[WIP][b:eae_mywip_paint] Paint Selection NG.

third_party/WebKit/Source/core/paint/NGTextFragmentPainter.cpp

Index: third_party/WebKit/Source/core/paint/NGTextFragmentPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/NGTextFragmentPainter.cpp b/third_party/WebKit/Source/core/paint/NGTextFragmentPainter.cpp
index 06d32ffda48718afee6d6822ff57773550427f40..1d3242fa795f8bc2d817bb29f19885318cee7141 100644
--- a/third_party/WebKit/Source/core/paint/NGTextFragmentPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/NGTextFragmentPainter.cpp
@@ -4,6 +4,7 @@
 
 #include "core/paint/NGTextFragmentPainter.h"
 
+#include "core/editing/FrameSelection.h"
 #include "core/frame/LocalFrame.h"
 #include "core/layout/ng/inline/ng_physical_text_fragment.h"
 #include "core/paint/NGTextPainter.h"
@@ -75,6 +76,40 @@ static void PaintDecorationsExceptLineThrough(
   //}
 }
 
+static std::pair<int, int> SelectionStartEnd(

[kojii, 2017/06/16 11:25:57]

Can add explanation what this function does and what the return is?

Shouldn't |int| be |unsigned|? Layout always use unsigned for offset, I'm not
sure about paint though.

[yoichio, 2017/06/21 08:16:43]

This returns 0-origin offset range in NGPhysicalTextFragment to be painted
 as selection.
Yes, this should be unsigned but |selection_start| in 
 NGTextFragmentPainter::Paint is defined as |int|.
I guess because legacy InlineTextBoxPainter defines selection range as 
 int pair, where it uses (-1,-1) as invalid range, and Emil just follows it.

+    const NGPhysicalTextFragment* text_fragment) {
+  const SelectionState& selection_state =
+      text_fragment->GetLayoutObject()->GetSelectionState();
+  if (selection_state == SelectionState::kNone)
+    return {0, 0};
+  if (selection_state == SelectionState::kInside)
+    return {0, text_fragment->Text().length()};

[kojii, 2017/06/16 11:25:57]

why it computes min/max to text_fragment->Start/EndOffset() but this part does
not?

[yoichio, 2017/06/21 08:16:43]

Ah, it should be {text_fragment->StartOffst(),
 text_fragment->EndOffset()}
What is 'it'? Could you explain more?

+
+  const std::pair<int, int> startend_in_ngblockflow =

[kojii, 2017/06/16 11:25:57]

I can't understand how this works...so you get two |int|s from FrameView. What
are they, and why can you subtract text_fragment->StartOffset() from it? Can you
explain?

[yoichio, 2017/06/21 08:16:43]

They are index in NGInlineNodeData.text_content_, but NGTextPainter.paint(start,
end) demands
 offset in NGPhysixalTextFragment.

[kojii, 2017/06/21 10:10:09]

But you get data from Frame, without passing text_fragment. How could it find
the relevant NGInlineNodeData?

+      text_fragment->GetLayoutObject()
+          ->GetFrameView()
+          ->GetFrame()
+          .Selection()
+          .LayoutSelectionStartEnd();
+  int selection_start = std::max<int>(
+      0, startend_in_ngblockflow.first - text_fragment->StartOffset());

[kojii, 2017/06/16 11:25:57]

This might not work, because StartOffset() is unsigned, no?

+  int selection_end = std::min<int>(
+      text_fragment->Text().length(),
+      startend_in_ngblockflow.second - text_fragment->StartOffset());
+
+  switch (selection_state) {
+    case SelectionState::kStart:
+      return {selection_start, text_fragment->Text().length()};
+    case SelectionState::kEnd:
+      return {0, selection_end};
+    case SelectionState::kStartAndEnd:
+      return {selection_start, selection_end};
+  }
+
+  NOTREACHED();
+  return {0, 0};
+}
+
 }  // anonymous namespace
 
 void NGTextFragmentPainter::Paint(const Document& document,
@@ -122,6 +157,7 @@ void NGTextFragmentPainter::Paint(const Document& document,
   //    text_fragment_.GetLineLayoutItem(), have_selection, paint_info,
   //    text_style);
   TextPainterBase::Style selection_style = text_style;
+  selection_style.fill_color = Color(1.0f, 0.0f, 0.0f, 1.0f);

[kojii, 2017/06/16 11:25:57]

this is temporary, correct? Can you add TODO comment?

[yoichio, 2017/06/21 08:16:43]

Yes, just for testing. Remove from reviewing.

   bool paint_selected_text_only = (paint_info.phase == kPaintPhaseSelection);
   bool paint_selected_text_separately =
       !paint_selected_text_only && text_style != selection_style;
@@ -158,8 +194,10 @@ void NGTextFragmentPainter::Paint(const Document& document,
   // 2. Now paint the foreground, including text and decorations.
   int selection_start = 0;
   int selection_end = 0;
-  // if (paint_selected_text_only || paint_selected_text_separately)
-  //  text_fragment_.SelectionStartEnd(selection_start, selection_end);
+  if (paint_selected_text_only || paint_selected_text_separately) {
+    std::tie(selection_start, selection_end) =
+        SelectionStartEnd(text_fragment_);
+  }
 
   // bool respect_hyphen =
   //    selection_end == static_cast<int>(text_fragment_.Len()) &&