Add some more comments.

Author: j4james

src/terminal/adapter/PageManager.cpp

@@ -104,20 +104,29 @@ Page PageManager::Get(const til::CoordType pageNumber) const
 {
     const auto requestedPageNumber = std::min(std::max(pageNumber, 1), MAX_PAGES);
     auto [visibleBuffer, visibleViewport, isMainBuffer] = _api.GetBufferAndViewport();
+
+    // If we're not in the main buffer (either because an app has enabled the
+    // alternate buffer mode, or switched the conhost screen buffer), then VT
+    // paging doesn't apply, so we disregard the requested page number and just
+    // use the visible buffer (with a fixed page number of 1).
     if (!isMainBuffer)
     {
         return { visibleBuffer, visibleViewport, 1 };
     }
-    else if (requestedPageNumber == _visiblePageNumber)
+
+    // If the requested page number happens to be the visible page, then we
+    // can also just use the visible buffer as is.
+    if (requestedPageNumber == _visiblePageNumber)
     {
         return { visibleBuffer, visibleViewport, _visiblePageNumber };
     }
-    else
-    {
-        const auto pageSize = visibleViewport.size();
-        auto& pageBuffer = _getBuffer(requestedPageNumber, pageSize);
-        return { pageBuffer, til::rect{ pageSize }, requestedPageNumber };
-    }
+
+    // Otherwise we're working with a background buffer, so we need to
+    // retrieve that from the buffer array, and resize it to match the
+    // active page size.
+    const auto pageSize = visibleViewport.size();
+    auto& pageBuffer = _getBuffer(requestedPageNumber, pageSize);
+    return { pageBuffer, til::rect{ pageSize }, requestedPageNumber };
 }
 
 Page PageManager::ActivePage() const