// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | |

// for details. All rights reserved. Use of this source code is governed by a | |

// BSD-style license that can be found in the LICENSE file. | |

part of dart.math; | |

/// A base class for representing two-dimensional axis-aligned rectangles. | |

/// | |

/// This rectangle uses a left-handed Cartesian coordinate system, with x | |

/// directed to the right and y directed down, as per the convention in 2D | |

/// computer graphics. | |

/// | |

/// See also: | |

/// [W3C Coordinate Systems Specification](http://www.w3.org/TR/SVG/coords.html#InitialCoordinateSystem). | |

/// | |

/// The rectangle is the set of points with representable coordinates greater | |

/// than or equal to left/top, and with distance to left/top no greater than | |

/// width/height (to the limit of the precision of the coordinates). | |

abstract class _RectangleBase<T extends num> { | |

const _RectangleBase(); | |

/// The x-coordinate of the left edge. | |

T get left; | |

/// The y-coordinate of the top edge. | |

T get top; | |

/// The width of the rectangle. | |

T get width; | |

/// The height of the rectangle. | |

T get height; | |

/// The x-coordinate of the right edge. | |

T get right => (left + width) as T; | |

/// The y-coordinate of the bottom edge. | |

T get bottom => (top + height) as T; | |

String toString() { | |

return 'Rectangle ($left, $top) $width x $height'; | |

} | |

bool operator ==(Object other) => | |

other is Rectangle && | |

left == other.left && | |

top == other.top && | |

right == other.right && | |

bottom == other.bottom; | |

int get hashCode => SystemHash.hash4( | |

left.hashCode, top.hashCode, right.hashCode, bottom.hashCode); | |

/// Computes the intersection of `this` and [other]. | |

/// | |

/// The intersection of two axis-aligned rectangles, if any, is always another | |

/// axis-aligned rectangle. | |

/// | |

/// Returns the intersection of this and `other`, or `null` if they don't | |

/// intersect. | |

Rectangle<T>? intersection(Rectangle<T> other) { | |

var x0 = max(left, other.left); | |

var x1 = min(left + width, other.left + other.width); | |

if (x0 <= x1) { | |

var y0 = max(top, other.top); | |

var y1 = min(top + height, other.top + other.height); | |

if (y0 <= y1) { | |

return Rectangle<T>(x0, y0, (x1 - x0) as T, (y1 - y0) as T); | |

} | |

} | |

return null; | |

} | |

/// Returns true if `this` intersects [other]. | |

bool intersects(Rectangle<num> other) { | |

return (left <= other.left + other.width && | |

other.left <= left + width && | |

top <= other.top + other.height && | |

other.top <= top + height); | |

} | |

/// Returns a new rectangle which completely contains `this` and [other]. | |

Rectangle<T> boundingBox(Rectangle<T> other) { | |

var right = max(this.left + this.width, other.left + other.width); | |

var bottom = max(this.top + this.height, other.top + other.height); | |

var left = min(this.left, other.left); | |

var top = min(this.top, other.top); | |

return Rectangle<T>(left, top, (right - left) as T, (bottom - top) as T); | |

} | |

/// Tests whether `this` entirely contains [another]. | |

bool containsRectangle(Rectangle<num> another) { | |

return left <= another.left && | |

left + width >= another.left + another.width && | |

top <= another.top && | |

top + height >= another.top + another.height; | |

} | |

/// Tests whether [another] is inside or along the edges of `this`. | |

bool containsPoint(Point<num> another) { | |

return another.x >= left && | |

another.x <= left + width && | |

another.y >= top && | |

another.y <= top + height; | |

} | |

Point<T> get topLeft => Point<T>(this.left, this.top); | |

Point<T> get topRight => Point<T>((this.left + this.width) as T, this.top); | |

Point<T> get bottomRight => | |

Point<T>((this.left + this.width) as T, (this.top + this.height) as T); | |

Point<T> get bottomLeft => Point<T>(this.left, (this.top + this.height) as T); | |

} | |

/// A class for representing two-dimensional rectangles whose properties are | |

/// immutable. | |

class Rectangle<T extends num> extends _RectangleBase<T> { | |

final T left; | |

final T top; | |

final T width; | |

final T height; | |

/// Create a rectangle spanned by `(left, top)` and | |

/// `(left+width, top+height)`. | |

/// | |

/// The rectangle contains the points | |

/// with x-coordinate between `left` and `left + width`, and | |

/// with y-coordinate between `top` and `top + height`, both inclusive. | |

/// | |

/// The `width` and `height` should be non-negative. | |

/// If `width` or `height` are negative, they are clamped to zero. | |

/// | |

/// If `width` and `height` are zero, the "rectangle" comprises only the | |

/// single point `(left, top)`. | |

const Rectangle(this.left, this.top, T width, T height) | |

: width = (width < 0) | |

? (-width * 0) as dynamic | |

: width, // Inline _clampToZero<num>. | |

height = (height < 0) ? (-height * 0) as dynamic : height; | |

/// Create a rectangle spanned by the points [a] and [b]; | |

/// | |

/// The rectangle contains the points | |

/// with x-coordinate between `a.x` and `b.x`, and | |

/// with y-coordinate between `a.y` and `b.y`, both inclusive. | |

/// | |

/// If the distance between `a.x` and `b.x` is not representable | |

/// (which can happen if one or both is a double), | |

/// the actual right edge might be slightly off from `max(a.x, b.x)`. | |

/// Similar for the y-coordinates and the bottom edge. | |

factory Rectangle.fromPoints(Point<T> a, Point<T> b) { | |

T left = min(a.x, b.x); | |

T width = (max(a.x, b.x) - left) as T; | |

T top = min(a.y, b.y); | |

T height = (max(a.y, b.y) - top) as T; | |

return Rectangle<T>(left, top, width, height); | |

} | |

} | |

/// A class for representing two-dimensional axis-aligned rectangles with | |

/// mutable properties. | |

class MutableRectangle<T extends num> extends _RectangleBase<T> | |

implements Rectangle<T> { | |

/// The x-coordinate of the left edge. | |

/// | |

/// Setting the value will move the rectangle without changing its width. | |

T left; | |

/// The y-coordinate of the left edge. | |

/// | |

/// Setting the value will move the rectangle without changing its height. | |

T top; | |

T _width; | |

T _height; | |

/// Create a mutable rectangle spanned by `(left, top)` and | |

/// `(left+width, top+height)`. | |

/// | |

/// The rectangle contains the points | |

/// with x-coordinate between `left` and `left + width`, and | |

/// with y-coordinate between `top` and `top + height`, both inclusive. | |

/// | |

/// The `width` and `height` should be non-negative. | |

/// If `width` or `height` are negative, they are clamped to zero. | |

/// | |

/// If `width` and `height` are zero, the "rectangle" comprises only the | |

/// single point `(left, top)`. | |

MutableRectangle(this.left, this.top, T width, T height) | |

: this._width = (width < 0) ? _clampToZero<T>(width) : width, | |

this._height = (height < 0) ? _clampToZero<T>(height) : height; | |

/// Create a mutable rectangle spanned by the points [a] and [b]; | |

/// | |

/// The rectangle contains the points | |

/// with x-coordinate between `a.x` and `b.x`, and | |

/// with y-coordinate between `a.y` and `b.y`, both inclusive. | |

/// | |

/// If the distance between `a.x` and `b.x` is not representable | |

/// (which can happen if one or both is a double), | |

/// the actual right edge might be slightly off from `max(a.x, b.x)`. | |

/// Similar for the y-coordinates and the bottom edge. | |

factory MutableRectangle.fromPoints(Point<T> a, Point<T> b) { | |

T left = min(a.x, b.x); | |

T width = (max(a.x, b.x) - left) as T; | |

T top = min(a.y, b.y); | |

T height = (max(a.y, b.y) - top) as T; | |

return MutableRectangle<T>(left, top, width, height); | |

} | |

T get width => _width; | |

/// Sets the width of the rectangle. | |

/// | |

/// The width must be non-negative. | |

/// If a negative width is supplied, it is clamped to zero. | |

/// | |

/// Setting the value will change the right edge of the rectangle, | |

/// but will not change [left]. | |

set width(T width) { | |

if (width < 0) width = _clampToZero<T>(width); | |

_width = width; | |

} | |

T get height => _height; | |

/// Sets the height of the rectangle. | |

/// | |

/// The height must be non-negative. | |

/// If a negative height is supplied, it is clamped to zero. | |

/// | |

/// Setting the value will change the bottom edge of the rectangle, | |

/// but will not change [top]. | |

set height(T height) { | |

if (height < 0) height = _clampToZero<T>(height); | |

_height = height; | |

} | |

} | |

/// Converts a negative [int] or [double] to a zero-value of the same type. | |

/// | |

/// Returns `0` if value is int, `0.0` if value is double. | |

T _clampToZero<T extends num>(T value) { | |

assert(value < 0); | |

return (-value * 0) as T; | |

} |