foot/terminal.c

#include "terminal.h"

#include <string.h>
#include <unistd.h>
#include <assert.h>

#include <linux/input-event-codes.h>

#define LOG_MODULE "terminal"
#define LOG_ENABLE_DBG 0
#include "log.h"
#include "grid.h"

#define min(x, y) ((x) < (y) ? (x) : (y))
#define max(x, y) ((x) > (y) ? (x) : (y))

void
term_damage_all(struct terminal *term)
{
    for (int i = 0; i < term->rows; i++)
        grid_row(term->grid, i)->dirty = true;
}

void
term_damage_scroll(struct terminal *term, enum damage_type damage_type,
                   struct scroll_region region, int lines)
{
    if (tll_length(term->grid->scroll_damage) > 0) {
        struct damage *dmg = &tll_back(term->grid->scroll_damage);

        if (dmg->type == damage_type &&
            dmg->scroll.region.start == region.start &&
            dmg->scroll.region.end == region.end)
        {
            dmg->scroll.lines += lines;
            return;
        }
    }
    struct damage dmg = {
        .type = damage_type,
        .scroll = {.region = region, .lines = lines},
    };
    tll_push_back(term->grid->scroll_damage, dmg);
}

static inline void
erase_cell_range(struct terminal *term, struct row *row, int start, int end)
{
    assert(start < term->cols);
    assert(end < term->cols);

    if (unlikely(term->vt.attrs.have_background)) {
        for (int col = start; col <= end; col++) {
            row->cells[col].c[0] = '\0';
            row->cells[col].attrs.have_background = true;
            row->cells[col].attrs.background = term->vt.attrs.background;
        }
    } else {
        memset(&row->cells[start], 0, (end - start + 1) * sizeof(row->cells[0]));
    }
    row->dirty = true;
}

static inline void
erase_line(struct terminal *term, struct row *row)
{
    erase_cell_range(term, row, 0, term->cols - 1);
}

void
term_erase(struct terminal *term, const struct coord *start, const struct coord *end)
{
    assert(start->row <= end->row);
    assert(start->col <= end->col || start->row < end->row);

    if (start->row == end->row) {
        struct row *row = grid_row(term->grid, start->row);
        erase_cell_range(term, row, start->col, end->col);
        return;
    }

    assert(end->row > start->row);

    erase_cell_range(
        term, grid_row(term->grid, start->row), start->col, term->cols - 1);

    for (int r = start->row + 1; r < end->row; r++)
        erase_line(term, grid_row(term->grid, r));

    erase_cell_range(term, grid_row(term->grid, end->row), 0, end->col);
}

void
term_cursor_to(struct terminal *term, int row, int col)
{
    assert(row < term->rows);
    assert(col < term->cols);

    term->print_needs_wrap = false;

    term->cursor.col = col;
    term->cursor.row = row;

    term->grid->cur_row = grid_row(term->grid, row);
}

void
term_cursor_left(struct terminal *term, int count)
{
    int move_amount = min(term->cursor.col, count);
    term->cursor.col -= move_amount;
    assert(term->cursor.col >= 0);
    term->print_needs_wrap = false;
}

void
term_cursor_right(struct terminal *term, int count)
{
    int move_amount = min(term->cols - term->cursor.col - 1, count);
    term->cursor.col += move_amount;
    assert(term->cursor.col < term->cols);
    term->print_needs_wrap = false;
}

void
term_cursor_up(struct terminal *term, int count)
{
    int move_amount = min(term->cursor.row, count);
    term_cursor_to(term, term->cursor.row - move_amount, term->cursor.col);
}

void
term_cursor_down(struct terminal *term, int count)
{
    int move_amount = min(term->rows - term->cursor.row - 1, count);
    term_cursor_to(term, term->cursor.row + move_amount, term->cursor.col);
}

void
term_scroll_partial(struct terminal *term, struct scroll_region region, int rows)
{
    LOG_DBG("scroll: %d rows", rows);

    assert(rows < term->rows && "unimplemented");

    /* Top non-scrolling region */
    for (int i = region.start - 1; i >= 0; i--)
        grid_swap_row(term->grid, i, i + rows);

    /* Bottom non-scrolling region */
    for (int i = term->rows - 1; i >= region.end; i--)
        grid_swap_row(term->grid, i, i + rows);

    /* Offset grid origin */
    bool view_follows = term->grid->view == term->grid->offset;
    term->grid->offset += rows;
    term->grid->offset %= term->grid->num_rows;

    if (view_follows)
        term->grid->view = term->grid->offset;

    for (int r = max(region.end - rows, 0); r < region.end; r++) {
        struct row *row = grid_row(term->grid, r);
        erase_line(term, row);
        row->initialized = true;
    }

    term_damage_scroll(term, DAMAGE_SCROLL, region, rows);
    term->grid->cur_row = grid_row(term->grid, term->cursor.row);
}

void
term_scroll(struct terminal *term, int rows)
{
    term_scroll_partial(term, term->scroll_region, rows);
}

void
term_scroll_reverse_partial(struct terminal *term,
                            struct scroll_region region, int rows)
{
    assert(rows < term->rows && "unimplemented");

    bool view_follows = term->grid->view == term->grid->offset;

    term->grid->offset += term->grid->num_rows - rows;
    term->grid->offset %= term->grid->num_rows;

    if (view_follows)
        term->grid->view = term->grid->offset;

    /* Bottom non-scrolling region */
    for (int i = region.end + rows; i < term->rows + rows; i++)
        grid_swap_row(term->grid, i, i - rows);

    /* Top non-scrolling region */
    for (int i = 0 + rows; i < region.start + rows; i++)
        grid_swap_row(term->grid, i, i - rows);

    term_erase(
        term,
        &(struct coord){0, region.start},
        &(struct coord){term->cols - 1, min(region.start + rows, region.end) - 1});

    term_damage_scroll(term, DAMAGE_SCROLL_REVERSE, region, rows);
    term->grid->cur_row = grid_row(term->grid, term->cursor.row);
}

void
term_scroll_reverse(struct terminal *term, int rows)
{
    term_scroll_reverse_partial(term, term->scroll_region, rows);
}

static int
linux_mouse_button_to_x(int button)
{
    switch (button) {
    case BTN_LEFT:    return 1;
    case BTN_RIGHT:   return 3;
    case BTN_MIDDLE:  return 2;
    case BTN_SIDE:    return 8;
    case BTN_EXTRA:   return 9;
    case BTN_FORWARD: return 4;
    case BTN_BACK:    return 5;
    case BTN_TASK:    return -1;  /* TODO: ??? */

    default:
        LOG_WARN("unrecognized mouse button: %d (0x%x)", button, button);
        return -1;
    }
}

static int
encode_xbutton(int xbutton)
{
    switch (xbutton) {
    case 1: case 2: case 3:
        return xbutton - 1;

    case 4: case 5:
        /* Like button 1 and 2, but with 64 added */
        return xbutton - 4 + 64;

    case 6: case 7:
        /* Same as 4 and 5. Note: the offset should be something else? */
        return xbutton - 6 + 64;

    case 8: case 9: case 10: case 11:
        /* Similar to 4 and 5, but adding 128 instead of 64 */
        return xbutton - 8 + 128;

    default:
        LOG_ERR("cannot encode X mouse button: %d", xbutton);
        return -1;
    }
}

static void
report_mouse_click(struct terminal *term, int encoded_button, int row, int col,
                   bool release)
{
    char response[128];

    switch (term->mouse_reporting) {
    case MOUSE_NORMAL:
        snprintf(response, sizeof(response), "\033[M%c%c%c",
                 32 + (release ? 3 : encoded_button), 32 + col + 1, 32 + row + 1);
        break;

    case MOUSE_SGR:
        snprintf(response, sizeof(response), "\033[<%d;%d;%d%c",
                 encoded_button, col + 1, row + 1, release ? 'm' : 'M');
        break;

    case MOUSE_URXVT:
        snprintf(response, sizeof(response), "\033[%d;%d;%dM",
                 32 + (release ? 3 : encoded_button), col + 1, row + 1);
        break;

    case MOUSE_UTF8:
        /* Unimplemented */
        return;
    }

    write(term->ptmx, response, strlen(response));
}

static void
report_mouse_motion(struct terminal *term, int encoded_button, int row, int col)
{
    report_mouse_click(term, encoded_button, row, col, false);
}

void
term_mouse_down(struct terminal *term, int button, int row, int col,
                bool shift, bool alt, bool ctrl)
{
    /* Map libevent button event code to X button number */
    int xbutton = linux_mouse_button_to_x(button);
    if (xbutton == -1)
        return;

    int encoded = encode_xbutton(xbutton);
    if (encoded == -1)
        return;

    encoded += (shift ? 4 : 0) + (alt ? 8 : 0) + (ctrl ? 16 : 0);

    switch (term->mouse_tracking) {
    case MOUSE_NONE:
        break;

    case MOUSE_X10:
    case MOUSE_CLICK:
    case MOUSE_DRAG:
    case MOUSE_MOTION:
        report_mouse_click(term, encoded, row, col, false);
        break;
    }
}

void
term_mouse_up(struct terminal *term, int button, int row, int col,
              bool shift, bool alt, bool ctrl)
{
    /* Map libevent button event code to X button number */
    int xbutton = linux_mouse_button_to_x(button);
    if (xbutton == -1)
        return;

    if (xbutton == 4 || xbutton == 5) {
        /* No release events for scroll buttons */
        return;
    }

    int encoded = encode_xbutton(xbutton);
    if (encoded == -1)
        return;

    encoded += (shift ? 4 : 0) + (alt ? 8 : 0) + (ctrl ? 16 : 0);

    switch (term->mouse_tracking) {
    case MOUSE_NONE:
        break;

    case MOUSE_X10:
    case MOUSE_CLICK:
    case MOUSE_DRAG:
    case MOUSE_MOTION:
        report_mouse_click(term, encoded, row, col, true);
        break;
    }
}

void
term_mouse_motion(struct terminal *term, int button, int row, int col,
                  bool shift, bool alt, bool ctrl)
{
    int encoded = 0;

    if (button != 0) {
        /* Map libevent button event code to X button number */
        int xbutton = linux_mouse_button_to_x(button);
        if (xbutton == -1)
            return;

        encoded = encode_xbutton(xbutton);
        if (encoded == -1)
            return;
    } else
        encoded = 3;  /* "released" */

    encoded += 32; /* Motion event */
    encoded += (shift ? 4 : 0) + (alt ? 8 : 0) + (ctrl ? 16 : 0);

    switch (term->mouse_tracking) {
    case MOUSE_NONE:
    case MOUSE_X10:
    case MOUSE_CLICK:
        return;

    case MOUSE_DRAG:
        if (button == 0)
            return;
        /* FALLTHROUGH */

    case MOUSE_MOTION:
        report_mouse_motion(term, encoded, row, col);
        break;
    }
}