Complete imaging and meshing integration gate (#44)

crates/libremetaverse-imaging/benches/image_pipeline.rs

@@ -0,0 +1,48 @@
+use std::alloc::System;
+use std::hint::black_box;
+use std::time::Instant;
+
+use libremetaverse_imaging::{ManagedImage, ManagedImageImageChannels};
+use stats_alloc::{INSTRUMENTED_SYSTEM, Region, StatsAlloc};
+
+#[global_allocator]
+static ALLOCATOR: &StatsAlloc<System> = &INSTRUMENTED_SYSTEM;
+
+fn main() {
+    const INPUT_SIDE: i32 = 2_048;
+    const OUTPUT_SIDE: i32 = 1_024;
+
+    let channels = ManagedImageImageChannels(
+        ManagedImageImageChannels::COLOR.0 | ManagedImageImageChannels::ALPHA.0,
+    );
+    let mut source = ManagedImage::new(INPUT_SIDE, INPUT_SIDE, channels)
+        .expect("large benchmark image must fit the documented pixel bound");
+    for (index, red) in source.red.iter_mut().enumerate() {
+        *red = u8::try_from(index & 0xff).expect("masked sample");
+    }
+    source.green.fill(97);
+    source.blue.fill(193);
+    source.alpha.fill(255);
+
+    // Warm the validation path before measuring the owned clone, resize, and export pipeline.
+    source.validate().expect("valid benchmark image");
+    let allocation_region = Region::new(ALLOCATOR);
+    let started = Instant::now();
+    let mut resized = source.clone().expect("bounded image clone");
+    resized
+        .resize_bilinear(OUTPUT_SIDE, OUTPUT_SIDE)
+        .expect("bounded bilinear resize");
+    let rgba = resized.export_raw().expect("bounded RGBA export");
+    let elapsed = started.elapsed();
+    let allocation_stats = allocation_region.change();
+
+    assert_eq!((resized.width, resized.height), (OUTPUT_SIDE, OUTPUT_SIDE));
+    assert_eq!(rgba.len(), 4 * OUTPUT_SIDE as usize * OUTPUT_SIDE as usize);
+    black_box((resized, rgba));
+    println!(
+        "image pipeline: {INPUT_SIDE}x{INPUT_SIDE} -> {OUTPUT_SIDE}x{OUTPUT_SIDE} in {elapsed:?}, {} allocations, {} reallocations, {} bytes allocated",
+        allocation_stats.allocations,
+        allocation_stats.reallocations,
+        allocation_stats.bytes_allocated,
+    );
+}