From 9e25d3b8b54f8482a92c5727610b6f47753fbf23 Mon Sep 17 00:00:00 2001
From: Matt Casey <mrcasey@google.com>
Date: Thu, 27 May 2021 17:45:42 -0400
Subject: [PATCH] Move ScrollView scroll capture to the center

Avoid most floating content by centering the requested content within
the view instead of just scrolling so that it's visible.

See ag/14213766 for the corresponding RecyclerView change.

Bug: 189487659
Test: atest ScrollViewCaptureHelperTest, plus manual testing.
Change-Id: I194288cf9e568614ffd7c45b7d046a5b982829d6
---
 .../internal/view/ScrollViewCaptureHelper.java       | 11 ++++++++++-
 .../internal/view/ScrollViewCaptureHelperTest.java   | 12 ++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/core/java/com/android/internal/view/ScrollViewCaptureHelper.java b/core/java/com/android/internal/view/ScrollViewCaptureHelper.java
index a1d202e3a39f7..a360f63e97d4a 100644
--- a/core/java/com/android/internal/view/ScrollViewCaptureHelper.java
+++ b/core/java/com/android/internal/view/ScrollViewCaptureHelper.java
@@ -125,10 +125,19 @@ public class ScrollViewCaptureHelper implements ScrollCaptureViewHelper<ViewGrou
                 view.getScrollX() - contentView.getLeft(),
                 view.getScrollY() - contentView.getTop());
 
+        Rect input = new Rect(requestedContentBounds);
+
+        // Expand input rect to get the requested rect to be in the center
+        int remainingHeight = view.getHeight() - view.getPaddingTop()
+                - view.getPaddingBottom() - input.height();
+        if (remainingHeight > 0) {
+            input.inset(0, -remainingHeight / 2);
+        }
+
         // requestRect is now local to contentView as requestedContentBounds
         // contentView (and each parent in turn if possible) will be scrolled
         // (if necessary) to make all of requestedContent visible, (if possible!)
-        contentView.requestRectangleOnScreen(new Rect(requestedContentBounds), true);
+        contentView.requestRectangleOnScreen(input, true);
 
         // update new offset between starting and current scroll position
         scrollDelta = view.getScrollY() - mStartScrollY;
diff --git a/core/tests/coretests/src/com/android/internal/view/ScrollViewCaptureHelperTest.java b/core/tests/coretests/src/com/android/internal/view/ScrollViewCaptureHelperTest.java
index ab13fd7d81e08..fc02ea9aee22d 100644
--- a/core/tests/coretests/src/com/android/internal/view/ScrollViewCaptureHelperTest.java
+++ b/core/tests/coretests/src/com/android/internal/view/ScrollViewCaptureHelperTest.java
@@ -164,7 +164,8 @@ public class ScrollViewCaptureHelperTest {
         assertRectEquals(request, scrollResult.requestedArea);
         assertRectEquals(request, scrollResult.availableArea);
         assertRequestedRectCompletelyVisible(startScrollY, request, getVisibleRect(mContent));
-        assertEquals(CAPTURE_HEIGHT, scrollResult.scrollDelta);
+        assertEquals(CAPTURE_HEIGHT + (WINDOW_HEIGHT - CAPTURE_HEIGHT) / 2,
+                scrollResult.scrollDelta);
     }
 
     @Test
@@ -182,7 +183,8 @@ public class ScrollViewCaptureHelperTest {
         assertRectEquals(request, scrollResult.requestedArea);
         assertRectEquals(request, scrollResult.availableArea);
         assertRequestedRectCompletelyVisible(startScrollY, request, getVisibleRect(mContent));
-        assertEquals(-CAPTURE_HEIGHT, scrollResult.scrollDelta);
+        assertEquals(-CAPTURE_HEIGHT - (WINDOW_HEIGHT - CAPTURE_HEIGHT) / 2,
+                scrollResult.scrollDelta);
     }
 
     @Test
@@ -201,7 +203,8 @@ public class ScrollViewCaptureHelperTest {
         assertRectEquals(request, scrollResult.requestedArea);
         assertRectEquals(request, scrollResult.availableArea);
         assertRequestedRectCompletelyVisible(startScrollY, request, getVisibleRect(mContent));
-        assertEquals(CAPTURE_HEIGHT, scrollResult.scrollDelta);
+        assertEquals(CAPTURE_HEIGHT + (WINDOW_HEIGHT - CAPTURE_HEIGHT) / 2,
+                scrollResult.scrollDelta);
 
     }
 
@@ -220,7 +223,8 @@ public class ScrollViewCaptureHelperTest {
         assertRectEquals(request, scrollResult.requestedArea);
         assertRectEquals(request, scrollResult.availableArea);
         assertRequestedRectCompletelyVisible(startScrollY, request, getVisibleRect(mContent));
-        assertEquals(-CAPTURE_HEIGHT, scrollResult.scrollDelta);
+        assertEquals(-CAPTURE_HEIGHT - (WINDOW_HEIGHT - CAPTURE_HEIGHT) / 2,
+                scrollResult.scrollDelta);
     }
 
     @Test