PDF: Manipulate the selected text buffer to deal with special 0xfffe hyphens.

Also format text to match Adobe Reader.

BUG=307523
TEST=Manual, see bug (and duplicates for more examples)

Review URL: https://codereview.chromium.org/566773005

Cr-Commit-Position: refs/heads/master@{#294638}

1 files changed, 69 insertions, 36 deletions

diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 28fca44..6457478 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -45,6 +45,8 @@
 
 namespace chrome_pdf {
 
+namespace {
+
 #define kPageShadowTop    3
 #define kPageShadowBottom 7
 #define kPageShadowLeft   5
@@ -458,46 +460,75 @@ void CalculateNonScaledClipBoxOffset(const pp::Rect& content_rect, int rotation,
   }
 }
 
-// Do an in-place transformation of objects on |page|. Translate all objects on
-// |page| in |source_clip_box| by (|offset_x|, |offset_y|) and scale them by
-// |scale_factor|.
-//
-// |page| Handle to the page. Returned by FPDF_LoadPage function.
-// |source_clip_box| specifies the source clip box positions, relative to
-// origin at left-bottom.
-// |scale_factor| specifies the scale factor that should be applied to page
-// objects.
-// |offset_x| and |offset_y| specifies the translation offsets for the page
-// objects, relative to origin at left-bottom.
-
-void TransformPageObjects(FPDF_PAGE page, const ClipBox& source_clip_box,
-                          const double scale_factor, double offset_x,
-                          double offset_y) {
-  const int obj_count = FPDFPage_CountObject(page);
-
-  // Create a new clip path.
-  FPDF_CLIPPATH clip_path = FPDF_CreateClipPath(
-      source_clip_box.left + offset_x, source_clip_box.bottom + offset_y,
-      source_clip_box.right + offset_x, source_clip_box.top + offset_y);
-
-  for (int obj_idx = 0; obj_idx < obj_count; ++obj_idx) {
-    FPDF_PAGEOBJECT page_obj = FPDFPage_GetObject(page, obj_idx);
-    FPDFPageObj_Transform(page_obj, scale_factor, 0, 0, scale_factor,
-                          offset_x, offset_y);
-    FPDFPageObj_TransformClipPath(page_obj, scale_factor, 0, 0, scale_factor,
-                                  offset_x, offset_y);
+// This formats a string with special 0xfffe end-of-line hyphens the same way
+// as Adobe Reader. When a hyphen is encountered, the next non-CR/LF whitespace
+// becomes CR+LF and the hyphen is erased. If there is no whitespace between
+// two hyphens, the latter hyphen is erased and ignored.
+void FormatStringWithHyphens(base::string16* text) {
+  // First pass marks all the hyphen positions.
+  struct HyphenPosition {
+    HyphenPosition() : position(0), next_whitespace_position(0) {}
+    size_t position;
+    size_t next_whitespace_position;  // 0 for none
+  };
+  std::vector<HyphenPosition> hyphen_positions;
+  HyphenPosition current_hyphen_position;
+  bool current_hyphen_position_is_valid = false;
+  const base::char16 kPdfiumHyphenEOL = 0xfffe;
+
+  for (size_t i = 0; i < text->size(); ++i) {
+    const base::char16& current_char = (*text)[i];
+    if (current_char == kPdfiumHyphenEOL) {
+      if (current_hyphen_position_is_valid)
+        hyphen_positions.push_back(current_hyphen_position);
+      current_hyphen_position = HyphenPosition();
+      current_hyphen_position.position = i;
+      current_hyphen_position_is_valid = true;
+    } else if (IsWhitespace(current_char)) {
+      if (current_hyphen_position_is_valid) {
+        if (current_char != L'\r' && current_char != L'\n')
+          current_hyphen_position.next_whitespace_position = i;
+        hyphen_positions.push_back(current_hyphen_position);
+        current_hyphen_position_is_valid = false;
+      }
+    }
   }
-  FPDFPage_TransformAnnots(page, scale_factor, 0, 0, scale_factor,
-                           offset_x, offset_y);
-  FPDFPage_GenerateContent(page);
+  if (current_hyphen_position_is_valid)
+    hyphen_positions.push_back(current_hyphen_position);
 
-  // Add a extra clip path to the new pdf page here.
-  FPDFPage_InsertClipPath(page, clip_path);
-
-  // Destroy the clip path.
-  FPDF_DestroyClipPath(clip_path);
+  // With all the hyphen positions, do the search and replace.
+  while (!hyphen_positions.empty()) {
+    static const base::char16 kCr[] = {L'\r', L'\0'};
+    const HyphenPosition& position = hyphen_positions.back();
+    if (position.next_whitespace_position != 0) {
+      (*text)[position.next_whitespace_position] = L'\n';
+      text->insert(position.next_whitespace_position, kCr);
+    }
+    text->erase(position.position, 1);
+    hyphen_positions.pop_back();
+  }
+
+  // Adobe Reader also get rid of trailing spaces right before a CRLF.
+  static const base::char16 kSpaceCrCn[] = {L' ', L'\r', L'\n', L'\0'};
+  static const base::char16 kCrCn[] = {L'\r', L'\n', L'\0'};
+  ReplaceSubstringsAfterOffset(text, 0, kSpaceCrCn, kCrCn);
+}
+
+// Replace CR/LF with just LF on POSIX.
+void FormatStringForOS(base::string16* text) {
+#if defined(OS_POSIX)
+  static const base::char16 kCr[] = {L'\r', L'\0'};
+  static const base::char16 kBlank[] = {L'\0'};
+  base::ReplaceChars(*text, kCr, kBlank, text);
+#elif defined(OS_WIN)
+  // Do nothing
+#else
+  NOTIMPLEMENTED();
+#endif
 }
 
+}  // namespace
+
 bool InitializeSDK(void* data) {
   FPDF_InitLibrary(data);
 
@@ -1882,6 +1913,8 @@ std::string PDFiumEngine::GetSelectedText() {
     }
   }
 
+  FormatStringWithHyphens(&result);
+  FormatStringForOS(&result);
   return base::UTF16ToUTF8(result);
 }