Move off of UIKit SPI: -[UIScrollView _is(Vertical|Horizontal)Bouncing]

https://bugs.webkit.org/show_bug.cgi?id=262013
rdar://112473874

Reviewed by Aditya Keerthi.

Stop using `-_isVerticalBouncing` and `-_isHorizontalBouncing` on `UIScrollView`; as an alternative,
add a new category helper method, `-[UIScrollView _wk_isScrolledBeyondExtents]`, that returns
whether or not the current content offset is scrolled beyond the minimum or maximum extents of the
scroll view, taking the `-adjustedContentInset` into account.

* Source/WebKit/Platform/spi/ios/UIKitSPI.h:
* Source/WebKit/UIProcess/ios/UIKitUtilities.h:
* Source/WebKit/UIProcess/ios/UIKitUtilities.mm:
(-[UIScrollView _wk_isScrolledBeyondExtents]):
* Source/WebKit/UIProcess/ios/WKScrollView.mm:
(-[WKScrollView _setContentSizePreservingContentOffsetDuringRubberband:]):
* Tools/WebKitTestRunner/WebKitTestRunner.xcodeproj/project.pbxproj:
* Tools/WebKitTestRunner/cocoa/TestRunnerWKWebView.mm:
* Tools/WebKitTestRunner/ios/UIKitSPIForTesting.h: Copied from Source/WebKit/UIProcess/ios/UIKitUtilities.h.

Continue using `-_isVerticalBouncing` and `-_isHorizontalBouncing` in WebKitTestRunner harness logic
to determine when scrolling/zooming animations are complete. We also add an SPI header, specific to
WebKitTestRunner for now, to house these new forward declarations and SPI include points. I'll move
various existing testing-only declarations and includes in UIKitSPI.h into this header in a
subsequent patch.

Canonical link: https://commits.webkit.org/268376@main

Source/WebKit/Platform/spi/ios/UIKitSPI.h

@@ -455,8 +455,6 @@ typedef struct CGSVGDocument *CGSVGDocumentRef;
 - (double)_verticalVelocity;
 - (void)_flashScrollIndicatorsForAxes:(UIAxis)axes persistingPreviousFlashes:(BOOL)persisting;
 @property (nonatomic, getter=isZoomEnabled) BOOL zoomEnabled;
-@property (nonatomic, readonly, getter=_isVerticalBouncing) BOOL isVerticalBouncing;
-@property (nonatomic, readonly, getter=_isHorizontalBouncing) BOOL isHorizontalBouncing;
 @property (nonatomic, readonly, getter=_isAnimatingZoom) BOOL isAnimatingZoom;
 @property (nonatomic, readonly, getter=_isAnimatingScroll) BOOL isAnimatingScroll;
 @property (nonatomic, getter=_contentScrollInset, setter=_setContentScrollInset:) UIEdgeInsets contentScrollInset;

Source/WebKit/UIProcess/ios/UIKitUtilities.h

@@ -32,6 +32,7 @@
 
 @interface UIScrollView (WebKitInternal)
 @property (readonly, nonatomic) BOOL _wk_isInterruptingDeceleration;
+@property (readonly, nonatomic) BOOL _wk_isScrolledBeyondExtents;
 @end
 
 @interface UIView (WebKitInternal)

Source/WebKit/UIProcess/ios/UIKitUtilities.mm

@@ -37,6 +37,22 @@ - (BOOL)_wk_isInterruptingDeceleration
     return self.decelerating && self.tracking;
 }
 
+- (BOOL)_wk_isScrolledBeyondExtents
+{
+    auto contentOffset = self.contentOffset;
+    auto inset = self.adjustedContentInset;
+    if (contentOffset.x < -inset.left || contentOffset.y < -inset.top)
+        return YES;
+
+    auto contentSize = self.contentSize;
+    auto boundsSize = self.bounds.size;
+    auto maxScrollExtent = CGPointMake(
+        contentSize.width + inset.right - std::min<CGFloat>(boundsSize.width, contentSize.width + inset.left + inset.right),
+        contentSize.height + inset.bottom - std::min<CGFloat>(boundsSize.height, contentSize.height + inset.top + inset.bottom)
+    );
+    return contentOffset.x > maxScrollExtent.x || contentOffset.y > maxScrollExtent.y;
+}
+
 @end
 
 @implementation UIView (WebKitInternal)

Source/WebKit/UIProcess/ios/WKScrollView.mm

@@ -30,6 +30,7 @@
 
 #import "Logging.h"
 #import "UIKitSPI.h"
+#import "UIKitUtilities.h"
 #import "WKDeferringGestureRecognizer.h"
 #import "WKWebViewIOS.h"
 #import "WebPage.h"
@@ -415,8 +416,7 @@ - (void)_restoreContentOffsetWithRubberbandAmount:(CGSize)rubberbandAmount
 - (void)_setContentSizePreservingContentOffsetDuringRubberband:(CGSize)contentSize
 {
     CGSize currentContentSize = [self contentSize];
-
-    BOOL mightBeRubberbanding = self.isDragging || self.isVerticalBouncing || self.isHorizontalBouncing || self.refreshControl;
+    BOOL mightBeRubberbanding = self.isDragging || (self.scrollEnabled && self._wk_isScrolledBeyondExtents) || self.refreshControl;
     if (!mightBeRubberbanding || CGSizeEqualToSize(currentContentSize, CGSizeZero) || CGSizeEqualToSize(currentContentSize, contentSize) || ((self.zoomScale < self.minimumZoomScale) && !WebKit::scalesAreEssentiallyEqual(self.zoomScale, self.minimumZoomScale))) {
         // FIXME: rdar://problem/65277759 Find out why iOS Mail needs this call even when the contentSize has not changed.
         [self setContentSize:contentSize];

Tools/WebKitTestRunner/WebKitTestRunner.xcodeproj/project.pbxproj

@@ -168,6 +168,7 @@
 		F44A531821B899E500DBB99C /* InstanceMethodSwizzler.mm in Sources */ = {isa = PBXBuildFile; fileRef = F44A531621B899DA00DBB99C /* InstanceMethodSwizzler.mm */; };
 		F46240B1217013E500917B16 /* UIScriptControllerCocoa.mm in Sources */ = {isa = PBXBuildFile; fileRef = F46240AF2170128300917B16 /* UIScriptControllerCocoa.mm */; };
 		F4C3578C20E8444600FA0748 /* LayoutTestSpellChecker.mm in Sources */ = {isa = PBXBuildFile; fileRef = F4C3578A20E8444000FA0748 /* LayoutTestSpellChecker.mm */; };
+		F4C80D4E2ABFBCB500DEB820 /* UIKitSPIForTesting.h in Headers */ = {isa = PBXBuildFile; fileRef = F4C80D4D2ABFBCB500DEB820 /* UIKitSPIForTesting.h */; };
 		F4FED324235823A3003C139C /* NSPasteboardAdditions.mm in Sources */ = {isa = PBXBuildFile; fileRef = F4FED3222358215E003C139C /* NSPasteboardAdditions.mm */; };
 /* End PBXBuildFile section */
 
@@ -450,6 +451,7 @@
 		F46240AF2170128300917B16 /* UIScriptControllerCocoa.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = UIScriptControllerCocoa.mm; sourceTree = "<group>"; };
 		F4C3578A20E8444000FA0748 /* LayoutTestSpellChecker.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = LayoutTestSpellChecker.mm; path = ../TestRunnerShared/cocoa/LayoutTestSpellChecker.mm; sourceTree = "<group>"; };
 		F4C3578B20E8444000FA0748 /* LayoutTestSpellChecker.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = LayoutTestSpellChecker.h; path = ../TestRunnerShared/cocoa/LayoutTestSpellChecker.h; sourceTree = "<group>"; };
+		F4C80D4D2ABFBCB500DEB820 /* UIKitSPIForTesting.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = UIKitSPIForTesting.h; sourceTree = "<group>"; };
 		F4FED3212358215E003C139C /* NSPasteboardAdditions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = NSPasteboardAdditions.h; path = ../TestRunnerShared/mac/NSPasteboardAdditions.h; sourceTree = "<group>"; };
 		F4FED3222358215E003C139C /* NSPasteboardAdditions.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = NSPasteboardAdditions.mm; path = ../TestRunnerShared/mac/NSPasteboardAdditions.mm; sourceTree = "<group>"; };
 /* End PBXFileReference section */
@@ -756,6 +758,7 @@
 				0FEBF8591BB61DF20028722D /* HIDEventGenerator.mm */,
 				2EE52D131890A9FB0010ED21 /* PlatformWebViewIOS.mm */,
 				2EE52D141890A9FB0010ED21 /* TestControllerIOS.mm */,
+				F4C80D4D2ABFBCB500DEB820 /* UIKitSPIForTesting.h */,
 				F415C22A27AF52D30028F505 /* UIPasteboardConsistencyEnforcer.h */,
 				F415C22B27AF52D30028F505 /* UIPasteboardConsistencyEnforcer.mm */,
 				2D0BEE1722EAD1360092B738 /* UIScriptControllerIOS.h */,
@@ -1002,6 +1005,7 @@
 				0F73B5521BA78968004B3EF4 /* JSUIScriptController.h in Headers */,
 				2DFA98481D7F70CF00AFF2C9 /* SharedEventStreamsMac.h in Headers */,
 				2904FA1E265CC5D900A7EBC9 /* StringFunctionsCocoa.h in Headers */,
+				F4C80D4E2ABFBCB500DEB820 /* UIKitSPIForTesting.h in Headers */,
 				F415C22C27AF52D30028F505 /* UIPasteboardConsistencyEnforcer.h in Headers */,
 				2D058E0922E2EE2200E4C145 /* UIScriptControllerCocoa.h in Headers */,
 				2D058E0B22E2EF6D00E4C145 /* UIScriptControllerMac.h in Headers */,

Tools/WebKitTestRunner/cocoa/TestRunnerWKWebView.mm

@@ -37,6 +37,7 @@
 
 #if PLATFORM(IOS_FAMILY)
 #import "UIKitSPI.h"
+#import "UIKitSPIForTesting.h"
 #import <WebKit/WKWebViewPrivate.h>
 
 @interface WKWebView ()

Tools/WebKitTestRunner/ios/UIKitSPIForTesting.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2023 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#if PLATFORM(IOS_FAMILY)
+
+#import <UIKit/UIKit.h>
+
+#if USE(APPLE_INTERNAL_SDK)
+
+#import <UIKit/UIScrollView_Private.h>
+
+#else
+
+@interface UIScrollView ()
+@property (nonatomic, readonly, getter=_isVerticalBouncing) BOOL isVerticalBouncing;
+@property (nonatomic, readonly, getter=_isHorizontalBouncing) BOOL isHorizontalBouncing;
+@end
+
+#endif
+
+#endif // PLATFORM(IOS_FAMILY)