Scrawl-canvas VS fabric.js

> working with glyphs and iterating them in reverse for RTL is brain-breaking. And line wrapping gets really complicated. It's also the most obscure because nobody has written down everything you need to know in one place

I can confirm this. I've been working on a (much simpler!) text layout engine for my canvas library over the past couple of months and the amount of complexity associated with just stamping some glyphs onto a canvas has left me screaming at my laptop on an almost daily basis. Getting a decent underline was a proud moment!

Question: did you ever find out what algorithm the various browsers are using to calculate how many words can fit on a given line? I'm almost there, except words will occasionally jump between lines when I scale the text. Really annoying!

The PR's still a work in progress, but I've got all the functionality I want in there (shaping lines to fit in non-rectangular containers, styling text, text along a non-straight line, dynamic updates, etc). Just need to test and document it all now ... https://github.com/KaliedaRik/Scrawl-canvas/pull/75

I've got myself organised and prepared a List Of Things To Do[1] to make my 2D Javascript library even better than it already is. Given that I've been working on the library for over 10 years now, and have never before set out such a list, I call this Progress!

[1] https://github.com/KaliedaRik/Scrawl-canvas/discussions/cate...

'Kay, I don't know if this anywhere close to what the OP wants, but this sort of live browser tab manipulation is possible to do using a mix of a a canvas element and the browser's Screen Capture API[1] (plus my JS canvas library, once I merge and publish the changes into its next release[2]).

This solution[3] shows the modified browser tab in a separate browser tab. I've got no idea whether it's possible to do the same sort of trick in the same tab (but probably not). I also have no idea how secure the Screen Capture API is - I'd get very nervous about doing this sort of thing when looking at my bank's online portal!

[1] https://developer.mozilla.org/en-US/docs/Web/API/Screen_Capt...

[2] https://github.com/KaliedaRik/Scrawl-canvas/pull/57

[3] Youtube video of the effect: https://www.youtube.com/watch?v=hCi6LmKMAo0

My canvas library's README[1] has a video embedded in it. FWIW I'm not convinced it adds anything to the library's sales pitch.

[1] https://github.com/KaliedaRik/Scrawl-canvas

> And I’m just mentioning some of the unfixable problems with this approach

I agree that using a canvas instead of leveraging existing accessibility supplied by HTML/CSS/JS and the DOM is an accessibility nightmare.

However, I disagree that canvas accessibility issues are "unfixable". Difficult? Yes. But not unfixable. In my view, the element works best in partnership with its wider environment (HTML/CSS/JS and the DOM), not as a replacement for it. With that in mind, we can start to tackle the accessibility issues you raise - fonts, links, interactions, etc.[1][2]

I have an ambition to one day become intelligent enough to understand/code in Rust, and I'm really glad to see that people are thinking about accessibility as a fundamental part of UIs being developed in Rust.

[1] - Which is what my JS 2d canvas library tries to do: https://scrawl-v8.rikweb.org.uk/

[2] - My thoughts on accessibility, and how I try to fix them using my library: https://scrawl-v8.rikweb.org.uk/learn/eleventh-lesson/

If, however, your company is set on this course, I very strongly suggest you use a canvas library - if only for the MVP. Here's my canvas library (spam alert!) ... even if you don't use it in your product, the library might help give you some ideas on how to overcome some of the responsive, interactive and accessibility issues you'll be facing.

Scrawl-canvas - example and another example (links to code at bottom of each page)

My personal experience as a library developer, who has written my library in JS, not TS ...

TS is an excellent choice for a lib dev starting a new project today. I can see the advantages of using TS for the library code - in particular for a library that gets popular and welcomes contributions from other developers. However TS is a nightmare for someone like me who: 1. started writing the library 9 years ago; 2. has let the library get "quite" big; and 3. has only learned to use TS in the past year (for the day job) and is nowhere near to becoming a types expert.

I've had experience of people suggesting I rewrite the library in TS. Sometimes those suggestions have been quite 'evangelical' in their tone. As an (essentially) solo developer I just don't have the time, capacity or willingness to do that work - however much the end results might please others.

I also understand that having type definitions file for the library's interface is, nowadays, a critical factor if the lib dev wants others to use the library in their projects. But writing a .d.ts file for a large, mature repo to at least help those potential users can quickly turn into a World of Hurt. I know this because I've done that work[1] and I never want to do it again.

As much as I know that TS is a Force for Good in the JS coding world, there are days when I detest it!

[1] - link to the Scrawl-canvas .d.ts file on GitHub - https://github.com/KaliedaRik/Scrawl-canvas/blob/master/sour...

This AI-powered Story Card Maker is built as a SvelteKit application with Typescript. Using Flowbite Svelte component library, the whole application was laid out. The layout for the Story Card (emulating the size of a postcard - 4" x 3") is created as an HTML Canvas using Fabric.js.

Fabric.js is a powerful and simple Javascript HTML5 canvas library. It provides an interactive object model on top of the canvas element. Fabric also has SVG-to-canvas (and canvas-to-SVG) parser.

Based on this, I found that some of the libraries are dead and no longer have any support. Only two libraries are still alive and have significant amount of stars on GitHub and downloads on NPM. They are Fabric.js and Konva.js.

I'm actually in the process of building something similar. It's a React app and I'm using the FabricJs library

I've played with this tech in early 2010s - they are using HTML5 Canvas tech + something like Fabric.js(http://fabricjs.com/) that controls Canvas objects.

this library might help you: http://fabricjs.com/

I did some research and the most promising result was using Fabric.js (http://fabricjs.com/) to put images on products. I may not be experienced enough in JS to understand the full capabilities of this library, but it looks like most of their stuff works on flat surfaces. I am trying to replicate the properly wrapped/textured affect that is achieved in the blanket below.

set up a canvas drawing & rendering framework, for example http://fabricjs.com/

body{ display:flex; flex-direction:column; align-items:center; }

Learning Fabric

Enter fullscreen mode Exit fullscreen mode

Next, we initiate a Canvas instance in our script tag:

Syntax

new fabric.Canvas(element: HTMLElement|String, options: Object)

Enter fullscreen mode Exit fullscreen mode

This allows Fabric.js to create this class instance so that we can use the provided methods of Fabric.js:

const canvas = new fabric.Canvas("canvas", {})

Enter fullscreen mode Exit fullscreen mode

Now, we’ll go ahead and give our canvas different properties, such as width, height, and background color:

const canvas = new fabric.Canvas("canvas", {
 width:500,
 height:500,
 backgroundColor:green
})

Enter fullscreen mode Exit fullscreen mode

Output

Creating a Rectangle with Fabric.js

Now that we’ve initialized a canvas and given it various properties, we’re going to create a rectangle using the Fabric.js object fabric.Rect:

Syntax

new fabric.Rect({object})

Enter fullscreen mode Exit fullscreen mode

Here the object houses the rectangle properties:

const canvas = new fabric.Canvas("canvas", {
 width:500,
 height:500,
 backgroundColor:green
});

const rectangle = new fabric.Rect({
 width:200,
 height:200,
 /* fill is used to define the background color*/
    fill:'red'
})
/*the add method is used to add objects to the canvas element */
canvas.add(rectangle)
/*the renderAll method used to render the canvas*/
canvas.renderAll();

Enter fullscreen mode Exit fullscreen mode

The add() method is used to add objects to the Canvas element. In this case, it adds the rectangle we created to the canvas:

Output

Creating a Circle

In the same way, we’ll create a circle. This time, we’ll use fabric.Circle:

const canvas = new fabric.Canvas("canvas", {
 width:500,
 height:500,
 backgroundColor:"lightgray"
});

const circle = new fabric.Circle({
 radius:60,
 fill:"blue"
})
canvas.add(circle);
canvas.renderALl();

Enter fullscreen mode Exit fullscreen mode

Output

With the above steps, we created a rectangle and a circle using Fabric.js. Note how interactive the objects are! Next, we’ll discuss images in Fabric.js.

Images with Fabric

The Fabric.Image is a Fabric.js object used to render images on a canvas. With Fabric.js, we can interact with the image. Images can be added to our canvas in two ways:

• Fabric.Image
• Fabric.Image.fromURL

Using the Fabric.Image constructor requires us to create an image element in our HTML and then insert it into the constructor:

Syntax

fabric.Image(image_element)

Enter fullscreen mode Exit fullscreen mode

HTML

Enter fullscreen mode Exit fullscreen mode

JS

const image_element = document.querySelector('#image');
const image = new fabric.Image(image_element)
canvas.add(image);
canvas.renderAll();

Enter fullscreen mode Exit fullscreen mode

However, Fabric.Image.fromURL requires only the image URL (the URL can be retrieved from a website or your local folder), and is simpler than the former:

fabric.Image.fromURL(URL, function());

Enter fullscreen mode Exit fullscreen mode

After passing the URL, the callback function after the image is loaded. The first default parameter of the callback function is the fabric.Image object. Now, we can modify the image properties and then add it to the canvas:

const canvas = new fabric.Canvas("canvas", {
 width:500,
 height:500,
 backgroundColor:"White"
});

fabric.Image.fromURL('my_image.png',(img) => {
 // the scaleToHeight property is use to set the image height
    img.scaleToHeight(250)
 // scaleToWidth is use to set the image width
    img.scaleToWidth(250)
    canvas.add(img)  
})
canvas.renderAll()

Enter fullscreen mode Exit fullscreen mode

Output

Editing Images with Fabric.js

Now that we know how to insert an image into a canvas, we’ll look at other image objects like image filters.

Image Filters

Fabric.js provides us with built-in filters:

• BaseFilter
• Brightness
• convolute
• GradientTransparency
• Grayscale
• Invert
• Mask
• Noise
• Pixelate
• RemoveWhite
• Sepia
• Sepia2
• Tint

Every instance of fabric.Image has the "filters" property, which is a simple array of filters. We can use the array method to perform any required operation, including removing filters (pop, slice, shift), adding filters (push, unshift, slice), and even combining multiple filters. When we call applyFilters, any filter in the “filters” array will be applied one by one. Let’s use some of these filters:

Syntax

new fabric.Image.filters
// after that you can add any filter of your choice
// Example 
new fabric.Image.filters.Grayscale()

Enter fullscreen mode Exit fullscreen mode

fabric.Image.fromURL('my_image.png', (image) => {
      image.scaleToHeight(300)
       image.ScaleToWidth(300)

 // Creating filter
 const filter = new fabric.Image.filters.Grayscale()

 //push the filter instance to filters
        image.filter.push(filter)

 // apply filter
         image.applyFilters()

 //add image into canvas (it also re-render the canvas)
         canvas.add(image)
},{crossOrigin: 'anonymous'});
canvas.renderAll();

Enter fullscreen mode Exit fullscreen mode

Output

Above, we used the Grayscale filter; we can also apply other filters. All we have to do is simply change the filter, as shown in this example:

fabric.Image.fromURL('my_image.png', (image) => {
      image.scaleToHeight(300)
       image.ScaleToWidth(300)

 // creating filter
 const filter = new fabric.Image.filters.Sepia()

 //add filter
        image.filter.push(filter)

 // apply filter
         image.applyFilters()

 //add image into canvas (it also re-render the canvas)
         canvas.add(image)
},{crossOrigin: 'anonymous'});
canvas.renderAll();

Enter fullscreen mode Exit fullscreen mode

Output

Image Blending

Blending is mixing two or more images to create a new image. Fabric.js gives us this ability. Here, we’re going to use the image blending filter for our image:

Syntax

new fabric.Image.filters.BlendImage({
 // the image that we want to blend
          image:imageA,
 // blend mode (in this case we are using the 'add' mode)
          mode:'add',

 alpha:0.5
      });

Enter fullscreen mode Exit fullscreen mode

fabric.Image.fromURL('my_image.png', (imageA) => {
    imageA.scaleToWidth(350)
    imageA.scaleToHeight(350)
    canvas.add(imageA)

 // Blending filter
    filter = new fabric.Image.filters.BlendImage({
 image:imageA,
 mode:'add',
 alpha:0.5
      });

 //Add the second image  
     fabric.Image.fromURL('my_image2.png',(imageB) => {
           imageB.scaleToHeight(100),
            imageB.scaleToWidth(100),
            canvas.add(imageB)
       }, {crossOrigin:''});

     imageA.filters.push(filter);
     imageA.applyFilters(canvas.renderAll.bind(canvas));
},{crossOrigin:''})

Enter fullscreen mode Exit fullscreen mode

Output

Image Clipping

A very popular effect used today is image clipping, or rather image cropping, which is done to remove parts of an image that we don’t want. With Fabric.js, we can achieve this by using the clipPath method.

First, we have to create our own clipPath using any Fabric.js object. Then, we’ll assign it to the clipPath property of the object we want to clip. Here, we’ll use a circle object:

const clipPath = new fabric.Circle({
 radius:150,
 top:200,
 left:250,
 // The originY and originX helps to center the image and the clipPath
    originY:"center",
 originX:"center"
})

Enter fullscreen mode Exit fullscreen mode

After that, we add it to the image that we want to clip using the filter method:

new fabric.Image.fromURL('my_image.png',(img) => {
  img.scaleToHeight(300)
  img.scaleToWidth(300)
 // positioning the image
  img.scale(o.5).set({top:50,left:100})
 // Clip Path
  clipPath = new fabric.Circle({
 radius:150,
 top:200,
 left:250,
 originY:"center",
 originX:"center"
    })
  canvas.add(img)
  canvas.clipPath = clipPath;
  });
canvas.renderAll();

Enter fullscreen mode Exit fullscreen mode

Output

Image Blurring

Like other image filters, the blur filter accepts objects because they can be adjusted. A practical example is changing the brightness of an image. You can apply other image filters without any additional configurations (like grayscale, invert, or sepia). Other image filters like brightness, pixelate, tint, and noise all operate in this way, too. However, the difference is that their values are not the same. The brightness filter's actual brightness level ranges from-1 (full black) to 1 (full white). The noise filter's value is between 0 and 1000. For the blur filter, the value ranges from 0 to 10.

Syntax

new fabric.Image.filters.Blur(object)

Enter fullscreen mode Exit fullscreen mode

fabric.Image.fromURL('my_image.png', (image) => {
      image.scaleToHeight(300)
       image.ScaleToWidth(300)

 // Creating the blur filter
 const filter = new fabric.Image.filters.Blur({
 blur:0.6
       })

 //push the filter instance to filters
        image.filter.push(filter)
         image.applyFilters()
         canvas.add(image)
},{crossOrigin: 'anonymous'});
canvas.renderAll();

Enter fullscreen mode Exit fullscreen mode

Output

Conclusion

In conclusion, Fabric.js gives us an awesome experience when working with Canvas. It also provides a lot of features, some of which we covered in this article. For full details on some of the Fabric.js objects, you can review its documentation here.