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. May be nil for an empty item. 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 the Flexbox layout. The contained // primitives are arranged horizontally or vertically. The way they are // distributed along that dimension depends on their layout settings, which is // either a fixed length or a proportional length. See AddItem() for details. // // See https://github.com/rivo/tview/wiki/Flex for an example. 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 no primitives and its // direction set to FlexColumn. To add primitives to this layout, see AddItem(). // To change the direction, see SetDirection(). 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. // // You can provide a nil value for the primitive. This will still consume screen // space but nothing will be drawn. 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) { f.Box.Draw(screen) // Calculate size and position of the items. // Do we use the entire screen? if f.fullScreen { width, height := screen.Size() f.SetRect(0, 0, width, 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 item.Item != nil { if f.direction == FlexColumn { item.Item.SetRect(pos, y, size, height) } else { item.Item.SetRect(x, pos, width, size) } } pos += size if item.Item != nil { 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.Item != nil && 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 != nil && item.Item.GetFocusable().HasFocus() { return true } } return false }