Move the focus from a surface: clicks, the wheel, point

Only the app's key handlers could move a list's focus. When the focus
view is a plain index position (`view tasks_list_focus = at.position`),
Vega now asks Pure for that index and moves it as a user pointing at a
row (pure_app_point), with no code in the app. The grid remembers which
item each line shows; in the TUI a click on a row focuses it and the
wheel moves the focus one row (SGR mouse reports, turned off on exit).
Scripts say point VIEW ROW or click LINE COLUMN on the last shown frame.
The focus is stored like any event, so the next run of any surface
starts from it.

The model now points too: random scripts with points (some past the
end) and TUI clicks still match it on every surface, a mouse click on a
real pseudo-terminal moves the focus, and the stored session keeps it.

1 files changed, 22 insertions, 5 deletions

diff --git a/src/draw.c b/src/draw.c
index bec3804..3c7a59d 100644
--- a/src/draw.c
+++ b/src/draw.c
@@ -193,11 +193,15 @@ void vega_say(FILE *out, PureApp *app, const VegaScreen *screen, bool all) {
 bool vega_grid(VegaGrid *grid, unsigned width, unsigned height) {
     size_t count = (size_t)width * height;
     VegaCell *cells = calloc(count ? count : 1, sizeof(*cells)), *shown = calloc(count ? count : 1, sizeof(*shown));
-    if (!cells || !shown) { free(cells); free(shown); return false; }
+    struct VegaRow *rows = calloc(height ? height : 1, sizeof(*rows));
+    if (!cells || !shown || !rows) { free(cells); free(shown); free(rows); return false; }
+    for (unsigned r = 0; r < height; ++r) rows[r].part = -1;
     free(grid->cells);
     free(grid->shown);
+    free(grid->rows);
     grid->cells = cells;
     grid->shown = shown;
+    grid->rows = rows;
     grid->painted = false;
     grid->width = width;
     grid->height = height;
@@ -207,6 +211,7 @@ bool vega_grid(VegaGrid *grid, unsigned width, unsigned height) {
 void vega_grid_free(VegaGrid *grid) {
     free(grid->cells);
     free(grid->shown);
+    free(grid->rows);
     *grid = (VegaGrid){0};
 }
 
@@ -272,11 +277,13 @@ static const char *key_symbol(const char *key) {
     return key;
 }
 
-static void draw_list(VegaGrid *grid, PureApp *app, const VegaPart *part, size_t first, unsigned top, unsigned height) {
+static void draw_list(VegaGrid *grid, PureApp *app, const VegaPart *part, int index, size_t first, unsigned top,
+                      unsigned height) {
     char text[VEGA_TEXT];
     size_t length, rows = vega_rows(app, part), focus = vega_focus(app, part);
     for (unsigned r = 0; r < height && first + r < rows; ++r) {
         size_t row = first + r;
+        grid->rows[top + r] = (struct VegaRow){index, row};
         bool focused = row == focus;
         VegaTone tone = vega_tone(app, part, row);
         Pen pen = {grid, top + r, 0, grid->width, (uint8_t)tone, focused, false};
@@ -307,7 +314,8 @@ static void draw_list(VegaGrid *grid, PureApp *app, const VegaPart *part, size_t
     }
 }
 
-static void draw_table(VegaGrid *grid, PureApp *app, const VegaPart *part, size_t first, unsigned top, unsigned height) {
+static void draw_table(VegaGrid *grid, PureApp *app, const VegaPart *part, int index, size_t first, unsigned top,
+                       unsigned height) {
     const PureModule *m = app->module;
     char text[VEGA_TEXT];
     size_t length, rows = vega_rows(app, part), focus = vega_focus(app, part);
@@ -338,6 +346,7 @@ static void draw_table(VegaGrid *grid, PureApp *app, const VegaPart *part, size_
     for (unsigned r = 0; r < visible && first + r < rows; ++r) {
         size_t row = first + r;
         bool focused = row == focus;
+        grid->rows[top + 1 + r] = (struct VegaRow){index, row};
         Pen pen = {grid, top + 1 + r, 0, grid->width, (uint8_t)vega_tone(app, part, row), focused, false};
         write_cstr(&pen, focused ? "> " : "  ");
         for (unsigned c = 0; c < part->column_count; ++c) {
@@ -351,10 +360,18 @@ static void draw_table(VegaGrid *grid, PureApp *app, const VegaPart *part, size_
     }
 }
 
+bool vega_hit(const VegaGrid *grid, unsigned line, unsigned *part, size_t *item) {
+    if (line >= grid->height || grid->rows[line].part < 0) return false;
+    *part = (unsigned)grid->rows[line].part;
+    *item = grid->rows[line].item;
+    return true;
+}
+
 void vega_draw(VegaGrid *grid, PureApp *app, const VegaScreen *screen, const char *prompt, size_t prompt_length,
                bool typing) {
     const PureModule *m = app->module;
     for (size_t i = 0; i < (size_t)grid->width * grid->height; ++i) grid->cells[i] = (VegaCell){' ', 0, 0, false, false};
+    for (unsigned r = 0; r < grid->height; ++r) grid->rows[r].part = -1;
     grid->cursor_row = grid->cursor_column = -1;
     if (!grid->width || !grid->height) return;
     char text[VEGA_TEXT];
@@ -398,8 +415,8 @@ void vega_draw(VegaGrid *grid, PureApp *app, const VegaScreen *screen, const cha
         if (focus < *first) *first = focus;
         if (visible && focus >= *first + visible) *first = focus - visible + 1;
         if (*first + visible > rows) *first = rows > visible ? rows - visible : 0;
-        if (part->kind == VEGA_LIST) draw_list(grid, app, part, *first, row + 1, area);
-        else draw_table(grid, app, part, *first, row + 1, area);
+        if (part->kind == VEGA_LIST) draw_list(grid, app, part, (int)i, *first, row + 1, area);
+        else draw_table(grid, app, part, (int)i, *first, row + 1, area);
         row += share;
     }
     /* Keys the app answers to, then the text being typed. */