Initial implementation of IAccessible2 scrollTo and setTextSelection and

chrome/browser/accessibility/browser_accessibility_win_unittest.cc

Index: chrome/browser/accessibility/browser_accessibility_win_unittest.cc
===================================================================
--- chrome/browser/accessibility/browser_accessibility_win_unittest.cc	(revision 112482)
+++ chrome/browser/accessibility/browser_accessibility_win_unittest.cc	(working copy)
@@ -365,3 +365,36 @@
   delete manager;
   ASSERT_EQ(0, CountedBrowserAccessibility::global_obj_count_);
 }
+
+TEST_F(BrowserAccessibilityTest, TestScrollingLogic) {
+  #define SCROLL BrowserAccessibility::ComputeBestScrollOffset
+
+  // Test some cases where the focus is already within the viewport.
+  EXPECT_EQ(0, SCROLL(0, 25, 75, 25, 75, 0, 100));
+  EXPECT_EQ(100, SCROLL(100, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(105, SCROLL(105, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(125, SCROLL(125, 125, 175, 125, 175, 0, 100));

[David Tseng, 2011/12/02 00:33:04]

Just for kicks, throw in a subfocus not equal to focus?

[dmazzoni, 2011/12/03 00:37:10]

Done.

+  EXPECT_EQ(75, SCROLL(75, 125, 175, 125, 175, 0, 100));

[David Tseng, 2011/12/02 00:33:04]

Curious, do we handle negative scrolling? (i.e. if the viewport min/max is 100,
200, and the focus min/max is 0, 50.

[dmazzoni, 2011/12/03 00:37:10]

This function will return a negative value, sure. The calling function will clip
it to the allowable values for the scroll offset. I added a comment.

+
+  // Test some cases where the focus needs to be scrolled to fit.
+  EXPECT_EQ(75, SCROLL(74, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(75, SCROLL(50, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(75, SCROLL(0, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(125, SCROLL(126, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(125, SCROLL(150, 125, 175, 125, 175, 0, 100));
+  EXPECT_EQ(125, SCROLL(200, 125, 175, 125, 175, 0, 100));
+
+  // Test some cases where the focus doesn't fit, so the subfocus is used.
+  EXPECT_EQ(125, SCROLL(0, 125, 130, 125, 175, 0, 25));
+  EXPECT_EQ(140, SCROLL(0, 140, 145, 125, 175, 0, 25));
+  EXPECT_EQ(150, SCROLL(0, 170, 175, 125, 175, 0, 25));

[David Tseng, 2011/12/02 00:33:04]

How about adding a case for nonzero initial offset?

[dmazzoni, 2011/12/03 00:37:10]

Done.

+
+  // Test some cases where the viewport is a single point - which can be
+  // used to force an object to be scrolled to a specific location.
+  EXPECT_EQ(50, SCROLL(0, 125, 175, 125, 175, 75, 75));
+  EXPECT_EQ(25, SCROLL(0, 125, 175, 125, 175, 100, 100));
+  EXPECT_EQ(0, SCROLL(0, 125, 175, 125, 175, 125, 125));
+
+  #undef SCROLL
+}
+