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Let a program ask how big the text grid is

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`RGR(1)` and `RGR(2)` gave the window in pixels and nothing gave columns, rows
or the cell size -- so anything placing a character *and* a sprite at the same
spot had to hardcode a number measured by hand against whatever font the host
loaded. The Breakout in examples/ does exactly that, `CW# = 16`, and it is the
one thing in that listing that breaks on a different font or window.

**`RWINDOW` is BASIC 7.0's own answer and had never been implemented here.**
`RWINDOW(0)` is the current text window's rows and `RWINDOW(1)` its columns.
`RWINDOW(2)` reports a C128's 40 or 80 column screen mode, and this interpreter
has neither -- refused by name, because answering 0 would be a plausible lie,
which is worse than a refusal that says why.

The cell size in pixels is `RGR(3)` and `RGR(4)`, beside the surface's own
dimensions rather than on `RWINDOW`. Two reasons: a cell size is a fact about
the surface, and `RWINDOW` reports the *window*, so dividing `RGR(1)` by a
column count stops being right the moment a program calls `WINDOW`.

Both read a new optional `grid` entry point on `akbasic_TextSink` -- columns,
rows, cell width, cell height -- implemented by the akgl sink and forwarded by
the tee, in the shape `moveto` and `window` already had. NULL everywhere else,
so both verbs refuse by name against a sink with no grid. `akbasic_sink_init_
stdio()` clears it for the same reason it now clears the other two.

Measured on the standalone build: `RGR(3)` answers 16 and `RWINDOW` answers 50
columns by 37 rows -- the three numbers the Breakout listing had written out as
constants -- and `RWINDOW` follows a `WINDOW` call while `RGR(3)` does not.

tests/console_verbs.c drives the answers through a stand-in sink with a grid,
since the harness sink is stdio and has none; tests/graphics_verbs.c covers the
new `RGR` fields, their refusal, and the moved range bound. The `c excerpt=`
block in docs/10-embedding.md moves with the header, which is `docs_examples`
doing its job.

TODO.md section 6 item 31's second half, struck.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Andrew Kesterson
2026-08-02 00:05:17 -04:00
parent fd1f0d7c19
commit 694b446ce4
15 changed files with 361 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
src/sink_tee.c
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@@ -143,6 +143,30 @@ static akerr_ErrorContext *tee_window(akbasic_TextSink *self, int left, int top,
SUCCEED_RETURN(errctx);
}
/**
* @brief Report the grid of whichever half has one.
*
* The first half that answers wins rather than both being consulted, because
* there is one grid and only one half can have it -- the same reasoning
* tee_moveto() gives about there being one cursor.
*/
static akerr_ErrorContext *tee_grid(akbasic_TextSink *self, int *columns, int *rows, int *cellw, int *cellh)
{
PREPARE_ERROR(errctx);
akbasic_TeeSink *state = NULL;
PASS(errctx, tee_state(self, &state));
if ( state->primary != NULL && state->primary->grid != NULL ) {
PASS(errctx, state->primary->grid(state->primary, columns, rows, cellw, cellh));
SUCCEED_RETURN(errctx);
}
if ( state->mirror != NULL && state->mirror->grid != NULL ) {
PASS(errctx, state->mirror->grid(state->mirror, columns, rows, cellw, cellh));
SUCCEED_RETURN(errctx);
}
FAIL_RETURN(errctx, AKBASIC_ERR_STATE, "neither half of this tee has a character grid");
}
akerr_ErrorContext *akbasic_sink_init_tee(akbasic_TextSink *obj, akbasic_TeeSink *state, akbasic_TextSink *primary, akbasic_TextSink *mirror, akbasic_TextSink *reader)
{
PREPARE_ERROR(errctx);
@@ -177,6 +201,7 @@ akerr_ErrorContext *akbasic_sink_init_tee(akbasic_TextSink *obj, akbasic_TeeSink
*/
obj->moveto = NULL;
obj->window = NULL;
obj->grid = NULL;
/*
* Offered only when a half can actually do it, so CHAR's refusal against a
* stdio-only driver still reads correctly through a tee.
@@ -191,5 +216,10 @@ akerr_ErrorContext *akbasic_sink_init_tee(akbasic_TextSink *obj, akbasic_TeeSink
(mirror != NULL && mirror->window != NULL) ) {
obj->window = tee_window;
}
/* And for the grid RWINDOW and RGR read. */
if ( (primary != NULL && primary->grid != NULL) ||
(mirror != NULL && mirror->grid != NULL) ) {
obj->grid = tee_grid;
}
SUCCEED_RETURN(errctx);
}