Terminal-based user interface toolkit
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package cview
import (
"sync"
"github.com/gdamore/tcell"
)
// page represents one page of a Pages object.
type page struct {
Name string // The page's name.
Item Primitive // The page's primitive.
Resize bool // Whether or not to resize the page when it is drawn.
Visible bool // Whether or not this page is visible.
}
// Pages is a container for other primitives often used as the application's
// root primitive. It allows to easily switch the visibility of the contained
// primitives.
type Pages struct {
*Box
// The contained pages. (Visible) pages are drawn from back to front.
pages []*page
// We keep a reference to the function which allows us to set the focus to
// a newly visible page.
setFocus func(p Primitive)
// An optional handler which is called whenever the visibility or the order of
// pages changes.
changed func()
sync.RWMutex
}
// NewPages returns a new Pages object.
func NewPages() *Pages {
p := &Pages{
Box: NewBox(),
}
p.focus = p
return p
}
// SetChangedFunc sets a handler which is called whenever the visibility or the
// order of any visible pages changes. This can be used to redraw the pages.
func (p *Pages) SetChangedFunc(handler func()) *Pages {
p.Lock()
defer p.Unlock()
p.changed = handler
return p
}
// GetPageCount returns the number of pages currently stored in this object.
func (p *Pages) GetPageCount() int {
p.RLock()
defer p.RUnlock()
return len(p.pages)
}
// AddPage adds a new page with the given name and primitive. If there was
// previously a page with the same name, it is overwritten. Leaving the name
// empty may cause conflicts in other functions so always specify a non-empty
// name.
//
// Visible pages will be drawn in the order they were added (unless that order
// was changed in one of the other functions). If "resize" is set to true, the
// primitive will be set to the size available to the Pages primitive whenever
// the pages are drawn.
func (p *Pages) AddPage(name string, item Primitive, resize, visible bool) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
for index, pg := range p.pages {
if pg.Name == name {
p.pages = append(p.pages[:index], p.pages[index+1:]...)
break
}
}
p.pages = append(p.pages, &page{Item: item, Name: name, Resize: resize, Visible: visible})
if p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// AddAndSwitchToPage calls AddPage(), then SwitchToPage() on that newly added
// page.
func (p *Pages) AddAndSwitchToPage(name string, item Primitive, resize bool) *Pages {
p.AddPage(name, item, resize, true)
p.SwitchToPage(name)
return p
}
// RemovePage removes the page with the given name. If that page was the only
// visible page, visibility is assigned to the last page.
func (p *Pages) RemovePage(name string) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
var isVisible bool
for index, page := range p.pages {
if page.Name == name {
isVisible = page.Visible
p.pages = append(p.pages[:index], p.pages[index+1:]...)
if page.Visible && p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
break
}
}
if isVisible {
for index, page := range p.pages {
if index < len(p.pages)-1 {
if page.Visible {
break // There is a remaining visible page.
}
} else {
page.Visible = true // We need at least one visible page.
}
}
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// HasPage returns true if a page with the given name exists in this object.
func (p *Pages) HasPage(name string) bool {
p.RLock()
defer p.RUnlock()
for _, page := range p.pages {
if page.Name == name {
return true
}
}
return false
}
// ShowPage sets a page's visibility to "true" (in addition to any other pages
// which are already visible).
func (p *Pages) ShowPage(name string) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
for _, page := range p.pages {
if page.Name == name {
page.Visible = true
if p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
break
}
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// HidePage sets a page's visibility to "false".
func (p *Pages) HidePage(name string) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
for _, page := range p.pages {
if page.Name == name {
page.Visible = false
if p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
break
}
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// SwitchToPage sets a page's visibility to "true" and all other pages'
// visibility to "false".
func (p *Pages) SwitchToPage(name string) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
for _, page := range p.pages {
if page.Name == name {
page.Visible = true
} else {
page.Visible = false
}
}
if p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// SendToFront changes the order of the pages such that the page with the given
// name comes last, causing it to be drawn last with the next update (if
// visible).
func (p *Pages) SendToFront(name string) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
for index, page := range p.pages {
if page.Name == name {
if index < len(p.pages)-1 {
p.pages = append(append(p.pages[:index], p.pages[index+1:]...), page)
}
if page.Visible && p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
break
}
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// SendToBack changes the order of the pages such that the page with the given
// name comes first, causing it to be drawn first with the next update (if
// visible).
func (p *Pages) SendToBack(name string) *Pages {
hasFocus := p.HasFocus()
p.Lock()
defer p.Unlock()
for index, pg := range p.pages {
if pg.Name == name {
if index > 0 {
p.pages = append(append([]*page{pg}, p.pages[:index]...), p.pages[index+1:]...)
}
if pg.Visible && p.changed != nil {
p.Unlock()
p.changed()
p.Lock()
}
break
}
}
if hasFocus {
p.Unlock()
p.Focus(p.setFocus)
p.Lock()
}
return p
}
// GetFrontPage returns the front-most visible page. If there are no visible
// pages, ("", nil) is returned.
func (p *Pages) GetFrontPage() (name string, item Primitive) {
p.RLock()
defer p.RUnlock()
for index := len(p.pages) - 1; index >= 0; index-- {
if p.pages[index].Visible {
return p.pages[index].Name, p.pages[index].Item
}
}
return
}
// HasFocus returns whether or not this primitive has focus.
func (p *Pages) HasFocus() bool {
p.RLock()
defer p.RUnlock()
for _, page := range p.pages {
if page.Item.GetFocusable().HasFocus() {
return true
}
}
return false
}
// Focus is called by the application when the primitive receives focus.
func (p *Pages) Focus(delegate func(p Primitive)) {
p.Lock()
defer p.Unlock()
if delegate == nil {
return // We cannot delegate so we cannot focus.
}
p.setFocus = delegate
var topItem Primitive
for _, page := range p.pages {
if page.Visible {
topItem = page.Item
}
}
if topItem != nil {
p.Unlock()
delegate(topItem)
p.Lock()
}
}
// Draw draws this primitive onto the screen.
func (p *Pages) Draw(screen tcell.Screen) {
p.Box.Draw(screen)
p.Lock()
defer p.Unlock()
for _, page := range p.pages {
if !page.Visible {
continue
}
if page.Resize {
x, y, width, height := p.GetInnerRect()
page.Item.SetRect(x, y, width, height)
}
page.Item.Draw(screen)
}
}
// MouseHandler returns the mouse handler for this primitive.
func (p *Pages) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
return p.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
if !p.InRect(event.Position()) {
return false, nil
}
// Pass mouse events along to the last visible page item that takes it.
for index := len(p.pages) - 1; index >= 0; index-- {
page := p.pages[index]
if page.Visible {
consumed, capture = page.Item.MouseHandler()(action, event, setFocus)
if consumed {
return
}
}
}
return
})
}