nt

flex.go (8120B)

---

 package tview
 
 import (
 	"github.com/gdamore/tcell/v2"
 )
 
 // Flex directions.
 const (
 	// One item per row.
 	FlexRow = 0
 	// One item per column.
 	FlexColumn = 1
 	// As defined in CSS, items distributed along a row.
 	FlexRowCSS = 1
 	// As defined in CSS, items distributed within a column.
 	FlexColumnCSS = 0
 )
 
 // 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, Flex 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().
 //
 // Note that Box, the superclass of Flex, will not clear its contents so that
 // any nil flex items will leave their background unchanged. To clear a Flex's
 // background before any items are drawn, set it to a box with the desired
 // color:
 //
 //	flex.Box = NewBox()
 func NewFlex() *Flex {
 	f := &Flex{
 		direction: FlexColumn,
 	}
 	f.Box = NewBox()
 	f.Box.dontClear = true
 	return f
 }
 
 // SetDirection sets the direction in which the contained primitives are
 // distributed. This can be either FlexColumn (default) or FlexRow. Note that
 // these are the opposite of what you would expect coming from CSS. You may also
 // use FlexColumnCSS or FlexRowCSS, to remain in line with the CSS definition.
 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. The proportion 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
 }
 
 // RemoveItem removes all items for the given primitive from the container,
 // keeping the order of the remaining items intact.
 func (f *Flex) RemoveItem(p Primitive) *Flex {
 	for index := len(f.items) - 1; index >= 0; index-- {
 		if f.items[index].Item == p {
 			f.items = append(f.items[:index], f.items[index+1:]...)
 		}
 	}
 	return f
 }
 
 // GetItemCount returns the number of items in this container.
 func (f *Flex) GetItemCount() int {
 	return len(f.items)
 }
 
 // GetItem returns the primitive at the given index, starting with 0 for the
 // first primitive in this container.
 //
 // This function will panic for out of range indices.
 func (f *Flex) GetItem(index int) Primitive {
 	return f.items[index].Item
 }
 
 // Clear removes all items from the container.
 func (f *Flex) Clear() *Flex {
 	f.items = nil
 	return f
 }
 
 // ResizeItem sets a new size for the item(s) with the given primitive. If there
 // are multiple Flex items with the same primitive, they will all receive the
 // same size. For details regarding the size parameters, see AddItem().
 func (f *Flex) ResizeItem(p Primitive, fixedSize, proportion int) *Flex {
 	for _, item := range f.items {
 		if item.Item == p {
 			item.FixedSize = fixedSize
 			item.Proportion = proportion
 		}
 	}
 	return f
 }
 
 // Draw draws this primitive onto the screen.
 func (f *Flex) Draw(screen tcell.Screen) {
 	f.Box.DrawForSubclass(screen, f)
 
 	// 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 {
 			if proportionSum > 0 {
 				size = distSize * item.Proportion / proportionSum
 				distSize -= size
 				proportionSum -= item.Proportion
 			} else {
 				size = 0
 			}
 		}
 		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.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
 		}
 	}
 	f.Box.Focus(delegate)
 }
 
 // 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.HasFocus() {
 			return true
 		}
 	}
 	return f.Box.HasFocus()
 }
 
 // MouseHandler returns the mouse handler for this primitive.
 func (f *Flex) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
 	return f.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
 		if !f.InRect(event.Position()) {
 			return false, nil
 		}
 
 		// Pass mouse events along to the first child item that takes it.
 		for _, item := range f.items {
 			if item.Item == nil {
 				continue
 			}
 			consumed, capture = item.Item.MouseHandler()(action, event, setFocus)
 			if consumed {
 				return
 			}
 		}
 
 		return
 	})
 }
 
 // InputHandler returns the handler for this primitive.
 func (f *Flex) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
 	return f.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
 		for _, item := range f.items {
 			if item.Item != nil && item.Item.HasFocus() {
 				if handler := item.Item.InputHandler(); handler != nil {
 					handler(event, setFocus)
 					return
 				}
 			}
 		}
 	})
 }
 
 // PasteHandler returns the handler for this primitive.
 func (f *Flex) PasteHandler() func(pastedText string, setFocus func(p Primitive)) {
 	return f.WrapPasteHandler(func(pastedText string, setFocus func(p Primitive)) {
 		for _, item := range f.items {
 			if item.Item != nil && item.Item.HasFocus() {
 				if handler := item.Item.PasteHandler(); handler != nil {
 					handler(pastedText, setFocus)
 					return
 				}
 			}
 		}
 	})
 }