为什么使用 Transform 属性？

Why Use the Transform Property?

The transform property in CSS is a powerful tool that allows developers to manipulate the visual appearance of an element without affecting its layout. This ability makes transform particularly valuable for optimizing performance, especially in scenarios where animations or interactive elements need to be frequently updated.

CSS 中的 transform 属性是一个强大的工具，允许开发人员在不影响元素布局的情况下操控其视觉外观。这种能力使 transform 在优化性能方面尤为宝贵，尤其是在需要频繁更新动画或交互元素的场景中。

1. How Transform Avoids Triggering Reflow

Transform 如何避免触发 Reflow

Impact on Visual Presentation, Not Layout

影响视觉呈现，而非布局

The transform property allows you to apply various transformations to an element, such as scaling, rotating, translating (moving), or skewing. These transformations change how the element is visually presented on the screen but do not alter its position in the document flow or the layout of surrounding elements.

This means that using transform does not require the browser to recalculate the layout of the page (reflow), which can be a computationally expensive process. Instead, transform manipulations are handled by the browser’s rendering engine, often directly by the GPU, making them much more efficient.

transform 属性允许您对元素应用各种变换，例如缩放、旋转、平移（移动）或倾斜。这些变换改变了元素在屏幕上的视觉呈现方式，但不会改变其在文档流中的位置或周围元素的布局。

这意味着使用 transform 不需要浏览器重新计算页面的布局（Reflow），这可能是一个计算成本很高的过程。相反，transform 的操作由浏览器的渲染引擎处理，通常直接由 GPU 处理，使得它们更为高效。

Example: Scaling an Element Without Reflow

示例：缩放元素而不触发 Reflow

.element {
    transition: transform 0.5s ease;
}

.element:hover {
    transform: scale(1.2);
}

Explanation:

• In this example, when the user hovers over the element, it scales up by 20%. This change is handled entirely by the GPU, as transform: scale only affects the rendering of the element, not its layout. No reflow is triggered, which helps maintain smooth performance.

解释：

• 在这个示例中，当用户将鼠标悬停在元素上时，元素会放大 20%。这个变化完全由 GPU 处理，因为 transform: scale 只影响元素的渲染，而不影响其布局。没有触发 Reflow，有助于保持流畅的性能。

2. Performance Benefits of Using Transform

使用 Transform 的性能优势

1. GPU Acceleration

GPU 加速

One of the major advantages of using the transform property is that it leverages GPU acceleration. When you apply transformations like scaling, rotating, or translating, the browser can offload these tasks to the GPU, which is specifically designed to handle complex graphical computations efficiently.

This offloading reduces the workload on the CPU, leading to faster and smoother animations, especially on devices with limited processing power.

使用 transform 属性的主要优势之一是它利用了 GPU 加速。当您应用缩放、旋转或平移等变换时，浏览器可以将这些任务卸载到 GPU 上，而 GPU 专门设计用于高效处理复杂的图形计算。

这种卸载减少了 CPU 的工作负载，从而带来更快、更流畅的动画，尤其是在处理能力有限的设备上。

2. Avoiding Layout Thrashing

避免布局抖动

Layout thrashing occurs when the browser is forced to repeatedly reflow the page due to frequent changes in layout properties. This can cause significant performance issues, particularly in complex or large-scale web applications.

By using transform for animations or dynamic effects, you avoid triggering reflows, thereby preventing layout thrashing. This leads to more efficient rendering and a better user experience.

布局抖动发生在由于布局属性的频繁更改，浏览器被迫反复重新布局页面时。这可能会导致显著的性能问题，特别是在复杂或大规模的 Web 应用程序中。

通过使用 transform 进行动画或动态效果，可以避免触发 Reflow，从而防止布局抖动。这带来了更高效的渲染和更好的用户体验。

3. Smoother Animations

更流畅的动画

Animations created with transform are typically smoother and more performant than those created by changing properties that trigger reflow, such as width, height, or margin. Because transform manipulations are handled by the GPU, they can be updated at a higher frame rate, resulting in a more fluid visual experience.

通过改变触发 Reflow 的属性（如 width、height 或 margin）创建的动画，通常不如使用 transform 创建的动画流畅且性能更好。因为 transform 操作由 GPU 处理，它们可以以更高的帧率更新，从而带来更流畅的视觉体验。

Example: Animated Transformations

示例：动画变换

.element {
    transition: transform 1s ease-in-out;
}

.element:hover {
    transform: rotate(45deg) translateX(50px);
}

Explanation:

• In this example, the element rotates 45 degrees and moves 50 pixels to the right when hovered over. These transformations are handled by the GPU, ensuring that the animation is smooth and does not trigger reflow.

解释：

• 在这个示例中，当鼠标悬停时，元素旋转 45 度并向右移动 50 像素。这些变换由 GPU 处理，确保动画流畅且不触发 Reflow。

3. Best Practices for Using Transform

使用 Transform 的最佳实践

1. Use for Animations and Interactive Elements

用于动画和交互元素

Whenever possible, use transform for creating animations and effects on interactive elements. This approach minimizes performance issues and ensures that your animations run smoothly, even on devices with lower processing power.

尽可能使用 transform 为交互元素创建动画和效果。这种方法最小化了性能问题，确保即使在处理能力较低的设备上，您的动画也能流畅运行。

2. Combine with will-change for Complex Animations

结合 will-change 进行复杂动画

If you plan to apply complex or frequent transformations to an element, consider using the will-change property. This tells the browser to optimize the rendering of the element in advance, which can further enhance performance.

如果您计划对元素应用复杂或频繁的变换，请考虑使用 will-change 属性。这告诉浏览器提前优化元素的渲染，这可以进一步提高性能。

.element {
    will-change: transform;
}

Explanation:

• The will-change: transform property informs the browser that the element will likely be transformed in the near future, allowing it to make optimizations in advance.

解释：

• will-change: transform 属性告诉浏览器该元素在不久的将来可能会被变换，从而允许它提前进行优化。

3. Avoid Overusing Transform

避免过度使用 Transform

While transform is a powerful tool, it’s important not to overuse it. Applying too many transformations or using them in ways that are not necessary can still lead to performance issues. Use transform strategically, focusing on elements that require it for animations or specific visual effects.

虽然 transform 是一个强大的工具，但重要的是不要过度使用它。应用过多的变换或以不必要的方式使用它们，仍可能导致性能问题。请策略性地使用 transform，专注于需要它来进行动画或特定视觉效果的元素。

4. Conclusion

结论

The transform property is an essential tool for optimizing the performance of web pages, especially when it comes to animations and interactive elements. By allowing developers to manipulate the visual presentation of elements without triggering reflows, transform helps ensure smooth, efficient rendering. Understanding when and how to use transform effectively can lead to significant performance improvements in your web applications, providing users with a more responsive and enjoyable experience.

transform 属性是优化网页性能的一个重要工具，尤其是在涉及动画和交互元素时。通过允许开发人员在不触发 Reflow 的情况下操控元素的视觉呈现，transform 有助于确保流畅、高效的渲染。理解何时以及如何有效地使用 transform 可以显著提高您的 Web 应用程序的性能，为用户提供更响应和愉快的体验。