Crate webrender

source ·
Expand description

A GPU based renderer for the web.

It serves as an experimental render backend for Servo, but it can also be used as such in a standalone application.

External dependencies

WebRender currently depends on FreeType

Api Structure

The main entry point to WebRender is the crate::Renderer.

By calling Renderer::new(...) you get a Renderer, as well as a RenderApiSender. Your Renderer is responsible to render the previously processed frames onto the screen.

By calling yourRenderApiSender.create_api(), you’ll get a RenderApi instance, which is responsible for managing resources and documents. A worker thread is used internally to untie the workload from the application thread and therefore be able to make better use of multicore systems.


What is referred to as a frame, is the current geometry on the screen. A new Frame is created by calling set_display_list() on the RenderApi. When the geometry is processed, the application will be informed via a RenderNotifier, a callback which you pass to Renderer::new. More information about stacking contexts.

set_display_list() also needs to be supplied with BuiltDisplayLists. These are obtained by finalizing a DisplayListBuilder. These are used to draw your geometry. But it doesn’t only contain trivial geometry, it can also store another StackingContext, as they’re nestable.


pub extern crate api;
pub extern crate euclid;
pub use api as webrender_api;


batch 🔒
border 🔒
box_shadow 🔒
capture 🔒
clip 🔒
Internal representation of clips in WebRender.
composite 🔒
device 🔒
ellipse 🔒
filterdata 🔒
freelist 🔒
A generic backing store for caches.
gpu_cache 🔒
Overview of the GPU cache.
gpu_types 🔒
hit_test 🔒
intern 🔒
The interning module provides a generic data structure interning container. It is similar in concept to a traditional string interning container, but it is specialized to the WR thread model.
lru_cache 🔒
picture 🔒
A picture represents a dynamically rendered image.
platform 🔒
prim_store 🔒
print_tree 🔒
profiler 🔒
The high-level module responsible for managing the pipeline and preparing commands to be issued by the Renderer.
This module contains the render task graph.
renderer 🔒
The high-level module responsible for interfacing with the GPU.
scene 🔒
Screen capture infrastructure for the Gecko Profiler and Composition Recorder.
segment 🔒
Primitive segmentation
shade 🔒
storage 🔒
util 🔒



A handle to a screenshot that is being asynchronously captured and scaled.
Flags to enable/disable various builtin debugging tools.
A globally, unique identifier
An arbitrary identifier for a native (OS compositor) surface
Information about a bound surface that the native compositor returns to WR.
A handle to a recorded frame that was captured.
Return type from render(), which contains some repr(C) statistics as well as some non-repr(C) data.
The renderer is responsible for submitting to the GPU the work prepared by the RenderBackend.
Some basic statistics about the rendered scene, used in Gecko, as well as in wrench reftests to ensure that tests are batching and/or allocating on render targets as we expect them to.
Flags that control how shaders are pre-cached, if at all.
A minimal subset of TileCacheInstance for debug capturing
Uniquely describes the content of this tile, in a way that can be (reasonably) efficiently hashed and compared.
A stable ID for a given tile, to help debugging. These are also used as unique identifiers for tile surfaces when using a native compositor.
A node in the dirty rect tracking quadtree.
A minimal subset of Tile for debug capturing


Optional extra information returned by is_same when logging is enabled.
Debugging information about why a tile was invalidated
The result of a primitive dependency comparison. Size is a u8 since this is a hot path in the code, and keeping the data small is a performance win.
A more detailed version of PrimitiveCompareResult used when debug logging is enabled.
Details for a node in a quadtree that tracks dirty rects for a tile.
Method of uploading texel data from CPU to GPU.



Allows callers to hook into the main render_backend loop and provide additional frame ops for generate_frame transactions. These functions are all called from the render backend thread.
Defines the interface for hooking up an external profiler to WR.
The interfaces that an application can implement to handle ProgramCache update
Allows callers to hook in at certain points of the async scene build. These functions are all called from the scene builder thread.


Set the profiler callbacks, or None to disable the profiler. This function must only ever be called before any WR instances have been created, or the hooks will not be set.

Type Definitions