Rectangle<T extends num>#

A class for representing two-dimensional rectangles whose properties are immutable.

Legacy: New usages of Rectangle are discouraged.

• If you are using the Rectangle class with dart:html, we recommend migrating to package:web. To learn how and why to migrate, check out the migration guide.
• If you want to store the boundaries of a rectangle in some coordinate system, consider using a record. Depending on how you will use it, this could look like var boundaries = (mixX: x1, maxX: x2, minY: y1, maxY: y2).
• If you need to perform intersection calculations or containment checks, consider using a dedicated library, such as package:vector_math.
• If you are developing a Flutter application or package, consider using the Rect type from dart:ui.

Constructors#

Rectangle() const#

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).

Example:

var rectangle = const Rectangle(20, 50, 300, 600);
print(rectangle.left); // 20
print(rectangle.top); // 50
print(rectangle.right); // 320
print(rectangle.bottom); // 650

Legacy: New usages of Rectangle are discouraged. To learn more, check out the Rectangle class API docs.

const Rectangle(this.left, this.top, T width, T height)
  : width = (width < 0)
        ? (width == double.negativeInfinity ? 0.0 : (-width * 0)) as dynamic
        : (width + 0 as dynamic), &#47;&#47; Inline _clampToZero<num>.
    height = (height < 0)
        ? (height == double.negativeInfinity ? 0.0 : (-height * 0)) as dynamic
        : (height + 0 as dynamic);

Rectangle.fromPoints() factory#

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.

Example:

var leftTop = const Point(20, 50);
var rightBottom = const Point(300, 600);

var rectangle = Rectangle.fromPoints(leftTop, rightBottom);
print(rectangle); // Rectangle (20, 50) 280 x 550
print(rectangle.left); // 20
print(rectangle.top); // 50
print(rectangle.right); // 300
print(rectangle.bottom); // 600

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);
}

Properties#

bottom no setter inherited#

Inherited from _RectangleBase.

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

bottomLeft no setter inherited#

Inherited from _RectangleBase.

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

bottomRight no setter inherited#

Inherited from _RectangleBase.

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

hashCode no setter inherited#

Inherited from _RectangleBase.

int get hashCode => SystemHash.hash4(
  left.hashCode,
  top.hashCode,
  right.hashCode,
  bottom.hashCode,
  0,
);

height final#

The height of the rectangle.

final T height;

left final#

The x-coordinate of the left edge.

final T left;

right no setter inherited#

Inherited from _RectangleBase.

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

runtimeType no setter inherited#

A representation of the runtime type of the object.

Inherited from Object.

external Type get runtimeType;

top final#

The y-coordinate of the top edge.

final T top;

topLeft no setter inherited#

Inherited from _RectangleBase.

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

topRight no setter inherited#

Inherited from _RectangleBase.

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

width final#

The width of the rectangle.

final T width;

Methods#

boundingBox() inherited#

Returns a new rectangle which completely contains this and other.

Inherited from _RectangleBase.

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);
}

containsPoint() inherited#

Tests whether another is inside or along the edges of this.

Inherited from _RectangleBase.

bool containsPoint(Point<num> another) {
  return another.x >= left &&
      another.x <= left + width &&
      another.y >= top &&
      another.y <= top + height;
}

containsRectangle() inherited#

Tests whether this entirely contains another.

Inherited from _RectangleBase.

bool containsRectangle(Rectangle<num> another) {
  return left <= another.left &&
      left + width >= another.left + another.width &&
      top <= another.top &&
      top + height >= another.top + another.height;
}

intersection() inherited#

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.

Inherited from _RectangleBase.

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;
}

intersects() inherited#

Returns true if this intersects other.

Inherited from _RectangleBase.

bool intersects(Rectangle<num> other) {
  return (left <= other.left + other.width &&
      other.left <= left + width &&
      top <= other.top + other.height &&
      other.top <= top + height);
}

noSuchMethod() inherited#

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

toString() inherited#

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from _RectangleBase.

String toString() {
  return 'Rectangle ($left, $top) $width x $height';
}

Operators#

operator ==() inherited#

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from _RectangleBase.

bool operator ==(Object other) =>
    other is Rectangle &&
    left == other.left &&
    top == other.top &&
    right == other.right &&
    bottom == other.bottom;