Fix caret moving to start of edit on click after the text.

It now moves to the end of the edit text instead.

In a multiline edit, clicking after the end of a line in the middle
of the text moves the caret to the beginning of the next line. This
is a known issue to be addressed later.

Bug: chromium:832293
Change-Id: I55ca1f7eebf935fbb7d9526f115489bdfbd8ba1c
Reviewed-on: https://pdfium-review.googlesource.com/31012
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

2 files changed, 28 insertions, 2 deletions

diff --git a/xfa/fde/cfde_texteditengine.cpp b/xfa/fde/cfde_texteditengine.cpp
index 39396ad00d..ac66fd7f99 100644
--- a/xfa/fde/cfde_texteditengine.cpp
+++ b/xfa/fde/cfde_texteditengine.cpp
@@ -899,12 +899,19 @@ size_t CFDE_TextEditEngine::GetIndexForPoint(const CFX_PointF& point) {
 
   size_t start_it_idx = start_it->nStart;
   for (; start_it <= end_it; ++start_it) {
-    if (!start_it->rtPiece.Contains(point))
+    // We need to handle clicking off the end of the line. Using Contains()
+    // would constrain the detection to the text on the line.
+    bool piece_contains_point_vertically =
+        (point.y >= start_it->rtPiece.top &&
+         point.y < start_it->rtPiece.bottom());
+    if (!piece_contains_point_vertically)
       continue;
 
     std::vector<CFX_RectF> rects = GetCharRects(*start_it);
     for (size_t i = 0; i < rects.size(); ++i) {
-      if (!rects[i].Contains(point))
+      bool character_contains_point_horizontally =
+          (point.x >= rects[i].left && point.x < rects[i].right());
+      if (!character_contains_point_horizontally)
         continue;
       size_t pos = start_it->nStart + i;
       if (pos >= text_length_)
@@ -920,6 +927,13 @@ size_t CFDE_TextEditEngine::GetIndexForPoint(const CFX_PointF& point) {
       // TODO(dsinclair): Old code had a before flag set based on bidi?
       return pos;
     }
+
+    // Point is not within the horizontal range of any characters, it's
+    // afterwards. Return the position after the the last character.
+    // The last line has nCount equal to the number of characters + 1 (sentinel
+    // character maybe?). Restrict to the text_length_ to account for that.
+    return std::min(static_cast<size_t>(start_it->nStart + start_it->nCount),
+                    text_length_);
   }
 
   if (start_it == text_piece_info_.end())
diff --git a/xfa/fde/cfde_texteditengine_unittest.cpp b/xfa/fde/cfde_texteditengine_unittest.cpp
index 522e61a011..e279f8eb34 100644
--- a/xfa/fde/cfde_texteditengine_unittest.cpp
+++ b/xfa/fde/cfde_texteditengine_unittest.cpp
@@ -415,6 +415,18 @@ TEST_F(CFDE_TextEditEngineTest, GetIndexForPoint) {
   engine()->Insert(0, L"Hello World");
   EXPECT_EQ(0U, engine()->GetIndexForPoint({0.0f, 0.0f}));
   EXPECT_EQ(11U, engine()->GetIndexForPoint({999999.0f, 9999999.0f}));
+  EXPECT_EQ(11U, engine()->GetIndexForPoint({999999.0f, 0.0f}));
+  EXPECT_EQ(1U, engine()->GetIndexForPoint({10.0f, 5.0f}));
+}
+
+TEST_F(CFDE_TextEditEngineTest, GetIndexForPointMultiline) {
+  engine()->SetFontSize(10.0f);
+  engine()->Insert(0,
+                   L"A text long enough to span multiple lines and test "
+                   L"getting indexes on multi-line edits.");
+  EXPECT_EQ(0U, engine()->GetIndexForPoint({0.0f, 0.0f}));
+  EXPECT_EQ(87U, engine()->GetIndexForPoint({999999.0f, 9999999.0f}));
+  EXPECT_EQ(12U, engine()->GetIndexForPoint({999999.0f, 0.0f}));
   EXPECT_EQ(1U, engine()->GetIndexForPoint({10.0f, 5.0f}));
 }