Refine player control-plane flow

src/player/public/js/player-page-rendering.js

@@ -893,6 +893,45 @@ function getSlideMarkupCacheKey(slide) {
   return [currentPlaylistSignature || '', slide && slide.id ? slide.id : '', slide && slide.template_id ? slide.template_id : '', slide && slide.modified_at ? slide.modified_at : '', viewportKey, videoRegionRenderVersion || 0].join('|');
 }
 
+function restorePlayerCanvasDimensions(width, height) {
+  if (!document || !document.documentElement) {
+    return;
+  }
+
+  var style = document.documentElement.style;
+  if (width) {
+    style.setProperty('--player-canvas-width', width);
+  } else {
+    style.removeProperty('--player-canvas-width');
+  }
+
+  if (height) {
+    style.setProperty('--player-canvas-height', height);
+  } else {
+    style.removeProperty('--player-canvas-height');
+  }
+}
+
+function primeSlideMarkup(slide) {
+  if (!slide) {
+    return '';
+  }
+
+  var cachedMarkup = getCachedSlideMarkup(slide);
+  if (cachedMarkup) {
+    return cachedMarkup;
+  }
+
+  var previousWidth = document && document.documentElement && document.documentElement.style ? String(document.documentElement.style.getPropertyValue('--player-canvas-width') || '') : '';
+  var previousHeight = document && document.documentElement && document.documentElement.style ? String(document.documentElement.style.getPropertyValue('--player-canvas-height') || '') : '';
+
+  try {
+    return buildSlideMarkupForState(slide, false);
+  } finally {
+    restorePlayerCanvasDimensions(previousWidth.trim(), previousHeight.trim());
+  }
+}
+
 function notifyVideoRegionSourceReady() {
   if (typeof videoRegionRenderVersion === 'number') {
     videoRegionRenderVersion += 1;
@@ -919,9 +958,12 @@ function setCachedSlideMarkup(slide, markup) {
 
 // Slide rendering and markup cache helpers.
 // Choose the right slide renderer and cache the result.
-function buildSlideMarkup(slide) {
-  lastRenderedSlide = slide || null;
-  syncBlackoutState();
+function buildSlideMarkupForState(slide, updateCurrentState) {
+  if (updateCurrentState) {
+    lastRenderedSlide = slide || null;
+    syncBlackoutState();
+  }
+
   var cachedMarkup = getCachedSlideMarkup(slide);
   if (cachedMarkup) {
     return cachedMarkup;
@@ -938,3 +980,7 @@ function buildSlideMarkup(slide) {
   setCachedSlideMarkup(slide, markup);
   return markup;
 }
+
+function buildSlideMarkup(slide) {
+  return buildSlideMarkupForState(slide, true);
+}