Optimizing Performance in Fabric.js 5: 14 Best Practices and Tips

Fabric.js is a powerful library for handling Canvas interactions and rendering. While it's already a performant library, there are certain techniques you can employ to further improve the interaction and rendering speed.

In this article, we will explore some valuable tips for optimizing performance in Fabric.js.

Content Overview

1. Utilize renderonAddRemove
2. EnlivenObjects instead of loadFromJSON
3. Optimize by excluding non-interactive shapes
4. Utilize fabric.StaticCanvas
5. Fine-tune object properties
6. Enable object caching
7. Use requestAnimationFrame
8. Minimize Redraws
9. Use object grouping
10. Limit object complexity
11. Use event delegation for interactivity
12. Optimize rendering performance with fabric.util.requestRenderAll()
13. Optimize image loading with lazy loading
14. Dispose of unused objects and canvases

Utilize renderOnAddRemove

One of the recommended tips for optimizing performance in Fabric.js is to set the renderOnAddRemove property to false when initializing the canvas. By adding { renderOnAddRemove: false } to the fabric.Canvas constructor, you prevent Fabric from rerendering the entire canvas whenever an object is added or removed.

This significantly improves performance during the initial load when adding multiple shapes to the canvas.

const canvas = new fabric.Canvas("myId", { renderOnAddRemove: false });
canvas.renderAll(); // Call this whenever you want changes to be visible on the canvas

EnlivenObjects instead of loadFromJSON

While loadFromJSON is a useful function for deserializing JSON to the canvas, it has some drawbacks. It clears the canvas before loading the JSON objects and automatically calls renderAll, which can be inefficient if you have additional operations to perform afterward.

Instead, you can use the enlivenObjects function to parse the serialized Fabric.js JSON and add the objects to the canvas manually.

The rendering can be controlled more easily this way.

const canvas = new fabric.Canvas("myId", { renderOnAddRemove: false });
fabric.util.enlivenObjects([{}, {}, {}], (objs) => {
    objs.forEach((item) => {
        canvas.add(item);
    });
    canvas.renderAll(); // Make sure to call this once you're ready!
});

Optimize by excluding non-interactive shapes

Imagine you have a Fabric.js canvas with multiple shapes, but some of them are static and don't need to be interacted with.

You can convert those non-interactive layers into image representations.

Here's an example:

// Convert non-interactive layers to images
var nonInteractiveLayer = new fabric.Rect({
    width: 200,
    height: 200,
    fill: 'red'
});
var image = new Image();
image.src = canvas.toDataURL('png');

// Render the image as an HTML <img> tag
document.body.appendChild(image);

// Overlay the canvas on top of the image
canvas.setOverlayImage(image, canvas.renderAll.bind(canvas));

By rendering non-interactive layers as images, you reduce the workload on Fabric.js and improve performance.

Utilize fabric.StaticCanvas

If you don't need interactivity in your canvas, you can use fabric.StaticCanvas instead of fabric.Canvas.

Here's an example:

// Create a static canvas
var staticCanvas = new fabric.StaticCanvas('myCanvas');

// Add objects to the static canvas
var rect = new fabric.Rect({
    width: 100,
    height: 100,
    fill: 'blue'
});
staticCanvas.add(rect);

// Perform other operations on the static canvas
// ...

// Render the static canvas
staticCanvas.renderAll();

Using fabric.StaticCanvas instead of fabric.Canvas improves performance by avoiding the rendering of controls, borders, and corner detection.

Fine-tune object properties

To optimize performance, you can fine-tune certain properties of objects in Fabric.js.

Here are some examples:

// Disable selection for an object
object.selectable = false;

// Disable controls and borders for an object
object.hasControls = false;
object.hasBorders = false;

// Disable rotating point for an object
object.hasRotatingPoint = false;

// Disable selection for the entire canvas
canvas.selection = false;

// Toggle skipTargetFind for mouse movement optimization
canvas.skipTargetFind = true; // or false, depending on your needs

By adjusting these properties, you can improve performance by avoiding unnecessary rendering of controls, borders, and object corner detection during mouse movement.

Enable object caching

Fabric.js provides automatic object caching, where objects are pre-painted on an offscreen canvas and then copied onto the main canvas during the rendering process. Object caching can significantly improve performance, especially when dealing with complex objects or large SVGs. By default, object caching is enabled in Fabric.js.

You can customize the caching behavior using the following properties:

• objectCaching: When set to true, objects are cached on an additional canvas. By default, this property is true for browsers and false for Node.js.

  
  

• statefulCache: When set to true, Fabric.js checks object properties for cache invalidation. If disabled, you may need to manually invalidate the cache when necessary. By default, this property is false.

  
  

• noScaleCache: When set to true, cache regeneration is disabled during scaling operations. This can help avoid blurry effects during scaling. By default, this property is true.

  
  

• dirty: This flag indicates whether the object's cache needs to be rerendered. It is automatically set to false after cache regeneration.

  
  

• needsItsOwnCache: A function that, when returning true, forces the object to have its own isolated cache, even if it is inside a group. By default, this function returns false.

Use requestAnimationFrame

To ensure smooth and efficient animation in Fabric.js, use the requestAnimationFrame function to update the canvas. Syncing this function with the browser's rendering engine results in better performance and smoother animations.

Here's an example:

function animate() {
  // Update canvas and objects here

  // Request the next animation frame
  fabric.util.requestAnimFrame(animate);
}

// Start the animation
animate();

By usingrequestAnimationFrame, you optimize the animation performance in Fabric.js.

Minimize Redraws

To avoid unnecessary redraws and improve performance, use the dirty property to track changes and selectively render only the objects that need updating. It is especially useful when you have a large canvas with a lot of objects on it.

Here's an example:

// Set an object as dirty to indicate changes
object.dirty = true;

// Render only dirty objects
canvas.renderAll();

// Reset dirty state after rendering
object.dirty = false;

By minimizing redraws to only the necessary objects, you optimize performance in Fabric.js.

Use object grouping

When you have multiple objects that are frequently updated together or share common properties, consider grouping them using fabric.Group. Grouping objects reduces the number of individual objects that Fabric.js needs to render and update, improving performance.

You can still interact with and manipulate the grouped objects as a single entity.

Here's an example:

// Create objects
var rect1 = new fabric.Rect({
    width: 50,
    height: 50,
    fill: 'red'
});
var rect2 = new fabric.Rect({
    width: 50,
    height: 50,
    fill: 'blue'
});

// Group objects
var group = new fabric.Group([rect1, rect2]);

// Add group to the canvas
canvas.add(group);

Limit object complexity

If you have complex objects with a large number of points, paths, or patterns, consider simplifying or optimizing them to improve performance. Simplifying the geometry or reducing the number of points in paths can significantly reduce the rendering and manipulation time for those objects. Additionally, avoid using overly large or high-resolution images as object fills or patterns, as they can slow down the rendering process.

Use event delegation for interactivity

With Fabric.js, you can respond to user interactions, such as clicks, mouse movements, and keyboard inputs. However, attaching event listeners to each individual object on the canvas can become inefficient, especially with a large number of objects.

To optimize performance, you can utilize event delegation. Instead of attaching event listeners to each object, you attach a single event listener to the canvas itself and use event delegation to handle the events.

Here's an example of using event delegation for mouse clicks:

canvas.on('mouse:down', function(event) {
  var target = event.target;
  // Handle the click event on the target object
  if (target) {
    // Do something with the clicked object
  }
});

By using event delegation, you reduce the number of event listeners and improve performance, especially when dealing with a complex canvas with many interactive objects.

Optimize rendering performance with fabric.util.requestRenderAll()

Fabric.js provides a utility function called fabric.util.requestRenderAll() that can be used to optimize rendering performance, especially when you have multiple changes happening on the canvas simultaneously.

Instead of calling canvas.renderAll() multiple times after each change, you can use fabric.util.requestRenderAll() to batch the rendering calls and ensure efficient rendering.

Here's an example:

fabric.util.requestRenderAll(); // Request rendering for all changes

// Make multiple changes to the canvas
object1.set({
    left: 100,
    top: 100
});
object2.set({
    fill: 'blue'
});
object3.remove();

// Call renderAll() once after making all the changes
canvas.renderAll();

By using fabric.util.requestRenderAll(), you optimize rendering performance by avoiding unnecessary intermediate rendering calls and ensuring that the final rendering is done efficiently.

Use canvas.renderAll() or canvas.requestRenderAll() at the appropriate point in your code to trigger actual canvas rendering.

Optimize image loading with lazy loading

If your canvas contains a large number of images or complex image assets, loading all of them upfront can slow down the initial rendering process. To improve performance, consider implementing lazy loading techniques for image assets.

Lazy loading involves loading images only when they are needed or when they come into the viewport. By deferring the loading of images that are initially out of view or not immediately required, you can reduce the initial load time and improve the overall performance of your Fabric.js canvas.

Here's an example of lazy loading images in Fabric.js

var imageElement = document.createElement('img');
imageElement.src = 'path/to/image.jpg';

// Add the image to the canvas when needed
imageElement.onload = function() {
    var fabricImage = new fabric.Image(imageElement);
    canvas.add(fabricImage);
};

By dynamically loading images when necessary, you can optimize the performance of your canvas and provide a smoother user experience, especially when dealing with large or numerous image assets.

Remember to handle any error cases and implement appropriate fallback mechanisms to ensure that images are still loaded correctly even if lazy loading fails for any reason.

Implementing lazy loading for images can be particularly beneficial when dealing with complex applications or scenarios where image assets are fetched dynamically based on user interactions or specific events.

Dispose of unused objects and canvases

When you no longer need certain objects or canvases in your Fabric.js application, it's important to dispose of them properly to free up memory and improve performance.

Canvas objects that are no longer needed should be removed from the canvas by calling the canvas.remove(object) method.

To properly dispose of canvas objects that are no longer in use, call canvas.dispose(). This will release any resources associated with the canvas and improve memory management.

Here's an example:

// Remove an object from the canvas
canvas.remove(object);

// Dispose of a canvas
canvas.dispose();

By disposing of unused objects and canvases, you prevent unnecessary memory usage and improve the overall performance of your Fabric.js application.

It's important to regularly check your code for any objects or canvases that are no longer needed and properly dispose of them. This practice helps maintain a lean and efficient application, especially when dealing with large or complex scenarios.

Conclusion

In conclusion, Fabric.js is a powerful library for Canvas interactions and rendering. To optimize its performance, you can employ the following techniques:

1. Utilize renderOnAddRemove: Set the renderOnAddRemove property to false when initializing the canvas to prevent the entire canvas from being rerendered when objects are added or removed.

   
   

2. Use enlivenObjects instead of loadFromJSON: Instead of using loadFromJSON, use enlivenObjects to manually add serialized JSON objects to the canvas, giving you more control over rendering and additional operations after loading.

   
   

3. Optimize by excluding non-interactive shapes: Convert non-interactive layers into image representations to reduce the workload on Fabric.js. Render those layers as images and overlay the canvas on top.

   
   

4. Utilize fabric.StaticCanvas: If interactivity is not needed, use fabric.StaticCanvas instead of fabric.Canvas to avoid rendering controls, borders, and corner detection.

   
   

5. Fine-tune object properties: Adjust object properties like selection, controls, borders, rotating points, and canvas selection to optimize performance.

   
   

6. Enable object caching: Take advantage of automatic object caching in Fabric.js to improve performance for complex objects or large SVGs. Customize caching behavior using properties like objectCaching, statefulCache, noScaleCache, dirty, and needsItsOwnCache.

   
   

7. Use requestAnimationFrame: Use requestAnimationFrame to update the canvas for smooth and efficient animation.

   
   

8. Minimize redraws: Use the dirty property to track changes and selectively render only the objects that need updating.

   
   

9. Use object grouping: Group objects together using fabric.Group to reduce the number of individual objects that need rendering and updating.

   
   

10. Limit object complexity: Simplify or optimize complex objects with a large number of points, paths, or patterns to improve performance.

    
    

11. Use event delegation for interactivity: Attach a single event listener to the canvas and utilize event delegation to handle events for multiple objects efficiently.

    
    

12. Optimize rendering performance with fabric.util.requestRenderAll(): Use this utility function to batch rendering calls when making multiple changes to the canvas.

    
    

13. Optimize image loading with lazy loading: Implement lazy loading techniques to load images only when needed, reducing initial load time.

    
    

14. Dispose of unused objects and canvases: Properly remove objects from the canvas and dispose of unused canvases to free up memory and improve performance.

You can optimize Fabric.js' performance and enhance your applications' user experience by applying these techniques.