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Optimize viewer syncing with IntersectionObserver to avoid tile request storms #104

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78 changes: 70 additions & 8 deletions webapp/src/viewers/images/images.js
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,52 @@ const openseadragon_config = {
var synced_viewers = {}


// Viewport-aware syncing: only sync viewers near the viewport to avoid
// animating and requesting tiles for all 50+ viewers on a page at once.
const visible_viewer_ids = new Set();
const observed_components = new WeakMap(); // DOM element -> ImgViewer instance

function onVisibilityChange(entries) {
entries.forEach(entry => {
const component = observed_components.get(entry.target);
if (!component) return;

const ids = [component.viewer_new?.id, component.viewer_ref?.id].filter(Boolean);
if (entry.isIntersecting) {
ids.forEach(id => visible_viewer_ids.add(id));
catchUpSyncState(component);
} else {
ids.forEach(id => visible_viewer_ids.delete(id));
}
});
}

// 200px margin so viewers just outside the viewport are pre-synced
const visibility_observer = typeof IntersectionObserver !== 'undefined'
? new IntersectionObserver(onVisibilityChange, { rootMargin: '200px' })
: null;

function isViewerVisible(viewer_id) {
if (!visibility_observer) return true; // fallback: sync all
return visible_viewer_ids.has(viewer_id);
}

// When a viewer scrolls into view, snap it to the current sync group state
function catchUpSyncState(component) {
const sync_key = component._sync_key;
if (!sync_key || !synced_viewers[sync_key]) return;
const sync_group = synced_viewers[sync_key];
if (sync_group.zoom == null || sync_group.center == null) return;

[component.viewer_new, component.viewer_ref].forEach(v => {
if (!v?.viewport) return;
try {
v.viewport.zoomTo(sync_group.zoom, null, true);
v.viewport.panTo(sync_group.center, true);
} catch(e) {}
});
}


// we create unique ids to identify openseadragon viewers as outputs change
// it's handy for smooth transitions, eg with videos, or when the list of viewers is updated/filtered
Expand All @@ -83,14 +129,15 @@ function maintain_zoom() {
return;
sync_group.leading = "resize";
try { // we should try to find how to identify when an image is not loaed...
sync_group.viewers.forEach(v => {
const visible = sync_group.viewers.filter(v => isViewerVisible(v.id));
visible.forEach(v => {
const size = new OpenSeadragon.Point(v.container.clientWidth ?? 1, v.container.clientHeight ?? 1);
v.viewport.resize(size, true);
v.viewport.zoomTo(sync_group.zoom, null, true);
v.viewport.panTo(sync_group.center, true);
})
sync_group.leading = null;
sync_group.viewers.forEach(v => v.forceRedraw())
visible.forEach(v => v.forceRedraw())
} catch { }
})
}
Expand All @@ -106,6 +153,7 @@ class ImgViewer extends React.PureComponent {

this.show_histogram = false;
this.canvas_diff = React.createRef();
this.wrapperRef = React.createRef();
// this.canvas_diff_ssim = React.createRef();

this.state = {
Expand Down Expand Up @@ -134,6 +182,11 @@ class ImgViewer extends React.PureComponent {
...openseadragon_config,
...this.viewer_ref,
});
// Start observing visibility for viewport-aware syncing
if (visibility_observer && this.wrapperRef.current) {
observed_components.set(this.wrapperRef.current, this);
visibility_observer.observe(this.wrapperRef.current);
}
this.Init().then(() => {
this.viewer_new.addOnceHandler('update-viewport', () => this.setState({ ready: true }), {}, 3);
this.InitMouseTracker(this.props);
Expand All @@ -155,6 +208,7 @@ class ImgViewer extends React.PureComponent {
const { viewer_new, viewer_ref } = this;
const { image_width, image_height } = this.state;
const sync_key = `${this.props.output_new.test_input_path}-${image_height}x${image_width}`;
this._sync_key = sync_key;
// console.log("sync_key", sync_key)

if (synced_viewers[sync_key] === undefined) {
Expand Down Expand Up @@ -191,8 +245,8 @@ class ImgViewer extends React.PureComponent {
return
synced_viewers[sync_key].leading = viewer.id;
synced_viewers[sync_key].viewers.filter(v => v.id !== viewer.id).forEach(v => {
// console.log(` follow for ${v.id} (${v.source.height}:${v.source.width})`)
// console.log(v.source.width)
// Only sync viewers that are near the viewport
if (!isViewerVisible(v.id)) return;
v.viewport.zoomTo(synced_viewers[sync_key].zoom);
v.viewport.panTo(synced_viewers[sync_key].center);
})
Expand Down Expand Up @@ -221,6 +275,14 @@ class ImgViewer extends React.PureComponent {


componentWillUnmount() {
// Stop observing visibility
if (visibility_observer && this.wrapperRef.current) {
visibility_observer.unobserve(this.wrapperRef.current);
observed_components.delete(this.wrapperRef.current);
}
visible_viewer_ids.delete(this.viewer_new?.id);
visible_viewer_ids.delete(this.viewer_ref?.id);

if (!!this.state.cancel_source.token)
this.state.cancel_source.cancel();
if (!!this.UnregisterZoomSync)
Expand All @@ -230,13 +292,13 @@ class ImgViewer extends React.PureComponent {

if (!!this.viewer_new) {
unregister_filter_sync(this.viewer_new)
// this.viewer_new.imageLoader.clear()
// this.viewer_new.imageLoader.clear()
// this.viewer_new.destroy();
// this.viewer_new = null;
}
if (!!this.viewer_ref) {
unregister_filter_sync(this.viewer_ref)
// this.viewer_new.imageLoader.clear()
// this.viewer_new.imageLoader.clear()
// this.viewer_ref.destroy();
// this.viewer_ref = null;
}
Expand Down Expand Up @@ -685,7 +747,7 @@ class ImgViewer extends React.PureComponent {
// {/* <canvas hidden={!diff || !has_reference} ref={this.canvas_diff_ssim} /> */}

// const empty_image = <canvas key="empty-image" {...single_image_size} />
return <>
return <div ref={this.wrapperRef}>
{error_messages}
{!has_error && <>
{this.state.ready &&
Expand Down Expand Up @@ -732,7 +794,7 @@ class ImgViewer extends React.PureComponent {
<div style={{ display: "flex", justifyContent: "center", alignItems: "center"}} hidden={has_error}>
{hist_info}
</div>
</>
</div>
}

switch_images = e => {
Expand Down
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