Documentation
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Overview ¶
Package Units supports full range of CSS-style length units (em, px, dp, etc)
The unit is stored along with a value, and can be converted at a later point into a raw display pixel value using the Context which contains all the necessary reference values to perform the conversion. Typically the unit value is parsed early from a style and then converted later once the context is fully resolved. The Value also holds the converted value (Dots) so it can be used directly without further re-conversion.
'Dots' are used as term for underlying raw display pixels because "Pixel" and the px unit are actually not conventionally used as raw display pixels in the current HiDPI environment. See https://developer.mozilla.org/en/docs/Web/CSS/length -- 1 px = 1/96 in Also supporting dp = density-independent pixel = 1/160 in
Index ¶
- Constants
- Variables
- type Context
- func (uc *Context) Defaults()
- func (uc *Context) Set(em, ex, ch, rem, vpw, vph, elw, elh float32)
- func (uc *Context) SetFont(em, ex, ch, rem float32)
- func (uc *Context) SetSizes(vpw, vph, elw, elh float32)
- func (uc *Context) ToDots(val float32, un Unit) float32
- func (uc *Context) ToDotsFactor(un Unit) float32
- type Unit
- type Value
Constants ¶
const ( PxPerInch = 96.0 DpPerInch = 160.0 MmPerInch = 25.4 CmPerInch = 2.54 PtPerInch = 72.0 PcPerInch = 6.0 )
standard conversion factors -- Px = DPI-independent pixel instead of actual "dot" raw pixel
Variables ¶
var KiT_Value = kit.Types.AddType(&Value{}, ValueProps)
var UnitNames = [...]string{ Px: "px", Dp: "dp", Pct: "pct", Rem: "rem", Em: "em", Ex: "ex", Ch: "ch", Vw: "vw", Vh: "vh", Vmin: "vmin", Vmax: "vmax", Cm: "cm", Mm: "mm", Q: "q", In: "in", Pc: "pc", Pt: "pt", Dot: "dot", }
var ValueProps = ki.Props{ "style-prop": true, }
Functions ¶
This section is empty.
Types ¶
type Context ¶
type Context struct {
// dots-per-inch of the display
DPI float32
// point size of font (in points)
FontEm float32
// x-height of font in points
FontEx float32
// ch-size of font in points
FontCh float32
// rem-size of font in points
FontRem float32
// viewport width in dots
VpW float32
// viewport height in dots
VpH float32
// width of surrounding contextual element in dots
ElW float32
// height of surrounding contextual element in dots
ElH float32
}
Context specifies everything about the current context necessary for converting the number into specific display-dependent pixels
func (*Context) ToDotsFactor ¶
factor needed to convert given unit into raw pixels (dots in DPI)
type Unit ¶
type Unit int32
const ( // Px = pixels -- 1px = 1/96th of 1in -- these are NOT raw display pixels Px Unit = iota // Dp = density-independent pixels -- 1dp = 1/160th of 1in Dp // Pct = percentage of surrounding contextual element Pct // Rem = font size of the root element -- fallback to 12pt by default Rem // Em = font size of the element -- fallback to 12pt by default Em // Ex = x-height of the element's font -- fallback to 0.5em by default Ex // Ch = with of the '0' glyph in the element's font -- fallback to 0.5em by default Ch // Vw = 1% of the viewport's width Vw // Vh = 1% of the viewport's height Vh // Vmin = 1% of the viewport's smaller dimension Vmin // Vmax = 1% of the viewport's larger dimension Vmax // Cm = centimeters -- 1cm = 96px/2.54 Cm // Mm = millimeters -- 1mm = 1/10th of cm Mm // Q = quarter-millimeters -- 1q = 1/40th of cm Q // In = inches -- 1in = 2.54cm = 96px In // Pc = picas -- 1pc = 1/6th of 1in Pc // Pt = points -- 1pt = 1/72th of 1in Pt // Dot = actual real display pixels -- generally only use internally Dot UnitN )
func (*Unit) FromString ¶
func (Unit) MarshalJSON ¶
func (*Unit) UnmarshalJSON ¶
type Value ¶
Value and units, and converted value into raw pixels (dots in DPI)
Source Files