unit

package
v0.0.0-...-6f71fe9 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Mar 2, 2024 License: Apache-2.0 Imports: 9 Imported by: 0

Documentation

Overview

Package units defines units of length such as inches or pixels.

Functions like Inches and Pixels return a Value in the corresponding unit. For example: 

v := unit.Inches(4.5)

represents four and a half inches.

Converting between pixels (px), physical units (dp, pt, in, mm) and font-face-relative measures (em, ex, ch) depends on the context, such as the screen's DPI resolution and the active font face. That context is represented by the Converter type.

Conversions may be lossy. Converting 4.5 inches to pixels and back may result in something slightly different than 4.5. Similarly, converting 4 inches and 0.5 inches to pixels and then adding the results won't necessarily equal the conversion of 4.5 inches to pixels.

Note that what CSS (Cascading Style Sheets) calls "px" differs from what this package calls "px". For legacy reasons, the CSS semantics are that 1 inch should roughly equal 96csspx regardless of the actual DPI resolution, as per https://developer.mozilla.org/en/docs/Web/CSS/length. This package's semantics are that 1px means exactly one physical pixel, always. This package represents 1csspx as 1.666666667dp, since there are 160 density independent pixels per inch, the same definition as Android.

Package units defines units of length such as inches or pixels.

Functions like Inches and Pixels return a Value in the corresponding unit. For example: 

v := unit.Inches(4.5)

represents four and a half inches.

Converting between pixels (px), physical units (dp, pt, in, mm) and font-face-relative measures (em, ex, ch) depends on the context, such as the screen's DPI resolution and the active font face. That context is represented by the Converter type.

Conversions may be lossy. Converting 4.5 inches to pixels and back may result in something slightly different than 4.5. Similarly, converting 4 inches and 0.5 inches to pixels and then adding the results won't necessarily equal the conversion of 4.5 inches to pixels.

Note that what CSS (Cascading Style Sheets) calls "px" differs from what this package calls "px". For legacy reasons, the CSS semantics are that 1 inch should roughly equal 96csspx regardless of the actual DPI resolution, as per https://developer.mozilla.org/en/docs/Web/CSS/length. This package's semantics are that 1px means exactly one physical pixel, always. This package represents 1csspx as 1.666666667dp, since there are 160 density independent pixels per inch, the same definition as Android.

Index

Constants

View Source 
const (
	DensityIndependentPixelsPerInch = 160
	MillimetresPerInch              = 25.4
	PointsPerInch                   = 72.0
)

Variables

This section is empty.

Functions

This section is empty.

Types

type Dimension 

type Dimension struct {
	Top    Value
	Bottom Value
	Left   Value
	Right  Value
}

func NewDimension 

func NewDimension(t, b, l, r Value) Dimension

func ParseDimension 

func ParseDimension(s string) (Dimension, error)

ParseDimension parses a string consisting of 1 to 4 Values that describe a Dimension. When 1 value is specified, it applies to all 4 sides When 2 values are specified, first is for Top and Bottom, second for Left & Right When 3 values, first is top, second left & right, and third bottom When 4 then in this order: top,right,bottom,left

This is based on how css works going clockwise from the top https://developer.mozilla.org/en-US/docs/Web/CSS/margin

func RectangleDimension 

func RectangleDimension(t, r Value) Dimension

func SquareDimension 

func SquareDimension(v Value) Dimension

func (Dimension) Add 

func (d Dimension) Add(gc *draw2dimg.GraphicContext, b Dimension) Dimension

Add adds two dimensions, increasing the values for each side. The result will be of the dimension on the left hand side

func (Dimension) Convert 

func (d Dimension) Convert(gc *draw2dimg.GraphicContext, to Unit) Dimension

func (Dimension) ExpandRect 

func (d Dimension) ExpandRect(gc *draw2dimg.GraphicContext, r util.Rectangle) util.Rectangle

ExpandRect expands a rectangle by the dimension

func (Dimension) IsZero 

func (d Dimension) IsZero() bool

func (Dimension) ReduceRect 

func (d Dimension) ReduceRect(gc *draw2dimg.GraphicContext, r util.Rectangle) util.Rectangle

ReduceRect reduces a rectangle by the dimension

func (Dimension) String 

func (d Dimension) String() string

func (Dimension) Sub 

func (d Dimension) Sub(gc *draw2dimg.GraphicContext, b Dimension) Dimension

Sub subtracts two dimensions, increasing the values for each side. The result will be of the dimension on the left hand side

type Rectangle 

type Rectangle struct {
	X1 Value
	Y1 Value
	X2 Value
	Y2 Value
}

func FromRectangle 

func FromRectangle(gc *draw2dimg.GraphicContext, r util.Rectangle, unit Unit) Rectangle

FromRectangle takes a plain rectangle and converts it into one with the specified units

func ParseRectangle 

func ParseRectangle(s string) (Rectangle, error)

ParseRectangle parses a string consisting of 4 Values that describe a Rectangle

func ParseSizedRectangle 

func ParseSizedRectangle(s string) (Rectangle, error)

func (Rectangle) Add 

func (d Rectangle) Add(gc *draw2dimg.GraphicContext, b Rectangle) Rectangle

func (Rectangle) Convert 

func (d Rectangle) Convert(gc *draw2dimg.GraphicContext, to Unit) Rectangle

func (Rectangle) Expand 

func (d Rectangle) Expand(gc *draw2dimg.GraphicContext, dim Dimension) Rectangle

func (Rectangle) Height 

func (d Rectangle) Height(gc *draw2dimg.GraphicContext) Value

func (Rectangle) IsZero 

func (d Rectangle) IsZero() bool

func (Rectangle) Rectangle 

func (d Rectangle) Rectangle(gc *draw2dimg.GraphicContext) util.Rectangle

func (Rectangle) Reduce 

func (d Rectangle) Reduce(gc *draw2dimg.GraphicContext, dim Dimension) Rectangle

func (Rectangle) SizeString 

func (d Rectangle) SizeString() string

func (Rectangle) String 

func (d Rectangle) String() string

func (Rectangle) Width 

func (d Rectangle) Width(gc *draw2dimg.GraphicContext) Value

type Unit 

type Unit uint8

Unit is a unit of length, such as inches or pixels. 

const (
	// Px is a physical pixel, regardless of the DPI resolution.
	Px Unit = iota

	// Dp is 1 density independent pixel: 1/160th of an inch.
	Dp
	// Pt is 1 point: 1/72th of an inch.
	Pt
	// Mm is 1 millimetre: 1/25.4th of an inch.
	Mm
	// In is 1 inch.
	//
	// If the context does not specify a DPI resolution, the recommended
	// fallback value for conversion is 72 pixels per inch.
	In

	// Em is the height of the active font face, disregarding extra leading
	// such as from double-spaced lines of text.
	//
	// If the context does not specify an active font face, the recommended
	// fallback value for conversion is 12pt.
	Em
	// Ex is the x-height of the active font face.
	//
	// If the context does not specify an x-height, the recommended fallback
	// value for conversion is 0.5em.
	Ex
	// Ch is the character width of the numeral zero glyph '0' of the active
	// font face.
	//
	// If the context does not specify a '0' glyph, the recommended fallback
	// value for conversion is 0.5em.
	Ch
)

func (Unit) PixelsPer 

func (u Unit) PixelsPer(gc *draw2dimg.GraphicContext) float64

PixelsPer returns the number of pixels in the unit u.

type Value 

type Value struct {
	F float64
	U Unit
}

Value is a number and a unit.

func ParseValue 

func ParseValue(s string) (Value, error)

func Pixels 

func Pixels(f float64) Value

func (Value) Add 

func (v Value) Add(gc *draw2dimg.GraphicContext, b Value) Value

Add adds two values. The result will be in the unit of the left hand side.

func (Value) Convert 

func (v Value) Convert(gc *draw2dimg.GraphicContext, to Unit) Value

func (Value) Equals 

func (v Value) Equals(b Value) bool

func (Value) IsZero 

func (v Value) IsZero() bool

func (Value) Max 

func (v Value) Max(gc *draw2dimg.GraphicContext, b Value) Value

func (Value) Min 

func (v Value) Min(gc *draw2dimg.GraphicContext, b Value) Value

func (Value) Pixels 

func (v Value) Pixels(gc *draw2dimg.GraphicContext) float64

Pixels returns the value in pixels as a float64

func (Value) String 

func (v Value) String() string

String implements the fmt.Stringer interface.

func (Value) Sub 

func (v Value) Sub(gc *draw2dimg.GraphicContext, b Value) Value

Sub subtracts two values. The result will be in the unit of the left hand side.

Source Files

View all Source files

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.