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package main
import (
"fmt"
"os"
"strings"
"github.com/gdamore/tcell/v2"
)
const (
gSixelBegin = "\033P"
// The filler character should be:
// - rarely used: the filler is used to trick tcell into redrawing, if the
// filler character appears in the user's preview, that cell might not
// be cleaned up properly
// - ideally renders as empty space: the filler alternates between bold
// and regular, using a non-space would look weird to the user.
gSixelFiller = '\u2000'
)
type sixelScreen struct {
xprev, yprev int
sixel *string
altFill bool
lastFile string // TODO maybe use hash of sixels instead to flip altFill
}
func (sxs *sixelScreen) fillerStyle(filePath string) tcell.Style {
if sxs.lastFile != filePath {
sxs.altFill = !sxs.altFill
}
if sxs.altFill {
return tcell.StyleDefault.Bold(true)
}
return tcell.StyleDefault
}
func (sxs *sixelScreen) showSixels() {
if sxs.sixel == nil {
return
}
// XXX: workaround for bug where quitting lf might leave the terminal in bold
fmt.Fprint(os.Stderr, "\033[0m")
fmt.Fprint(os.Stderr, "\0337") // Save cursor position
fmt.Fprintf(os.Stderr, "\033[%d;%dH", sxs.yprev, sxs.xprev) // Move cursor to position
fmt.Fprint(os.Stderr, *sxs.sixel) //
fmt.Fprint(os.Stderr, "\0338") // Restore cursor position
}
func (sxs *sixelScreen) printSixel(win *win, screen tcell.Screen, reg *reg) {
if reg.sixel == nil {
return
}
// HACK: fillers are used to control when tcell redraws the region where a sixel image is drawn.
// alternating between bold and regular is to clear the image before drawing a new one.
st := sxs.fillerStyle(reg.path)
for y := 0; y < win.h; y++ {
st = win.print(screen, 0, y, st, strings.Repeat(string(gSixelFiller), win.w))
}
sxs.xprev, sxs.yprev = win.x+1, win.y+1
sxs.sixel = reg.sixel
}
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