feat: Current page as QR (#1099)

## Summary

* **What is the goal of this PR?** Implements QR text of the current
page
* **What changes are included?**

## Additional Context

I saw this feature request at #982 
It made sense to me so I implemented. But if the team thinks it is not
necessary please let me know and we can close the PR.

| Page | Menu | QR |
|------|-------|----|
|
![IMG_6601.bmp](https://github.com/user-attachments/files/25473201/IMG_6601.bmp)
|
![IMG_6599.bmp](https://github.com/user-attachments/files/25473202/IMG_6599.bmp)
|
![IMG_6600.bmp](https://github.com/user-attachments/files/25473205/IMG_6600.bmp)
|


---

### AI Usage


Did you use AI tools to help write this code? _** YES

---------

Co-authored-by: Eliz Kilic <elizk@google.com>

src/activities/reader/EpubReaderActivity.cpp

@@ -1,6 +1,7 @@
 #include "EpubReaderActivity.h"
 
 #include <Epub/Page.h>
+#include <Epub/blocks/TextBlock.h>
 #include <FsHelpers.h>
 #include <GfxRenderer.h>
 #include <HalStorage.h>
@@ -14,6 +15,7 @@
 #include "KOReaderCredentialStore.h"
 #include "KOReaderSyncActivity.h"
 #include "MappedInputManager.h"
+#include "QrDisplayActivity.h"
 #include "RecentBooksStore.h"
 #include "components/UITheme.h"
 #include "fontIds.h"
@@ -403,6 +405,38 @@ void EpubReaderActivity::onReaderMenuConfirm(EpubReaderMenuActivity::MenuAction
           }));
       break;
     }
+    case EpubReaderMenuActivity::MenuAction::DISPLAY_QR: {
+      if (section && section->currentPage >= 0 && section->currentPage < section->pageCount) {
+        auto p = section->loadPageFromSectionFile();
+        if (p) {
+          std::string fullText;
+          for (const auto& el : p->elements) {
+            if (el->getTag() == TAG_PageLine) {
+              const auto& line = static_cast<const PageLine&>(*el);
+              if (line.getBlock()) {
+                const auto& words = line.getBlock()->getWords();
+                for (const auto& w : words) {
+                  if (!fullText.empty()) fullText += " ";
+                  fullText += w;
+                }
+              }
+            }
+          }
+          if (!fullText.empty()) {
+            exitActivity();
+            enterNewActivity(new QrDisplayActivity(renderer, mappedInput, fullText, [this]() {
+              exitActivity();
+              requestUpdate();
+            }));
+            break;
+          }
+        }
+      }
+      // If no text or page loading failed, just close menu
+      exitActivity();
+      requestUpdate();
+      break;
+    }
     case EpubReaderMenuActivity::MenuAction::GO_HOME: {
       // Defer go home to avoid race condition with display task
       pendingGoHome = true;

src/activities/reader/EpubReaderMenuActivity.h

@@ -12,7 +12,16 @@
 class EpubReaderMenuActivity final : public ActivityWithSubactivity {
  public:
   // Menu actions available from the reader menu.
-  enum class MenuAction { SELECT_CHAPTER, GO_TO_PERCENT, ROTATE_SCREEN, SCREENSHOT, GO_HOME, SYNC, DELETE_CACHE };
+  enum class MenuAction {
+    SELECT_CHAPTER,
+    GO_TO_PERCENT,
+    ROTATE_SCREEN,
+    SCREENSHOT,
+    DISPLAY_QR,
+    GO_HOME,
+    SYNC,
+    DELETE_CACHE
+  };
 
   explicit EpubReaderMenuActivity(GfxRenderer& renderer, MappedInputManager& mappedInput, const std::string& title,
                                   const int currentPage, const int totalPages, const int bookProgressPercent,
@@ -39,11 +48,14 @@ class EpubReaderMenuActivity final : public ActivityWithSubactivity {
   };
 
   // Fixed menu layout (order matters for up/down navigation).
-  const std::vector<MenuItem> menuItems = {
-      {MenuAction::SELECT_CHAPTER, StrId::STR_SELECT_CHAPTER}, {MenuAction::ROTATE_SCREEN, StrId::STR_ORIENTATION},
-      {MenuAction::GO_TO_PERCENT, StrId::STR_GO_TO_PERCENT},   {MenuAction::SCREENSHOT, StrId::STR_SCREENSHOT_BUTTON},
-      {MenuAction::GO_HOME, StrId::STR_GO_HOME_BUTTON},        {MenuAction::SYNC, StrId::STR_SYNC_PROGRESS},
-      {MenuAction::DELETE_CACHE, StrId::STR_DELETE_CACHE}};
+  const std::vector<MenuItem> menuItems = {{MenuAction::SELECT_CHAPTER, StrId::STR_SELECT_CHAPTER},
+                                           {MenuAction::ROTATE_SCREEN, StrId::STR_ORIENTATION},
+                                           {MenuAction::GO_TO_PERCENT, StrId::STR_GO_TO_PERCENT},
+                                           {MenuAction::SCREENSHOT, StrId::STR_SCREENSHOT_BUTTON},
+                                           {MenuAction::DISPLAY_QR, StrId::STR_DISPLAY_QR},
+                                           {MenuAction::GO_HOME, StrId::STR_GO_HOME_BUTTON},
+                                           {MenuAction::SYNC, StrId::STR_SYNC_PROGRESS},
+                                           {MenuAction::DELETE_CACHE, StrId::STR_DELETE_CACHE}};
   int selectedIndex = 0;
 
   ButtonNavigator buttonNavigator;

src/activities/reader/QrDisplayActivity.cpp

@@ -0,0 +1,45 @@
+#include "QrDisplayActivity.h"
+
+#include <GfxRenderer.h>
+#include <I18n.h>
+
+#include "MappedInputManager.h"
+#include "components/UITheme.h"
+#include "fontIds.h"
+#include "util/QrUtils.h"
+
+void QrDisplayActivity::onEnter() {
+  Activity::onEnter();
+  requestUpdate();
+}
+
+void QrDisplayActivity::onExit() { Activity::onExit(); }
+
+void QrDisplayActivity::loop() {
+  if (mappedInput.wasReleased(MappedInputManager::Button::Back) ||
+      mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+    onGoBack();
+    return;
+  }
+}
+
+void QrDisplayActivity::render(Activity::RenderLock&&) {
+  renderer.clearScreen();
+  auto metrics = UITheme::getInstance().getMetrics();
+  const auto pageWidth = renderer.getScreenWidth();
+  const auto pageHeight = renderer.getScreenHeight();
+
+  GUI.drawHeader(renderer, Rect{0, metrics.topPadding, pageWidth, metrics.headerHeight}, tr(STR_DISPLAY_QR), nullptr);
+
+  const int availableWidth = pageWidth - 40;
+  const int availableHeight = pageHeight - metrics.topPadding - metrics.headerHeight - metrics.verticalSpacing * 2 - 40;
+  const int startY = metrics.topPadding + metrics.headerHeight + metrics.verticalSpacing;
+
+  const Rect qrBounds(20, startY, availableWidth, availableHeight);
+  QrUtils::drawQrCode(renderer, qrBounds, textPayload);
+
+  const auto labels = mappedInput.mapLabels(tr(STR_BACK), "", "", "");
+  GUI.drawButtonHints(renderer, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
+  renderer.displayBuffer();
+}

src/activities/reader/QrDisplayActivity.h

@@ -0,0 +1,22 @@
+#pragma once
+#include <I18n.h>
+
+#include <string>
+
+#include "activities/Activity.h"
+
+class QrDisplayActivity final : public Activity {
+ public:
+  explicit QrDisplayActivity(GfxRenderer& renderer, MappedInputManager& mappedInput, const std::string& textPayload,
+                             const std::function<void()>& onGoBack)
+      : Activity("QrDisplay", renderer, mappedInput), textPayload(textPayload), onGoBack(onGoBack) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+  void render(Activity::RenderLock&&) override;
+
+ private:
+  std::string textPayload;
+  const std::function<void()> onGoBack;
+};