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

/* 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 https://mozilla.org/MPL/2.0/. */

use std::sync::Arc;

use base::id::PipelineId;
use fnv::FnvHashMap;
use fonts::{FontCacheThread, FontContext};
use net_traits::image_cache::{
    ImageCache, ImageCacheResult, ImageOrMetadataAvailable, UsePlaceholder,
};
use parking_lot::{Mutex, RwLock};
use script_layout_interface::{PendingImage, PendingImageState};
use servo_url::{ImmutableOrigin, ServoUrl};
use style::context::SharedStyleContext;
use style::dom::OpaqueNode;

use crate::display_list::WebRenderImageInfo;

pub struct LayoutContext<'a> {
    pub id: PipelineId,
    pub use_rayon: bool,
    pub origin: ImmutableOrigin,

    /// Bits shared by the layout and style system.
    pub style_context: SharedStyleContext<'a>,

    /// A FontContext to be used during layout.
    pub font_context: Arc<FontContext<FontCacheThread>>,

    /// Reference to the script thread image cache.
    pub image_cache: Arc<dyn ImageCache>,

    /// A list of in-progress image loads to be shared with the script thread.
    pub pending_images: Mutex<Vec<PendingImage>>,

    pub webrender_image_cache:
        Arc<RwLock<FnvHashMap<(ServoUrl, UsePlaceholder), WebRenderImageInfo>>>,
}

impl<'a> Drop for LayoutContext<'a> {
    fn drop(&mut self) {
        if !std::thread::panicking() {
            assert!(self.pending_images.lock().is_empty());
        }
    }
}

impl<'a> LayoutContext<'a> {
    #[inline(always)]
    pub fn shared_context(&self) -> &SharedStyleContext {
        &self.style_context
    }

    pub fn get_or_request_image_or_meta(
        &self,
        node: OpaqueNode,
        url: ServoUrl,
        use_placeholder: UsePlaceholder,
    ) -> Option<ImageOrMetadataAvailable> {
        // Check for available image or start tracking.
        let cache_result = self.image_cache.get_cached_image_status(
            url.clone(),
            self.origin.clone(),
            None,
            use_placeholder,
        );

        match cache_result {
            ImageCacheResult::Available(img_or_meta) => Some(img_or_meta),
            // Image has been requested, is still pending. Return no image for this paint loop.
            // When the image loads it will trigger a reflow and/or repaint.
            ImageCacheResult::Pending(id) => {
                let image = PendingImage {
                    state: PendingImageState::PendingResponse,
                    node: node.into(),
                    id,
                    origin: self.origin.clone(),
                };
                self.pending_images.lock().push(image);
                None
            },
            // Not yet requested - request image or metadata from the cache
            ImageCacheResult::ReadyForRequest(id) => {
                let image = PendingImage {
                    state: PendingImageState::Unrequested(url),
                    node: node.into(),
                    id,
                    origin: self.origin.clone(),
                };
                self.pending_images.lock().push(image);
                None
            },
            // Image failed to load, so just return nothing
            ImageCacheResult::LoadError => None,
        }
    }

    pub fn get_webrender_image_for_url(
        &self,
        node: OpaqueNode,
        url: ServoUrl,
        use_placeholder: UsePlaceholder,
    ) -> Option<WebRenderImageInfo> {
        if let Some(existing_webrender_image) = self
            .webrender_image_cache
            .read()
            .get(&(url.clone(), use_placeholder))
        {
            return Some(*existing_webrender_image);
        }

        match self.get_or_request_image_or_meta(node, url.clone(), use_placeholder) {
            Some(ImageOrMetadataAvailable::ImageAvailable { image, .. }) => {
                let image_info = WebRenderImageInfo {
                    width: image.width,
                    height: image.height,
                    key: image.id,
                };
                if image_info.key.is_none() {
                    Some(image_info)
                } else {
                    let mut webrender_image_cache = self.webrender_image_cache.write();
                    webrender_image_cache.insert((url, use_placeholder), image_info);
                    Some(image_info)
                }
            },
            None | Some(ImageOrMetadataAvailable::MetadataAvailable(_)) => None,
        }
    }
}