webrender 0.60.0

A GPU accelerated 2D renderer for web content
Documentation 
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commit 74d218d77e26876e7e2ecd4d6babba3c0dba5098
Author: Nicolas Silva <nical@fastmail.com>
Date:   Tue Aug 28 11:20:15 2018 +0200

    Expose low priority transactions in the API.

diff --git a/webrender/src/render_backend.rs b/webrender/src/render_backend.rs
index ccc779c9..215cd10d 100644
--- a/webrender/src/render_backend.rs
+++ b/webrender/src/render_backend.rs
@@ -763,6 +763,7 @@ impl RenderBackend {
                             resource_updates,
                             generate_frame: render,
                             use_scene_builder_thread: false,
+                            low_priority: false,
                         };
 
                         self.resource_cache.add_rasterized_blob_images(rasterized_blobs);
@@ -1033,6 +1034,12 @@ impl RenderBackend {
             let scene_id = self.make_unique_scene_id();
             let doc = self.documents.get_mut(&document_id).unwrap();
 
+            let tx = if transaction_msg.low_priority {
+                &self.low_priority_scene_tx
+            } else {
+                &self.scene_tx
+            };
+
             doc.forward_transaction_to_scene_builder(
                 transaction_msg,
                 blob_requests,
@@ -1040,7 +1047,7 @@ impl RenderBackend {
                 document_id,
                 scene_id,
                 &mut self.resource_cache,
-                &self.scene_tx,
+                tx,
             );
 
             return;
diff --git a/webrender_api/src/api.rs b/webrender_api/src/api.rs
index 8debdd35..505aaf5c 100644
--- a/webrender_api/src/api.rs
+++ b/webrender_api/src/api.rs
@@ -56,6 +56,8 @@ pub struct Transaction {
     use_scene_builder_thread: bool,
 
     generate_frame: bool,
+
+    low_priority: bool,
 }
 
 impl Transaction {
@@ -67,6 +69,7 @@ impl Transaction {
             payloads: Vec::new(),
             use_scene_builder_thread: false, // TODO: make this true by default.
             generate_frame: false,
+            low_priority: false,
         }
     }
 
@@ -256,6 +259,7 @@ impl Transaction {
                 resource_updates: self.resource_updates,
                 use_scene_builder_thread: self.use_scene_builder_thread,
                 generate_frame: self.generate_frame,
+                low_priority: self.low_priority,
             },
             self.payloads,
         )
@@ -337,6 +341,14 @@ impl Transaction {
         self.resource_updates.push(ResourceUpdate::DeleteFontInstance(key));
     }
 
+    // A hint that this transaction can be processed at a lower priority. High-
+    // priority transactions can jump ahead of regular-priority transactions,
+    // but both high- and regular-priority transactions are processed in order
+    // relative to other transactions of the same priority.
+    pub fn mark_low_priority(&mut self) {
+        self.low_priority = true;
+    }
+
     pub fn merge(&mut self, mut other: Vec<ResourceUpdate>) {
         self.resource_updates.append(&mut other);
     }
@@ -354,6 +366,7 @@ pub struct TransactionMsg {
     pub resource_updates: Vec<ResourceUpdate>,
     pub generate_frame: bool,
     pub use_scene_builder_thread: bool,
+    pub low_priority: bool,
 }
 
 impl TransactionMsg {
@@ -372,6 +385,7 @@ impl TransactionMsg {
             resource_updates: Vec::new(),
             generate_frame: false,
             use_scene_builder_thread: false,
+            low_priority: false,
         }
     }
 
@@ -382,6 +396,7 @@ impl TransactionMsg {
             resource_updates: Vec::new(),
             generate_frame: false,
             use_scene_builder_thread: false,
+            low_priority: false,
         }
     }
 }