Rotation Support (#77)

•  What is the goal of this PR?  
Implement a horizontal EPUB reading mode so books can be read in
landscape orientation (both 90° and 270°), while keeping the rest of the
UI in portrait.

•  What changes are included?
◦  Rendering / Display
▪ Added an orientation model to GfxRenderer (Portrait, LandscapeNormal,
LandscapeFlipped) and made:
▪ drawPixel, drawImage, displayWindow map logical coordinates
differently depending on orientation.
▪ getScreenWidth() / getScreenHeight() return orientation‑aware logical
dimensions (480×800 in portrait, 800×480 in landscape).
◦  Settings / Configuration
▪  Extended CrossPointSettings with:
▪  landscapeReading (toggle for portrait vs. landscape EPUB reading).
▪ landscapeFlipped (toggle to flip landscape 180° so both horizontal
holding directions are supported).
▪ Updated settings serialization/deserialization to persist these fields
while remaining backward‑compatible with existing settings files.
▪  Updated SettingsActivity to expose two new toggles:
▪  “Landscape Reading”
▪  “Flip Landscape (swap top/bottom)”
◦  EPUB Reader
▪  In EpubReaderActivity:
▪ On onEnter, set GfxRenderer orientation based on the new settings
(Portrait, LandscapeNormal, or LandscapeFlipped).
▪ On onExit, reset orientation back to Portrait so Home, WiFi, Settings,
etc. continue to render as before.
▪ Adjusted renderStatusBar to position the status bar and battery
indicator relative to GfxRenderer::getScreenHeight() instead of
hard‑coded Y coordinates, so it stays correctly at the bottom in both
portrait and landscape.
◦  EPUB Caching / Layout
▪ Extended Section cache metadata (section.bin) to include the logical
screenWidth and screenHeight used when pages were generated; bumped
SECTION_FILE_VERSION.
▪  Updated loadCacheMetadata to compare:
▪ font/margins/line compression/extraParagraphSpacing and screen
dimensions; mismatches now invalidate and clear the cache.
▪ Updated persistPageDataToSD and all call sites in EpubReaderActivity
to pass the current GfxRenderer::getScreenWidth() / getScreenHeight() so
portrait and landscape caches are kept separate and correctly sized.



Additional Context

•  Cache behavior / migration
◦ Existing section.bin files (old SECTION_FILE_VERSION) will be detected
as incompatible and their caches cleared and rebuilt once per chapter
when first opened after this change.
◦ Within a given orientation, caches will be reused as before. Switching
orientation (portrait ↔ landscape) will cause a one‑time re‑index of
each chapter in the new orientation.
•  Scope and risks
◦ Orientation changes are scoped to the EPUB reader; the Home screen,
Settings, WiFi selection, sleep screens, and web server UI continue to
assume portrait orientation.
◦ The renderer’s orientation is a static/global setting; if future code
uses GfxRenderer outside the reader while a reader instance is active,
it should be aware that orientation is no longer implicitly fixed.
◦ All drawing primitives now go through orientation‑aware coordinate
transforms; any code that previously relied on edge‑case behavior or
out‑of‑bounds writes might surface as logged “Outside range” warnings
instead.
•  Testing suggestions / areas to focus on
◦  Verify in hardware:
▪ Portrait mode still renders correctly (boot, home, settings, WiFi,
reader).
▪  Landscape reading in both directions:
▪  Landscape Reading = ON, Flip Landscape = OFF.
▪  Landscape Reading = ON, Flip Landscape = ON.
▪ Status bar (page X/Y, % progress, battery icon) is fully visible and
aligned at the bottom in all three combinations.
◦  Open the same book:
▪  In portrait first, then switch to landscape and reopen it.
▪  Confirm that:
▪ Old portrait caches are rebuilt once for landscape (you should see the
“Indexing…” page).
▪ Progress save/restore still works (resume opens to the correct page in
the current orientation).
◦ Ensure grayscale rendering (the secondary pass in
EpubReaderActivity::renderContents) still looks correct in both
orientations.

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h

@@ -32,11 +32,9 @@ class ChapterHtmlSlimParser {
   int16_t currentPageNextY = 0;
   int fontId;
   float lineCompression;
-  int marginTop;
-  int marginRight;
-  int marginBottom;
-  int marginLeft;
   bool extraParagraphSpacing;
+  int viewportWidth;
+  int viewportHeight;
 
   void startNewTextBlock(TextBlock::BLOCK_STYLE style);
   void makePages();
@@ -47,19 +45,17 @@ class ChapterHtmlSlimParser {
 
  public:
   explicit ChapterHtmlSlimParser(const std::string& filepath, GfxRenderer& renderer, const int fontId,
-                                 const float lineCompression, const int marginTop, const int marginRight,
-                                 const int marginBottom, const int marginLeft, const bool extraParagraphSpacing,
+                                 const float lineCompression, const bool extraParagraphSpacing, const int viewportWidth,
+                                 const int viewportHeight,
                                  const std::function<void(std::unique_ptr<Page>)>& completePageFn,
                                  const std::function<void(int)>& progressFn = nullptr)
       : filepath(filepath),
         renderer(renderer),
         fontId(fontId),
         lineCompression(lineCompression),
-        marginTop(marginTop),
-        marginRight(marginRight),
-        marginBottom(marginBottom),
-        marginLeft(marginLeft),
         extraParagraphSpacing(extraParagraphSpacing),
+        viewportWidth(viewportWidth),
+        viewportHeight(viewportHeight),
         completePageFn(completePageFn),
         progressFn(progressFn) {}
   ~ChapterHtmlSlimParser() = default;