Add helper function GetInsetSizes() to PDFiumEngine.

Currently PDFiumEngine::EnlargePage() and PDFiumEngine::InsetPage()
have common logic for retrieving the inset sizes given the current
layout and position of the page in the document.

This CL adds PDFiumEngine::GetInsetSizes() which extracts the logic for
retrieving insets sizes and puts it into a helper function. This helps
manage the complexity of PDFiumEngine.

Change-Id: I2aabba1f08770dbc16e033c64607627675ff0b58
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1715904
Commit-Queue: Jeremy Chinsen <chinsenj@google.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680188}

pdf/pdfium/pdfium_engine.cc

@@ -2833,17 +2833,24 @@ pp::Size PDFiumEngine::GetPageSize(int index) {
   return size;
 }
 
-void PDFiumEngine::EnlargePage(size_t page_index,
-                               size_t num_of_pages,
-                               pp::Size* page_size) {
+draw_utils::PageInsetSizes PDFiumEngine::GetInsetSizes(
+    size_t page_index,
+    size_t num_of_pages) const {
   DCHECK_LT(page_index, num_of_pages);
 
-  draw_utils::PageInsetSizes inset_sizes = kSingleViewInsets;
   if (two_up_view_) {
-    inset_sizes = draw_utils::GetPageInsetsForTwoUpView(
+    return draw_utils::GetPageInsetsForTwoUpView(
         page_index, num_of_pages, kSingleViewInsets, kHorizontalSeparator);
   }
 
+  return kSingleViewInsets;
+}
+
+void PDFiumEngine::EnlargePage(size_t page_index,
+                               size_t num_of_pages,
+                               pp::Size* page_size) const {
+  draw_utils::PageInsetSizes inset_sizes =
+      GetInsetSizes(page_index, num_of_pages);
   page_size->Enlarge(inset_sizes.left + inset_sizes.right,
                      inset_sizes.top + inset_sizes.bottom);
 }
@@ -2851,15 +2858,9 @@ void PDFiumEngine::EnlargePage(size_t page_index,
 void PDFiumEngine::InsetPage(size_t page_index,
                              size_t num_of_pages,
                              double multiplier,
-                             pp::Rect* rect) {
-  DCHECK_LT(page_index, num_of_pages);
-
-  draw_utils::PageInsetSizes inset_sizes = kSingleViewInsets;
-  if (two_up_view_) {
-    inset_sizes = draw_utils::GetPageInsetsForTwoUpView(
-        page_index, num_of_pages, kSingleViewInsets, kHorizontalSeparator);
-  }
-
+                             pp::Rect* rect) const {
+  draw_utils::PageInsetSizes inset_sizes =
+      GetInsetSizes(page_index, num_of_pages);
   rect->Inset(static_cast<int>(ceil(inset_sizes.left * multiplier)),
               static_cast<int>(ceil(inset_sizes.top * multiplier)),
               static_cast<int>(ceil(inset_sizes.right * multiplier)),

pdf/pdfium/pdfium_engine.h

@@ -41,6 +41,7 @@ class PDFiumDocument;
 
 namespace draw_utils {
 class ShadowMatrix;
+struct PageInsetSizes;
 }
 
 class PDFiumEngine : public PDFEngine,
@@ -267,18 +268,26 @@ class PDFiumEngine : public PDFEngine,
   // PDFiumPage because we might not have that structure when we need this.
   pp::Size GetPageSize(int index);
 
+  // Helper function for getting the inset sizes for the current layout. If
+  // |two_up_view_| is true, the configuration of inset sizes depends on
+  // the position of the page, specified by |page_index| and |num_of_pages|.
+  draw_utils::PageInsetSizes GetInsetSizes(size_t page_index,
+                                           size_t num_of_pages) const;
+
   // If |two_up_view_| is false, enlarges |page_size| with inset sizes for
-  // single-view. If |two_up_view_| is true, gets the appropriate two-up view
-  // inset sizes for the position of the page (dependent on |page_index| and
-  // |num_of_pages|) and then enlarges |page_size|.
-  void EnlargePage(size_t page_index, size_t num_of_pages, pp::Size* page_size);
+  // single-view. If |two_up_view_| is true, calls GetInsetSizes() with
+  // |page_index| and |num_of_pages|, and uses the returned inset sizes to
+  // enlarge |page_size|.
+  void EnlargePage(size_t page_index,
+                   size_t num_of_pages,
+                   pp::Size* page_size) const;
 
   // Similar to EnlargePage(), but insets a |rect|. Also multiplies the inset
   // sizes by |multiplier|, using the ceiling of the result.
   void InsetPage(size_t page_index,
                  size_t num_of_pages,
                  double multiplier,
-                 pp::Rect* rect);
+                 pp::Rect* rect) const;
 
   void GetAllScreenRectsUnion(const std::vector<PDFiumRange>& rect_range,
                               const pp::Point& offset_point,