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C++

/*
* terminal.hpp
* MontaukOS terminal emulator with ANSI escape sequence support
* Copyright (c) 2026 Daniel Hammer
*/
#pragma once
#include "gui/gui.hpp"
#include "gui/font.hpp"
#include <montauk/syscall.h>
#include <montauk/string.h>
#include <Api/Syscall.hpp>
namespace gui {
struct TermCell {
char ch;
Color fg;
Color bg;
};
static constexpr int TERM_MAX_SCROLLBACK = 500;
static constexpr int TERM_READ_BUF_SIZE = 8192;
static constexpr int TERM_MAX_DRAIN_BYTES_PER_POLL = 256 * 1024;
static constexpr int TERM_DRAIN_GRACE_YIELDS = 2;
struct TerminalState {
TermCell* cells;
TermCell* alt_cells; // alternate screen buffer
TermCell* render_cells; // last visible cells painted into the window buffer
int cols, rows;
int cursor_x, cursor_y;
int saved_cursor_x, saved_cursor_y; // saved cursor for alternate screen
int scrollback_lines; // lines of history above visible screen (0..max_scrollback)
int max_scrollback; // 0 for viewers (klog), TERM_MAX_SCROLLBACK for terminal
int view_offset; // how many rows scrolled back (0 = live view)
int child_pid;
void* desktop; // DesktopState* for closing window on child exit
Color current_fg;
Color current_bg;
bool cursor_visible;
bool alt_screen_active;
bool reverse_video;
bool dirty; // true when content changed since last render
bool render_valid;
bool render_cursor_visible;
int render_cols, render_rows;
int render_term_cols, render_term_rows;
int render_base_row;
int render_pw, render_ph;
int render_cell_w, render_cell_h;
int render_cursor_x, render_cursor_y;
uint32_t* render_pixels;
enum { STATE_NORMAL, STATE_ESC, STATE_CSI } parse_state;
bool csi_private; // true if '?' was seen after CSI
int csi_params[8];
int csi_param_count;
int csi_current_param;
};
// Standard ANSI color palette as ARGB pixels
static inline Color term_ansi_color(int idx) {
switch (idx) {
case 0: return Color::from_hex(0x000000);
case 1: return Color::from_hex(0xCC0000);
case 2: return Color::from_hex(0x4E9A06);
case 3: return Color::from_hex(0xC4A000);
case 4: return Color::from_hex(0x3465A4);
case 5: return Color::from_hex(0x75507B);
case 6: return Color::from_hex(0x06989A);
case 7: return Color::from_hex(0xD3D7CF);
case 8: return Color::from_hex(0x555753);
case 9: return Color::from_hex(0xEF2929);
case 10: return Color::from_hex(0x8AE234);
case 11: return Color::from_hex(0xFCE94F);
case 12: return Color::from_hex(0x729FCF);
case 13: return Color::from_hex(0xAD7FA8);
case 14: return Color::from_hex(0x34E2E2);
case 15: return Color::from_hex(0xEEEEEC);
default: return colors::TERM_FG;
}
}
// ANSI 256-color palette (0-15 = standard, 16-231 = RGB cube, 232-255 = grayscale)
static inline Color term_ansi_256_color(int idx) {
if (idx < 0) return colors::TERM_FG;
if (idx <= 15) return term_ansi_color(idx);
if (idx <= 231) {
// 6x6x6 RGB cube: idx 16 = (0,0,0), idx 231 = (5,5,5)
int r = ((idx - 16) / 36) * 51;
int g = (((idx - 16) % 36) / 6) * 51;
int b = ((idx - 16) % 6) * 51;
return Color::from_rgb(r, g, b);
}
// Grayscale: idx 232 = #080808, idx 255 = #eeeeee
int gray = 8 + (idx - 232) * 10;
if (gray > 238) gray = 238;
return Color::from_rgb(gray, gray, gray);
}
// Helper: pointer to start of screen-relative row r in the cells buffer
static inline TermCell* term_screen_row(TerminalState* t, int r) {
return &t->cells[(t->scrollback_lines + r) * t->cols];
}
static inline bool term_color_equal(Color a, Color b) {
return a.r == b.r && a.g == b.g && a.b == b.b && a.a == b.a;
}
static inline bool term_cell_equal(const TermCell& a, const TermCell& b) {
return a.ch == b.ch && term_color_equal(a.fg, b.fg) && term_color_equal(a.bg, b.bg);
}
static inline void terminal_invalidate_render_cache(TerminalState* t) {
if (!t) return;
t->render_valid = false;
t->render_cursor_visible = false;
}
static inline Color terminal_erase_bg(TerminalState* t) {
return t->current_bg;
}
static inline void terminal_scroll_up(TerminalState* t) {
if (!t->alt_screen_active && t->scrollback_lines < t->max_scrollback) {
// Room for scrollback: top visible row becomes scrollback, no data movement
t->scrollback_lines++;
} else if (!t->alt_screen_active && t->max_scrollback > 0) {
// Scrollback full: discard oldest line, shift entire buffer up by one row
int total = (t->max_scrollback + t->rows - 1) * t->cols * sizeof(TermCell);
montauk::memmove(t->cells, t->cells + t->cols, total);
} else {
// Alt screen or no scrollback (klog): shift visible area up
TermCell* screen = term_screen_row(t, 0);
montauk::memmove(screen, screen + t->cols, (t->rows - 1) * t->cols * sizeof(TermCell));
}
// Clear the new bottom visible row
TermCell* bottom = term_screen_row(t, t->rows - 1);
for (int c = 0; c < t->cols; c++) {
bottom[c] = {' ', t->current_fg, terminal_erase_bg(t)};
}
// Keep user's scrolled-back viewport stable
if (t->view_offset > 0) {
t->view_offset++;
if (t->view_offset > t->scrollback_lines)
t->view_offset = t->scrollback_lines;
}
}
// Initialize only the cell grid (no child process). Used by viewers like klog.
// max_sb = 0 for viewers, TERM_MAX_SCROLLBACK for the real terminal.
static inline void terminal_init_cells(TerminalState* t, int cols, int rows, int max_sb = 0) {
t->cols = cols;
t->rows = rows;
t->cursor_x = 0;
t->cursor_y = 0;
t->saved_cursor_x = 0;
t->saved_cursor_y = 0;
t->scrollback_lines = 0;
t->max_scrollback = max_sb;
t->view_offset = 0;
t->current_fg = colors::TERM_FG;
t->current_bg = colors::TERM_BG;
t->cursor_visible = false;
t->alt_screen_active = false;
t->reverse_video = false;
t->dirty = true;
t->render_cells = nullptr;
t->render_valid = false;
t->render_cursor_visible = false;
t->render_cols = 0;
t->render_rows = 0;
t->render_term_cols = 0;
t->render_term_rows = 0;
t->render_base_row = 0;
t->render_pw = 0;
t->render_ph = 0;
t->render_cell_w = 0;
t->render_cell_h = 0;
t->render_cursor_x = 0;
t->render_cursor_y = 0;
t->render_pixels = nullptr;
t->parse_state = TerminalState::STATE_NORMAL;
t->csi_private = false;
t->csi_param_count = 0;
t->csi_current_param = 0;
t->child_pid = 0;
int total_cells = (rows + max_sb) * cols;
int screen_cells = rows * cols;
t->cells = (TermCell*)montauk::alloc(total_cells * sizeof(TermCell));
t->alt_cells = (TermCell*)montauk::alloc(screen_cells * sizeof(TermCell));
if (!t->cells || !t->alt_cells) {
// Allocation failed — leave terminal in a safe but unusable state
if (t->cells) { montauk::free(t->cells); t->cells = nullptr; }
if (t->alt_cells) { montauk::free(t->alt_cells); t->alt_cells = nullptr; }
t->cols = 0; t->rows = 0;
return;
}
for (int i = 0; i < total_cells; i++) {
t->cells[i] = {' ', colors::TERM_FG, colors::TERM_BG};
}
for (int i = 0; i < screen_cells; i++) {
t->alt_cells[i] = {' ', colors::TERM_FG, colors::TERM_BG};
}
}
static inline void terminal_init(TerminalState* t, int cols, int rows) {
terminal_init_cells(t, cols, rows, TERM_MAX_SCROLLBACK);
t->cursor_visible = true;
t->child_pid = montauk::spawn_redir("0:/os/shell.elf");
if (t->child_pid > 0)
montauk::childio_settermsz(t->child_pid, cols, rows);
}
static inline void terminal_put_char(TerminalState* t, char ch) {
if (t->cursor_x >= t->cols) {
t->cursor_x = 0;
t->cursor_y++;
}
if (t->cursor_y >= t->rows) {
terminal_scroll_up(t);
t->cursor_y = t->rows - 1;
}
TermCell* row = term_screen_row(t, t->cursor_y);
row[t->cursor_x].ch = ch;
row[t->cursor_x].fg = t->current_fg;
row[t->cursor_x].bg = t->current_bg;
t->cursor_x++;
}
static inline void terminal_enter_alt_screen(TerminalState* t) {
if (t->alt_screen_active) return;
t->alt_screen_active = true;
t->dirty = true;
// Save cursor
t->saved_cursor_x = t->cursor_x;
t->saved_cursor_y = t->cursor_y;
// Save visible screen to alt_cells, clear visible screen
int total = t->cols * t->rows;
TermCell* screen = term_screen_row(t, 0);
for (int i = 0; i < total; i++) {
t->alt_cells[i] = screen[i];
screen[i] = {' ', colors::TERM_FG, colors::TERM_BG};
}
t->view_offset = 0;
t->cursor_x = 0;
t->cursor_y = 0;
}
static inline void terminal_exit_alt_screen(TerminalState* t) {
if (!t->alt_screen_active) return;
t->alt_screen_active = false;
t->dirty = true;
// Restore visible screen from alt_cells
int total = t->cols * t->rows;
TermCell* screen = term_screen_row(t, 0);
for (int i = 0; i < total; i++) {
screen[i] = t->alt_cells[i];
}
// Restore cursor
t->cursor_x = t->saved_cursor_x;
t->cursor_y = t->saved_cursor_y;
}
static inline void terminal_process_private_mode(TerminalState* t, char cmd) {
int p0 = t->csi_param_count > 0 ? t->csi_params[0] : 0;
if (cmd == 'h') {
// Set private mode
if (p0 == 25) {
t->cursor_visible = true;
} else if (p0 == 1049) {
terminal_enter_alt_screen(t);
}
} else if (cmd == 'l') {
// Reset private mode
if (p0 == 25) {
t->cursor_visible = false;
} else if (p0 == 1049) {
terminal_exit_alt_screen(t);
}
}
}
static inline void terminal_process_csi(TerminalState* t, char cmd) {
// Finalize current param
if (t->csi_param_count < 8) {
t->csi_params[t->csi_param_count] = t->csi_current_param;
t->csi_param_count++;
}
// Handle private mode sequences (ESC[?...)
if (t->csi_private) {
terminal_process_private_mode(t, cmd);
return;
}
int p0 = t->csi_param_count > 0 ? t->csi_params[0] : 0;
int p1 = t->csi_param_count > 1 ? t->csi_params[1] : 0;
switch (cmd) {
case 'H': case 'f': {
// Cursor position: ESC[row;colH (1-based)
int row = (p0 > 0 ? p0 : 1) - 1;
int col = (p1 > 0 ? p1 : 1) - 1;
if (row < 0) row = 0;
if (row >= t->rows) row = t->rows - 1;
if (col < 0) col = 0;
if (col >= t->cols) col = t->cols - 1;
t->cursor_y = row;
t->cursor_x = col;
break;
}
case 'A': {
// Cursor up
int n = p0 > 0 ? p0 : 1;
t->cursor_y -= n;
if (t->cursor_y < 0) t->cursor_y = 0;
break;
}
case 'B': {
// Cursor down
int n = p0 > 0 ? p0 : 1;
t->cursor_y += n;
if (t->cursor_y >= t->rows) t->cursor_y = t->rows - 1;
break;
}
case 'C': {
// Cursor forward
int n = p0 > 0 ? p0 : 1;
t->cursor_x += n;
if (t->cursor_x >= t->cols) t->cursor_x = t->cols - 1;
break;
}
case 'D': {
// Cursor backward
int n = p0 > 0 ? p0 : 1;
t->cursor_x -= n;
if (t->cursor_x < 0) t->cursor_x = 0;
break;
}
case 'J': {
// Erase in display
Color erase_bg = terminal_erase_bg(t);
if (p0 == 0) {
// Clear from cursor to end
TermCell* row = term_screen_row(t, t->cursor_y);
for (int x = t->cursor_x; x < t->cols; x++)
row[x] = {' ', t->current_fg, erase_bg};
for (int r = t->cursor_y + 1; r < t->rows; r++) {
TermCell* rp = term_screen_row(t, r);
for (int c = 0; c < t->cols; c++)
rp[c] = {' ', t->current_fg, erase_bg};
}
} else if (p0 == 1) {
// Clear from start to cursor
for (int r = 0; r < t->cursor_y; r++) {
TermCell* rp = term_screen_row(t, r);
for (int c = 0; c < t->cols; c++)
rp[c] = {' ', t->current_fg, erase_bg};
}
TermCell* row = term_screen_row(t, t->cursor_y);
for (int x = 0; x <= t->cursor_x; x++)
row[x] = {' ', t->current_fg, erase_bg};
} else if (p0 == 2) {
// Clear entire screen
for (int r = 0; r < t->rows; r++) {
TermCell* rp = term_screen_row(t, r);
for (int c = 0; c < t->cols; c++)
rp[c] = {' ', t->current_fg, erase_bg};
}
t->cursor_x = 0;
t->cursor_y = 0;
}
break;
}
case 'K': {
// Erase in line
int start = 0, end = t->cols;
if (p0 == 0) { start = t->cursor_x; end = t->cols; }
else if (p0 == 1) { start = 0; end = t->cursor_x + 1; }
else if (p0 == 2) { start = 0; end = t->cols; }
Color erase_bg = terminal_erase_bg(t);
TermCell* row = term_screen_row(t, t->cursor_y);
for (int x = start; x < end; x++)
row[x] = {' ', t->current_fg, erase_bg};
break;
}
case 'm': {
// SGR - Set Graphics Rendition
for (int i = 0; i < t->csi_param_count; i++) {
int code = t->csi_params[i];
// Handle extended color sequences: 38;5;N or 48;5;N or 38;2;R;G;B or 48;2;R;G;B
if ((code == 38 || code == 48) && i + 2 < t->csi_param_count) {
if (t->csi_params[i + 1] == 5) {
// 256-color: 38;5;N or 48;5;N
int color_idx = t->csi_params[i + 2];
if (code == 38) {
t->current_fg = term_ansi_256_color(color_idx);
} else {
t->current_bg = term_ansi_256_color(color_idx);
}
i += 2;
continue;
} else if (t->csi_params[i + 1] == 2 && i + 4 < t->csi_param_count) {
// Truecolor: 38;2;R;G;B or 48;2;R;G;B
int r = t->csi_params[i + 2];
int g = t->csi_params[i + 3];
int b = t->csi_params[i + 4];
if (code == 38) {
t->current_fg = Color::from_rgb(r, g, b);
} else {
t->current_bg = Color::from_rgb(r, g, b);
}
i += 4;
continue;
}
}
if (code == 0) {
t->current_fg = colors::TERM_FG;
t->current_bg = colors::TERM_BG;
t->reverse_video = false;
} else if (code == 1) {
// Bold: map to bright version of current color
uint8_t r = t->current_fg.r;
uint8_t g = t->current_fg.g;
uint8_t b = t->current_fg.b;
int add = 50;
r = (r + add > 255) ? 255 : r + add;
g = (g + add > 255) ? 255 : g + add;
b = (b + add > 255) ? 255 : b + add;
t->current_fg = Color::from_rgb(r, g, b);
} else if (code == 2) {
// Dim: darken current fg color
t->current_fg.r = t->current_fg.r / 2;
t->current_fg.g = t->current_fg.g / 2;
t->current_fg.b = t->current_fg.b / 2;
} else if (code == 7) {
// Reverse video
if (!t->reverse_video) {
t->reverse_video = true;
Color tmp = t->current_fg;
t->current_fg = t->current_bg;
t->current_bg = tmp;
}
} else if (code == 27) {
// Reverse off
if (t->reverse_video) {
t->reverse_video = false;
Color tmp = t->current_fg;
t->current_fg = t->current_bg;
t->current_bg = tmp;
}
} else if (code >= 30 && code <= 37) {
t->current_fg = term_ansi_color(code - 30);
if (t->reverse_video) {
// In reverse mode, fg is displayed as bg
Color tmp = t->current_fg;
t->current_fg = t->current_bg;
t->current_bg = tmp;
}
} else if (code >= 40 && code <= 47) {
t->current_bg = term_ansi_color(code - 40);
} else if (code >= 90 && code <= 97) {
t->current_fg = term_ansi_color(code - 90 + 8);
} else if (code >= 100 && code <= 107) {
t->current_bg = term_ansi_color(code - 100 + 8);
} else if (code == 39) {
t->current_fg = colors::TERM_FG;
} else if (code == 49) {
t->current_bg = colors::TERM_BG;
}
}
if (t->csi_param_count == 0) {
// ESC[m with no params = reset
t->current_fg = colors::TERM_FG;
t->current_bg = colors::TERM_BG;
t->reverse_video = false;
}
break;
}
default:
break;
}
}
static inline void terminal_feed(TerminalState* t, const char* data, int len) {
if (len > 0) t->dirty = true;
for (int i = 0; i < len; i++) {
char ch = data[i];
switch (t->parse_state) {
case TerminalState::STATE_NORMAL:
if (ch == '\033') {
t->parse_state = TerminalState::STATE_ESC;
} else if (ch == '\n') {
t->cursor_x = 0; // CR+LF: shell sends \n without \r
t->cursor_y++;
if (t->cursor_y >= t->rows) {
terminal_scroll_up(t);
t->cursor_y = t->rows - 1;
}
} else if (ch == '\r') {
t->cursor_x = 0;
} else if (ch == '\b') {
if (t->cursor_x > 0) t->cursor_x--;
} else if (ch == '\t') {
int next = (t->cursor_x + 8) & ~7;
if (next > t->cols) next = t->cols;
while (t->cursor_x < next) {
terminal_put_char(t, ' ');
}
} else if (ch >= 32 || ch < 0) {
// Printable character (also treat high-bit chars as printable)
terminal_put_char(t, ch);
}
break;
case TerminalState::STATE_ESC:
if (ch == '[') {
t->parse_state = TerminalState::STATE_CSI;
t->csi_private = false;
t->csi_param_count = 0;
t->csi_current_param = 0;
for (int j = 0; j < 8; j++) t->csi_params[j] = 0;
} else if (ch == 'c') {
// Reset terminal
t->current_fg = colors::TERM_FG;
t->current_bg = colors::TERM_BG;
t->cursor_x = 0;
t->cursor_y = 0;
t->parse_state = TerminalState::STATE_NORMAL;
} else {
// Unknown ESC sequence, ignore
t->parse_state = TerminalState::STATE_NORMAL;
}
break;
case TerminalState::STATE_CSI:
if (ch >= '0' && ch <= '9') {
t->csi_current_param = t->csi_current_param * 10 + (ch - '0');
} else if (ch == ';') {
if (t->csi_param_count < 8) {
t->csi_params[t->csi_param_count] = t->csi_current_param;
t->csi_param_count++;
}
t->csi_current_param = 0;
} else if (ch == '?') {
t->csi_private = true;
} else if (ch >= 0x40 && ch <= 0x7E) {
// Final byte - execute command
terminal_process_csi(t, ch);
t->parse_state = TerminalState::STATE_NORMAL;
} else {
// Unknown, abort CSI
t->parse_state = TerminalState::STATE_NORMAL;
}
break;
}
}
}
static inline void terminal_fill_pixel_rect(uint32_t* pixels, int pw, int ph,
int x, int y, int w, int h,
uint32_t color) {
if (!pixels || pw <= 0 || ph <= 0 || w <= 0 || h <= 0) return;
int x0 = x < 0 ? 0 : x;
int y0 = y < 0 ? 0 : y;
int x1 = x + w > pw ? pw : x + w;
int y1 = y + h > ph ? ph : y + h;
for (int row = y0; row < y1; row++) {
uint32_t* dst = &pixels[row * pw + x0];
for (int col = x0; col < x1; col++)
*dst++ = color;
}
}
static inline void terminal_draw_bitmap_char(uint32_t* pixels, int pw, int ph,
int x, int y, unsigned char ch,
uint32_t color) {
const uint8_t* glyph = &font_data[ch * FONT_HEIGHT];
for (int fy = 0; fy < FONT_HEIGHT; fy++) {
int dy = y + fy;
if (dy >= ph) break;
if (dy < 0) continue;
uint8_t bits = glyph[fy];
for (int fx = 0; fx < FONT_WIDTH; fx++) {
if (bits & (0x80 >> fx)) {
int dx = x + fx;
if (dx >= pw) break;
if (dx >= 0) pixels[dy * pw + dx] = color;
}
}
}
}
static inline void terminal_draw_cell_pixels(const TermCell& cell,
uint32_t* pixels, int pw, int ph,
int px, int py, int cell_w, int cell_h,
bool fill_bg, bool use_ttf,
GlyphCache* gc) {
if (fill_bg) {
terminal_fill_pixel_rect(pixels, pw, ph, px, py, cell_w, cell_h,
cell.bg.to_pixel());
}
if (cell.ch <= 32 && cell.ch >= 0) return;
if (use_ttf) {
int baseline = py + gc->ascent;
fonts::mono->draw_char_to_buffer(pixels, pw, ph,
px, baseline, (unsigned char)cell.ch, cell.fg, gc);
} else {
terminal_draw_bitmap_char(pixels, pw, ph, px, py, (unsigned char)cell.ch,
cell.fg.to_pixel());
}
}
static inline void terminal_draw_cursor_pixels(const TermCell& cell,
uint32_t* pixels, int pw, int ph,
int px, int py, int cell_w, int cell_h,
bool use_ttf, GlyphCache* gc) {
terminal_fill_pixel_rect(pixels, pw, ph, px, py, cell_w, cell_h,
colors::WHITE.to_pixel());
if (cell.ch <= 32 && cell.ch >= 0) return;
if (use_ttf) {
int baseline = py + gc->ascent;
fonts::mono->draw_char_to_buffer(pixels, pw, ph,
px, baseline, (unsigned char)cell.ch, colors::BLACK, gc);
} else {
terminal_draw_bitmap_char(pixels, pw, ph, px, py, (unsigned char)cell.ch,
colors::BLACK.to_pixel());
}
}
static inline bool terminal_prepare_render_cache(TerminalState* t,
int visible_cols,
int visible_rows) {
if (visible_cols <= 0 || visible_rows <= 0) return false;
if (t->render_cells && t->render_cols == visible_cols && t->render_rows == visible_rows)
return true;
if (t->render_cells) {
montauk::free(t->render_cells);
t->render_cells = nullptr;
}
int cells = visible_cols * visible_rows;
t->render_cells = (TermCell*)montauk::alloc(cells * sizeof(TermCell));
if (!t->render_cells) {
terminal_invalidate_render_cache(t);
t->render_cols = 0;
t->render_rows = 0;
return false;
}
t->render_cols = visible_cols;
t->render_rows = visible_rows;
terminal_invalidate_render_cache(t);
return true;
}
static inline TermCell terminal_visible_cell(TerminalState* t, int base_row, int x, int y) {
return t->cells[(base_row + y) * t->cols + x];
}
static inline void terminal_render(TerminalState* t, uint32_t* pixels, int pw, int ph) {
if (!t->dirty || !t->cells || !pixels || pw <= 0 || ph <= 0) return;
int cell_w = mono_cell_width();
int cell_h = mono_cell_height();
if (cell_w <= 0 || cell_h <= 0) return;
bool use_ttf = fonts::mono && fonts::mono->valid;
GlyphCache* gc = use_ttf ? fonts::mono->get_cache(fonts::TERM_SIZE) : nullptr;
int base_row = t->scrollback_lines - t->view_offset;
if (base_row < 0) base_row = 0;
int visible_rows = ph / cell_h;
int visible_cols = pw / cell_w;
if (visible_rows > t->rows) visible_rows = t->rows;
if (visible_cols > t->cols) visible_cols = t->cols;
if (visible_rows <= 0 || visible_cols <= 0) return;
bool have_cache = terminal_prepare_render_cache(t, visible_cols, visible_rows);
bool full_redraw = !have_cache || !t->render_valid ||
t->render_pixels != pixels ||
t->render_pw != pw || t->render_ph != ph ||
t->render_cell_w != cell_w || t->render_cell_h != cell_h ||
t->render_base_row != base_row ||
t->render_term_cols != t->cols || t->render_term_rows != t->rows;
uint32_t bg_px = colors::TERM_BG.to_pixel();
if (full_redraw) {
int row_bytes = pw * sizeof(uint32_t);
for (int i = 0; i < pw; i++) pixels[i] = bg_px;
for (int r = 1; r < ph; r++)
montauk::memcpy(&pixels[r * pw], pixels, row_bytes);
} else if (t->render_cursor_visible) {
int x = t->render_cursor_x;
int y = t->render_cursor_y;
if (x >= 0 && x < visible_cols && y >= 0 && y < visible_rows) {
TermCell cell = terminal_visible_cell(t, base_row, x, y);
terminal_draw_cell_pixels(cell, pixels, pw, ph,
x * cell_w, y * cell_h,
cell_w, cell_h, true, use_ttf, gc);
if (have_cache)
t->render_cells[y * visible_cols + x] = cell;
}
}
for (int r = 0; r < visible_rows; r++) {
int py = r * cell_h;
for (int c = 0; c < visible_cols; c++) {
TermCell cell = terminal_visible_cell(t, base_row, c, r);
int cache_idx = r * visible_cols + c;
bool changed = full_redraw || !have_cache ||
!term_cell_equal(t->render_cells[cache_idx], cell);
if (!changed) continue;
bool fill_bg = !full_redraw || cell.bg.to_pixel() != bg_px;
terminal_draw_cell_pixels(cell, pixels, pw, ph,
c * cell_w, py,
cell_w, cell_h, fill_bg, use_ttf, gc);
if (have_cache)
t->render_cells[cache_idx] = cell;
}
}
bool cursor_now_visible = t->view_offset == 0 && t->cursor_visible &&
t->cursor_x >= 0 && t->cursor_y >= 0 &&
t->cursor_x < visible_cols && t->cursor_y < visible_rows;
if (cursor_now_visible) {
TermCell cell = terminal_visible_cell(t, base_row, t->cursor_x, t->cursor_y);
terminal_draw_cursor_pixels(cell, pixels, pw, ph,
t->cursor_x * cell_w, t->cursor_y * cell_h,
cell_w, cell_h, use_ttf, gc);
}
t->render_valid = have_cache;
t->render_cursor_visible = cursor_now_visible;
t->render_cursor_x = t->cursor_x;
t->render_cursor_y = t->cursor_y;
t->render_term_cols = t->cols;
t->render_term_rows = t->rows;
t->render_base_row = base_row;
t->render_pw = pw;
t->render_ph = ph;
t->render_cell_w = cell_w;
t->render_cell_h = cell_h;
t->render_pixels = pixels;
t->dirty = false;
}
static inline void terminal_resize(TerminalState* t, int new_cols, int new_rows) {
if (new_cols == t->cols && new_rows == t->rows) return;
if (new_cols < 1 || new_rows < 1) return;
t->dirty = true;
int new_capacity = new_rows + t->max_scrollback;
int new_total = new_capacity * new_cols;
TermCell* new_cells = (TermCell*)montauk::alloc(new_total * sizeof(TermCell));
TermCell* new_alt = (TermCell*)montauk::alloc(new_rows * new_cols * sizeof(TermCell));
if (!new_cells || !new_alt) {
if (new_cells) montauk::free(new_cells);
if (new_alt) montauk::free(new_alt);
return; // keep existing buffers
}
// Clear new buffers
for (int i = 0; i < new_total; i++)
new_cells[i] = {' ', colors::TERM_FG, colors::TERM_BG};
for (int i = 0; i < new_rows * new_cols; i++)
new_alt[i] = {' ', colors::TERM_FG, colors::TERM_BG};
// Copy content: scrollback + visible screen
int old_content = t->scrollback_lines + t->rows;
int keep = old_content < new_capacity ? old_content : new_capacity;
int discard = old_content - keep;
int copy_cols = t->cols < new_cols ? t->cols : new_cols;
for (int r = 0; r < keep; r++) {
for (int c = 0; c < copy_cols; c++) {
new_cells[r * new_cols + c] = t->cells[(discard + r) * t->cols + c];
}
}
// Anchor the new visible region to the cursor's line. Treating the bottom
// new_rows of kept content as the screen (the naive keep - new_rows) only
// works when the screen is full: with a partly filled screen -- e.g. a
// shell prompt a few lines down with blank rows below it -- it would push
// the real text up into scrollback and drop the view onto the blank region,
// so a zoom appears to scroll down and strands the cursor in empty space.
// Instead pin the cursor to the bottom row when there is enough history
// above it, otherwise keep the content anchored at the top.
int abs_cursor_y = t->scrollback_lines + t->cursor_y - discard;
if (abs_cursor_y < 0) abs_cursor_y = 0;
int new_scrollback = abs_cursor_y - (new_rows - 1);
if (new_scrollback < 0) new_scrollback = 0;
if (new_scrollback > t->max_scrollback) new_scrollback = t->max_scrollback;
// Adjust cursor
int new_cursor_y = abs_cursor_y - new_scrollback;
if (new_cursor_y < 0) new_cursor_y = 0;
if (new_cursor_y >= new_rows) new_cursor_y = new_rows - 1;
int new_cursor_x = t->cursor_x < new_cols ? t->cursor_x : new_cols - 1;
if (t->cells) montauk::free(t->cells);
if (t->alt_cells) montauk::free(t->alt_cells);
if (t->render_cells) {
montauk::free(t->render_cells);
t->render_cells = nullptr;
}
t->cells = new_cells;
t->alt_cells = new_alt;
t->cols = new_cols;
t->rows = new_rows;
t->scrollback_lines = new_scrollback;
t->cursor_x = new_cursor_x;
t->cursor_y = new_cursor_y;
terminal_invalidate_render_cache(t);
// Clamp view offset
if (t->view_offset > t->scrollback_lines)
t->view_offset = t->scrollback_lines;
// Notify child process of new terminal size
if (t->child_pid > 0) {
montauk::childio_settermsz(t->child_pid, new_cols, new_rows);
}
}
static inline void terminal_handle_key(TerminalState* t, const montauk::abi::KeyEvent& key) {
// Snap to live on any keyboard input
if (t->view_offset > 0) {
t->view_offset = 0;
t->dirty = true;
}
if (t->child_pid > 0) {
montauk::childio_writekey(t->child_pid, &key);
}
}
// Returns false if the child process has exited
static inline bool terminal_poll(TerminalState* t) {
if (t->child_pid <= 0) return false;
char buf[TERM_READ_BUF_SIZE];
int drained = 0;
int grace_yields = 0;
// Drain bursty TUI output as one frame. When a child was blocked on a full
// stream, a short yield lets it finish the redraw before we present.
for (;;) {
int n = montauk::childio_read(t->child_pid, buf, sizeof(buf));
if (n > 0) {
terminal_feed(t, buf, n);
drained += n;
grace_yields = 0;
if (drained >= TERM_MAX_DRAIN_BYTES_PER_POLL)
break;
} else {
// n == -1 means child process is gone; n == 0 means no data yet
if (n < 0) { t->child_pid = 0; return false; }
if (drained > 0 && grace_yields < TERM_DRAIN_GRACE_YIELDS) {
grace_yields++;
montauk::yield();
continue;
}
break;
}
}
return true;
}
} // namespace gui