Terminal-based user interface toolkit
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package tview
import (
"github.com/gdamore/tcell"
)
// Configuration values.
const (
FlexRow = iota
FlexColumn
)
// flexItem holds layout options for one item.
type flexItem struct {
Item Primitive // The item to be positioned.
FixedSize int // The item's fixed size which may not be changed, 0 if it has no fixed size.
Proportion int // The item's proportion.
Focus bool // Whether or not this item attracts the layout's focus.
}
// Flex is a basic implementation of a flexbox layout.
type Flex struct {
*Box
// The items to be positioned.
items []flexItem
// FlexRow or FlexColumn.
direction int
// If set to true, will use the entire screen as its available space instead
// its box dimensions.
fullScreen bool
}
// NewFlex returns a new flexbox layout container with the given primitives.
// The items all have no fixed size. If more control is needed, call AddItem().
// The direction argument must be FlexRow or FlexColumn.
func NewFlex() *Flex {
f := &Flex{
Box: NewBox(),
direction: FlexColumn,
}
f.focus = f
return f
}
// SetDirection sets the direction in which the contained primitives are
// distributed. This can be either FlexColumn (default) or FlexRow.
func (f *Flex) SetDirection(direction int) *Flex {
f.direction = direction
return f
}
// SetFullScreen sets the flag which, when true, causes the flex layout to use
// the entire screen space instead of whatever size it is currently assigned to.
func (f *Flex) SetFullScreen(fullScreen bool) *Flex {
f.fullScreen = fullScreen
return f
}
// AddItem adds a new item to the container. The "fixedSize" argument is a width
// or height that may not be changed by the layout algorithm. A value of 0 means
// that its size is flexible and may be changed. The "proportion" argument
// defines the relative size of the item compared to other flexible-size items.
// For example, items with a proportion of 2 will be twice as large as items
// with a proportion of 1. Must be at least 1 if fixedSize > 0 (ignored
// otherwise)
//
// If "focus" is set to true, the item will receive focus when the Flex
// primitive receives focus. If multiple items have the "focus" flag set to
// true, the first one will receive focus.
func (f *Flex) AddItem(item Primitive, fixedSize, proportion int, focus bool) *Flex {
f.items = append(f.items, flexItem{Item: item, FixedSize: fixedSize, Proportion: proportion, Focus: focus})
return f
}
// Draw draws this primitive onto the screen.
func (f *Flex) Draw(screen tcell.Screen) {
// Calculate size and position of the items.
// Do we use the entire screen?
if f.fullScreen {
f.x = 0
f.y = 0
width, height := screen.Size()
f.width = width
f.height = height
}
// How much space can we distribute?
x, y, width, height := f.GetInnerRect()
var proportionSum int
distSize := width
if f.direction == FlexRow {
distSize = height
}
for _, item := range f.items {
if item.FixedSize > 0 {
distSize -= item.FixedSize
} else {
proportionSum += item.Proportion
}
}
// Calculate positions and draw items.
pos := x
if f.direction == FlexRow {
pos = y
}
for _, item := range f.items {
size := item.FixedSize
if size <= 0 {
size = distSize * item.Proportion / proportionSum
distSize -= size
proportionSum -= item.Proportion
}
if f.direction == FlexColumn {
item.Item.SetRect(pos, y, size, height)
} else {
item.Item.SetRect(x, pos, width, size)
}
pos += size
if item.Item.GetFocusable().HasFocus() {
defer item.Item.Draw(screen)
} else {
item.Item.Draw(screen)
}
}
}
// Focus is called when this primitive receives focus.
func (f *Flex) Focus(delegate func(p Primitive)) {
for _, item := range f.items {
if item.Focus {
delegate(item.Item)
return
}
}
}
// HasFocus returns whether or not this primitive has focus.
func (f *Flex) HasFocus() bool {
for _, item := range f.items {
if item.Item.GetFocusable().HasFocus() {
return true
}
}
return false
}