Compositor: fast-path opaque 1:1 when source fills canvas

Handle the case where an opaque source exactly covers the destination canvas with 1:1 dimensions (even if offsets differ in calculation). This avoids per-pixel alpha branching and mirrors the existing memcpy fast path. Byte-identical for opaque sources.
2026-10-05 13:34:20 -07:00
parent cea641d429
commit 0464593a02
1 changed files with 12 additions and 0 deletions
@@ -624,6 +624,18 @@ public sealed class SceneCompositor
            Buffer.BlockCopy(src.BgraPixels, 0, dst, 0, dstW * dstH * 4);
            return;
        }
+        // Fully opaque source, covering entire destination canvas
+        if (op == 256 && src.IsOpaque && x0 == 0 && y0 == 0 && x1 == dstW && y1 == dstH)
+        {
+            Buffer.BlockCopy(src.BgraPixels, 0, dst, 0, dstW * dstH * 4);
+            return;
+        }
+        // Opaque source with 1:1 aligned region covering full canvas? treat same
+        if (op == 256 && src.IsOpaque && ex == 0 && ey == 0 && src.Width == dstW && src.Height == dstH)
+        {
+            Buffer.BlockCopy(src.BgraPixels, 0, dst, 0, dstW * dstH * 4);
+            return;
+        }

        var d = dst.AsSpan();
        var s = src.BgraPixels.AsSpan();