PHP生成的特定图像尺寸

Question

As we know, if we specify width and height attributes in <img /> element, browser can immidiately locate image in rendered layout. It's not a really big boost of speed, but it's really nice optimisation practice.

Ok, but sometimes image has different dimensions. So we can get it by PHP getimagesize() function.

And here is the question, if we don't have specific dimensions is it worthwhile to use PHP? Of course, we have to write additional code, but if we cope with gallery we anyhow use PHP, so in that case it's only 2 lines of code.

What is your opinion?

Answer 1

It depends on what you're trying to do. The benefits of having the dimensions on the <img/> tag are:

1. Browser knows the space to reserve for the image as it's downloaded. This means your layout won't jump around as the images load.
2. It saves the browser from performing a reflow and repaint once the images load (speed optimization).
3. You'll have the dimensions available to any Javascript processing as soon as the HTML is finished loading.

On the other hand, adding the dimensions will increase your page size and cause you to use more bandwidth.