[Debugger] Add some info about substitution font

When pdfBug is true, the substitution font is used in the text layer in order
to be able to know what is the font really used thanks to the devtools.
And to be sure that fonts are loaded, the font cache isn't cleaned up when
the debugger is active.

src/core/evaluator.js

@@ -2427,13 +2427,17 @@ class PartialEvaluator {
       const { font, loadedName } = textState;
       if (!seenStyles.has(loadedName)) {
         seenStyles.add(loadedName);
-
         textContent.styles[loadedName] = {
           fontFamily: font.fallbackName,
           ascent: font.ascent,
           descent: font.descent,
           vertical: font.vertical,
         };
+        if (self.options.fontExtraProperties && font.systemFontInfo) {
+          const style = textContent.styles[loadedName];
+          style.fontSubstitution = font.systemFontInfo.css;
+          style.fontSubstitutionLoadedName = font.systemFontInfo.loadedName;
+        }
       }
       textContentItem.fontName = loadedName;
 

src/display/font_loader.js

@@ -80,7 +80,7 @@ class FontLoader {
     }
   }
 
-  async loadSystemFont(info) {
+  async loadSystemFont({ systemFontInfo: info, _inspectFont }) {
     if (!info || this.#systemFonts.has(info.loadedName)) {
       return;
     }
@@ -96,6 +96,7 @@ class FontLoader {
       try {
         await fontFace.load();
         this.#systemFonts.add(loadedName);
+        _inspectFont?.(info);
       } catch {
         warn(
           `Cannot load system font: ${info.baseFontName}, installing it could help to improve PDF rendering.`
@@ -119,7 +120,7 @@ class FontLoader {
     font.attached = true;
 
     if (font.systemFontInfo) {
-      await this.loadSystemFont(font.systemFontInfo);
+      await this.loadSystemFont(font);
       return;
     }
 

src/display/text_layer.js

@@ -172,9 +172,12 @@ function appendText(task, geom, styles) {
   if (style.vertical) {
     angle += Math.PI / 2;
   }
+
+  const fontFamily =
+    (task._fontInspectorEnabled && style.fontSubstitution) || style.fontFamily;
   const fontHeight = Math.hypot(tx[2], tx[3]);
   const fontAscent =
-    fontHeight * getAscent(style.fontFamily, task._isOffscreenCanvasSupported);
+    fontHeight * getAscent(fontFamily, task._isOffscreenCanvasSupported);
 
   let left, top;
   if (angle === 0) {
@@ -198,7 +201,7 @@ function appendText(task, geom, styles) {
     divStyle.top = `${scaleFactorStr}${top.toFixed(2)}px)`;
   }
   divStyle.fontSize = `${scaleFactorStr}${fontHeight.toFixed(2)}px)`;
-  divStyle.fontFamily = style.fontFamily;
+  divStyle.fontFamily = fontFamily;
 
   textDivProperties.fontSize = fontHeight;
 
@@ -212,7 +215,8 @@ function appendText(task, geom, styles) {
   // `fontName` is only used by the FontInspector, and we only use `dataset`
   // here to make the font name available in the debugger.
   if (task._fontInspectorEnabled) {
-    textDiv.dataset.fontName = geom.fontName;
+    textDiv.dataset.fontName =
+      style.fontSubstitutionLoadedName || geom.fontName;
   }
   if (angle !== 0) {
     textDivProperties.angle = angle * (180 / Math.PI);

web/app.js

@@ -1816,7 +1816,9 @@ const PDFViewerApplication = {
     this.pdfViewer.cleanup();
     this.pdfThumbnailViewer?.cleanup();
 
-    this.pdfDocument.cleanup();
+    this.pdfDocument.cleanup(
+      /* keepLoadedFonts = */ AppOptions.get("fontExtraProperties")
+    );
   },
 
   forceRendering() {

web/debugger.mjs

@@ -111,21 +111,29 @@ const FontInspector = (function FontInspectorClosure() {
         }
         return moreInfo;
       }
-      const moreInfo = properties(fontObj, ["name", "type"]);
+
+      const moreInfo = fontObj.css
+        ? properties(fontObj, ["baseFontName"])
+        : properties(fontObj, ["name", "type"]);
+
       const fontName = fontObj.loadedName;
       const font = document.createElement("div");
       const name = document.createElement("span");
       name.textContent = fontName;
-      const download = document.createElement("a");
-      if (url) {
-        url = /url\(['"]?([^)"']+)/.exec(url);
-        download.href = url[1];
-      } else if (fontObj.data) {
-        download.href = URL.createObjectURL(
-          new Blob([fontObj.data], { type: fontObj.mimetype })
-        );
+      let download;
+      if (!fontObj.css) {
+        download = document.createElement("a");
+        if (url) {
+          url = /url\(['"]?([^)"']+)/.exec(url);
+          download.href = url[1];
+        } else if (fontObj.data) {
+          download.href = URL.createObjectURL(
+            new Blob([fontObj.data], { type: fontObj.mimetype })
+          );
+        }
+        download.textContent = "Download";
       }
-      download.textContent = "Download";
+
       const logIt = document.createElement("a");
       logIt.href = "";
       logIt.textContent = "Log";
@@ -139,7 +147,11 @@ const FontInspector = (function FontInspectorClosure() {
       select.addEventListener("click", function () {
         selectFont(fontName, select.checked);
       });
-      font.append(select, name, " ", download, " ", logIt, moreInfo);
+      if (download) {
+        font.append(select, name, " ", download, " ", logIt, moreInfo);
+      } else {
+        font.append(select, name, " ", logIt, moreInfo);
+      }
       fonts.append(font);
       // Somewhat of a hack, should probably add a hook for when the text layer
       // is done rendering.