79 lines
3.1 KiB
Go
79 lines
3.1 KiB
Go
// Fenrir console screen reader.
|
|
// Copyright (c) 2026 Storm Dragon
|
|
// SPDX-License-Identifier: GPL-3.0-or-later
|
|
//
|
|
// This program is free software: you can redistribute it and/or modify it
|
|
// under the terms of the GNU General Public License as published by the Free
|
|
// Software Foundation, either version 3 of the License, or (at your option)
|
|
// any later version.
|
|
//
|
|
// This program is distributed in the hope that it will be useful, but WITHOUT
|
|
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
// more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License along with
|
|
// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.
|
|
|
|
//go:build linux && cgo
|
|
|
|
package console
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"fmt"
|
|
"unicode/utf8"
|
|
|
|
"git.stormux.org/storm/fenrir/internal/screen"
|
|
)
|
|
|
|
// decode_snapshot uses the VCSA header and native-endian UTF-32 VCSU cells. Glyph
|
|
// numbers from VCSA are deliberately not treated as Unicode characters.
|
|
func decode_snapshot(tty int, header, text []byte) (screen.Snapshot, error) {
|
|
if len(header) < 4 {
|
|
return screen.Snapshot{}, fmt.Errorf("short VCSA header")
|
|
}
|
|
snapshot := screen.Snapshot{Terminal: tty, Active: true, Rows: int(header[0]), Cols: int(header[1]), X: int(header[2]), Y: int(header[3])}
|
|
if snapshot.Rows == 0 || snapshot.Cols == 0 || snapshot.X >= snapshot.Cols || snapshot.Y >= snapshot.Rows {
|
|
return screen.Snapshot{}, fmt.Errorf("invalid console geometry or cursor")
|
|
}
|
|
count := snapshot.Rows * snapshot.Cols
|
|
if len(text) != count*4 {
|
|
return screen.Snapshot{}, fmt.Errorf("VCSU size %d does not match %dx%d console", len(text), snapshot.Cols, snapshot.Rows)
|
|
}
|
|
snapshot.Cells = make([]rune, count)
|
|
for index := range snapshot.Cells {
|
|
value := binary.NativeEndian.Uint32(text[index*4:])
|
|
switch {
|
|
case value == 0:
|
|
snapshot.Cells[index] = ' '
|
|
case value > utf8.MaxRune || value >= 0xd800 && value <= 0xdfff:
|
|
snapshot.Cells[index] = utf8.RuneError
|
|
default:
|
|
snapshot.Cells[index] = rune(value)
|
|
}
|
|
}
|
|
return snapshot, nil
|
|
}
|
|
|
|
func decode_attributes(snapshot *screen.Snapshot, data []byte) error {
|
|
if len(data) != 4+len(snapshot.Cells)*2 {
|
|
return fmt.Errorf("VCSA size %d does not match %dx%d console", len(data), snapshot.Cols, snapshot.Rows)
|
|
}
|
|
snapshot.Attributes = make([]screen.Attribute, len(snapshot.Cells))
|
|
for index := range snapshot.Attributes {
|
|
// VCSA stores native-endian glyph/attribute words. Glyph bytes remain
|
|
// unused: Unicode always comes from VCSU, including non-ASCII fonts.
|
|
attribute := binary.NativeEndian.Uint16(data[4+index*2:]) >> 8
|
|
// VGA palette order swaps ANSI red/blue. Intensity is a color, not
|
|
// proof of bold; VCSA cannot recover the original SGR font styles.
|
|
ansi := func(value uint16) uint32 { return uint32(value&10 | (value&1)<<2 | (value&4)>>2) }
|
|
style := uint32(0)
|
|
if attribute&128 != 0 {
|
|
style = screen.ConsoleHigh
|
|
}
|
|
snapshot.Attributes[index] = screen.Attribute{Foreground: screen.ColorIndexed | ansi(attribute&15), Background: screen.ColorIndexed | ansi((attribute>>4)&7), Style: style}
|
|
}
|
|
return nil
|
|
}
|