Fix discrepancies in form text selection between PDF and HTML forms.

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index eb7f4cb08fb315aac8cb6540a857b39c3212fd21..50926470710ee2f4977aa134f1ffaa593ad5250e 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -1638,7 +1638,7 @@ void PDFiumEngine::SetFormSelectedText(FPDF_FORMHANDLE form_handle,
   // Check to see if there is selected text in the form. When
   // |form_sel_text_len| is 2, that represents a wide string with just a
   // NUL-terminator.
-  if (form_sel_text_len <= 2)
+  if (form_sel_text_len <= 2 && old_selected_form_text_.empty())
     return;
 
   base::string16 selected_form_text16;
@@ -1647,10 +1647,12 @@ void PDFiumEngine::SetFormSelectedText(FPDF_FORMHANDLE form_handle,
   string_adapter.Close(FORM_GetSelectedText(
       form_handle, page, string_adapter.GetData(), form_sel_text_len));
 
-  std::string selected_form_text = base::UTF16ToUTF8(selected_form_text16);
-  if (!selected_form_text.empty()) {
-    pp::PDF::SetSelectedText(GetPluginInstance(), selected_form_text.c_str());
-  }
+  // Update previous and current selections, then compare them to check if

[Lei Zhang, 2017/06/29 02:52:46]

If this method does not have |old_selected_form_text_|, and this code just
became:

  std::string selected_form_text = base::UTF16ToUTF8(selected_form_text16);
  if (selected_form_text != selected_form_text_) {
    selected_form_text_ = selected_form_text;
    pp::PDF::SetSelectedText(GetPluginInstance(), selected_form_text_.c_str());
  }

Would that work? Can you explain what purpose |old_selected_form_text_| serves?

[drgage, 2017/06/29 17:49:59]

Yes, something like that would work. That's actually what I had first, but I
changed it so that |old_selected_text_| was a member variable because I was
thinking it was necessary for making the check on line 1641 and exiting early if
possible. Looking at it again today, I see that it's not necessary and the check
can be made without it.

+  // selection has changed. If so, set plugin text selection.
+  old_selected_form_text_ = selected_form_text_;
+  selected_form_text_ = base::UTF16ToUTF8(selected_form_text16);
+  if (old_selected_form_text_ != selected_form_text_)
+    pp::PDF::SetSelectedText(GetPluginInstance(), selected_form_text_.c_str());
 }
 
 void PDFiumEngine::PrintEnd() {
@@ -1729,6 +1731,7 @@ bool PDFiumEngine::OnMouseDown(const pp::MouseInputEvent& event) {
   PDFiumPage::Area area =
       GetCharIndex(event, &page_index, &char_index, &form_type, &target);
   mouse_down_state_.Set(area, target);
+  SetMouseHeldDown(true);
 
   // Decide whether to open link or not based on user action in mouse up and
   // mouse move events.
@@ -1820,6 +1823,7 @@ bool PDFiumEngine::OnMouseUp(const pp::MouseInputEvent& event) {
   PDFiumPage::LinkTarget target;
   PDFiumPage::Area area =
       GetCharIndex(event, &page_index, &char_index, &form_type, &target);
+  SetMouseHeldDown(false);
 
   // Open link on mouse up for same link for which mouse down happened earlier.
   if (mouse_down_state_.Matches(area, target)) {
@@ -1857,9 +1861,6 @@ bool PDFiumEngine::OnMouseUp(const pp::MouseInputEvent& event) {
     FORM_OnLButtonUp(form_, pages_[page_index]->GetPage(), 0, page_x, page_y);
   }
 
-  if (area == PDFiumPage::FORM_TEXT_AREA)

[Lei Zhang, 2017/06/29 02:52:46]

This change is a bit out of date and won't apply anymore.

[drgage, 2017/06/29 17:49:58]

I'm not sure what you mean. I removed this check because it doesn't apply
anymore.

[Lei Zhang, 2017/06/29 22:38:04]

Didn't you already change this block of code to also check:
last_page_mouse_down_ != -1 ? That change needs to be reflected in the diff, for
it to apply correctly. i.e. your local git branch associated with this CL likely
does not include https://crbug.com/483133 .

[drgage, 2017/06/29 23:00:50]

Oh yeah, at the time that I started working on this I had checked out this
branch from master, not the branch where I fixed that. But now since master
includes that change, I'll rebase and upload a new patchset.

-    SetFormSelectedText(form_, pages_[last_page_mouse_down_]->GetPage());
-
   if (!selecting_)
     return false;
 
@@ -1924,6 +1925,14 @@ bool PDFiumEngine::OnMouseMove(const pp::MouseInputEvent& event) {
       link_under_cursor_ = url;
       pp::PDF::SetLinkUnderCursor(GetPluginInstance(), url.c_str());
     }
+
+    // If in form text area while left mouse button is held down, check if form
+    // text selection needs to be updated.
+    if (mouse_held_down_ && area == PDFiumPage::FORM_TEXT_AREA &&
+        last_page_mouse_down_ != -1) {
+      SetFormSelectedText(form_, pages_[last_page_mouse_down_]->GetPage());
+    }
+
     // No need to swallow the event, since this might interfere with the
     // scrollbars if the user is dragging them.
     return false;
@@ -2018,14 +2027,6 @@ bool PDFiumEngine::OnKeyDown(const pp::KeyboardInputEvent& event) {
     OnChar(synthesized);
   }
 
-  // If form selected text is empty and key pressed within form text area,
-  // plugin text selection should be cleared.
-  if (in_form_text_area_ &&
-      FORM_GetSelectedText(form_, pages_[last_page_mouse_down_]->GetPage(),
-                           nullptr, 0) <= 2) {
-    pp::PDF::SetSelectedText(GetPluginInstance(), "");
-  }
-
   return rv;
 }
 
@@ -2033,9 +2034,9 @@ bool PDFiumEngine::OnKeyUp(const pp::KeyboardInputEvent& event) {
   if (last_page_mouse_down_ == -1)
     return false;
 
+  // Check if form text selection needs to be updated.
   if (in_form_text_area_) {
-    if (event.GetKeyCode() == ui::VKEY_SHIFT)
-      SetFormSelectedText(form_, pages_[last_page_mouse_down_]->GetPage());
+    SetFormSelectedText(form_, pages_[last_page_mouse_down_]->GetPage());
   }
 
   return !!FORM_OnKeyUp(form_, pages_[last_page_mouse_down_]->GetPage(),
@@ -3610,6 +3611,10 @@ void PDFiumEngine::SetInFormTextArea(bool in_form_text_area) {
   in_form_text_area_ = in_form_text_area;
 }
 
+void PDFiumEngine::SetMouseHeldDown(bool mouse_held_down) {
+  mouse_held_down_ = mouse_held_down;
+}
+
 void PDFiumEngine::ScheduleTouchTimer(const pp::TouchInputEvent& evt) {
   touch_timers_[++next_touch_timer_id_] = evt;
   client_->ScheduleTouchTimerCallback(next_touch_timer_id_,