RenderText: Allow setting display offset explicitly

ui/gfx/render_text_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 1022 matching lines @@
       render_text->SelectAll(false);
       EXPECT_EQ(render_text->selection_model(), expected_forwards);
       render_text->SelectAll(true);
       EXPECT_EQ(render_text->selection_model(), expected_reversed);
     }
   }
 
   EXPECT_EQ(was_rtl, base::i18n::IsRTL());
 }
 
-  TEST_F(RenderTextTest, MoveCursorLeftRightWithSelection) {
+TEST_F(RenderTextTest, MoveCursorLeftRightWithSelection) {
   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
   render_text->SetText(WideToUTF16(L"abc\x05d0\x05d1\x05d2"));
   // Left arrow on select ranging (6, 4).
   render_text->MoveCursor(LINE_BREAK, CURSOR_RIGHT, false);
   EXPECT_EQ(Range(6), render_text->selection());
   render_text->MoveCursor(CHARACTER_BREAK, CURSOR_LEFT, false);
   EXPECT_EQ(Range(4), render_text->selection());
   render_text->MoveCursor(CHARACTER_BREAK, CURSOR_LEFT, false);
   EXPECT_EQ(Range(5), render_text->selection());
   render_text->MoveCursor(CHARACTER_BREAK, CURSOR_LEFT, false);
@@ skipping 427 matching lines @@
   const int kEnlargement = 2;
   const Size font_size(render_text->GetContentWidth() + kEnlargement,
                        render_text->GetStringSize().height());
   Rect display_rect(font_size);
   render_text->SetDisplayRect(display_rect);
   Vector2d offset = render_text->GetLineOffset(0);
   EXPECT_EQ(kEnlargement, offset.x());
   SetRTL(was_rtl);
 }
 
+TEST_F(RenderTextTest, SetDisplayOffset) {
+  scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
+  render_text->SetText(ASCIIToUTF16("abcdefg"));
+  render_text->SetFontList(FontList("Arial, 13px"));
+
+  const Size font_size(render_text->GetContentWidth(),
+                       render_text->font_list().GetHeight());
+  const int kEnlargement = 10;
+
+  // Set display width |kEnlargement| pixels greater than content width and test
+  // different possible situations. In this case the only possible display
+  // offset is zero.
+  Rect display_rect(font_size);
+  display_rect.Inset(0, 0, -kEnlargement, 0);
+  render_text->SetDisplayRect(display_rect);
+
+  struct {
+    HorizontalAlignment alignment;
+    int offset;
+  } small_content_cases[] = {
+    { ALIGN_LEFT, -kEnlargement },
+    { ALIGN_LEFT, 0 },
+    { ALIGN_LEFT, kEnlargement },
+    { ALIGN_RIGHT, -kEnlargement },
+    { ALIGN_RIGHT, 0 },
+    { ALIGN_RIGHT, kEnlargement },
+    { ALIGN_CENTER, -kEnlargement },
+    { ALIGN_CENTER, 0 },
+    { ALIGN_CENTER, kEnlargement },
+  };
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(small_content_cases); i++) {
+    render_text->SetHorizontalAlignment(small_content_cases[i].alignment);
+    render_text->SetDisplayOffset(small_content_cases[i].offset);
+    EXPECT_EQ(0, render_text->GetUpdatedDisplayOffset().x());
+  }
+
+  // Set display width |kEnlargement| pixels less than content width and test
+  // different possible situations.
+  display_rect = Rect(font_size);
+  display_rect.Inset(0, 0, kEnlargement, 0);
+  render_text->SetDisplayRect(display_rect);
+
+  struct {
+    HorizontalAlignment alignment;
+    int offset;
+    int expected_offset;
+  } large_content_cases[] = {
+    // When text is left-aligned, display offset can be in range
+    // [-kEnlargement, 0].
+    { ALIGN_LEFT, -2 * kEnlargement, -kEnlargement },
+    { ALIGN_LEFT, -kEnlargement / 2, -kEnlargement / 2 },
+    { ALIGN_LEFT, kEnlargement, 0 },
+    // When text is right-aligned, display offset can be in range
+    // [0, kEnlargement].
+    { ALIGN_RIGHT, -kEnlargement, 0 },
+    { ALIGN_RIGHT, kEnlargement / 2, kEnlargement / 2 },
+    { ALIGN_RIGHT, 2 * kEnlargement, kEnlargement },
+    // When text is center-aligned, display offset can be in range
+    // [-kEnlargement / 2, kEnlargement / 2].
+    { ALIGN_CENTER, -kEnlargement, -kEnlargement / 2 },
+    { ALIGN_CENTER, -kEnlargement / 4, -kEnlargement / 4 },
+    { ALIGN_CENTER, kEnlargement / 4, kEnlargement / 4 },
+    { ALIGN_CENTER, kEnlargement, kEnlargement / 2 },
+  };
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(large_content_cases); i++) {
+    render_text->SetHorizontalAlignment(large_content_cases[i].alignment);
+    render_text->SetDisplayOffset(large_content_cases[i].offset);
+    EXPECT_EQ(large_content_cases[i].expected_offset,
+              render_text->GetUpdatedDisplayOffset().x());
+  }
+}
+
 TEST_F(RenderTextTest, SameFontForParentheses) {
   struct {
     const base::char16 left_char;
     const base::char16 right_char;
   } punctuation_pairs[] = {
     { '(', ')' },
     { '{', '}' },
     { '<', '>' },
   };
   struct {
@@ skipping 533 matching lines @@
   for (size_t i = 0; i < arraysize(kTestStrings); ++i) {
     render_text->SetText(WideToUTF16(kTestStrings[i]));
     render_text->EnsureLayout();
 
     for (size_t j = 0; j < render_text->text().length(); ++j)
       EXPECT_FALSE(render_text->GetGlyphBounds(j).is_empty());
   }
 }
 
 }  // namespace gfx