Reland: Return unclipped bounds for get_characterExtents

For get_characterExtents():
- The x,y position should be unclipped (allowed to be negative or larger than the screen width/height).
- The width/height should not be changed to 1 for offscreen objects.

TBR=dmazzoni@chromium.org

Bug: 864195
Change-Id: Ib8a57bee7f3b70f46c1c6791ea4c5a294c5ccfe5
Reviewed-on: https://chromium-review.googlesource.com/1146877Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577285}

content/browser/accessibility/accessibility_win_browsertest.cc

@@ -1290,16 +1290,12 @@ IN_PROC_BROWSER_TEST_F(AccessibilityWinBrowserTest,
       EXPECT_EQ(previous_height, height) << "at offset " << offset;
     }
 
-    // Vertically offscreen objects should have a height of 1px so that if an
-    // assistive aid ignores the offscreen state, they will still be too small
-    // to be visible and thus not appear outside the window. Note that a height
-    // of 0 is not used because it signifies an invalid size.
     EXPECT_HRESULT_SUCCEEDED(editable_container->get_characterExtents(
         last_line_start, coordinate_type, &x, &y, &width, &height));
     EXPECT_LT(0, x) << "at offset " << last_line_start;
     EXPECT_LT(previous_y, y) << "at offset " << last_line_start;
     EXPECT_LT(1, width) << "at offset " << last_line_start;
-    EXPECT_EQ(1, height) << "at offset " << last_line_start;
+    EXPECT_EQ(previous_height, height) << "at offset " << last_line_start;
 
     for (LONG offset = last_line_start + 1; offset < n_characters; ++offset) {
       previous_x = x;
@@ -1310,7 +1306,7 @@ IN_PROC_BROWSER_TEST_F(AccessibilityWinBrowserTest,
       EXPECT_LT(previous_x, x) << "at offset " << offset;
       EXPECT_EQ(previous_y, y) << "at offset " << offset;
       EXPECT_LT(1, width) << "at offset " << offset;
-      EXPECT_EQ(1, height) << "at offset " << offset;
+      EXPECT_EQ(previous_height, height) << "at offset " << offset;
     }
   }
 }
@@ -1334,21 +1330,13 @@ IN_PROC_BROWSER_TEST_F(AccessibilityWinBrowserTest,
        coordinate <= IA2_COORDTYPE_PARENT_RELATIVE; ++coordinate) {
     auto coordinate_type = static_cast<IA2CoordinateType>(coordinate);
 
-    // Horizontally offscreen objects should have a width of 1px so that if an
-    // assistive aid ignores the offscreen state, they will still be too small
-    // to be visible and thus not appear outside the window. Note that a width
-    // of 0 is not used because it signifies an invalid size.
     EXPECT_HRESULT_SUCCEEDED(input_text->get_characterExtents(
         0, coordinate_type, &x, &y, &width, &height));
-    EXPECT_LT(0, x + width) << "at offset 0";
+    EXPECT_GT(0, x + width) << "at offset 0";
     EXPECT_LT(0, y) << "at offset 0";
-    EXPECT_EQ(1, width) << "at offset 0";
+    EXPECT_LT(1, width) << "at offset 0";
     EXPECT_LT(1, height) << "at offset 0";
 
-    // Test that characters at the start of the input field are offscreen by
-    // checking that their x coordinate is at the start of the field and their
-    // width is 1.
-    // Exclude the character that is partly visible.
     for (LONG offset = 1; offset < (visible_characters_start - 1); ++offset) {
       previous_x = x;
       previous_y = y;
@@ -1356,9 +1344,9 @@ IN_PROC_BROWSER_TEST_F(AccessibilityWinBrowserTest,
 
       EXPECT_HRESULT_SUCCEEDED(input_text->get_characterExtents(
           offset, coordinate_type, &x, &y, &width, &height));
-      EXPECT_EQ(previous_x, x) << "at offset " << offset;
+      EXPECT_LT(previous_x, x) << "at offset " << offset;
       EXPECT_EQ(previous_y, y) << "at offset " << offset;
-      EXPECT_EQ(1, width) << "at offset " << offset;
+      EXPECT_LT(1, width) << "at offset " << offset;
       EXPECT_EQ(previous_height, height) << "at offset " << offset;
     }
 
@@ -1366,7 +1354,7 @@ IN_PROC_BROWSER_TEST_F(AccessibilityWinBrowserTest,
     // width that is greater than 1px.
     EXPECT_HRESULT_SUCCEEDED(input_text->get_characterExtents(
         visible_characters_start, coordinate_type, &x, &y, &width, &height));
-    EXPECT_EQ(previous_x, x) << "at offset " << visible_characters_start;
+    EXPECT_LT(previous_x, x) << "at offset " << visible_characters_start;
     EXPECT_EQ(previous_y, y) << "at offset " << visible_characters_start;
     EXPECT_LT(1, width) << "at offset " << visible_characters_start;
     EXPECT_EQ(previous_height, height)

content/browser/accessibility/browser_accessibility.cc

@@ -343,8 +343,9 @@ gfx::Rect BrowserAccessibility::GetPageBoundsRect(bool* offscreen,
   return RelativeToAbsoluteBounds(gfx::RectF(), false, offscreen, clip_bounds);
 }
 
-gfx::Rect BrowserAccessibility::GetPageBoundsForRange(int start, int len)
-    const {
+gfx::Rect BrowserAccessibility::GetPageBoundsForRange(int start,
+                                                      int len,
+                                                      bool clipped) const {
   DCHECK_GE(start, 0);
   DCHECK_GE(len, 0);
 
@@ -464,9 +465,11 @@ gfx::Rect BrowserAccessibility::GetPageBoundsForRange(int start, int len)
       }
     }
 
+    // Don't clip bounds. Some screen magnifiers (e.g. ZoomText) prefer to
+    // get unclipped bounds so that they can make smooth scrolling calculations.
     gfx::Rect absolute_child_rect = child->RelativeToAbsoluteBounds(
         child_overlap_rect, false /* frame_only */, nullptr /* offscreen */,
-        true /* clip_bounds */);
+        clipped /* clip_bounds */);
     if (bounds.width() == 0 && bounds.height() == 0) {
       bounds = absolute_child_rect;
     } else {
@@ -477,9 +480,10 @@ gfx::Rect BrowserAccessibility::GetPageBoundsForRange(int start, int len)
   return bounds;
 }
 
-gfx::Rect BrowserAccessibility::GetScreenBoundsForRange(int start, int len)
-    const {
-  gfx::Rect bounds = GetPageBoundsForRange(start, len);
+gfx::Rect BrowserAccessibility::GetScreenBoundsForRange(int start,
+                                                        int len,
+                                                        bool clipped) const {
+  gfx::Rect bounds = GetPageBoundsForRange(start, len, clipped);
 
   // Adjust the bounds by the top left corner of the containing view's bounds
   // in screen coordinates.

content/browser/accessibility/browser_accessibility.h

@@ -160,10 +160,14 @@ class CONTENT_EXPORT BrowserAccessibility : public ui::AXPlatformNodeDelegate {
   // Returns the bounds of the given range in coordinates relative to the
   // top-left corner of the overall web area. Only valid when the
   // role is WebAXRoleStaticText.
-  gfx::Rect GetPageBoundsForRange(int start, int len) const;
+  gfx::Rect GetPageBoundsForRange(int start,
+                                  int len,
+                                  bool clipped = false) const;
 
   // Same as |GetPageBoundsForRange| but in screen coordinates.
-  gfx::Rect GetScreenBoundsForRange(int start, int len) const;
+  gfx::Rect GetScreenBoundsForRange(int start,
+                                    int len,
+                                    bool clipped = false) const;
 
   // Convert a bounding rectangle from this node's coordinate system
   // (which is relative to its nearest scrollable ancestor) to

content/browser/accessibility/web_contents_accessibility_android.cc

@@ -1189,7 +1189,7 @@ WebContentsAccessibilityAndroid::GetCharacterBoundingBoxes(
   gfx::Rect object_bounds = node->GetPageBoundsRect();
   int coords[4 * len];
   for (int i = 0; i < len; i++) {
-    gfx::Rect char_bounds = node->GetPageBoundsForRange(start + i, 1);
+    gfx::Rect char_bounds = node->GetPageBoundsForRange(start + i, 1, false);
     if (char_bounds.IsEmpty())
       char_bounds = object_bounds;
     coords[4 * i + 0] = char_bounds.x();