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fix(linux/capture): cursor meta size range must cover Mutter's fixed 384x384 offer

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Mutter offers SPA_META_Cursor with a FIXED size pod —
SPA_POD_Int(CURSOR_META_SIZE(384, 384)) in meta-screen-cast-stream-src.c —
while our request capped the range at meta_size(256, 256). The intersection
is empty, so the Meta param silently failed to negotiate and no buffer ever
carried the meta region: the entire Linux cursor pipeline (forward AND
blend) was blind on GNOME, proven by an on-glass probe counting 32k+
buffers with zero metas. KWin's offer fits inside 256², which is why the
same consumer code passed there. Raise the max to 1024² headroom (the
negotiated allocation follows the producer's value, not our max) and align
the bitmap parse guard.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
enricobuehler
2026-07-22 23:47:53 +02:00
co-authored by Claude Fable 5
parent 151adc4bcc
commit 9db4841ce4
1 changed files with 11 additions and 3 deletions
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crates/pf-capture/src/linux/mod.rs
+11 -3
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@@ -1323,10 +1323,17 @@ mod pipewire {
value: pw::spa::pod::Value::Choice(pw::spa::pod::ChoiceValue::Int(
pw::spa::utils::Choice(
pw::spa::utils::ChoiceFlags::empty(),
// The max must cover the producer's offer or the Meta param silently
// fails to negotiate and NO buffer ever carries the meta region:
// Mutter offers a FIXED `SPA_POD_Int(CURSOR_META_SIZE(384, 384))`
// (meta-screen-cast-stream-src.c, GNOME 50) — a 256² max made the
// intersection empty, which cost the whole Linux cursor channel
// on-glass. 1024² is headroom, not an allocation: the negotiated
// region follows the producer's value.
pw::spa::utils::ChoiceEnum::Range {
default: meta_size(64, 64),
min: meta_size(1, 1),
max: meta_size(256, 256),
max: meta_size(1024, 1024),
},
),
)),
@@ -1444,8 +1451,9 @@ mod pipewire {
(*bmp).offset as usize,
)
};
// Ignore empty or implausibly large bitmaps (we requested <= 256×256).
if bw == 0 || bh == 0 || bw > 256 || bh > 256 {
// Ignore empty or implausibly large bitmaps (the meta-size request covers <= 1024×1024;
// real cursors are ≤96px — the cursor channel downscales >120px for the wire anyway).
if bw == 0 || bh == 0 || bw > 1024 || bh > 1024 {
return;
}
let row = bw as usize * 4;