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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
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23
tests/graphics_verbs.c
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@@ -266,9 +266,28 @@ static void test_rgr(void)
TEST_REQUIRE_STR(MOCK.log, "point 639.0,399.0 " WHITE "\n");
harness_stop();
TEST_REQUIRE_OK(run_program("10 PRINT RGR(5)\n"));
TEST_REQUIRE(strstr(HARNESS_OUTPUT, "outside 0..4") != NULL,
"RGR(5) should be refused, got \"%s\"", HARNESS_OUTPUT);
harness_stop();
/*
* 3 and 4 are the character cell, and they come from the *sink* rather than
* the graphics device -- a grid belongs to a text device. The harness sink
* is stdio and has none, so what a device-less build can assert is the
* refusal; tests/console_verbs.c drives the answers through a stand-in sink
* that does have a grid.
*/
TEST_REQUIRE_OK(run_program("10 PRINT RGR(3)\n"));
TEST_REQUIRE(strstr(HARNESS_OUTPUT, "outside 0..2") != NULL,
"RGR(3) should be refused, got \"%s\"", HARNESS_OUTPUT);
TEST_REQUIRE(strstr(HARNESS_OUTPUT, "text device with a character grid") != NULL,
"RGR(3) against a grid-less sink should refuse by name, got \"%s\"",
HARNESS_OUTPUT);
harness_stop();
TEST_REQUIRE_OK(run_program("10 PRINT RGR(4)\n"));
TEST_REQUIRE(strstr(HARNESS_OUTPUT, "text device with a character grid") != NULL,
"RGR(4) against a grid-less sink should refuse by name, got \"%s\"",
HARNESS_OUTPUT);
harness_stop();
/*