summaryrefslogtreecommitdiffstats
path: root/gfx/wr/webrender/src/frame_builder.rs
blob: 4ff798c103093eb3097f7868022cdfda8bdf1a27 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
/* 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::{ColorF, DebugFlags, FontRenderMode, PremultipliedColorF, ExternalScrollId, MinimapData};
use api::units::*;
use plane_split::BspSplitter;
use crate::batch::{BatchBuilder, AlphaBatchBuilder, AlphaBatchContainer};
use crate::clip::{ClipStore, ClipTree};
use crate::command_buffer::{PrimitiveCommand, CommandBufferList, CommandBufferIndex};
use crate::debug_colors;
use crate::spatial_node::SpatialNodeType;
use crate::spatial_tree::{SpatialTree, SpatialNodeIndex};
use crate::composite::{CompositorKind, CompositeState, CompositeStatePreallocator};
use crate::debug_item::DebugItem;
use crate::gpu_cache::{GpuCache, GpuCacheHandle};
use crate::gpu_types::{PrimitiveHeaders, TransformPalette, ZBufferIdGenerator};
use crate::gpu_types::{QuadSegment, TransformData};
use crate::internal_types::{FastHashMap, PlaneSplitter, FrameId, FrameStamp};
use crate::picture::{DirtyRegion, SliceId, TileCacheInstance};
use crate::picture::{SurfaceInfo, SurfaceIndex};
use crate::picture::{SubpixelMode, RasterConfig, PictureCompositeMode};
use crate::prepare::{prepare_primitives};
use crate::prim_store::{PictureIndex, PrimitiveScratchBuffer};
use crate::prim_store::{DeferredResolve, PrimitiveInstance};
use crate::profiler::{self, TransactionProfile};
use crate::render_backend::{DataStores, ScratchBuffer};
use crate::renderer::{GpuBuffer, GpuBufferBuilder};
use crate::render_target::{RenderTarget, PictureCacheTarget, TextureCacheRenderTarget, PictureCacheTargetKind};
use crate::render_target::{RenderTargetContext, RenderTargetKind, AlphaRenderTarget, ColorRenderTarget};
use crate::render_task_graph::{RenderTaskGraph, Pass, SubPassSurface};
use crate::render_task_graph::{RenderPass, RenderTaskGraphBuilder};
use crate::render_task::{RenderTaskKind, StaticRenderTaskSurface};
use crate::resource_cache::{ResourceCache};
use crate::scene::{BuiltScene, SceneProperties};
use crate::space::SpaceMapper;
use crate::segment::SegmentBuilder;
use crate::surface::SurfaceBuilder;
use std::{f32, mem};
use crate::util::{VecHelper, Preallocator};
use crate::visibility::{update_prim_visibility, FrameVisibilityState, FrameVisibilityContext};

#[derive(Clone, Copy, Debug)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub struct FrameBuilderConfig {
    pub default_font_render_mode: FontRenderMode,
    pub dual_source_blending_is_supported: bool,
    /// True if we're running tests (i.e. via wrench).
    pub testing: bool,
    pub gpu_supports_fast_clears: bool,
    pub gpu_supports_advanced_blend: bool,
    pub advanced_blend_is_coherent: bool,
    pub gpu_supports_render_target_partial_update: bool,
    /// Whether ImageBufferKind::TextureExternal images must first be copied
    /// to a regular texture before rendering.
    pub external_images_require_copy: bool,
    pub batch_lookback_count: usize,
    pub background_color: Option<ColorF>,
    pub compositor_kind: CompositorKind,
    pub tile_size_override: Option<DeviceIntSize>,
    pub max_surface_override: Option<usize>,
    pub max_depth_ids: i32,
    pub max_target_size: i32,
    pub force_invalidation: bool,
    pub is_software: bool,
    pub low_quality_pinch_zoom: bool,
    pub max_shared_surface_size: i32,
}

/// A set of common / global resources that are retained between
/// new display lists, such that any GPU cache handles can be
/// persisted even when a new display list arrives.
#[cfg_attr(feature = "capture", derive(Serialize))]
pub struct FrameGlobalResources {
    /// The image shader block for the most common / default
    /// set of image parameters (color white, stretch == rect.size).
    pub default_image_handle: GpuCacheHandle,

    /// A GPU cache config for drawing cut-out rectangle primitives.
    /// This is used to 'cut out' overlay tiles where a compositor
    /// surface exists.
    pub default_black_rect_handle: GpuCacheHandle,
}

impl FrameGlobalResources {
    pub fn empty() -> Self {
        FrameGlobalResources {
            default_image_handle: GpuCacheHandle::new(),
            default_black_rect_handle: GpuCacheHandle::new(),
        }
    }

    pub fn update(
        &mut self,
        gpu_cache: &mut GpuCache,
    ) {
        if let Some(mut request) = gpu_cache.request(&mut self.default_image_handle) {
            request.push(PremultipliedColorF::WHITE);
            request.push(PremultipliedColorF::WHITE);
            request.push([
                -1.0,       // -ve means use prim rect for stretch size
                0.0,
                0.0,
                0.0,
            ]);
        }

        if let Some(mut request) = gpu_cache.request(&mut self.default_black_rect_handle) {
            request.push(PremultipliedColorF::BLACK);
        }
    }
}

pub struct FrameScratchBuffer {
    dirty_region_stack: Vec<DirtyRegion>,
    surface_stack: Vec<(PictureIndex, SurfaceIndex)>,
}

impl Default for FrameScratchBuffer {
    fn default() -> Self {
        FrameScratchBuffer {
            dirty_region_stack: Vec::new(),
            surface_stack: Vec::new(),
        }
    }
}

impl FrameScratchBuffer {
    pub fn begin_frame(&mut self) {
        self.dirty_region_stack.clear();
        self.surface_stack.clear();
    }
}

/// Produces the frames that are sent to the renderer.
#[cfg_attr(feature = "capture", derive(Serialize))]
pub struct FrameBuilder {
    pub globals: FrameGlobalResources,
    #[cfg_attr(feature = "capture", serde(skip))]
    prim_headers_prealloc: Preallocator,
    #[cfg_attr(feature = "capture", serde(skip))]
    composite_state_prealloc: CompositeStatePreallocator,
    #[cfg_attr(feature = "capture", serde(skip))]
    plane_splitters: Vec<PlaneSplitter>,
}

pub struct FrameBuildingContext<'a> {
    pub global_device_pixel_scale: DevicePixelScale,
    pub scene_properties: &'a SceneProperties,
    pub global_screen_world_rect: WorldRect,
    pub spatial_tree: &'a SpatialTree,
    pub max_local_clip: LayoutRect,
    pub debug_flags: DebugFlags,
    pub fb_config: &'a FrameBuilderConfig,
    pub root_spatial_node_index: SpatialNodeIndex,
}

pub struct FrameBuildingState<'a> {
    pub rg_builder: &'a mut RenderTaskGraphBuilder,
    pub clip_store: &'a mut ClipStore,
    pub resource_cache: &'a mut ResourceCache,
    pub gpu_cache: &'a mut GpuCache,
    pub transforms: &'a mut TransformPalette,
    pub segment_builder: SegmentBuilder,
    pub surfaces: &'a mut Vec<SurfaceInfo>,
    pub dirty_region_stack: Vec<DirtyRegion>,
    pub composite_state: &'a mut CompositeState,
    pub num_visible_primitives: u32,
    pub plane_splitters: &'a mut [PlaneSplitter],
    pub surface_builder: SurfaceBuilder,
    pub cmd_buffers: &'a mut CommandBufferList,
    pub clip_tree: &'a ClipTree,
    pub frame_gpu_data: &'a mut GpuBufferBuilder,
}

impl<'a> FrameBuildingState<'a> {
    /// Retrieve the current dirty region during primitive traversal.
    pub fn current_dirty_region(&self) -> &DirtyRegion {
        self.dirty_region_stack.last().unwrap()
    }

    /// Push a new dirty region for child primitives to cull / clip against.
    pub fn push_dirty_region(&mut self, region: DirtyRegion) {
        self.dirty_region_stack.push(region);
    }

    /// Pop the top dirty region from the stack.
    pub fn pop_dirty_region(&mut self) {
        self.dirty_region_stack.pop().unwrap();
    }

    /// Push a primitive command to a set of command buffers
    pub fn push_prim(
        &mut self,
        cmd: &PrimitiveCommand,
        spatial_node_index: SpatialNodeIndex,
        targets: &[CommandBufferIndex],
    ) {
        for cmd_buffer_index in targets {
            let cmd_buffer = self.cmd_buffers.get_mut(*cmd_buffer_index);
            cmd_buffer.add_prim(cmd, spatial_node_index);
        }
    }

    /// Push a command to a set of command buffers
    pub fn push_cmd(
        &mut self,
        cmd: &PrimitiveCommand,
        targets: &[CommandBufferIndex],
    ) {
        for cmd_buffer_index in targets {
            let cmd_buffer = self.cmd_buffers.get_mut(*cmd_buffer_index);
            cmd_buffer.add_cmd(cmd);
        }
    }

    /// Set the active list of segments in a set of command buffers
    pub fn set_segments(
        &mut self,
        segments: &[QuadSegment],
        targets: &[CommandBufferIndex],
    ) {
        for cmd_buffer_index in targets {
            let cmd_buffer = self.cmd_buffers.get_mut(*cmd_buffer_index);
            cmd_buffer.set_segments(segments);
        }
    }
}

/// Immutable context of a picture when processing children.
#[derive(Debug)]
pub struct PictureContext {
    pub pic_index: PictureIndex,
    pub surface_spatial_node_index: SpatialNodeIndex,
    pub raster_spatial_node_index: SpatialNodeIndex,
    /// The surface that this picture will render on.
    pub surface_index: SurfaceIndex,
    pub dirty_region_count: usize,
    pub subpixel_mode: SubpixelMode,
}

/// Mutable state of a picture that gets modified when
/// the children are processed.
pub struct PictureState {
    pub map_local_to_pic: SpaceMapper<LayoutPixel, PicturePixel>,
    pub map_pic_to_world: SpaceMapper<PicturePixel, WorldPixel>,
}

impl FrameBuilder {
    pub fn new() -> Self {
        FrameBuilder {
            globals: FrameGlobalResources::empty(),
            prim_headers_prealloc: Preallocator::new(0),
            composite_state_prealloc: CompositeStatePreallocator::default(),
            plane_splitters: Vec::new(),
        }
    }

    /// Compute the contribution (bounding rectangles, and resources) of layers and their
    /// primitives in screen space.
    fn build_layer_screen_rects_and_cull_layers(
        &mut self,
        scene: &mut BuiltScene,
        global_screen_world_rect: WorldRect,
        resource_cache: &mut ResourceCache,
        gpu_cache: &mut GpuCache,
        rg_builder: &mut RenderTaskGraphBuilder,
        global_device_pixel_scale: DevicePixelScale,
        scene_properties: &SceneProperties,
        transform_palette: &mut TransformPalette,
        data_stores: &mut DataStores,
        scratch: &mut ScratchBuffer,
        debug_flags: DebugFlags,
        composite_state: &mut CompositeState,
        tile_caches: &mut FastHashMap<SliceId, Box<TileCacheInstance>>,
        spatial_tree: &SpatialTree,
        cmd_buffers: &mut CommandBufferList,
        frame_gpu_data: &mut GpuBufferBuilder,
        profile: &mut TransactionProfile,
    ) {
        profile_scope!("build_layer_screen_rects_and_cull_layers");

        let root_spatial_node_index = spatial_tree.root_reference_frame_index();

        const MAX_CLIP_COORD: f32 = 1.0e9;

        // Reset all plane splitters. These are retained from frame to frame to reduce
        // per-frame allocations
        self.plane_splitters.resize_with(scene.num_plane_splitters, BspSplitter::new);
        for splitter in &mut self.plane_splitters {
            splitter.reset();
        }

        let frame_context = FrameBuildingContext {
            global_device_pixel_scale,
            scene_properties,
            global_screen_world_rect,
            spatial_tree,
            max_local_clip: LayoutRect {
                min: LayoutPoint::new(-MAX_CLIP_COORD, -MAX_CLIP_COORD),
                max: LayoutPoint::new(MAX_CLIP_COORD, MAX_CLIP_COORD),
            },
            debug_flags,
            fb_config: &scene.config,
            root_spatial_node_index,
        };

        scene.picture_graph.build_update_passes(
            &mut scene.prim_store.pictures,
            &frame_context,
        );

        scene.picture_graph.assign_surfaces(
            &mut scene.prim_store.pictures,
            &mut scene.surfaces,
            tile_caches,
            &frame_context,
        );

        scene.picture_graph.propagate_bounding_rects(
            &mut scene.prim_store.pictures,
            &mut scene.surfaces,
            &frame_context,
        );

        {
            profile_scope!("UpdateVisibility");
            profile_marker!("UpdateVisibility");
            profile.start_time(profiler::FRAME_VISIBILITY_TIME);

            let visibility_context = FrameVisibilityContext {
                global_device_pixel_scale,
                spatial_tree,
                global_screen_world_rect,
                debug_flags,
                scene_properties,
                config: scene.config,
                root_spatial_node_index,
            };

            for pic_index in scene.tile_cache_pictures.iter().rev() {
                let pic = &mut scene.prim_store.pictures[pic_index.0];

                match pic.raster_config {
                    Some(RasterConfig { surface_index, composite_mode: PictureCompositeMode::TileCache { slice_id }, .. }) => {
                        let tile_cache = tile_caches
                            .get_mut(&slice_id)
                            .expect("bug: non-existent tile cache");

                        let mut visibility_state = FrameVisibilityState {
                            surface_stack: scratch.frame.surface_stack.take(),
                            resource_cache,
                            gpu_cache,
                            clip_store: &mut scene.clip_store,
                            scratch,
                            data_stores,
                            composite_state,
                            clip_tree: &mut scene.clip_tree,
                            rg_builder,
                        };

                        // If we have a tile cache for this picture, see if any of the
                        // relative transforms have changed, which means we need to
                        // re-map the dependencies of any child primitives.
                        let surface = &scene.surfaces[surface_index.0];
                        let world_culling_rect = tile_cache.pre_update(
                            surface.unclipped_local_rect,
                            surface_index,
                            &visibility_context,
                            &mut visibility_state,
                        );

                        // Push a new surface, supplying the list of clips that should be
                        // ignored, since they are handled by clipping when drawing this surface.
                        visibility_state.push_surface(
                            *pic_index,
                            surface_index,
                        );
                        visibility_state.clip_tree.push_clip_root_node(tile_cache.shared_clip_node_id);

                        update_prim_visibility(
                            *pic_index,
                            None,
                            &world_culling_rect,
                            &mut scene.prim_store,
                            &mut scene.prim_instances,
                            &mut scene.surfaces,
                            true,
                            &visibility_context,
                            &mut visibility_state,
                            tile_cache,
                        );

                        // Build the dirty region(s) for this tile cache.
                        tile_cache.post_update(
                            &visibility_context,
                            &mut visibility_state,
                        );

                        visibility_state.clip_tree.pop_clip_root();
                        visibility_state.pop_surface();
                        visibility_state.scratch.frame.surface_stack = visibility_state.surface_stack.take();
                    }
                    _ => {
                        panic!("bug: not a tile cache");
                    }
                }
            }

            profile.end_time(profiler::FRAME_VISIBILITY_TIME);
        }

        profile.start_time(profiler::FRAME_PREPARE_TIME);

        let mut frame_state = FrameBuildingState {
            rg_builder,
            clip_store: &mut scene.clip_store,
            resource_cache,
            gpu_cache,
            transforms: transform_palette,
            segment_builder: SegmentBuilder::new(),
            surfaces: &mut scene.surfaces,
            dirty_region_stack: scratch.frame.dirty_region_stack.take(),
            composite_state,
            num_visible_primitives: 0,
            plane_splitters: &mut self.plane_splitters,
            surface_builder: SurfaceBuilder::new(),
            cmd_buffers,
            clip_tree: &mut scene.clip_tree,
            frame_gpu_data,
        };

        // Push a default dirty region which culls primitives
        // against the screen world rect, in absence of any
        // other dirty regions.
        let mut default_dirty_region = DirtyRegion::new(
            root_spatial_node_index,
        );
        default_dirty_region.add_dirty_region(
            frame_context.global_screen_world_rect.cast_unit(),
            frame_context.spatial_tree,
        );
        frame_state.push_dirty_region(default_dirty_region);

        for pic_index in &scene.tile_cache_pictures {
            if let Some((pic_context, mut pic_state, mut prim_list)) = scene
                .prim_store
                .pictures[pic_index.0]
                .take_context(
                    *pic_index,
                    None,
                    SubpixelMode::Allow,
                    &mut frame_state,
                    &frame_context,
                    &mut scratch.primitive,
                    tile_caches,
                )
            {
                profile_marker!("PreparePrims");

                prepare_primitives(
                    &mut scene.prim_store,
                    &mut prim_list,
                    &pic_context,
                    &mut pic_state,
                    &frame_context,
                    &mut frame_state,
                    data_stores,
                    &mut scratch.primitive,
                    tile_caches,
                    &mut scene.prim_instances,
                );

                let pic = &mut scene.prim_store.pictures[pic_index.0];
                pic.restore_context(
                    *pic_index,
                    prim_list,
                    pic_context,
                    &scene.prim_instances,
                    &frame_context,
                    &mut frame_state,
                );
            }
        }

        frame_state.pop_dirty_region();
        frame_state.surface_builder.finalize();
        profile.end_time(profiler::FRAME_PREPARE_TIME);
        profile.set(profiler::VISIBLE_PRIMITIVES, frame_state.num_visible_primitives);

        scratch.frame.dirty_region_stack = frame_state.dirty_region_stack.take();

        {
            profile_marker!("BlockOnResources");

            resource_cache.block_until_all_resources_added(
                gpu_cache,
                profile,
            );
        }
    }

    pub fn build(
        &mut self,
        scene: &mut BuiltScene,
        resource_cache: &mut ResourceCache,
        gpu_cache: &mut GpuCache,
        rg_builder: &mut RenderTaskGraphBuilder,
        stamp: FrameStamp,
        device_origin: DeviceIntPoint,
        scene_properties: &SceneProperties,
        data_stores: &mut DataStores,
        scratch: &mut ScratchBuffer,
        debug_flags: DebugFlags,
        tile_caches: &mut FastHashMap<SliceId, Box<TileCacheInstance>>,
        spatial_tree: &mut SpatialTree,
        dirty_rects_are_valid: bool,
        profile: &mut TransactionProfile,
        minimap_data: FastHashMap<ExternalScrollId, MinimapData>
    ) -> Frame {
        profile_scope!("build");
        profile_marker!("BuildFrame");

        profile.set(profiler::PRIMITIVES, scene.prim_instances.len());
        profile.set(profiler::PICTURE_CACHE_SLICES, scene.tile_cache_config.picture_cache_slice_count);
        scratch.begin_frame();
        gpu_cache.begin_frame(stamp);
        resource_cache.begin_frame(stamp, gpu_cache, profile);

        // TODO(gw): Follow up patches won't clear this, as they'll be assigned
        //           statically during scene building.
        scene.surfaces.clear();

        self.globals.update(gpu_cache);

        spatial_tree.update_tree(scene_properties);
        let mut transform_palette = spatial_tree.build_transform_palette();
        scene.clip_store.begin_frame(&mut scratch.clip_store);

        rg_builder.begin_frame(stamp.frame_id());

        // TODO(dp): Remove me completely!!
        let global_device_pixel_scale = DevicePixelScale::new(1.0);

        let output_size = scene.output_rect.size();
        let screen_world_rect = (scene.output_rect.to_f32() / global_device_pixel_scale).round_out();

        let mut composite_state = CompositeState::new(
            scene.config.compositor_kind,
            scene.config.max_depth_ids,
            dirty_rects_are_valid,
            scene.config.low_quality_pinch_zoom,
        );

        self.composite_state_prealloc.preallocate(&mut composite_state);

        let mut cmd_buffers = CommandBufferList::new();

        // TODO(gw): Recycle backing vec buffers for gpu buffer builder between frames
        let mut gpu_buffer_builder = GpuBufferBuilder::new();

        self.build_layer_screen_rects_and_cull_layers(
            scene,
            screen_world_rect,
            resource_cache,
            gpu_cache,
            rg_builder,
            global_device_pixel_scale,
            scene_properties,
            &mut transform_palette,
            data_stores,
            scratch,
            debug_flags,
            &mut composite_state,
            tile_caches,
            spatial_tree,
            &mut cmd_buffers,
            &mut gpu_buffer_builder,
            profile,
        );

        self.render_minimap(&mut scratch.primitive, &spatial_tree, minimap_data);

        profile.start_time(profiler::FRAME_BATCHING_TIME);

        let mut deferred_resolves = vec![];

        // Finish creating the frame graph and build it.
        let render_tasks = rg_builder.end_frame(
            resource_cache,
            gpu_cache,
            &mut deferred_resolves,
            scene.config.max_shared_surface_size,
        );

        let mut passes = Vec::new();
        let mut has_texture_cache_tasks = false;
        let mut prim_headers = PrimitiveHeaders::new();
        self.prim_headers_prealloc.preallocate_vec(&mut prim_headers.headers_int);
        self.prim_headers_prealloc.preallocate_vec(&mut prim_headers.headers_float);

        {
            profile_marker!("Batching");

            // Used to generated a unique z-buffer value per primitive.
            let mut z_generator = ZBufferIdGenerator::new(scene.config.max_depth_ids);
            let use_dual_source_blending = scene.config.dual_source_blending_is_supported;

            for pass in render_tasks.passes.iter().rev() {
                let mut ctx = RenderTargetContext {
                    global_device_pixel_scale,
                    prim_store: &scene.prim_store,
                    clip_store: &scene.clip_store,
                    resource_cache,
                    use_dual_source_blending,
                    use_advanced_blending: scene.config.gpu_supports_advanced_blend,
                    break_advanced_blend_batches: !scene.config.advanced_blend_is_coherent,
                    batch_lookback_count: scene.config.batch_lookback_count,
                    spatial_tree,
                    data_stores,
                    surfaces: &scene.surfaces,
                    scratch: &mut scratch.primitive,
                    screen_world_rect,
                    globals: &self.globals,
                    tile_caches,
                    root_spatial_node_index: spatial_tree.root_reference_frame_index(),
                };

                let pass = build_render_pass(
                    pass,
                    output_size,
                    &mut ctx,
                    gpu_cache,
                    &mut gpu_buffer_builder,
                    &render_tasks,
                    &scene.clip_store,
                    &mut transform_palette,
                    &mut prim_headers,
                    &mut z_generator,
                    scene.config.gpu_supports_fast_clears,
                    &scene.prim_instances,
                    &cmd_buffers,
                );

                has_texture_cache_tasks |= !pass.texture_cache.is_empty();
                has_texture_cache_tasks |= !pass.picture_cache.is_empty();

                passes.push(pass);
            }

            let mut ctx = RenderTargetContext {
                global_device_pixel_scale,
                clip_store: &scene.clip_store,
                prim_store: &scene.prim_store,
                resource_cache,
                use_dual_source_blending,
                use_advanced_blending: scene.config.gpu_supports_advanced_blend,
                break_advanced_blend_batches: !scene.config.advanced_blend_is_coherent,
                batch_lookback_count: scene.config.batch_lookback_count,
                spatial_tree,
                data_stores,
                surfaces: &scene.surfaces,
                scratch: &mut scratch.primitive,
                screen_world_rect,
                globals: &self.globals,
                tile_caches,
                root_spatial_node_index: spatial_tree.root_reference_frame_index(),
            };

            self.build_composite_pass(
                scene,
                &mut ctx,
                gpu_cache,
                &mut deferred_resolves,
                &mut composite_state,
            );
        }

        profile.end_time(profiler::FRAME_BATCHING_TIME);

        let gpu_cache_frame_id = gpu_cache.end_frame(profile).frame_id();

        resource_cache.end_frame(profile);

        self.prim_headers_prealloc.record_vec(&mut prim_headers.headers_int);
        self.composite_state_prealloc.record(&composite_state);

        composite_state.end_frame();
        scene.clip_store.end_frame(&mut scratch.clip_store);
        scratch.end_frame();

        let gpu_buffer = gpu_buffer_builder.finalize(&render_tasks);

        Frame {
            device_rect: DeviceIntRect::from_origin_and_size(
                device_origin,
                scene.output_rect.size(),
            ),
            passes,
            transform_palette: transform_palette.finish(),
            render_tasks,
            deferred_resolves,
            gpu_cache_frame_id,
            has_been_rendered: false,
            has_texture_cache_tasks,
            prim_headers,
            debug_items: mem::replace(&mut scratch.primitive.debug_items, Vec::new()),
            composite_state,
            gpu_buffer,
        }
    }

    fn render_minimap(
        &self,
        scratch: &mut PrimitiveScratchBuffer,
        spatial_tree: &SpatialTree,
        minimap_data_store: FastHashMap<ExternalScrollId, MinimapData>) {
      // TODO: Replace minimap_data_store with Option<FastHastMap>?
      if minimap_data_store.is_empty() {
        return
      }

      // In our main walk over the spatial tree (below), for nodes inside a 
      // subtree rooted at a root-content node, we need some information from
      // that enclosing root-content node. To collect this information, do an
      // preliminary walk over the spatial tree now and collect the root-content
      // info in a HashMap.
      struct RootContentInfo {
        transform: LayoutToWorldTransform,
        clip: LayoutRect
      }
      let mut root_content_info = FastHashMap::<ExternalScrollId, RootContentInfo>::default();
      spatial_tree.visit_nodes(|index, node| {
        if let SpatialNodeType::ScrollFrame(ref scroll_frame_info) = node.node_type {
          if let Some(minimap_data) = minimap_data_store.get(&scroll_frame_info.external_id) {
            if minimap_data.is_root_content {
              let transform = spatial_tree.get_world_viewport_transform(index).into_transform();
              root_content_info.insert(scroll_frame_info.external_id, RootContentInfo{
                transform,
                clip: scroll_frame_info.viewport_rect
              });
            }
          }
        }
      });

      // This is the main walk over the spatial tree. For every scroll frame node which
      // has minimap data, compute the rects we want to render for that minimap in world
      // coordinates and add them to `scratch.debug_items`.
      spatial_tree.visit_nodes(|index, node| {
        if let SpatialNodeType::ScrollFrame(ref scroll_frame_info) = node.node_type {
          if let Some(minimap_data) = minimap_data_store.get(&scroll_frame_info.external_id) {
            const HORIZONTAL_PADDING: f32 = 5.0;
            const VERTICAL_PADDING: f32 = 10.0;
            const PAGE_BORDER_COLOR: ColorF = debug_colors::BLACK;
            const BACKGROUND_COLOR: ColorF = ColorF { r: 0.3, g: 0.3, b: 0.3, a: 0.3};
            const DISPLAYPORT_BACKGROUND_COLOR: ColorF = ColorF { r: 1.0, g: 1.0, b: 1.0, a: 0.4};
            const LAYOUT_PORT_COLOR: ColorF = debug_colors::RED;
            const VISUAL_PORT_COLOR: ColorF = debug_colors::BLUE;
            const DISPLAYPORT_COLOR: ColorF = debug_colors::LIME;
            const NOTHING: ColorF = ColorF { r: 0.0, g: 0.0, b: 0.0, a: 0.0 };

            let viewport = scroll_frame_info.viewport_rect;

            // Scale the minimap to make it 100px wide (if there's space), and the full height
            // of the scroll frame's viewport, minus some padding. Position it at the left edge
            // of the scroll frame's viewport.
            let scale_factor_x = 100f32.min(viewport.width() - (2.0 * HORIZONTAL_PADDING))
                                   / minimap_data.scrollable_rect.width();
            let scale_factor_y = (viewport.height() - (2.0 * VERTICAL_PADDING))
                                / minimap_data.scrollable_rect.height();
            if scale_factor_x <= 0.0 || scale_factor_y <= 0.0 {
              return;
            }
            let transform = LayoutTransform::scale(scale_factor_x, scale_factor_y, 1.0)
                .then_translate(LayoutVector3D::new(HORIZONTAL_PADDING, VERTICAL_PADDING, 0.0))
                .then_translate(LayoutVector3D::new(viewport.min.x, viewport.min.y, 0.0));

            // Transforms for transforming rects in this scroll frame's local coordintes, to world coordinates.
            // For scroll frames inside a root-content subtree, we apply this transform in two parts
            // (local to root-content, and root-content to world), so that we can make additional
            // adjustments in root-content space. For scroll frames outside of a root-content subtree,
            // the entire world transform will be in `local_to_root_content`.
            let world_transform = spatial_tree
                .get_world_viewport_transform(index)
                .into_transform();
            let mut local_to_root_content = 
                world_transform.with_destination::<LayoutPixel>();
            let mut root_content_to_world = LayoutToWorldTransform::default();
            let mut root_content_clip = None;
            if minimap_data.root_content_scroll_id != 0 {
              if let Some(RootContentInfo{transform: root_content_transform, clip}) = root_content_info.get(&ExternalScrollId(minimap_data.root_content_scroll_id, minimap_data.root_content_pipeline_id)) {
                // Exclude the root-content node's zoom transform from `local_to_root_content`.
                // This ensures that the minimap remains unaffected by pinch-zooming
                // (in essence, remaining attached to the *visual* viewport, rather than to
                // the *layout* viewport which is what happens by default).
                let zoom_transform = minimap_data.zoom_transform;
                local_to_root_content = world_transform
                  .then(&root_content_transform.inverse().unwrap())
                  .then(&zoom_transform.inverse().unwrap());
                root_content_to_world = root_content_transform.clone();
                root_content_clip = Some(clip);
              }
            }

            let mut add_rect = |rect, border, fill| -> Option<()> {
              // Place rect in scroll frame's local coordinate space
              let transformed_rect = transform.outer_transformed_box2d(&rect)?;
              
              // Transform to world coordinates, using root-content coords as an intermediate step.
              let mut root_content_rect = local_to_root_content.outer_transformed_box2d(&transformed_rect)?;
              // In root-content coords, apply the root content node's viewport clip.
              // This prevents subframe minimaps from leaking into the chrome area when the root
              // scroll frame is scrolled.
              // TODO: The minimaps of nested subframes can still leak outside of the viewports of
              // their containing subframes. Should have a more proper fix for this.
              if let Some(clip) = root_content_clip {
                root_content_rect = root_content_rect.intersection(clip)?;
              }
              let world_rect = root_content_to_world.outer_transformed_box2d(&root_content_rect)?;

              // Add world coordinate rects to scratch.debug_items
              // TODO: Add a parameter to control the border thickness of the rects, and make them a bit thicker. 
              scratch.push_debug_rect(world_rect * DevicePixelScale::new(1.0), border, fill);

              Some(())
            };

            add_rect(minimap_data.scrollable_rect, PAGE_BORDER_COLOR, BACKGROUND_COLOR);
            add_rect(minimap_data.visual_viewport, VISUAL_PORT_COLOR, NOTHING);
            add_rect(minimap_data.displayport, DISPLAYPORT_COLOR, DISPLAYPORT_BACKGROUND_COLOR);
            // Only render a distinct layout viewport for the root content.
            // For other scroll frames, the visual and layout viewports coincide.
            if minimap_data.is_root_content {
              add_rect(minimap_data.layout_viewport, LAYOUT_PORT_COLOR, NOTHING);
            }
          }
        }
      });
    }

    fn build_composite_pass(
        &self,
        scene: &BuiltScene,
        ctx: &RenderTargetContext,
        gpu_cache: &mut GpuCache,
        deferred_resolves: &mut Vec<DeferredResolve>,
        composite_state: &mut CompositeState,
    ) {
        for pic_index in &scene.tile_cache_pictures {
            let pic = &ctx.prim_store.pictures[pic_index.0];

            match pic.raster_config {
                Some(RasterConfig { composite_mode: PictureCompositeMode::TileCache { slice_id }, .. }) => {
                    // Tile cache instances are added to the composite config, rather than
                    // directly added to batches. This allows them to be drawn with various
                    // present modes during render, such as partial present etc.
                    let tile_cache = &ctx.tile_caches[&slice_id];
                    let map_local_to_world = SpaceMapper::new_with_target(
                        ctx.root_spatial_node_index,
                        tile_cache.spatial_node_index,
                        ctx.screen_world_rect,
                        ctx.spatial_tree,
                    );
                    let world_clip_rect = map_local_to_world
                        .map(&tile_cache.local_clip_rect)
                        .expect("bug: unable to map clip rect");
                    let device_clip_rect = (world_clip_rect * ctx.global_device_pixel_scale).round();

                    composite_state.push_surface(
                        tile_cache,
                        device_clip_rect,
                        ctx.resource_cache,
                        gpu_cache,
                        deferred_resolves,
                    );
                }
                _ => {
                    panic!("bug: found a top-level prim that isn't a tile cache");
                }
            }
        }
    }
}

/// Processes this pass to prepare it for rendering.
///
/// Among other things, this allocates output regions for each of our tasks
/// (added via `add_render_task`) in a RenderTarget and assigns it into that
/// target.
pub fn build_render_pass(
    src_pass: &Pass,
    screen_size: DeviceIntSize,
    ctx: &mut RenderTargetContext,
    gpu_cache: &mut GpuCache,
    gpu_buffer_builder: &mut GpuBufferBuilder,
    render_tasks: &RenderTaskGraph,
    clip_store: &ClipStore,
    transforms: &mut TransformPalette,
    prim_headers: &mut PrimitiveHeaders,
    z_generator: &mut ZBufferIdGenerator,
    gpu_supports_fast_clears: bool,
    prim_instances: &[PrimitiveInstance],
    cmd_buffers: &CommandBufferList,
) -> RenderPass {
    profile_scope!("build_render_pass");

    // TODO(gw): In this initial frame graph work, we try to maintain the existing
    //           build_render_pass code as closely as possible, to make the review
    //           simpler and reduce chance of regressions. However, future work should
    //           include refactoring this to more closely match the built frame graph.
    let mut pass = RenderPass::new(src_pass);

    for sub_pass in &src_pass.sub_passes {
        match sub_pass.surface {
            SubPassSurface::Dynamic { target_kind, texture_id, used_rect } => {
                match target_kind {
                    RenderTargetKind::Color => {
                        let mut target = ColorRenderTarget::new(
                            texture_id,
                            screen_size,
                            gpu_supports_fast_clears,
                            used_rect,
                        );

                        for task_id in &sub_pass.task_ids {
                            target.add_task(
                                *task_id,
                                ctx,
                                gpu_cache,
                                gpu_buffer_builder,
                                render_tasks,
                                clip_store,
                                transforms,
                            );
                        }

                        pass.color.targets.push(target);
                    }
                    RenderTargetKind::Alpha => {
                        let mut target = AlphaRenderTarget::new(
                            texture_id,
                            screen_size,
                            gpu_supports_fast_clears,
                            used_rect,
                        );

                        for task_id in &sub_pass.task_ids {
                            target.add_task(
                                *task_id,
                                ctx,
                                gpu_cache,
                                gpu_buffer_builder,
                                render_tasks,
                                clip_store,
                                transforms,
                            );
                        }

                        pass.alpha.targets.push(target);
                    }
                }
            }
            SubPassSurface::Persistent { surface: StaticRenderTaskSurface::PictureCache { ref surface, .. }, .. } => {
                assert_eq!(sub_pass.task_ids.len(), 1);
                let task_id = sub_pass.task_ids[0];
                let task = &render_tasks[task_id];
                let target_rect = task.get_target_rect();
                let mut gpu_buffer_builder = GpuBufferBuilder::new();

                match task.kind {
                    RenderTaskKind::Picture(ref pic_task) => {
                        let cmd_buffer = cmd_buffers.get(pic_task.cmd_buffer_index);
                        let scissor_rect = pic_task.scissor_rect.expect("bug: must be set for cache tasks");
                        let valid_rect = pic_task.valid_rect.expect("bug: must be set for cache tasks");

                        let batcher = AlphaBatchBuilder::new(
                            screen_size,
                            ctx.break_advanced_blend_batches,
                            ctx.batch_lookback_count,
                            task_id,
                            task_id.into(),
                        );

                        let mut batch_builder = BatchBuilder::new(batcher);

                        cmd_buffer.iter_prims(&mut |cmd, spatial_node_index, segments| {
                            batch_builder.add_prim_to_batch(
                                cmd,
                                spatial_node_index,
                                ctx,
                                gpu_cache,
                                render_tasks,
                                prim_headers,
                                transforms,
                                pic_task.raster_spatial_node_index,
                                pic_task.surface_spatial_node_index,
                                z_generator,
                                prim_instances,
                                &mut gpu_buffer_builder,
                                segments,
                            );
                        });

                        let batcher = batch_builder.finalize();

                        let mut batch_containers = Vec::new();
                        let mut alpha_batch_container = AlphaBatchContainer::new(Some(scissor_rect));

                        batcher.build(
                            &mut batch_containers,
                            &mut alpha_batch_container,
                            target_rect,
                            None,
                        );
                        debug_assert!(batch_containers.is_empty());

                        let target = PictureCacheTarget {
                            surface: surface.clone(),
                            clear_color: pic_task.clear_color,
                            kind: PictureCacheTargetKind::Draw {
                                alpha_batch_container,
                            },
                            dirty_rect: scissor_rect,
                            valid_rect,
                        };

                        pass.picture_cache.push(target);
                    }
                    RenderTaskKind::TileComposite(ref tile_task) => {
                        let target = PictureCacheTarget {
                            surface: surface.clone(),
                            clear_color: Some(tile_task.clear_color),
                            kind: PictureCacheTargetKind::Blit {
                                task_id: tile_task.task_id.expect("bug: no source task_id set"),
                                sub_rect_offset: tile_task.sub_rect_offset,
                            },
                            dirty_rect: tile_task.scissor_rect,
                            valid_rect: tile_task.valid_rect,
                        };

                        pass.picture_cache.push(target);
                    }
                    _ => {
                        unreachable!();
                    }
                };
            }
            SubPassSurface::Persistent { surface: StaticRenderTaskSurface::TextureCache { target_kind, texture, .. } } => {
                let texture = pass.texture_cache
                    .entry(texture)
                    .or_insert_with(||
                        TextureCacheRenderTarget::new(target_kind)
                    );
                for task_id in &sub_pass.task_ids {
                    texture.add_task(*task_id, render_tasks);
                }
            }
            SubPassSurface::Persistent { surface: StaticRenderTaskSurface::ReadOnly { .. } } => {
                panic!("Should not create a render pass for read-only task locations.");
            }
        }
    }

    pass.color.build(
        ctx,
        gpu_cache,
        render_tasks,
        prim_headers,
        transforms,
        z_generator,
        prim_instances,
        cmd_buffers,
    );
    pass.alpha.build(
        ctx,
        gpu_cache,
        render_tasks,
        prim_headers,
        transforms,
        z_generator,
        prim_instances,
        cmd_buffers,
    );

    pass
}

/// A rendering-oriented representation of the frame built by the render backend
/// and presented to the renderer.
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub struct Frame {
    /// The rectangle to show the frame in, on screen.
    pub device_rect: DeviceIntRect,
    pub passes: Vec<RenderPass>,

    pub transform_palette: Vec<TransformData>,
    pub render_tasks: RenderTaskGraph,
    pub prim_headers: PrimitiveHeaders,

    /// The GPU cache frame that the contents of Self depend on
    pub gpu_cache_frame_id: FrameId,

    /// List of textures that we don't know about yet
    /// from the backend thread. The render thread
    /// will use a callback to resolve these and
    /// patch the data structures.
    pub deferred_resolves: Vec<DeferredResolve>,

    /// True if this frame contains any render tasks
    /// that write to the texture cache.
    pub has_texture_cache_tasks: bool,

    /// True if this frame has been drawn by the
    /// renderer.
    pub has_been_rendered: bool,

    /// Debugging information to overlay for this frame.
    pub debug_items: Vec<DebugItem>,

    /// Contains picture cache tiles, and associated information.
    /// Used by the renderer to composite tiles into the framebuffer,
    /// or hand them off to an OS compositor.
    pub composite_state: CompositeState,

    /// Main GPU data buffer constructed (primarily) during the prepare
    /// pass for primitives that were visible and dirty.
    pub gpu_buffer: GpuBuffer,
}

impl Frame {
    // This frame must be flushed if it writes to the
    // texture cache, and hasn't been drawn yet.
    pub fn must_be_drawn(&self) -> bool {
        self.has_texture_cache_tasks && !self.has_been_rendered
    }

    // Returns true if this frame doesn't alter what is on screen currently.
    pub fn is_nop(&self) -> bool {
        // If there are no off-screen passes, that implies that there are no
        // picture cache tiles, and no texture cache tasks being updates. If this
        // is the case, we can consider the frame a nop (higher level checks
        // test if a composite is needed due to picture cache surfaces moving
        // or external surfaces being updated).
        self.passes.is_empty()
    }
}