| 🛟 Updated. 28d5985 k33g 20h ago | 1 | package terminal |
| 2 | |
| 3 | import "github.com/gdamore/tcell/v2" |
| 4 | |
| 5 | // Encode turns a key press into the bytes a terminal program expects to read. |
| 6 | // |
| 7 | // applicationCursor is the screen's DECCKM setting: a program that has asked |
| 8 | // for application cursor keys expects ESC O A for the up arrow rather than |
| 9 | // ESC [ A, and gets the arrow keys wrong if it is given the other form. |
| 10 | // |
| 11 | // A key with no terminal meaning encodes to nothing at all, which the caller |
| 12 | // should treat as "nothing to send" rather than as an empty line. |
| 13 | // |
| 14 | // terminal.Encode(tcell.NewEventKey(tcell.KeyEnter, 0, tcell.ModNone), false) |
| 15 | // // []byte{'\r'} |
| 16 | func Encode(ev *tcell.EventKey, applicationCursor bool) []byte { |
| 17 | if sequence, ok := encodeCursor(ev.Key(), applicationCursor); ok { |
| 18 | return sequence |
| 19 | } |
| 20 | if sequence, ok := namedKeys[ev.Key()]; ok { |
| 21 | return []byte(sequence) |
| 22 | } |
| 23 | if ev.Key() == tcell.KeyRune { |
| 24 | return encodeRune(ev) |
| 25 | } |
| 26 | return encodeControl(ev) |
| 27 | } |
| 28 | |
| 29 | // cursorKeys are the four arrows and the two keys that travel with them, whose |
| 30 | // encoding depends on the mode the program asked for. |
| 31 | var cursorKeys = map[tcell.Key]byte{ |
| 32 | tcell.KeyUp: 'A', |
| 33 | tcell.KeyDown: 'B', |
| 34 | tcell.KeyRight: 'C', |
| 35 | tcell.KeyLeft: 'D', |
| 36 | tcell.KeyHome: 'H', |
| 37 | tcell.KeyEnd: 'F', |
| 38 | } |
| 39 | |
| 40 | // encodeCursor encodes an arrow, Home or End in whichever form the program is |
| 41 | // expecting. |
| 42 | func encodeCursor(key tcell.Key, applicationCursor bool) ([]byte, bool) { |
| 43 | final, ok := cursorKeys[key] |
| 44 | if !ok { |
| 45 | return nil, false |
| 46 | } |
| 47 | |
| 48 | introducer := byte('[') |
| 49 | if applicationCursor { |
| 50 | introducer = 'O' |
| 51 | } |
| 52 | return []byte{escape, introducer, final}, true |
| 53 | } |
| 54 | |
| 55 | // namedKeys are the keys with a fixed sequence of their own. |
| 56 | var namedKeys = map[tcell.Key]string{ |
| 57 | tcell.KeyEnter: "\r", |
| 58 | tcell.KeyTab: "\t", |
| 59 | tcell.KeyEscape: "\x1b", |
| 60 | tcell.KeyBackspace: "\x7f", |
| 61 | tcell.KeyBackspace2: "\x7f", |
| 62 | tcell.KeyBacktab: "\x1b[Z", |
| 63 | tcell.KeyInsert: "\x1b[2~", |
| 64 | tcell.KeyDelete: "\x1b[3~", |
| 65 | tcell.KeyPgUp: "\x1b[5~", |
| 66 | tcell.KeyPgDn: "\x1b[6~", |
| 67 | |
| 68 | tcell.KeyF1: "\x1bOP", |
| 69 | tcell.KeyF2: "\x1bOQ", |
| 70 | tcell.KeyF3: "\x1bOR", |
| 71 | tcell.KeyF4: "\x1bOS", |
| 72 | tcell.KeyF5: "\x1b[15~", |
| 73 | tcell.KeyF6: "\x1b[17~", |
| 74 | tcell.KeyF7: "\x1b[18~", |
| 75 | tcell.KeyF8: "\x1b[19~", |
| 76 | tcell.KeyF9: "\x1b[20~", |
| 77 | tcell.KeyF10: "\x1b[21~", |
| 78 | tcell.KeyF11: "\x1b[23~", |
| 79 | tcell.KeyF12: "\x1b[24~", |
| 80 | } |
| 81 | |
| 82 | // encodeRune encodes a printable character, with the escape prefix that stands |
| 83 | // for Alt. |
| 84 | func encodeRune(ev *tcell.EventKey) []byte { |
| 85 | text := []byte(string(ev.Rune())) |
| 86 | if ev.Modifiers()&tcell.ModAlt != 0 { |
| 87 | return append([]byte{escape}, text...) |
| 88 | } |
| 89 | return text |
| 90 | } |
| 91 | |
| 92 | // encodeControl encodes a Ctrl-key press. |
| 93 | // |
| 94 | // tcell does not report the control byte itself: reading 0x03 from the |
| 95 | // terminal, it posts KeyCtrlSpace+3, and KeyCtrlSpace is 64. So the whole |
| 96 | // range 64…95 stands for the control bytes 0…31, and turning a key back into |
| 97 | // what a terminal expects means subtracting that offset again. |
| 98 | // |
| 99 | // Getting this wrong is silent: every Ctrl-key would simply send nothing. |
| 100 | func encodeControl(ev *tcell.EventKey) []byte { |
| 101 | key := ev.Key() |
| 102 | if key < tcell.KeyCtrlSpace || key > tcell.KeyCtrlUnderscore { |
| 103 | return nil |
| 104 | } |
| 105 | |
| 106 | control := byte(key - tcell.KeyCtrlSpace) |
| 107 | if ev.Modifiers()&tcell.ModAlt != 0 { |
| 108 | return []byte{escape, control} |
| 109 | } |
| 110 | return []byte{control} |
| 111 | } |