To make this possible, I also had to give each LayoutNode a Document&
so it can resolve document-specific colors correctly. There's probably
ways to avoid having this extra member by resolving colors later, but
this works for now.
We now use the ImageDecoder service in LibWeb for everything except
GIF images (we'll have to deal with them later, ofc.)
This has a little bit of overhead but we should be able to optimize
it until it becomes negligible.
Since more DOM nodes are going to want to load images (<object>, ...)
this patch splits out the image loading logic into an ImageLoader class
and then HTMLImageElement simply has an ImageLoader.
LayoutImage is then given a const ImageLoader& at construction and can
then provide layout and rendering for many kinds of DOM nodes.
This patch adds ImageResource as a subclass of Resource. This new class
also keeps a Gfx::ImageDecoder so that we can share decoded bitmaps
between all clients of an image resource inside LibWeb.
With this, we now share both encoded and decoded data for images. :^)
I had to change how the purgeable-volatile flag is updated to keep the
volatile-images-outside-the-visible-viewport optimization working.
HTMLImageElement now inherits from ImageResourceClient (a subclass of
ResourceClient with additional image-specific stuff) and informs its
ImageResource about whether it's inside the viewport or outside.
This is pretty awesome! :^)
A Resource represents a resource that we're loading, have loaded or
will soon load. Basically, it's a downloadable resource that can be
shared by multiple clients.
A typical usecase is multiple <img> elements with the same src.
In a future patch, we will try to make sure that those <img> elements
get the same Resource if possible. This will reduce network usage,
memory usage, and CPU usage. :^)
For now, this first patch simply introduces the mechanism.
You get a Resource by calling ResourceLoader::load_resource().
To get notified about changes to a Resource's load status, you inherit
from ResourceClient and implement the callbacks you're interested in.
This patch turns HTMLImageElement into a ResourceClient.
