An extension to Core Graphics Geometry. Intersections, scaling, etc.
Objective-C C Ruby
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MTGeometry.xcodeproj adding more functions Apr 23, 2014
MTGeometry add CGCircleIntersectsLineWithPoints, which returns the number of col… Dec 18, 2015
MTGeometryTests Added functionality and tests for circles. Oct 16, 2015
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LICENSE initial commit Dec 17, 2012
MTGeometry.podspec updating pod Jan 30, 2016
README.md Added functionality and tests for circles. Oct 16, 2015

README.md

MTGeometry

An extension to Core Graphics Geometry. Intersections, scaling, etc.

Installation

In your Podfile, add this line:

pod "MTGeometry"

pod? => https://github.com/CocoaPods/CocoaPods/

NOTE: You may need to add -all_load to "Other Linker Flags" in your targets build settings if the pods library only contains categories.

Functions

Points

// Create a delta from x and y deltas
CGDelta CGDeltaMake(CGFloat deltaX, CGFloat deltaY);

// Get the distance between two points
CGFloat	CGPointDistance(CGPoint p1, CGPoint p2);

// A point along a line distance from point1.
CGPoint CGPointAlongLine(CGLine line, CGFloat distance);

// A point rotated around the pivot point by degrees.
CGPoint CGPointRotatedAroundPoint(CGPoint point, CGPoint pivot, CGFloat degrees);

Lines

// Create a line from 2 points.
CGLine CGLineMake(CGPoint point1, CGPoint point2);

// Returns true if two lines are exactly coincident.
bool CGLineEqualToLine(CGLine line1, CGLine line2);

// Get a line's midpoint.
CGPoint CGLineMidPoint(CGLine line);

// Get the point at which two lines intersect. Returns NOPOINT if they don't intersect.
CGPoint CGLinesIntersectAtPoint(CGLine line1, CGLine line2);

// Get the length of a line.
CGFloat CGLineLength(CGLine line);

// Returns a scaled line. Point 1 acts as the anchor and Point 2 is extended.
CGLine CGLineScale(CGLine line, CGFloat scale);

// Returns the delta x and y of the line from point 1 to point 2.
CGDelta CGLineDelta(CGLine line);

Rectangles

// Corner points of a CGRect
CGPoint CGRectTopLeftPoint(CGRect rect);
CGPoint CGRectTopRightPoint(CGRect rect);
CGPoint CGRectBottomLeftPoint(CGRect rect);
CGPoint CGRectBottomRightPoint(CGRect rect);

// Returns a resized rect with the same centerpoint.
CGRect	CGRectResize(CGRect rect, CGSize newSize);

// Similar to CGRectInset but only insets one edge. All other edges do not move.
CGRect	CGRectInsetEdge(CGRect rect, CGRectEdge edge, CGFloat amount);

// Calculates the stacking of rectangles within a larger rectangle. The resulting rectangle is stacked counter clockwise along the edge specified. As soon as there are more rects than will fit, a new row is started, thus, they are stacked by column, then by row. `reverse` will cause them to be stacked counter-clockwise along the specified edge.
CGRect	CGRectStackedWithinRectFromEdge(CGRect rect, CGSize size, int count, CGRectEdge edge, bool reverse);

// Find the centerpoint of a rectangle.
CGPoint CGRectCenterPoint(CGRect rect);

// Assigns the closest two corner points to point1 and point2 of the rect to the passed in point.
void	CGRectClosestTwoCornerPoints(CGRect rect, CGPoint point, CGPoint *point1, CGPoint *point2);

// The point at which a line, extended infinitely past its second point, intersects the rectangle. Returns NOPOINT if no intersection is found.
CGPoint CGLineIntersectsRectAtPoint(CGRect rect, CGLine line);

Circles

// Create a circle from a center and a radius
CGCircle CGCircleMake(CGPoint center, CGFloat radius);

// Returns true if two circles are exactly coincident
bool CGCircleEqualToCircle(CGCircle circle1, CGCircle circle2);

// Returns a scaled circle.
CGCircle CGCircleScale(CGCircle circle, CGFloat scale);

// Returns a circle translated by delta.
CGCircle CGCircleTranslate(CGCircle circle, CGDelta delta);

// Returns true if point is inside or on the boundary of the circle
bool CGCircleContainsPoint(CGCircle circle, CGPoint point);

// Returns true if two circles intersect or one is contained within the other
bool CGCircleIntersectsCircle(CGCircle circle1, CGCircle circle2);

// Returns true if circle and line intersect
bool CGCircleIntersectsLine(CGCircle circle, CGLine line);

// Returns true if circle and rectangle intersect
bool CGCircleIntersectsRectangle(CGCircle circle, CGRect rect);

// Returns the minimum size rectangle that contains circle
CGRect CGCircleGetBoundingRect(CGCircle circle);

// Returns the distance from a point to a circle
// Returns 0 if the point is inside the circle
CGFloat CGGetDistanceFromPointToCircle(CGPoint point, CGCircle circle);

Example Usage

Finding the point where two lines intersect:

CGLine line1 = CGLineMake(CGPointMake(2, 0), CGPointMake(2, 4));
CGLine line2 = CGLineMake(CGPointMake(0, 2), CGPointMake(4, 2));
CGLinesIntersectAtPoint(line1, line2)	// => (2,2)

Find the closest two corner points of a rectangle to a point in space:

CGRect rect = CGRectMake(2, 1, 4, 4);
CGPoint point = CGPointMake(0, 0);
CGPoint point1 = CGPointZero;
CGPoint point2 = CGPointZero;
CGRectClosestTwoCornerPoints(rect, point, &point1, &point2);	// => (0,0) (2,1)

The point where a line intersects a rect, if at all:

CGRect rect = CGRectMake(1, 1, 4, 4);
CGLine line = CGLineMake(CGPointMake(0, 1), CGPointMake(2, 2));
CGLineIntersectsRectAtPoint(rect, line);	// => (5, 3.5)

Find if a circle contains a given point:

CGCircle circle = CGCircleMake(CGPointMake(1,2), 3);
CGPoint point = CGPointMake(5,2);
bool containsPoint = CGCircleContainsPoint(circle, point);