = EXIF.pretty(this);
// Render resized image into canvas element.
var resCanvas1 = document.getElementById('annoCanvas');
var ctx = resCanvas1.getContext('2d');
ctx.save();
//setting the orientation flips it
mpImg.render(resCanvas1, {
maxWidth: 700,
maxHeight: 700,
orientation: orientation
});
ctx.restore();
//...
}
I ended up fixing this by adding another canvas to my html (named "annoCanvas2"). Then, I updated megapix-image.js to include this function, which draws the contents of the new canvas to a fresh one:
function drawTwin(sourceCanvas)
{
var id = sourceCanvas.id + "2";
var destCanvas = document.getElementById(id);
if (destCanvas !== null) {
var twinCtx = destCanvas.getContext("2d");
destCanvas.width = sourceCanvas.width;
destCanvas.height = sourceCanvas.height;
twinCtx.drawImage(sourceCanvas, 0, 0, sourceCanvas.width, sourceCanvas.height);
}
}
Then, just after the first is rotated and flipped and rendered, I rendered the resulting canvas to my "twin". Then I had a nice canvas, with my updated image that I could then draw on and also save!
var tagName = target.tagName.toLowerCase();
if (tagName === 'img') {
target.src = renderImageToDataURL(this.srcImage, opt, doSquash);
} else if (tagName === 'canvas') {
renderImageToCanvas(this.srcImage, target, opt, doSquash);
//------I added this-----------
drawTwin(target);
}
I was glad to have it fixed so I met my deadline, but I am still not sure why I had to do this. If anyone out there can explain it, I'd love to know why.
I am working on a collage in HTML5 canvas. However, I am finding difficulty in arranging the images in different angles. I want to arrange first pic at angle of PI/4 and the other one at angle -PI/70. Here is the jsFiddle with the problem.
var pic1 = new Image();
pic1.src = "http://www.fantom-xp.com/wallpapers/23/Windows_7_-_Swan.jpg";
context.translate(170,170);
context.rotate(Math.PI/8);
pic1.onload = function(){
context.drawImage(pic1, 20, 20, 200, 200);
}
var pic2 = new Image();
pic2.src = "http://www.redorbit.com/media/uploads/2004/10/38_ec8164eb3e4bddf76ef1b8eb564b9514.jpg";
context.translate(100,10);
context.rotate(-Math.PI/70);
pic2.onload = function(){
context.drawImage(pic2, 0, 0, 200, 200);
}
What am I missing?
Assuming you want to rotate your images around their center points you need to use this drawImage:
context.drawImage(image, -image.width/2, -image.height/2).
That's because the translate point becomes the rotation point.
Here's a generic image rotation function:
function tiltedPicture(centerX,centerY,degreeAngle,image){
ctx.save();
ctx.translate(centerX,centerY);
ctx.rotate(degreeAngle*Math.PI/180);
ctx.drawImage(image,-image.width/2,-image.height/2);
ctx.restore();
}
There are some issues in your code.
First of all, your first image couldn't be loaded. You will see it when you add:
pic1.onerror = function() {
console.log('Error loading');
}
Next you should use save and restore methods. Read here.
The problem is when you call twice context.translate(170,170); you will get th final translation at x: 340, y: 340. If you will combine more complex transformaions you could get result which is hard to predict. Fortunatelly there are methods save and restore. Save - saves current transformation state, and Restore - restores last saved state.
Usage in your case (for the first pic):
pic1.onload = function(){
context.save();
context.translate(170,170);
context.rotate(Math.PI/2);
context.drawImage(pic1, 20, 20, 200, 200);
context.restore();
}
pic1.onerror = function() {
console.log('error loading');
}
See demo.
Creating a new object on mouseclick as a way for users to create reference points (which I call 'crumbs') when reading large web documents. I've got this working with a new Image() function, however, that won't let me assign a tabindex to each new image created by mouseclick (posX, posY). 'crumbtoggle' simply acknowledges that the crumb dropping tool has been selected.
working new Image() function:
function draw_crumb()
{
var b_canvas = document.getElementById("b");
var b_context = b_canvas.getContext("2d");
var crumb = new Image();
crumb.src = "crumb.gif";
if(crumbtoggle.className == "on")
{
b_context.drawImage(crumb, posX-20, posY-20, 50, 75);
}
}
non-working new Object () function:
function draw_crumb()
{
var b_canvas = document.getElementById("b");
var b_context = b_canvas.getContext("2d");
var crumb = new Object();
crumb.type = "button";
crumb.src = "crumb.gif";
crumb.tabindex = 1;
if(crumbtoggle.className == "on")
{
b_context.drawObject(crumb, posX-20, posY-20, 50, 75);
}
}
I've looked in to applying focus to the new Image objects, but that doesn't seem to be a good alternative to tabindex attributes. Any ideas would be greatly appreciated.
An HTML5 Canvas is like a real-world canvas with instantly-drying paint. When you paint a rectangle or line or image on the canvas, it becomes part of the canvas. You cannot later re-order the items, or move them relative to each other. It is not a separate entity that can get focus.
Any sort of focus management integrated with the browser's handling of focus will have to be done through form inputs or anchors recognized by the browser.
It's not clear to me why you need a canvas, or if you need one at all.