Angular ThreeJS Canvas has not initializer - javascript

I can't download canvas from html file
[enter image description here](https://i.stack.imgur.com/hZfa3.png)
I want to get canvas and implement ThreeJS animation

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How to reuse base64 bitmap images in the final SVG with fabric.js

I'm working on a web editor app that generates SVG Images.
I allow users to upload bitmap images as base64 into the editor.
The Problem is, that if a user uses an image multiple times, the SVG file size increases far too much.
With the SVG format, it's possible to reuse images (<use href="ID">). Is there a possibility to do this in fabric.js?

How to draw a polygon on the lower canvas background image using fabric js?

I have a loaded image on canvas as a background image using fabric js. Since then the canvas element is splitted as two. Class name for these canvas element are,
lower-canvas - (uploaded background image)
upper-canvas - (Parent for the lower canvas)
When I try to draw something on the image that is being drawn on the upper-canvas only and unable to draw on the lower canvas.
Please find the image:
I am able to draw only on this layer only. Unable to draw outside this.

Are there any ways to convert a SVG progressive draw to a video?

I've created an web app that client can upload an svg file, the app will create a progressive draw animation from that file, and then create a downloadable video from that animation.
I'm using Progressive Draw - SVG for the progressive draw animation.
Are there any ways to convert this to an video file or just record this in the screen to render a video file? I was using RecordRTC to record the animation but it seems that this can't record the SVG format as the video is all blank.
Any suggestion? Thanks in advance!

Crop an image using FabricJS

I would like to crop an image using (javascript)FabricJS + HTML5 canvas.
Background image of canvas is a Fabric image object.
Crop area
is a FabricJS Rectangle.
I attached an image too. (you can see what i would like to accomplish)
Is it possible to resize FabricJS canvas somehow to keep only the area selected by rectangle(green dotted rectangle). I think i have all necessary coordinates as you can see on attachment.
Anybody have any ideas/(algorithm,pseudo code) how can i solve it using javascript(FabricJS) ?
The code is already provided in the comment to your question.
But in short what you need to do is listed below:
Draw a rectangular on your image (objectBeingCropped)
Using the function objectBeingCropped.toDataURL() to export the cropped area (rectangular area on the image) in blob/url format to another image object's src.
Now draw the new image which you have the src as blob, on canvas using fabric.Image()

Create Thumbnail of MP3 Waveform in HTML5 Canvas

I would like to create a WaveForm image from an MP3 file on my server.
I have tried using the wavesurfer.js plugin. I would rather do it without a plugin, but I cannot find a tutorial or any good resources.
Now, I would like save a thumbnail of the waveform (from mp3 file) on my server. As wavesurfer.js uses an HTML5 Canvas, I don't know how to create a thumbnail of the waveform. How can I create a thumbnail?
This article explains how they got audio wave form images in the browser.
http://www.bbc.co.uk/rd/blog/2013/10/audio-waveforms
This can be used to interact with, generate etc. waveform data (e.g. into JSON).
https://github.com/bbcrd/peaks.js
This can be used for drawing in the canvas.
https://github.com/bbcrd/waveform-data.js
You can created a thumbnail by scaling the canvas image down to the desired size and then uploading this to your server, although the same is true for wavesurfer.js
You can use http://www.w3schools.com/tags/canvas_scale.asp to scale canvas images. You can alter the canvas size using it's width and height properties.

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