added files via upload

Tweaks/FLEX/ViewHierarchy/SnapshotExplorer/FHSView.m

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+//
+//  FHSView.m
+//  FLEX
+//
+//  Created by Tanner Bennett on 1/6/20.
+//
+
+#import "FHSView.h"
+#import "FLEXUtility.h"
+#import "NSArray+FLEX.h"
+
+@interface FHSView (Snapshotting)
++ (UIImage *)_snapshotView:(UIView *)view;
+@end
+
+@implementation FHSView
+
++ (instancetype)forView:(UIView *)view isInScrollView:(BOOL)inScrollView {
+    return [[self alloc] initWithView:view isInScrollView:inScrollView];
+}
+
+- (id)initWithView:(UIView *)view isInScrollView:(BOOL)inScrollView {
+    self = [super init];
+    if (self) {
+        _view = view;
+        _inScrollView = inScrollView;
+        _identifier = NSUUID.UUID.UUIDString;
+
+        UIViewController *controller = [FLEXUtility viewControllerForView:view];
+        if (controller) {
+            _important = YES;
+            _title = [NSString stringWithFormat:
+                @"%@ (for %@)",
+                NSStringFromClass([controller class]),
+                NSStringFromClass([view class])
+            ];
+        } else {
+            _title = NSStringFromClass([view class]);
+        }
+    }
+
+    return self;
+}
+
+- (CGRect)frame {
+    if (_inScrollView) {
+        CGPoint offset = [(UIScrollView *)self.view.superview contentOffset];
+        return CGRectOffset(self.view.frame, -offset.x, -offset.y);
+    } else {
+        return self.view.frame;
+    }
+}
+
+- (BOOL)hidden {
+    return self.view.isHidden;
+}
+
+- (UIImage *)snapshotImage {
+    return [FHSView _snapshotView:self.view];
+}
+
+- (NSArray<FHSView *> *)children {
+    BOOL isScrollView = [self.view isKindOfClass:[UIScrollView class]];
+    return [self.view.subviews flex_mapped:^id(UIView *subview, NSUInteger idx) {
+        return [FHSView forView:subview isInScrollView:isScrollView];
+    }];
+}
+
+- (NSString *)summary {
+    CGRect f = self.frame;
+    return [NSString stringWithFormat:
+        @"%@ (%.1f, %.1f, %.1f, %.1f)",
+        NSStringFromClass([self.view class]),
+        f.origin.x, f.origin.y, f.size.width, f.size.height
+    ];
+}
+
+- (NSString *)description{
+    return self.view.description;
+}
+
+- (id)ifImportant:(id)importantAttr ifNormal:(id)normalAttr {
+    return self.important ? importantAttr : normalAttr;
+}
+
+@end
+
+@implementation FHSView (Snapshotting)
+
++ (UIImage *)drawView:(UIView *)view {
+    UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 0);
+    [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
+/// Recursively hides all views that may be obscuring the given view and collects them
+/// in the given array. You should unhide them all when you are done.
++ (BOOL)_hideViewsCoveringView:(UIView *)view
+                          root:(UIView *)rootView
+                   hiddenViews:(NSMutableArray<UIView *> *)hiddenViews {
+    // Stop when we reach this view
+    if (view == rootView) {
+        return YES;
+    }
+
+    for (UIView *subview in rootView.subviews.reverseObjectEnumerator.allObjects) {
+        if ([self _hideViewsCoveringView:view root:subview hiddenViews:hiddenViews]) {
+            return YES;
+        }
+    }
+
+    if (!rootView.isHidden) {
+        rootView.hidden = YES;
+        [hiddenViews addObject:rootView];
+    }
+
+    return NO;
+}
+
+
+/// Recursively hides all views that may be obscuring the given view and collects them
+/// in the given array. You should unhide them all when you are done.
++ (void)hideViewsCoveringView:(UIView *)view doWhileHidden:(void(^)(void))block {
+    NSMutableArray *viewsToUnhide = [NSMutableArray new];
+    if ([self _hideViewsCoveringView:view root:view.window hiddenViews:viewsToUnhide]) {
+        block();
+    }
+
+    for (UIView *v in viewsToUnhide) {
+        v.hidden = NO;
+    }
+}
+
++ (UIImage *)_snapshotVisualEffectBackdropView:(UIView *)view {
+    NSParameterAssert(view.window);
+
+    // UIVisualEffectView is a special case that cannot be snapshotted
+    // the same way as any other view. From Apple docs:
+    //
+    //   Many effects require support from the window that hosts the
+    //   UIVisualEffectView. Attempting to take a snapshot of only the
+    //   UIVisualEffectView will result in a snapshot that does not
+    //   contain the effect. To take a snapshot of a view hierarchy
+    //   that contains a UIVisualEffectView, you must take a snapshot
+    //   of the entire UIWindow or UIScreen that contains it.
+    //
+    // To snapshot this view, we traverse the view hierarchy starting
+    // from the window and hide any views that are on top of the
+    // _UIVisualEffectBackdropView so that it is visible in a snapshot
+    // of the window. We then take a snapshot of the window and crop
+    // it to the part that contains the backdrop view. This appears to
+    // be the same technique that Xcode's own view debugger uses to
+    // snapshot visual effect views.
+    __block UIImage *image = nil;
+    [self hideViewsCoveringView:view doWhileHidden:^{
+        image = [self drawView:view];
+        CGRect cropRect = [view.window convertRect:view.bounds fromView:view];
+        image = [UIImage imageWithCGImage:CGImageCreateWithImageInRect(image.CGImage, cropRect)];
+    }];
+
+    return image;
+}
+
++ (UIImage *)_snapshotView:(UIView *)view {
+    UIView *superview = view.superview;
+    // Is this view inside a UIVisualEffectView?
+    if ([superview isKindOfClass:[UIVisualEffectView class]]) {
+        // Is it (probably) the "backdrop" view of this UIVisualEffectView?
+        if (superview.subviews.firstObject == view) {
+            return [self _snapshotVisualEffectBackdropView:view];
+        }
+    }
+
+    // Hide the view's subviews before we snapshot it
+    NSMutableIndexSet *toUnhide = [NSMutableIndexSet new];
+    [view.subviews flex_forEach:^(UIView *v, NSUInteger idx) {
+        if (!v.isHidden) {
+            v.hidden = YES;
+            [toUnhide addIndex:idx];
+        }
+    }];
+
+    // Snapshot the view, then unhide the previously-unhidden views
+    UIImage *snapshot = [self drawView:view];
+    for (UIView *v in [view.subviews objectsAtIndexes:toUnhide]) {
+        v.hidden = NO;
+    }
+
+    return snapshot;
+}
+
+@end