func (r Rectangle) Size() Point {
	return Point{
		r.Max.X - r.Min.X,
		r.Max.Y - r.Min.Y,
	}
}

// Add returns the rectangle r translated by p.
func (r Rectangle) Add(p Point) Rectangle {
	return Rectangle{
		Point{r.Min.X + p.X, r.Min.Y + p.Y},
		Point{r.Max.X + p.X, r.Max.Y + p.Y},
	}
}

// Sub returns the rectangle r translated by -p.
func (r Rectangle) Sub(p Point) Rectangle {

	desc          string
	r, dr, sr, mr image.Rectangle
	sp, mp        image.Point
	nilMask       bool
	r0            image.Rectangle
	sp0, mp0      image.Point
}

var clipTests = []clipTest{
	// The following tests all have a nil mask.
	{
		"basic",
		image.Rect(0, 0, 100, 100),
		image.Rect(0, 0, 100, 100),
		image.Rect(0, 0, 100, 100),
		image.Rectangle{},
		image.Point{},
		image.Point{},
		true,

    app = FastAPI()

    from pydantic import BaseModel, computed_field

    class Rectangle(BaseModel):
        width: int
        length: int

        @computed_field
        @property
        def area(self) -> int:
            return self.width * self.length

    @app.get("/")
    def read_root() -> Rectangle:
        return Rectangle(width=3, length=4)

    client = TestClient(app)
    return client

!define Container(e_alias, e_label, e_techn) rectangle "==e_label\n//<size:TECHN_FONT_SIZE>[e_techn]</size>//" <<container>> as e_alias
!define Container(e_alias, e_label, e_techn, e_descr) rectangle "==e_label\n//<size:TECHN_FONT_SIZE>[e_techn]</size>//\n\n e_descr" <<container>> as e_alias

' Boundaries
' ##################################

!define System(e_alias, e_label, e_descr) rectangle "==e_label\n\n e_descr" <<system>> as e_alias

!define System_Ext(e_alias, e_label) rectangle "==e_label" <<external_system>> as e_alias
!define System_Ext(e_alias, e_label, e_descr) rectangle "==e_label\n\n e_descr" <<external_system>> as e_alias

' Boundaries
' ##################################

// ratio.
func NewYCbCr(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *YCbCr {
	w, h, cw, ch := yCbCrSize(r, subsampleRatio)

	// totalLength should be the same as i2, below, for a valid Rectangle r.
	totalLength := add2NonNeg(
		mul3NonNeg(1, w, h),
		mul3NonNeg(2, cw, ch),
	)
	if totalLength < 0 {
		panic("image: NewYCbCr Rectangle has huge or negative dimensions")
	}

!define Component(e_alias, e_label, e_techn) rectangle "==e_label\n//<size:TECHN_FONT_SIZE>[e_techn]</size>//" <<component>> as e_alias
!define Component(e_alias, e_label, e_techn, e_descr) rectangle "==e_label\n//<size:TECHN_FONT_SIZE>[e_techn]</size>//\n\n e_descr" <<component>> as e_alias

' Boundaries
' ##################################

// compatibility. The NewXxx functions do not return an error.
func pixelBufferLength(bytesPerPixel int, r Rectangle, imageTypeName string) int {
	totalLength := mul3NonNeg(bytesPerPixel, r.Dx(), r.Dy())
	if totalLength < 0 {
		panic("image: New" + imageTypeName + " Rectangle has huge or negative dimensions")
	}
	return totalLength
}

// RGBA is an in-memory image whose At method returns [color.RGBA] values.

skinparam defaultTextAlignment center

skinparam wrapWidth 200
skinparam maxMessageSize 150

skinparam rectangle {
    StereotypeFontSize 12
    shadowing false
}

skinparam Arrow {
    Color #666666
    FontColor #666666
    FontSize 12
}

skinparam rectangle<<boundary>> {
    Shadowing false
    StereotypeFontSize 0
    FontSize 12
    FontColor #444444
    BorderColor #444444

// [Op].
func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
	DrawMask(dst, r, src, sp, nil, image.Point{}, op)
}

// Drawer contains the [Draw] method.
type Drawer interface {
	// Draw aligns r.Min in dst with sp in src and then replaces the
	// rectangle r in dst with the result of drawing src on dst.
	Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
}