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// Copyright 2019-2022 Graham Clark. All rights reserved. Use of this source
// code is governed by the MIT license that can be found in the LICENSE
// file.
// Package scrollabletext provides a text widget that can be placed inside
// withscrollbar.Widget
package scrollabletext
import (
"strings"
"github.com/gcla/gowid"
"github.com/gcla/gowid/gwutil"
"github.com/gcla/gowid/widgets/selectable"
"github.com/gcla/gowid/widgets/text"
"github.com/gdamore/tcell/v2"
)
//======================================================================
// Widget constructs a text widget and allows it to be scrolled. But this widget is limited - it assumes no
// line will wrap. To make this happen it ensures that any lines that are too long are clipped. It makes this
// assumption because my scrollbar APIs are not well designed, and functions like ScrollPosition and
// ScrollLength don't understand the current rendering context. That means if the app is resized, and a line
// now takes two screen lines to render and not one, the scrollbar can't be built accurately. Until I design
// a better scrollbar API, this will work - I'm only using it for limited information dialogs at the moment.
type Widget struct {
*selectable.Widget
splitText []string
linesFromTop int // how many lines down we are
cachedLength int
}
var _ gowid.IWidget = (*Widget)(nil)
func New(txt string) *Widget {
splitText := strings.Split(txt, "\n")
res := &Widget{
splitText: splitText,
cachedLength: len(splitText),
}
res.makeText()
return res
}
func (w *Widget) makeText() {
w.Widget = selectable.New(
text.New(
strings.Join(w.splitText[w.linesFromTop:], "\n"),
text.Options{
Wrap: text.WrapClip,
ClipIndicator: "...",
},
),
)
}
func (w *Widget) UserInput(ev interface{}, size gowid.IRenderSize, focus gowid.Selector, app gowid.IApp) bool {
handled := true
linesFromTop := w.linesFromTop
switch ev := ev.(type) {
case *tcell.EventKey:
switch ev.Key() {
case tcell.KeyPgUp:
w.UpPage(1, size, app)
case tcell.KeyUp, tcell.KeyCtrlP:
w.Up(1, size, app)
case tcell.KeyDown, tcell.KeyCtrlN:
w.Down(1, size, app)
case tcell.KeyPgDn:
w.DownPage(1, size, app)
default:
handled = false
}
}
if handled && linesFromTop == w.linesFromTop {
handled = false
}
if !handled {
handled = w.Widget.UserInput(ev, size, focus, app)
}
return handled
}
// Implement functions for withscrollbar.Widget
func (w *Widget) ScrollPosition() int {
return w.linesFromTop
}
func (w *Widget) ScrollLength() int {
return w.cachedLength
}
func (w *Widget) Up(lines int, size gowid.IRenderSize, app gowid.IApp) {
pos := w.linesFromTop
w.linesFromTop = gwutil.Max(0, w.linesFromTop-lines)
if pos != w.linesFromTop {
w.makeText()
}
}
func (w *Widget) Down(lines int, size gowid.IRenderSize, app gowid.IApp) {
pos := w.linesFromTop
w.linesFromTop = gwutil.Min(w.cachedLength-1, w.linesFromTop+lines)
if pos != w.linesFromTop {
w.makeText()
}
}
func (w *Widget) UpPage(num int, size gowid.IRenderSize, app gowid.IApp) {
pos := w.linesFromTop
pg := 1
if size, ok := size.(gowid.IRows); ok {
pg = size.Rows()
}
w.linesFromTop = gwutil.Max(0, w.linesFromTop-(pg*num))
if pos != w.linesFromTop {
w.makeText()
}
}
func (w *Widget) DownPage(num int, size gowid.IRenderSize, app gowid.IApp) {
pos := w.linesFromTop
pg := 1
if size, ok := size.(gowid.IRows); ok {
pg = size.Rows()
}
w.linesFromTop = gwutil.Min(w.cachedLength-1, w.linesFromTop+(pg*num))
if pos != w.linesFromTop {
w.makeText()
}
}
//======================================================================
// Local Variables:
// mode: Go
// fill-column: 110
// End:
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