1 files changed, 336 insertions, 0 deletions
diff --git a/gfx/wr/webrender/src/render_task_cache.rs b/gfx/wr/webrender/src/render_task_cache.rs
new file mode 100644
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+++ b/gfx/wr/webrender/src/render_task_cache.rs
@@ -0,0 +1,336 @@
+/* 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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+use api::{ImageDescriptor, ImageDescriptorFlags, DirtyRect};
+use api::units::*;
+use crate::border::BorderSegmentCacheKey;
+use crate::box_shadow::{BoxShadowCacheKey};
+use crate::device::TextureFilter;
+use crate::freelist::{FreeList, FreeListHandle, WeakFreeListHandle};
+use crate::gpu_cache::GpuCache;
+use crate::internal_types::FastHashMap;
+use crate::picture::{SurfaceIndex, SurfaceInfo};
+use crate::prim_store::image::ImageCacheKey;
+use crate::prim_store::gradient::GradientCacheKey;
+use crate::prim_store::line_dec::LineDecorationCacheKey;
+use crate::resource_cache::CacheItem;
+use std::{mem, usize, f32, i32};
+use crate::texture_cache::{TextureCache, TextureCacheHandle, Eviction, TargetShader};
+use crate::render_target::RenderTargetKind;
+use crate::render_task::{RenderTask, StaticRenderTaskSurface, RenderTaskLocation};
+use crate::render_task_graph::{RenderTaskGraphBuilder, RenderTaskId};
+use crate::frame_builder::add_child_render_task;
+use euclid::Scale;
+
+const MAX_CACHE_TASK_SIZE: f32 = 4096.0;
+
+/// Describes a parent dependency for a render task. Render tasks
+/// may depend on a surface (e.g. when a surface uses a cached border)
+/// or an arbitrary render task (e.g. when a clip mask uses a blurred
+/// box-shadow input).
+pub enum RenderTaskParent {
+    /// Parent is a surface
+    Surface(SurfaceIndex),
+    /// Parent is a render task
+    RenderTask(RenderTaskId),
+}
+
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+#[cfg_attr(feature = "capture", derive(Serialize))]
+#[cfg_attr(feature = "replay", derive(Deserialize))]
+pub enum RenderTaskCacheKeyKind {
+    BoxShadow(BoxShadowCacheKey),
+    Image(ImageCacheKey),
+    BorderSegment(BorderSegmentCacheKey),
+    LineDecoration(LineDecorationCacheKey),
+    Gradient(GradientCacheKey),
+}
+
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+#[cfg_attr(feature = "capture", derive(Serialize))]
+#[cfg_attr(feature = "replay", derive(Deserialize))]
+pub struct RenderTaskCacheKey {
+    pub size: DeviceIntSize,
+    pub kind: RenderTaskCacheKeyKind,
+}
+
+#[derive(Debug)]
+#[cfg_attr(feature = "capture", derive(Serialize))]
+#[cfg_attr(feature = "replay", derive(Deserialize))]
+pub struct RenderTaskCacheEntry {
+    user_data: Option<[f32; 3]>,
+    is_opaque: bool,
+    pub handle: TextureCacheHandle,
+    /// If a render task was generated for this cache entry on _this_ frame,
+    /// we need to track the task id here. This allows us to hook it up as
+    /// a dependency of any parent tasks that make a reqiest from the render
+    /// task cache.
+    pub render_task_id: Option<RenderTaskId>,
+}
+
+#[derive(Debug, MallocSizeOf)]
+#[cfg_attr(feature = "capture", derive(Serialize))]
+pub enum RenderTaskCacheMarker {}
+
+// A cache of render tasks that are stored in the texture
+// cache for usage across frames.
+#[derive(Debug)]
+#[cfg_attr(feature = "capture", derive(Serialize))]
+#[cfg_attr(feature = "replay", derive(Deserialize))]
+pub struct RenderTaskCache {
+    map: FastHashMap<RenderTaskCacheKey, FreeListHandle<RenderTaskCacheMarker>>,
+    cache_entries: FreeList<RenderTaskCacheEntry, RenderTaskCacheMarker>,
+}
+
+pub type RenderTaskCacheEntryHandle = WeakFreeListHandle<RenderTaskCacheMarker>;
+
+impl RenderTaskCache {
+    pub fn new() -> Self {
+        RenderTaskCache {
+            map: FastHashMap::default(),
+            cache_entries: FreeList::new(),
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.map.clear();
+        self.cache_entries.clear();
+    }
+
+    pub fn begin_frame(
+        &mut self,
+        texture_cache: &mut TextureCache,
+    ) {
+        profile_scope!("begin_frame");
+        // Drop any items from the cache that have been
+        // evicted from the texture cache.
+        //
+        // This isn't actually necessary for the texture
+        // cache to be able to evict old render tasks.
+        // It will evict render tasks as required, since
+        // the access time in the texture cache entry will
+        // be stale if this task hasn't been requested
+        // for a while.
+        //
+        // Nonetheless, we should remove stale entries
+        // from here so that this hash map doesn't
+        // grow indefinitely!
+        let cache_entries = &mut self.cache_entries;
+
+        self.map.retain(|_, handle| {
+            let retain = texture_cache.is_allocated(
+                &cache_entries.get(handle).handle,
+            );
+            if !retain {
+                let handle = mem::replace(handle, FreeListHandle::invalid());
+                cache_entries.free(handle);
+            }
+            retain
+        });
+
+        // Clear out the render task ID of any remaining cache entries that were drawn
+        // on the previous frame, so we don't accidentally hook up stale dependencies
+        // when building the frame graph.
+        for (_, handle) in &self.map {
+            let entry = self.cache_entries.get_mut(handle);
+            entry.render_task_id = None;
+        }
+    }
+
+    fn alloc_render_task(
+        render_task: &mut RenderTask,
+        entry: &mut RenderTaskCacheEntry,
+        gpu_cache: &mut GpuCache,
+        texture_cache: &mut TextureCache,
+    ) {
+        // Find out what size to alloc in the texture cache.
+        let size = render_task.location.size();
+        let target_kind = render_task.target_kind();
+
+        // Select the right texture page to allocate from.
+        let image_format = match target_kind {
+            RenderTargetKind::Color => texture_cache.shared_color_expected_format(),
+            RenderTargetKind::Alpha => texture_cache.shared_alpha_expected_format(),
+        };
+
+        let flags = if entry.is_opaque {
+            ImageDescriptorFlags::IS_OPAQUE
+        } else {
+            ImageDescriptorFlags::empty()
+        };
+
+        let descriptor = ImageDescriptor::new(
+            size.width,
+            size.height,
+            image_format,
+            flags,
+        );
+
+        // Allocate space in the texture cache, but don't supply
+        // and CPU-side data to be uploaded.
+        texture_cache.update(
+            &mut entry.handle,
+            descriptor,
+            TextureFilter::Linear,
+            None,
+            entry.user_data.unwrap_or([0.0; 3]),
+            DirtyRect::All,
+            gpu_cache,
+            None,
+            render_task.uv_rect_kind(),
+            Eviction::Auto,
+            TargetShader::Default,
+        );
+
+        // Get the allocation details in the texture cache, and store
+        // this in the render task. The renderer will draw this
+        // task into the appropriate layer and rect of the texture
+        // cache on this frame.
+        let (texture_id, texture_layer, uv_rect, _, _, _) =
+            texture_cache.get_cache_location(&entry.handle);
+
+        let surface = StaticRenderTaskSurface::TextureCache {
+            texture: texture_id,
+            layer: texture_layer,
+            target_kind,
+        };
+
+        render_task.location = RenderTaskLocation::Static {
+            surface,
+            rect: uv_rect.to_i32(),
+        };
+    }
+
+    pub fn request_render_task<F>(
+        &mut self,
+        key: RenderTaskCacheKey,
+        texture_cache: &mut TextureCache,
+        gpu_cache: &mut GpuCache,
+        rg_builder: &mut RenderTaskGraphBuilder,
+        user_data: Option<[f32; 3]>,
+        is_opaque: bool,
+        parent: RenderTaskParent,
+        surfaces: &[SurfaceInfo],
+        f: F,
+    ) -> Result<RenderTaskCacheEntryHandle, ()>
+    where
+        F: FnOnce(&mut RenderTaskGraphBuilder) -> Result<RenderTaskId, ()>,
+    {
+        // Get the texture cache handle for this cache key,
+        // or create one.
+        let cache_entries = &mut self.cache_entries;
+        let entry_handle = self.map.entry(key).or_insert_with(|| {
+            let entry = RenderTaskCacheEntry {
+                handle: TextureCacheHandle::invalid(),
+                user_data,
+                is_opaque,
+                render_task_id: None,
+            };
+            cache_entries.insert(entry)
+        });
+        let cache_entry = cache_entries.get_mut(entry_handle);
+
+        // Check if this texture cache handle is valid.
+        if texture_cache.request(&cache_entry.handle, gpu_cache) {
+            // Invoke user closure to get render task chain
+            // to draw this into the texture cache.
+            let render_task_id = f(rg_builder)?;
+
+            cache_entry.user_data = user_data;
+            cache_entry.is_opaque = is_opaque;
+            cache_entry.render_task_id = Some(render_task_id);
+
+            let render_task = rg_builder.get_task_mut(render_task_id);
+
+            RenderTaskCache::alloc_render_task(
+                render_task,
+                cache_entry,
+                gpu_cache,
+                texture_cache,
+            );
+        }
+
+        // If this render task cache is being drawn this frame, ensure we hook up the
+        // render task for it as a dependency of any render task that uses this as
+        // an input source.
+        if let Some(render_task_id) = cache_entry.render_task_id {
+            match parent {
+                RenderTaskParent::Surface(surface_index) => {
+                    // If parent is a surface, use helper fn to add this dependency,
+                    // which correctly takes account of the render task configuration
+                    // of the surface.
+                    add_child_render_task(
+                        surface_index,
+                        render_task_id,
+                        surfaces,
+                        rg_builder
+                    );
+                }
+                RenderTaskParent::RenderTask(parent_render_task_id) => {
+                    // For render tasks, just add it as a direct dependency on the
+                    // task graph builder.
+                    rg_builder.add_dependency(
+                        parent_render_task_id,
+                        render_task_id,
+                    );
+                }
+            }
+        }
+
+        Ok(entry_handle.weak())
+    }
+
+    pub fn get_cache_entry(
+        &self,
+        handle: &RenderTaskCacheEntryHandle,
+    ) -> &RenderTaskCacheEntry {
+        self.cache_entries
+            .get_opt(handle)
+            .expect("bug: invalid render task cache handle")
+    }
+
+    #[allow(dead_code)]
+    pub fn get_cache_item_for_render_task(&self,
+                                          texture_cache: &TextureCache,
+                                          key: &RenderTaskCacheKey)
+                                          -> CacheItem {
+        // Get the texture cache handle for this cache key.
+        let handle = self.map.get(key).unwrap();
+        let cache_entry = self.cache_entries.get(handle);
+        texture_cache.get(&cache_entry.handle)
+    }
+
+    #[allow(dead_code)]
+    pub fn get_allocated_size_for_render_task(&self,
+                                              texture_cache: &TextureCache,
+                                              key: &RenderTaskCacheKey)
+                                              -> Option<usize> {
+        let handle = self.map.get(key).unwrap();
+        let cache_entry = self.cache_entries.get(handle);
+        texture_cache.get_allocated_size(&cache_entry.handle)
+    }
+}
+
+// TODO(gw): Rounding the content rect here to device pixels is not
+// technically correct. Ideally we should ceil() here, and ensure that
+// the extra part pixel in the case of fractional sizes is correctly
+// handled. For now, just use rounding which passes the existing
+// Gecko tests.
+// Note: zero-square tasks are prohibited in WR task graph, so
+// we ensure each dimension to be at least the length of 1 after rounding.
+pub fn to_cache_size(size: LayoutSize, device_pixel_scale: &mut Scale<f32, LayoutPixel, DevicePixel>) -> DeviceIntSize {
+    let mut device_size = (size * *device_pixel_scale).round();
+
+    if device_size.width > MAX_CACHE_TASK_SIZE || device_size.height > MAX_CACHE_TASK_SIZE {
+        let scale = MAX_CACHE_TASK_SIZE / f32::max(device_size.width, device_size.height);
+        *device_pixel_scale = *device_pixel_scale * Scale::new(scale);
+        device_size = (size * *device_pixel_scale).round();
+    }
+
+    DeviceIntSize::new(
+        1.max(device_size.width as i32),
+        1.max(device_size.height as i32),
+    )
+}