Add functionality for copying text within form text fields and form combobox text fields

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 afc8b71633bcd2bbab24880da6b033316bfe63a9..91aeb00b19450dc7c8693b84a309a9e1e4e39d90 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -1625,6 +1625,29 @@ void PDFiumEngine::FitContentsToPrintableAreaIfRequired(
 void PDFiumEngine::SaveSelectedFormForPrint() {
   FORM_ForceToKillFocus(form_);
   client_->FormTextFieldFocusChange(false);
+  SetInFormTextArea(false);
+}
+
+void PDFiumEngine::SetFormSelectedText(FPDF_FORMHANDLE form_handle,
+                                       FPDF_PAGE page) {
+  size_t form_sel_text_len =
+      FORM_GetSelectedText(form_handle, page, nullptr, 0);
+
+  // Initial length = 2 (not 0) because chars are two bytes and

[Lei Zhang, 2017/06/20 00:26:24]

This statement is confusing. It can be read as: char (the variable type) is two
bytes, but that's clearly not the case.

[drgage, 2017/06/20 23:14:27]

Done.

+  // NUL char is included in count.
+  if (form_sel_text_len <= 2)

[dsinclair, 2017/06/20 15:21:44]

Is this check needed? Won't we just end up creating a std::string on 1647 which
is empty and then do nothing because of the following if?

[Lei Zhang, 2017/06/20 21:21:22]

Might as well bale out early if we knows continuing onwards is going to do more
work for nothing.

[drgage, 2017/06/20 23:14:27]

Done.

[drgage, 2017/06/20 23:14:27]

Yeah, you're right. I just wasn't sure if I should be trying to return as soon
as possible, which could potentially be on 1639. I guess by that logic, that
would make the check on 1648 unnecessary, but I put it there just in case. Do
you think it's okay to remove the check on 1638 and let it go until 1648?

[dsinclair, 2017/06/21 13:03:28]

Leaving it is fine, early exiting does make it a bit clearer what's happening.

[drgage, 2017/06/23 22:16:13]

Done.

+    return;
+
+  base::string16 selected_form_text16;
+  PDFiumAPIStringBufferSizeInBytesAdapter<base::string16> string_adapter(
+      &selected_form_text16, form_sel_text_len, false);
+  string_adapter.Close(FORM_GetSelectedText(
+      form_handle, page, string_adapter.GetData(), form_sel_text_len));
+
+  std::string selected_form_text = UTF16ToUTF8(selected_form_text16);
+  if (!selected_form_text.empty()) {
+    pp::PDF::SetSelectedText(GetPluginInstance(), selected_form_text.c_str());
+  }
 }
 
 void PDFiumEngine::PrintEnd() {
@@ -1721,18 +1744,26 @@ bool PDFiumEngine::OnMouseDown(const pp::MouseInputEvent& event) {
 
     FORM_OnLButtonDown(form_, pages_[page_index]->GetPage(), 0, page_x, page_y);
     if (form_type > FPDF_FORMFIELD_UNKNOWN) {  // returns -1 sometimes...
-      mouse_down_state_.Set(PDFiumPage::NONSELECTABLE_AREA, target);
+      mouse_down_state_.Set(form_type == FPDF_FORMFIELD_TEXTFIELD

[Lei Zhang, 2017/06/20 00:26:24]

What about FPDF_FORMFIELD_COMBOBOX?

[drgage, 2017/06/20 23:14:27]

I think I got confused while refactoring this yesterday, I'll fix that.

+                                ? PDFiumPage::FORM_TEXT_AREA
+                                : PDFiumPage::NONSELECTABLE_AREA,
+                            target);
+
       bool is_valid_control = (form_type == FPDF_FORMFIELD_TEXTFIELD ||
                                form_type == FPDF_FORMFIELD_COMBOBOX);
+
+// TODO(bug_62400): figure out selection and copying
+// for XFA fields
 #if defined(PDF_ENABLE_XFA)
       is_valid_control |= (form_type == FPDF_FORMFIELD_XFA);
 #endif
       client_->FormTextFieldFocusChange(is_valid_control);
+      SetInFormTextArea(is_valid_control);
       return true;  // Return now before we get into the selection code.
     }
   }
-
   client_->FormTextFieldFocusChange(false);
+  SetInFormTextArea(false);
 
   if (area != PDFiumPage::TEXT_AREA)
     return true;  // Return true so WebKit doesn't do its own highlighting.
@@ -1808,11 +1839,13 @@ bool PDFiumEngine::OnMouseUp(const pp::MouseInputEvent& event) {
 
       client_->NavigateTo(target.url, disposition);
       client_->FormTextFieldFocusChange(false);
+      SetInFormTextArea(false);
       return true;
     }
     if (area == PDFiumPage::DOCLINK_AREA) {
       client_->ScrollToPage(target.page);
       client_->FormTextFieldFocusChange(false);
+      SetInFormTextArea(false);

[dsinclair, 2017/06/20 15:21:43]

Should we add a SetFormTextAreaStatus(bool) or something that calls these two
methods as they appear to get called together with the same value?

[drgage, 2017/06/20 23:14:27]

I could do this, or I could add the line
"client_->FormTextFieldFocusChange(in_form_text_area)" to my existing function
SetInFormTextArea(). What do you think would be better?

[dsinclair, 2017/06/21 13:03:28]

Moving the FormTextFieldFocusChange into SetInFormTextArea makes sense to me.

[drgage, 2017/06/23 22:16:12]

Done.

       return true;
     }
   }
@@ -1828,6 +1861,9 @@ 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)
+    SetFormSelectedText(form_, pages_[last_page_mouse_down_]->GetPage());
+
   if (!selecting_)
     return false;
 
@@ -1859,6 +1895,7 @@ bool PDFiumEngine::OnMouseMove(const pp::MouseInputEvent& event) {
         cursor = PP_CURSORTYPE_HAND;
         break;
       case PDFiumPage::NONSELECTABLE_AREA:
+      case PDFiumPage::FORM_TEXT_AREA:
       default:
         switch (form_type) {
           case FPDF_FORMFIELD_PUSHBUTTON:
@@ -1985,6 +2022,13 @@ 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 (FORM_GetSelectedText(form_, pages_[last_page_mouse_down_]->GetPage(),

[Lei Zhang, 2017/06/20 00:26:24]

Since the conditional is evaluated from left to right, FORM_GetSelectedText()
will be called even if |in_form_text_area_| is false. Calling
FORM_GetSelectedText() is much more expensive than checking
|in_form_text_area_|. So reversing the order of the two checks means the code
will run faster when |in_form_text_area_| is false.

[drgage, 2017/06/20 23:14:27]

Done.

+                           nullptr, 0) <= 2 &&
+      in_form_text_area_)
+    pp::PDF::SetSelectedText(GetPluginInstance(), "");
+
   return rv;
 }
 
@@ -1992,6 +2036,11 @@ bool PDFiumEngine::OnKeyUp(const pp::KeyboardInputEvent& event) {
   if (last_page_mouse_down_ == -1)
     return false;
 
+  if (in_form_text_area_) {
+    if (event.GetKeyCode() == ui::VKEY_SHIFT)
+      SetFormSelectedText(form_, pages_[last_page_mouse_down_]->GetPage());
+  }
+
   return !!FORM_OnKeyUp(form_, pages_[last_page_mouse_down_]->GetPage(),
                         event.GetKeyCode(), event.GetModifiers());
 }
@@ -3553,6 +3602,10 @@ void PDFiumEngine::SetSelecting(bool selecting) {
     client_->IsSelectingChanged(selecting);
 }
 
+void PDFiumEngine::SetInFormTextArea(bool in_form_text_area) {
+  in_form_text_area_ = in_form_text_area;
+}
+
 void PDFiumEngine::ScheduleTouchTimer(const pp::TouchInputEvent& evt) {
   touch_timers_[++next_touch_timer_id_] = evt;
   client_->ScheduleTouchTimerCallback(next_touch_timer_id_,