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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
extern crate gleam;
extern crate glutin;
extern crate rayon;
extern crate webrender;
extern crate winit;
#[path = "common/boilerplate.rs"]
mod boilerplate;
use crate::boilerplate::{Example, HandyDandyRectBuilder};
use rayon::{ThreadPool, ThreadPoolBuilder};
use rayon::prelude::*;
use std::collections::HashMap;
use std::sync::Arc;
use webrender::api::{self, DisplayListBuilder, DocumentId, PipelineId, PrimitiveFlags};
use webrender::api::{ColorF, CommonItemProperties, SpaceAndClipInfo, ImageDescriptorFlags};
use webrender::api::units::*;
use webrender::render_api::*;
use webrender::euclid::size2;
// This example shows how to implement a very basic BlobImageHandler that can only render
// a checkerboard pattern.
// The deserialized command list internally used by this example is just a color.
type ImageRenderingCommands = api::ColorU;
// Serialize/deserialize the blob.
// For real usecases you should probably use serde rather than doing it by hand.
fn serialize_blob(color: api::ColorU) -> Arc<Vec<u8>> {
Arc::new(vec![color.r, color.g, color.b, color.a])
}
fn deserialize_blob(blob: &[u8]) -> Result<ImageRenderingCommands, ()> {
let mut iter = blob.iter();
return match (iter.next(), iter.next(), iter.next(), iter.next()) {
(Some(&r), Some(&g), Some(&b), Some(&a)) => Ok(api::ColorU::new(r, g, b, a)),
(Some(&a), None, None, None) => Ok(api::ColorU::new(a, a, a, a)),
_ => Err(()),
};
}
// This is the function that applies the deserialized drawing commands and generates
// actual image data.
fn render_blob(
commands: Arc<ImageRenderingCommands>,
descriptor: &api::BlobImageDescriptor,
tile: TileOffset,
) -> api::BlobImageResult {
let color = *commands;
// Note: This implementation ignores the dirty rect which isn't incorrect
// but is a missed optimization.
// Allocate storage for the result. Right now the resource cache expects the
// tiles to have have no stride or offset.
let bpp = 4;
let mut texels = Vec::with_capacity((descriptor.rect.area() * bpp) as usize);
// Generate a per-tile pattern to see it in the demo. For a real use case it would not
// make sense for the rendered content to depend on its tile.
let tile_checker = (tile.x % 2 == 0) != (tile.y % 2 == 0);
let [w, h] = descriptor.rect.size().to_array();
let offset = descriptor.rect.min;
for y in 0..h {
for x in 0..w {
// Apply the tile's offset. This is important: all drawing commands should be
// translated by this offset to give correct results with tiled blob images.
let x2 = x + offset.x;
let y2 = y + offset.y;
// Render a simple checkerboard pattern
let checker = if (x2 % 20 >= 10) != (y2 % 20 >= 10) {
1
} else {
0
};
// ..nested in the per-tile checkerboard pattern
let tc = if tile_checker { 0 } else { (1 - checker) * 40 };
match descriptor.format {
api::ImageFormat::BGRA8 => {
texels.push(color.b * checker + tc);
texels.push(color.g * checker + tc);
texels.push(color.r * checker + tc);
texels.push(color.a * checker + tc);
}
api::ImageFormat::R8 => {
texels.push(color.a * checker + tc);
}
_ => {
return Err(api::BlobImageError::Other(
format!("Unsupported image format"),
));
}
}
}
}
Ok(api::RasterizedBlobImage {
data: Arc::new(texels),
rasterized_rect: size2(w, h).into(),
})
}
struct CheckerboardRenderer {
// We are going to defer the rendering work to worker threads.
// Using a pre-built Arc<ThreadPool> rather than creating our own threads
// makes it possible to share the same thread pool as the glyph renderer (if we
// want to).
workers: Arc<ThreadPool>,
// The deserialized drawing commands.
// In this example we store them in Arcs. This isn't necessary since in this simplified
// case the command list is a simple 32 bits value and would be cheap to clone before sending
// to the workers. But in a more realistic scenario the commands would typically be bigger
// and more expensive to clone, so let's pretend it is also the case here.
image_cmds: HashMap<api::BlobImageKey, Arc<ImageRenderingCommands>>,
}
impl CheckerboardRenderer {
fn new(workers: Arc<ThreadPool>) -> Self {
CheckerboardRenderer {
image_cmds: HashMap::new(),
workers,
}
}
}
impl api::BlobImageHandler for CheckerboardRenderer {
fn create_similar(&self) -> Box<dyn api::BlobImageHandler> {
Box::new(CheckerboardRenderer::new(Arc::clone(&self.workers)))
}
fn add(&mut self, key: api::BlobImageKey, cmds: Arc<api::BlobImageData>,
_visible_rect: &DeviceIntRect, _: api::TileSize) {
self.image_cmds
.insert(key, Arc::new(deserialize_blob(&cmds[..]).unwrap()));
}
fn update(&mut self, key: api::BlobImageKey, cmds: Arc<api::BlobImageData>,
_visible_rect: &DeviceIntRect, _dirty_rect: &BlobDirtyRect) {
// Here, updating is just replacing the current version of the commands with
// the new one (no incremental updates).
self.image_cmds
.insert(key, Arc::new(deserialize_blob(&cmds[..]).unwrap()));
}
fn delete(&mut self, key: api::BlobImageKey) {
self.image_cmds.remove(&key);
}
fn prepare_resources(
&mut self,
_services: &dyn api::BlobImageResources,
_requests: &[api::BlobImageParams],
) {}
fn enable_multithreading(&mut self, _: bool) {}
fn delete_font(&mut self, _font: api::FontKey) {}
fn delete_font_instance(&mut self, _instance: api::FontInstanceKey) {}
fn clear_namespace(&mut self, _namespace: api::IdNamespace) {}
fn create_blob_rasterizer(&mut self) -> Box<dyn api::AsyncBlobImageRasterizer> {
Box::new(Rasterizer {
workers: Arc::clone(&self.workers),
image_cmds: self.image_cmds.clone(),
})
}
}
struct Rasterizer {
workers: Arc<ThreadPool>,
image_cmds: HashMap<api::BlobImageKey, Arc<ImageRenderingCommands>>,
}
impl api::AsyncBlobImageRasterizer for Rasterizer {
fn rasterize(
&mut self,
requests: &[api::BlobImageParams],
_low_priority: bool
) -> Vec<(api::BlobImageRequest, api::BlobImageResult)> {
let requests: Vec<(&api::BlobImageParams, Arc<ImageRenderingCommands>)> = requests.into_iter().map(|params| {
(params, Arc::clone(&self.image_cmds[¶ms.request.key]))
}).collect();
self.workers.install(|| {
requests.into_par_iter().map(|(params, commands)| {
(params.request, render_blob(commands, ¶ms.descriptor, params.request.tile))
}).collect()
})
}
}
struct App {}
impl Example for App {
fn render(
&mut self,
api: &mut RenderApi,
builder: &mut DisplayListBuilder,
txn: &mut Transaction,
_device_size: DeviceIntSize,
pipeline_id: PipelineId,
_document_id: DocumentId,
) {
let space_and_clip = SpaceAndClipInfo::root_scroll(pipeline_id);
builder.push_simple_stacking_context(
LayoutPoint::zero(),
space_and_clip.spatial_id,
PrimitiveFlags::IS_BACKFACE_VISIBLE,
);
let size1 = DeviceIntSize::new(500, 500);
let blob_img1 = api.generate_blob_image_key();
txn.add_blob_image(
blob_img1,
api::ImageDescriptor::new(
size1.width,
size1.height,
api::ImageFormat::BGRA8,
ImageDescriptorFlags::IS_OPAQUE,
),
serialize_blob(api::ColorU::new(50, 50, 150, 255)),
size1.into(),
Some(128),
);
let bounds = (30, 30).by(size1.width, size1.height);
builder.push_image(
&CommonItemProperties::new(bounds, space_and_clip),
bounds,
api::ImageRendering::Auto,
api::AlphaType::PremultipliedAlpha,
blob_img1.as_image(),
ColorF::WHITE,
);
let size2 = DeviceIntSize::new(256, 256);
let blob_img2 = api.generate_blob_image_key();
txn.add_blob_image(
blob_img2,
api::ImageDescriptor::new(
size2.width,
size2.height,
api::ImageFormat::BGRA8,
ImageDescriptorFlags::IS_OPAQUE,
),
serialize_blob(api::ColorU::new(50, 150, 50, 255)),
size2.into(),
None,
);
let bounds = (600, 600).by(size2.width, size2.height);
builder.push_image(
&CommonItemProperties::new(bounds, space_and_clip),
bounds,
api::ImageRendering::Auto,
api::AlphaType::PremultipliedAlpha,
blob_img2.as_image(),
ColorF::WHITE,
);
builder.pop_stacking_context();
}
}
fn main() {
let workers =
ThreadPoolBuilder::new().thread_name(|idx| format!("WebRender:Worker#{}", idx))
.build();
let workers = Arc::new(workers.unwrap());
let opts = webrender::WebRenderOptions {
workers: Some(Arc::clone(&workers)),
// Register our blob renderer, so that WebRender integrates it in the resource cache..
// Share the same pool of worker threads between WebRender and our blob renderer.
blob_image_handler: Some(Box::new(CheckerboardRenderer::new(Arc::clone(&workers)))),
..Default::default()
};
let mut app = App {};
boilerplate::main_wrapper(&mut app, Some(opts));
}