/** * Copyright (c) 2015-present, Facebook, Inc. * All rights reserved. * * This source code is licensed under the BSD-style license found in the * LICENSE file in the root directory of this source tree. An additional grant * of patent rights can be found in the PATENTS file in the same directory. */ #import "RCTView.h" #import "RCTAutoInsetsProtocol.h" #import "RCTConvert.h" #import "RCTLog.h" #import "RCTUtils.h" #import "UIView+React.h" static void *RCTViewCornerRadiusKVOContext = &RCTViewCornerRadiusKVOContext; static UIView *RCTViewHitTest(UIView *view, CGPoint point, UIEvent *event) { for (UIView *subview in [view.subviews reverseObjectEnumerator]) { if (!subview.isHidden && subview.isUserInteractionEnabled && subview.alpha > 0) { CGPoint convertedPoint = [subview convertPoint:point fromView:view]; UIView *subviewHitTestView = [subview hitTest:convertedPoint withEvent:event]; if (subviewHitTestView != nil) { return subviewHitTestView; } } } return nil; } static BOOL RCTEllipseGetIntersectionsWithLine(CGRect ellipseBoundingRect, CGPoint p1, CGPoint p2, CGPoint intersections[2]); static CGPathRef RCTPathCreateWithRoundedRect(CGRect rect, CGFloat topLeftRadiusX, CGFloat topLeftRadiusY, CGFloat topRightRadiusX, CGFloat topRightRadiusY, CGFloat bottomLeftRadiusX, CGFloat bottomLeftRadiusY, CGFloat bottomRightRadiusX, CGFloat bottomRightRadiusY, const CGAffineTransform *transform); static void RCTPathAddEllipticArc(CGMutablePathRef path, const CGAffineTransform *m, CGFloat x, CGFloat y, CGFloat xRadius, CGFloat yRadius, CGFloat startAngle, CGFloat endAngle, bool clockwise); @implementation UIView (RCTViewUnmounting) - (void)react_remountAllSubviews { // Normal views don't support unmounting, so all // this does is forward message to our subviews, // in case any of those do support it for (UIView *subview in self.subviews) { [subview react_remountAllSubviews]; } } - (void)react_updateClippedSubviewsWithClipRect:(CGRect)clipRect relativeToView:(UIView *)clipView { // Even though we don't support subview unmounting // we do support clipsToBounds, so if that's enabled // we'll update the clipping if (self.clipsToBounds && [self.subviews count] > 0) { clipRect = [clipView convertRect:clipRect toView:self]; clipRect = CGRectIntersection(clipRect, self.bounds); clipView = self; } // Normal views don't support unmounting, so all // this does is forward message to our subviews, // in case any of those do support it for (UIView *subview in self.subviews) { [subview react_updateClippedSubviewsWithClipRect:clipRect relativeToView:clipView]; } } - (UIView *)react_findClipView { UIView *testView = self; UIView *clipView = nil; CGRect clipRect = self.bounds; while (testView) { if (testView.clipsToBounds) { if (clipView) { CGRect testRect = [clipView convertRect:clipRect toView:testView]; if (!CGRectContainsRect(testView.bounds, testRect)) { clipView = testView; clipRect = CGRectIntersection(testView.bounds, testRect); } } else { clipView = testView; clipRect = [self convertRect:self.bounds toView:clipView]; } } testView = testView.superview; } return clipView ?: self.window; } @end static NSString *RCTRecursiveAccessibilityLabel(UIView *view) { NSMutableString *str = [NSMutableString stringWithString:@""]; for (UIView *subview in view.subviews) { NSString *label = [subview accessibilityLabel]; if (label) { [str appendString:@" "]; [str appendString:label]; } else { [str appendString:RCTRecursiveAccessibilityLabel(subview)]; } } return str; } @implementation RCTView { NSMutableArray *_reactSubviews; UIColor *_backgroundColor; } - (instancetype)initWithFrame:(CGRect)frame { if ((self = [super initWithFrame:frame])) { _borderWidth = -1; _borderTopWidth = -1; _borderRightWidth = -1; _borderBottomWidth = -1; _borderLeftWidth = -1; _backgroundColor = [super backgroundColor]; [super setBackgroundColor:[UIColor clearColor]]; [self.layer addObserver:self forKeyPath:@"cornerRadius" options:0 context:RCTViewCornerRadiusKVOContext]; } return self; } - (void)dealloc { [self.layer removeObserver:self forKeyPath:@"cornerRadius" context:RCTViewCornerRadiusKVOContext]; } - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (context == RCTViewCornerRadiusKVOContext) { [self.layer setNeedsDisplay]; } else { [super observeValueForKeyPath:keyPath ofObject:object change:change context:context]; } } - (NSString *)accessibilityLabel { if (super.accessibilityLabel) { return super.accessibilityLabel; } return RCTRecursiveAccessibilityLabel(self); } - (void)setPointerEvents:(RCTPointerEvents)pointerEvents { _pointerEvents = pointerEvents; self.userInteractionEnabled = (pointerEvents != RCTPointerEventsNone); if (pointerEvents == RCTPointerEventsBoxNone) { self.accessibilityViewIsModal = NO; } } - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event { switch (_pointerEvents) { case RCTPointerEventsNone: return nil; case RCTPointerEventsUnspecified: return RCTViewHitTest(self, point, event) ?: [super hitTest:point withEvent:event]; case RCTPointerEventsBoxOnly: return [super hitTest:point withEvent:event] ? self: nil; case RCTPointerEventsBoxNone: return RCTViewHitTest(self, point, event); default: RCTLogError(@"Invalid pointer-events specified %zd on %@", _pointerEvents, self); return [super hitTest:point withEvent:event]; } } #pragma mark - Statics for dealing with layoutGuides + (void)autoAdjustInsetsForView:(UIView *)parentView withScrollView:(UIScrollView *)scrollView updateOffset:(BOOL)updateOffset { UIEdgeInsets baseInset = parentView.contentInset; CGFloat previousInsetTop = scrollView.contentInset.top; CGPoint contentOffset = scrollView.contentOffset; if (parentView.automaticallyAdjustContentInsets) { UIEdgeInsets autoInset = [self contentInsetsForView:parentView]; baseInset.top += autoInset.top; baseInset.bottom += autoInset.bottom; baseInset.left += autoInset.left; baseInset.right += autoInset.right; } [scrollView setContentInset:baseInset]; [scrollView setScrollIndicatorInsets:baseInset]; if (updateOffset) { // If we're adjusting the top inset, then let's also adjust the contentOffset so that the view // elements above the top guide do not cover the content. // This is generally only needed when your views are initially laid out, for // manual changes to contentOffset, you can optionally disable this step CGFloat currentInsetTop = scrollView.contentInset.top; if (currentInsetTop != previousInsetTop) { contentOffset.y -= (currentInsetTop - previousInsetTop); scrollView.contentOffset = contentOffset; } } } + (UIEdgeInsets)contentInsetsForView:(UIView *)view { while (view) { UIViewController *controller = view.backingViewController; if (controller) { return (UIEdgeInsets){ controller.topLayoutGuide.length, 0, controller.bottomLayoutGuide.length, 0 }; } view = view.superview; } return UIEdgeInsetsZero; } #pragma mark - View unmounting - (void)react_remountAllSubviews { if (_reactSubviews) { NSInteger index = 0; for (UIView *view in _reactSubviews) { if (view.superview != self) { if (index < [self subviews].count) { [self insertSubview:view atIndex:index]; } else { [self addSubview:view]; } [view react_remountAllSubviews]; } index++; } } else { // If react_subviews is nil, we must already be showing all subviews [super react_remountAllSubviews]; } } - (void)remountSubview:(UIView *)view { // Calculate insertion index for view NSInteger index = 0; for (UIView *subview in _reactSubviews) { if (subview == view) { [self insertSubview:view atIndex:index]; break; } if (subview.superview) { // View is mounted, so bump the index index++; } } } - (void)mountOrUnmountSubview:(UIView *)view withClipRect:(CGRect)clipRect relativeToView:(UIView *)clipView { if (view.clipsToBounds) { // View has cliping enabled, so we can easily test if it is partially // or completely within the clipRect, and mount or unmount it accordingly if (CGRectIntersectsRect(clipRect, view.frame)) { // View is at least partially visible, so remount it if unmounted if (view.superview == nil) { [self remountSubview:view]; } // Then test its subviews if (CGRectContainsRect(clipRect, view.frame)) { [view react_remountAllSubviews]; } else { [view react_updateClippedSubviewsWithClipRect:clipRect relativeToView:clipView]; } } else if (view.superview) { // View is completely outside the clipRect, so unmount it [view removeFromSuperview]; } } else { // View has clipping disabled, so there's no way to tell if it has // any visible subviews without an expensive recursive test, so we'll // just add it. if (view.superview == nil) { [self remountSubview:view]; } // Check if subviews need to be mounted/unmounted [view react_updateClippedSubviewsWithClipRect:clipRect relativeToView:clipView]; } } - (void)react_updateClippedSubviewsWithClipRect:(CGRect)clipRect relativeToView:(UIView *)clipView { // TODO (#5906496): for scrollviews (the primary use-case) we could // optimize this by only doing a range check along the scroll axis, // instead of comparing the whole frame if (_reactSubviews == nil) { // Use default behavior if unmounting is disabled return [super react_updateClippedSubviewsWithClipRect:clipRect relativeToView:clipView]; } if ([_reactSubviews count] == 0) { // Do nothing if we have no subviews return; } if (CGSizeEqualToSize(self.bounds.size, CGSizeZero)) { // Do nothing if layout hasn't happened yet return; } // Convert clipping rect to local coordinates clipRect = [clipView convertRect:clipRect toView:self]; clipView = self; if (self.clipsToBounds) { clipRect = CGRectIntersection(clipRect, self.bounds); } // Mount / unmount views for (UIView *view in _reactSubviews) { [self mountOrUnmountSubview:view withClipRect:clipRect relativeToView:clipView]; } } - (void)setRemoveClippedSubviews:(BOOL)removeClippedSubviews { if (removeClippedSubviews && !_reactSubviews) { _reactSubviews = [self.subviews mutableCopy]; } else if (!removeClippedSubviews && _reactSubviews) { [self react_remountAllSubviews]; _reactSubviews = nil; } } - (BOOL)removeClippedSubviews { return _reactSubviews != nil; } - (void)insertReactSubview:(UIView *)view atIndex:(NSInteger)atIndex { if (_reactSubviews == nil) { [self insertSubview:view atIndex:atIndex]; } else { [_reactSubviews insertObject:view atIndex:atIndex]; // Find a suitable view to use for clipping UIView *clipView = [self react_findClipView]; if (clipView) { // If possible, don't add subviews if they are clipped [self mountOrUnmountSubview:view withClipRect:clipView.bounds relativeToView:clipView]; } else { // Fallback if we can't find a suitable clipView [self remountSubview:view]; } } } - (void)removeReactSubview:(UIView *)subview { [_reactSubviews removeObject:subview]; [subview removeFromSuperview]; } - (NSArray *)reactSubviews { // The _reactSubviews array is only used when we have hidden // offscreen views. If _reactSubviews is nil, we can assume // that [self reactSubviews] and [self subviews] are the same return _reactSubviews ?: [self subviews]; } - (void)updateClippedSubviews { // Find a suitable view to use for clipping UIView *clipView = [self react_findClipView]; if (clipView) { [self react_updateClippedSubviewsWithClipRect:clipView.bounds relativeToView:clipView]; } } - (void)layoutSubviews { // TODO (#5906496): this a nasty performance drain, but necessary // to prevent gaps appearing when the loading spinner disappears. // We might be able to fix this another way by triggering a call // to updateClippedSubviews manually after loading [super layoutSubviews]; if (_reactSubviews) { [self updateClippedSubviews]; } } #pragma mark - Borders - (UIColor *)backgroundColor { return _backgroundColor; } - (void)setBackgroundColor:(UIColor *)backgroundColor { if ([_backgroundColor isEqual:backgroundColor]) { return; } _backgroundColor = backgroundColor; [self.layer setNeedsDisplay]; } - (UIImage *)generateBorderImage:(out CGRect *)contentsCenter { const CGFloat maxRadius = MIN(self.bounds.size.height, self.bounds.size.width) / 2.0; const CGFloat radius = MAX(0, MIN(self.layer.cornerRadius, maxRadius)); const CGFloat borderWidth = MAX(0, _borderWidth); const CGFloat topWidth = _borderTopWidth >= 0 ? _borderTopWidth : borderWidth; const CGFloat rightWidth = _borderRightWidth >= 0 ? _borderRightWidth : borderWidth; const CGFloat bottomWidth = _borderBottomWidth >= 0 ? _borderBottomWidth : borderWidth; const CGFloat leftWidth = _borderLeftWidth >= 0 ? _borderLeftWidth : borderWidth; const CGFloat topRadius = MAX(0, radius - topWidth); const CGFloat rightRadius = MAX(0, radius - rightWidth); const CGFloat bottomRadius = MAX(0, radius - bottomWidth); const CGFloat leftRadius = MAX(0, radius - leftWidth); const UIEdgeInsets edgeInsets = UIEdgeInsetsMake(topWidth + topRadius, leftWidth + leftRadius, bottomWidth + bottomRadius, rightWidth + rightRadius); const CGSize size = CGSizeMake(edgeInsets.left + 1 + edgeInsets.right, edgeInsets.top + 1 + edgeInsets.bottom); UIScreen *screen = self.window.screen ?: [UIScreen mainScreen]; UIGraphicsBeginImageContextWithOptions(size, NO, screen.scale * 2); CGContextRef ctx = UIGraphicsGetCurrentContext(); const CGRect rect = {CGPointZero, size}; CGPathRef path = CGPathCreateWithRoundedRect(rect, radius, radius, NULL); if (_backgroundColor) { CGContextSaveGState(ctx); CGContextAddPath(ctx, path); CGContextSetFillColorWithColor(ctx, _backgroundColor.CGColor); CGContextFillPath(ctx); CGContextRestoreGState(ctx); } CGContextAddPath(ctx, path); CGPathRelease(path); if (radius > 0 && topWidth > 0 && rightWidth > 0 && bottomWidth > 0 && leftWidth > 0) { const UIEdgeInsets insetEdgeInsets = UIEdgeInsetsMake(topWidth, leftWidth, bottomWidth, rightWidth); const CGRect insetRect = UIEdgeInsetsInsetRect(rect, insetEdgeInsets); CGPathRef insetPath = RCTPathCreateWithRoundedRect(insetRect, leftRadius, topRadius, rightRadius, topRadius, leftRadius, bottomRadius, rightRadius, bottomRadius, NULL); CGContextAddPath(ctx, insetPath); CGPathRelease(insetPath); } CGContextEOClip(ctx); BOOL hasEqualColor = !_borderTopColor && !_borderRightColor && !_borderBottomColor && !_borderLeftColor; BOOL hasEqualBorder = _borderWidth >= 0 && _borderTopWidth < 0 && _borderRightWidth < 0 && _borderBottomWidth < 0 && _borderLeftWidth < 0; if (radius <= 0 && hasEqualBorder && hasEqualColor) { CGContextSetStrokeColorWithColor(ctx, _borderColor); CGContextSetLineWidth(ctx, 2 * _borderWidth); CGContextClipToRect(ctx, rect); CGContextStrokeRect(ctx, rect); } else if (radius <= 0 && hasEqualColor) { CGContextSetFillColorWithColor(ctx, _borderColor); CGContextAddRect(ctx, rect); const CGRect insetRect = UIEdgeInsetsInsetRect(rect, edgeInsets); CGContextAddRect(ctx, insetRect); CGContextEOFillPath(ctx); } else { BOOL didSet = NO; CGPoint topLeft; if (topRadius > 0 && leftRadius > 0) { CGPoint points[2]; RCTEllipseGetIntersectionsWithLine(CGRectMake(leftWidth, topWidth, 2 * leftRadius, 2 * topRadius), CGPointMake(0, 0), CGPointMake(leftWidth, topWidth), points); if (!isnan(points[1].x) && !isnan(points[1].y)) { topLeft = points[1]; didSet = YES; } } if (!didSet) { topLeft = CGPointMake(leftWidth, topWidth); } didSet = NO; CGPoint bottomLeft; if (bottomRadius > 0 && leftRadius > 0) { CGPoint points[2]; RCTEllipseGetIntersectionsWithLine(CGRectMake(leftWidth, (size.height - bottomWidth) - 2 * bottomRadius, 2 * leftRadius, 2 * bottomRadius), CGPointMake(0, size.height), CGPointMake(leftWidth, size.height - bottomWidth), points); if (!isnan(points[1].x) && !isnan(points[1].y)) { bottomLeft = points[1]; didSet = YES; } } if (!didSet) { bottomLeft = CGPointMake(leftWidth, size.height - bottomWidth); } didSet = NO; CGPoint topRight; if (topRadius > 0 && rightRadius > 0) { CGPoint points[2]; RCTEllipseGetIntersectionsWithLine(CGRectMake((size.width - rightWidth) - 2 * rightRadius, topWidth, 2 * rightRadius, 2 * topRadius), CGPointMake(size.width, 0), CGPointMake(size.width - rightWidth, topWidth), points); if (!isnan(points[0].x) && !isnan(points[0].y)) { topRight = points[0]; didSet = YES; } } if (!didSet) { topRight = CGPointMake(size.width - rightWidth, topWidth); } didSet = NO; CGPoint bottomRight; if (bottomRadius > 0 && rightRadius > 0) { CGPoint points[2]; RCTEllipseGetIntersectionsWithLine(CGRectMake((size.width - rightWidth) - 2 * rightRadius, (size.height - bottomWidth) - 2 * bottomRadius, 2 * rightRadius, 2 * bottomRadius), CGPointMake(size.width, size.height), CGPointMake(size.width - rightWidth, size.height - bottomWidth), points); if (!isnan(points[0].x) && !isnan(points[0].y)) { bottomRight = points[0]; didSet = YES; } } if (!didSet) { bottomRight = CGPointMake(size.width - rightWidth, size.height - bottomWidth); } // RIGHT if (rightWidth > 0) { CGContextSaveGState(ctx); const CGPoint points[] = { CGPointMake(size.width, 0), topRight, bottomRight, CGPointMake(size.width, size.height), }; CGContextSetFillColorWithColor(ctx, _borderRightColor ?: _borderColor); CGContextAddLines(ctx, points, sizeof(points)/sizeof(*points)); CGContextFillPath(ctx); CGContextRestoreGState(ctx); } // BOTTOM if (bottomWidth > 0) { CGContextSaveGState(ctx); const CGPoint points[] = { CGPointMake(0, size.height), bottomLeft, bottomRight, CGPointMake(size.width, size.height), }; CGContextSetFillColorWithColor(ctx, _borderBottomColor ?: _borderColor); CGContextAddLines(ctx, points, sizeof(points)/sizeof(*points)); CGContextFillPath(ctx); CGContextRestoreGState(ctx); } // LEFT if (leftWidth > 0) { CGContextSaveGState(ctx); const CGPoint points[] = { CGPointMake(0, 0), topLeft, bottomLeft, CGPointMake(0, size.height), }; CGContextSetFillColorWithColor(ctx, _borderLeftColor ?: _borderColor); CGContextAddLines(ctx, points, sizeof(points)/sizeof(*points)); CGContextFillPath(ctx); CGContextRestoreGState(ctx); } // TOP if (topWidth > 0) { CGContextSaveGState(ctx); const CGPoint points[] = { CGPointMake(0, 0), topLeft, topRight, CGPointMake(size.width, 0), }; CGContextSetFillColorWithColor(ctx, _borderTopColor ?: _borderColor); CGContextAddLines(ctx, points, sizeof(points)/sizeof(*points)); CGContextFillPath(ctx); CGContextRestoreGState(ctx); } } UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); *contentsCenter = CGRectMake(edgeInsets.left / size.width, edgeInsets.top / size.height, 1.0 / size.width, 1.0 / size.height); return [image resizableImageWithCapInsets:edgeInsets]; } - (void)displayLayer:(CALayer *)layer { CGRect contentsCenter; UIImage *image = [self generateBorderImage:&contentsCenter]; if (RCTRunningInTestEnvironment()) { const CGSize size = self.bounds.size; UIGraphicsBeginImageContextWithOptions(size, NO, image.scale); [image drawInRect:(CGRect){CGPointZero, size}]; image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); contentsCenter = CGRectMake(0, 0, 1, 1); } layer.contents = (id)image.CGImage; layer.contentsCenter = contentsCenter; layer.contentsScale = image.scale; layer.magnificationFilter = kCAFilterNearest; } #pragma mark Border Color #define setBorderColor(side) \ - (void)setBorder##side##Color:(CGColorRef)border##side##Color \ { \ if (CGColorEqualToColor(_border##side##Color, border##side##Color)) { \ return; \ } \ _border##side##Color = border##side##Color; \ [self.layer setNeedsDisplay]; \ } setBorderColor() setBorderColor(Top) setBorderColor(Right) setBorderColor(Bottom) setBorderColor(Left) #pragma mark - Border Width #define setBorderWidth(side) \ - (void)setBorder##side##Width:(CGFloat)border##side##Width \ { \ if (_border##side##Width == border##side##Width) { \ return; \ } \ _border##side##Width = border##side##Width; \ [self.layer setNeedsDisplay]; \ } setBorderWidth() setBorderWidth(Top) setBorderWidth(Right) setBorderWidth(Bottom) setBorderWidth(Left) @end static void RCTPathAddEllipticArc(CGMutablePathRef path, const CGAffineTransform *m, CGFloat x, CGFloat y, CGFloat xRadius, CGFloat yRadius, CGFloat startAngle, CGFloat endAngle, bool clockwise) { CGFloat xScale = 1, yScale = 1, radius = 0; if (xRadius != 0) { xScale = 1; yScale = yRadius / xRadius; radius = xRadius; } else if (yRadius != 0) { xScale = xRadius / yRadius; yScale = 1; radius = yRadius; } CGAffineTransform t = CGAffineTransformMakeTranslation(x, y); t = CGAffineTransformScale(t, xScale, yScale); if (m != NULL) { t = CGAffineTransformConcat(t, *m); } CGPathAddArc(path, &t, 0, 0, radius, startAngle, endAngle, clockwise); } static CGPathRef RCTPathCreateWithRoundedRect(CGRect rect, CGFloat topLeftRadiusX, CGFloat topLeftRadiusY, CGFloat topRightRadiusX, CGFloat topRightRadiusY, CGFloat bottomLeftRadiusX, CGFloat bottomLeftRadiusY, CGFloat bottomRightRadiusX, CGFloat bottomRightRadiusY, const CGAffineTransform *transform) { const CGFloat minX = CGRectGetMinX(rect); const CGFloat minY = CGRectGetMinY(rect); const CGFloat maxX = CGRectGetMaxX(rect); const CGFloat maxY = CGRectGetMaxY(rect); CGMutablePathRef path = CGPathCreateMutable(); RCTPathAddEllipticArc(path, transform, minX + topLeftRadiusX, minY + topLeftRadiusY, topLeftRadiusX, topLeftRadiusY, M_PI, 3 * M_PI_2, false); RCTPathAddEllipticArc(path, transform, maxX - topRightRadiusX, minY + topRightRadiusY, topRightRadiusX, topRightRadiusY, 3 * M_PI_2, 0, false); RCTPathAddEllipticArc(path, transform, maxX - bottomRightRadiusX, maxY - bottomRightRadiusY, bottomRightRadiusX, bottomRightRadiusY, 0, M_PI_2, false); RCTPathAddEllipticArc(path, transform, minX + bottomLeftRadiusX, maxY - bottomLeftRadiusY, bottomLeftRadiusX, bottomLeftRadiusY, M_PI_2, M_PI, false); CGPathCloseSubpath(path); return path; } static BOOL RCTEllipseGetIntersectionsWithLine(CGRect ellipseBoundingRect, CGPoint p1, CGPoint p2, CGPoint intersections[2]) { const CGFloat ellipseCenterX = CGRectGetMidX(ellipseBoundingRect); const CGFloat ellipseCenterY = CGRectGetMidY(ellipseBoundingRect); // ellipseBoundingRect.origin.x -= ellipseCenterX; // ellipseBoundingRect.origin.y -= ellipseCenterY; p1.x -= ellipseCenterX; p1.y -= ellipseCenterY; p2.x -= ellipseCenterX; p2.y -= ellipseCenterY; const CGFloat m = (p2.y - p1.y) / (p2.x - p1.x); const CGFloat a = ellipseBoundingRect.size.width / 2; const CGFloat b = ellipseBoundingRect.size.height / 2; const CGFloat c = p1.y - m * p1.x; const CGFloat A = (b * b + a * a * m * m); const CGFloat B = 2 * a * a * c * m; const CGFloat D = sqrt((a * a * (b * b - c * c)) / A + pow(B / (2 * A), 2)); const CGFloat x_ = -B / (2 * A); const CGFloat x1 = x_ + D; const CGFloat x2 = x_ - D; const CGFloat y1 = m * x1 + c; const CGFloat y2 = m * x2 + c; intersections[0] = CGPointMake(x1 + ellipseCenterX, y1 + ellipseCenterY); intersections[1] = CGPointMake(x2 + ellipseCenterX, y2 + ellipseCenterY); return YES; }