GPU-accelerated CSS properties

GPU-accelerated CSS properties leverage the power of the Graphics Processing Unit (GPU) to offload rendering tasks from the Central Processing Unit (CPU), resulting in smoother and more efficient animations and transitions. When certain CSS properties are modified using JavaScript, the rendering engine determines whether GPU acceleration should be applied based on a variety of factors. These factors can include the specific CSS properties being modified, the capabilities of the user’s device and browser, and other performance considerations.

Can you remember this short note I posted a couple of days before on my LinkedIn handle? If you have missed that, please find the link below:?https://www.dhirubhai.net/feed/update/urn:li:activity:706521953667691315. As promised, I have written about it in detail. In this article, my objective is to articulate some facts about a few CSS properties and how they leverage GPU to produce a better user experience. So, let's deep dive into this matter thoroughly.

How does it work?

When rendering an HTML component with CSS properties, the browser engine, CPU, and GPU work together in a coordinated manner to achieve the final rendered result. Here’s an overview of how these components collaborate:

Browser Engine (Render Engine):

The browser engine, responsible for parsing HTML-CSS, and executing JavaScript, initiates the rendering process.

It parses the HTML markup, constructs the Document Object Model (DOM), and processes the CSS to create the CSS Object Model (CSSOM).

The browser engine combines the DOM and CSSOM to form the Render Tree, which represents the final structure of elements to be rendered.

Layout (Reflow):

The layout phase, also known as reflow, calculates the size, position, and geometry of each element in the Render Tree.

The browser engine traverses the Render Tree, determining the dimensions and placement of each element based on its CSS properties, such as width, height, padding, margin, and positioning.

This process may involve recalculating the layout of parent and descendant elements affected by changes or dependencies.

Paint:

Once the layout is determined, the browser engine initiates the painting phase to convert the Render Tree into pixels on the screen.

It traverses the Render Tree, determining the visual styles and properties for each element, such as background color, border, and text styles.

The browser engine creates a series of drawing commands, often in a retained graphics system, to represent the visual appearance of the elements.

GPU Acceleration:

If GPU-accelerated CSS properties are present, the browser engine offloads some rendering tasks to the GPU.

The GPU performs parallel processing to handle graphics computations, including transformations, opacity changes, and other visual effects.

GPU acceleration enables faster rendering, smoother animations, and improved visual quality by leveraging the parallel processing power of the GPU.

Composition:

Once the GPU-accelerated rendering and other rendering tasks are complete, the browser engine composites the rendered elements together to form the final image to be displayed on the screen.

This process involves blending layers, handling transparency, and applying other composition-related operations.

Display:

Finally, the composed image is sent to the display hardware for presentation on the screen.

The display hardware refreshes the screen at a specific rate (display refresh rate), typically 60Hz or higher, to show the rendered content.

List of these special CSS properties

Here are some examples of GPU-accelerated CSS properties:

transfor

opacity

transition

will-change

backface-visibility

perspective and perspective-origin

filter

mask-image and mask-mode

mix-blend-mode

clip-path

shape-outside

image-rendering

paint-order

scroll-snap-type

scroll-behavior

scroll-snap-align

scroll-snap-stop

isolation

contain

overscroll-behavior

transform-style

animation and animation-fill-mode

image-rendering

will-change

user-select

cursor

overflow-scrolling

text-size-adjust

backdrop-filter

shape-rendering

image-rendering

webkit-appearancem        

How does GPU accelerate the rendering?

1. Parallel Processing:?GPUs are designed for parallel processing, allowing them to perform numerous calculations simultaneously. This parallelism is advantageous for rendering tasks that involve manipulating and transforming a large number of graphical elements.

2. Geometry Processing:?The GPU excels at processing geometric data, such as vertices and polygons. It performs operations like vertex transformations, perspective projection, and clipping, which are essential for rendering 2D and 3D graphics.

3. Rasterization:?Once the geometric data is processed, the GPU rasterizes the primitives (e.g., triangles) to determine the fragments (pixels) that need to be shaded and rendered. This includes operations like determining the coverage of each pixel, applying anti-aliasing techniques, and handling occlusion.

4. Shading and Texturing:?The GPU applies shading techniques to determine the final color and appearance of each fragment. This involves evaluating lighting models, applying materials and textures, and performing calculations like interpolation and texture mapping.

5. Compositing:?The GPU composites the shaded fragments together, taking into account factors like transparency, blending modes, and depth ordering. This process ensures that the final image accurately represents the composition of different graphical elements.

By offloading these computationally intensive rendering tasks to the GPU, the CPU is freed up to handle other non-graphical computations and maintain smooth overall performance. The parallel nature of GPU processing enables faster rendering, improved visual quality, and smoother animations and transitions.

Does it have any pitfalls?

Overusing GPU-accelerated CSS properties can have some potentially negative impacts, although it largely depends on the specific context and the performance characteristics of the target devices. Here are a few considerations:

1. Increased GPU Workload: GPU-accelerated CSS properties offload rendering tasks to the GPU, which can increase the workload on the GPU. If too many elements or properties are GPU-accelerated, it can strain the GPU and potentially lead to performance issues. This can result in decreased responsiveness, lower frame rates, and increased power consumption.
2. Compatibility and Performance Variations: GPU acceleration support and performance characteristics can vary across devices and browsers. While modern browsers generally handle GPU acceleration well, older or less-capable devices may struggle with excessive GPU usage. It’s crucial to test and optimize the performance of GPU-accelerated effects across a range of target devices to ensure a smooth user experience.
3. Battery Drain on Mobile Devices: GPU usage consumes more power compared to the CPU. Overusing GPU-accelerated effects, especially on mobile devices, can drain the battery faster. This can be a concern for applications or websites that heavily rely on battery-powered devices.
4. Increased Rendering Complexity: Complex GPU-accelerated effects, such as 3D transformations or heavy animations, require more computational resources and memory bandwidth. This can impact the overall performance and responsiveness of the page, particularly on devices with limited resources.
5. Accessibility Considerations: Some GPU-accelerated effects, like parallax scrolling or rapid animations, can introduce visual distractions and motion-related issues for users with certain visual impairments or vestibular disorders. It’s important to consider accessibility guidelines and provide options for users to customize or disable GPU-accelerated effects if needed.

How to use this optimally?

To mitigate the above-mentioned potential negative impacts, it’s recommended to refer to some crucial measures as follows:

• Use GPU-accelerated effects judiciously and only where they provide significant visual or user experience benefits.
• Test and optimize performance across a range of devices to ensure smooth rendering and responsiveness.
• Provide fallbacks or alternatives for devices that do not support or struggle with GPU acceleration.
• Consider the impact on accessibility and provide customization options for users.
• By balancing the usage of GPU-accelerated CSS properties and considering the performance implications, you can ensure a positive user experience across different devices and usage scenarios.

I know, many of us are used to using these CSS properties without knowing their relations with GPU acceleration. I hope that this knowledge sharing will add some value. So, please leave a comment about your opinion on this or how you use them in your projects.

By the way, I'd like to give an article link below that you might feel interested in as it illustrates how GPU acceleration works at the hardware level.?https://www.chromium.org/developers/design-documents/gpu-accelerated-compositing-in-chrome/?A special thanks to one of my acquainted netizens who shared this link in the comment section of my previous post. Happy learning and sharing!