Render: bounded PNG/JPEG texture input admission (#909)

Bounded in-memory PNG/JPEG texture decoding with explicit base-colour/data-map roles; RGBA8 pixels are published only after a complete decode. Input only: no material assignment, GPU shading or persistence. Refs #900.

Contributed by @0xlillith.

Co-authored-by: lillith <[email protected]>

ROADMAP.md

@@ -89,6 +89,11 @@ PCB / Package, Render, Animation, Simulation, Manufacture/CAM, Drawings.
 
 ## Render foundation
 
+- Bounded PNG/JPEG texture admission (#900) validates in-memory sources and returns
+  completed RGBA8 pixels with explicit color/data roles. It is an input utility only:
+  ICC/16-bit normalization, local wood mapping, resource persistence and the renderer
+  consumer remain separate work. See [limits and licensed-file probes](docs/render-texture-input.md).
+
 - The initial opaque surface numerical contract for #1004 provides bounded linear
   color/metallic/roughness/IOR admission and an original tested direct-light BRDF.
   It does not enable PBR rendering or change stored appearances. See

crates/render/Cargo.toml

@@ -11,7 +11,7 @@ workspace = true
 [dependencies]
 solidcraft-geom = { workspace = true }
 serde = { workspace = true }
-image = { workspace = true }
+image = { workspace = true, features = ["jpeg"] }
 
 [dev-dependencies]
 serde_json = { workspace = true }

crates/render/src/lib.rs

@@ -10,6 +10,7 @@ mod curve_display;
 pub mod lighting;
 mod raster;
 pub mod surface;
+pub mod texture_input;
 
 pub use backend::{
     Availability, BackendDescriptor, BackendId, ExecutorDescriptor, ExecutorId, MAX_RENDER_ID_BYTES, RenderFeature, RenderFormat, RenderLimits,

crates/render/src/texture_input.rs

@@ -0,0 +1,152 @@
+//! Bounded texture admission, independent of documents, files, schedulers and GPU handles.
+//! This utility does not advertise texture/PBR support or define a persistent pack schema.
+use image::{ImageDecoder, ImageFormat, ImageReader, Limits};
+use serde::{Deserialize, Serialize};
+use std::{io::Cursor, sync::Arc};
+
+pub const MAX_TEXTURE_BYTES: usize = 16 * 1024 * 1024;
+pub const MAX_TEXTURE_EDGE: u32 = 2048;
+const MAX_CODEC_BYTES: u64 = 64 * 1024 * 1024;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum MapRole {
+    BaseColor,
+    NormalOpenGl,
+    Roughness,
+    Metallic,
+    AmbientOcclusion,
+}
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum Interpretation {
+    Srgb,
+    Data,
+}
+impl MapRole {
+    pub fn interpretation(self) -> Interpretation {
+        if self == Self::BaseColor { Interpretation::Srgb } else { Interpretation::Data }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct TextureError(pub String);
+impl std::fmt::Display for TextureError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&self.0)
+    }
+}
+impl std::error::Error for TextureError {}
+type Result<T> = std::result::Result<T, TextureError>;
+fn invalid(message: impl Into<String>) -> TextureError {
+    TextureError(message.into())
+}
+
+#[derive(Clone, Debug, Serialize)]
+pub struct TextureInfo {
+    pub width: u32,
+    pub height: u32,
+    pub encoded_bytes: usize,
+    pub rgba_bytes: u64,
+    pub role: MapRole,
+    pub interpretation: Interpretation,
+}
+
+/// Header-admitted source. Full decoding must succeed before publishing pixels.
+#[derive(Clone)]
+pub struct TextureSource {
+    bytes: Arc<Vec<u8>>,
+    format: ImageFormat,
+    info: TextureInfo,
+}
+fn reader(bytes: &[u8], format: ImageFormat) -> ImageReader<Cursor<&[u8]>> {
+    let mut reader = ImageReader::with_format(Cursor::new(bytes), format);
+    let mut limits = Limits::default();
+    limits.max_image_width = Some(MAX_TEXTURE_EDGE);
+    limits.max_image_height = Some(MAX_TEXTURE_EDGE);
+    limits.max_alloc = Some(MAX_CODEC_BYTES);
+    reader.limits(limits);
+    reader
+}
+fn guarded<T>(work: impl FnOnce() -> Result<T>) -> Result<T> {
+    std::panic::catch_unwind(std::panic::AssertUnwindSafe(work)).map_err(|_| invalid("texture decoder failed"))?
+}
+impl TextureSource {
+    pub fn new(bytes: Vec<u8>, role: MapRole) -> Result<Self> {
+        if bytes.is_empty() || bytes.len() > MAX_TEXTURE_BYTES || bytes.capacity() > MAX_TEXTURE_BYTES {
+            return Err(invalid("texture input must contain at most 16 MiB"));
+        }
+        let format = image::guess_format(&bytes).map_err(|_| invalid("texture must be PNG or JPEG"))?;
+        if !matches!(format, ImageFormat::Png | ImageFormat::Jpeg) {
+            return Err(invalid("texture must be PNG or JPEG; HDR uses the Radiance input utility"));
+        }
+        // Whole-image codecs may return pixels before noticing a missing trailer. This
+        // marker check rejects that truncation; it is not a general container validator.
+        let complete = match format {
+            ImageFormat::Png => bytes.ends_with(b"\x00\x00\x00\x00IEND\xae\x42\x60\x82"),
+            ImageFormat::Jpeg => bytes.ends_with(b"\xff\xd9"),
+            _ => false,
+        };
+        if !complete {
+            return Err(invalid("texture is missing its final terminator"));
+        }
+        let (width, height) = guarded(|| {
+            let mut decoder = reader(&bytes, format).into_decoder().map_err(|e| invalid(e.to_string()))?;
+            if !matches!(decoder.color_type(), image::ColorType::L8 | image::ColorType::La8 | image::ColorType::Rgb8 | image::ColorType::Rgba8) {
+                return Err(invalid("only 8-bit texture channels are supported"));
+            }
+            if decoder.icc_profile().map_err(|e| invalid(e.to_string()))?.is_some() {
+                return Err(invalid("embedded ICC profiles need explicit color conversion before admission"));
+            }
+            if decoder.orientation().map_err(|e| invalid(e.to_string()))? != image::metadata::Orientation::NoTransforms {
+                return Err(invalid("texture orientation must be normalized before admission"));
+            }
+            Ok(decoder.dimensions())
+        })?;
+        if width == 0 || height == 0 || width > MAX_TEXTURE_EDGE || height > MAX_TEXTURE_EDGE {
+            return Err(invalid("texture dimensions exceed 2048x2048"));
+        }
+        let rgba_bytes = u64::from(width) * u64::from(height) * 4;
+        let info = TextureInfo { width, height, encoded_bytes: bytes.len(), rgba_bytes, role, interpretation: role.interpretation() };
+        Ok(Self { bytes: Arc::new(bytes), format, info })
+    }
+    pub fn info(&self) -> &TextureInfo {
+        &self.info
+    }
+    /// Bounded whole-image codec work, intended for a caller-owned worker. Cancellation is
+    /// checked at the codec boundary, not during PNG/JPEG decoding. No partial image escapes.
+    pub fn decode(&self, cancelled: impl Fn() -> bool) -> Result<DecodedTexture> {
+        if cancelled() {
+            return Err(invalid("texture decoding cancelled"));
+        }
+        let image = guarded(|| reader(&self.bytes, self.format).decode().map_err(|e| invalid(e.to_string())))?;
+        if cancelled() {
+            return Err(invalid("texture decoding cancelled"));
+        }
+        let pixels = guarded(|| Ok(image.into_rgba8().into_raw()))?;
+        if cancelled() {
+            return Err(invalid("texture decoding cancelled"));
+        }
+        if pixels.len() as u64 != self.info.rgba_bytes {
+            return Err(invalid("decoded texture dimensions changed"));
+        }
+        Ok(DecodedTexture { info: self.info.clone(), pixels })
+    }
+}
+/// Completed pixels retain encoded channel values. sRGB conversion, normal basis handling
+/// and sampling belong to the eventual renderer adapter, not this input utility.
+pub struct DecodedTexture {
+    info: TextureInfo,
+    pixels: Vec<u8>,
+}
+impl DecodedTexture {
+    pub fn info(&self) -> &TextureInfo {
+        &self.info
+    }
+    pub fn rgba(&self) -> &[u8] {
+        &self.pixels
+    }
+}
+
+#[cfg(test)]
+mod tests;

crates/render/src/texture_input/tests.rs

@@ -0,0 +1,65 @@
+use super::*;
+
+fn png(width: u32, height: u32) -> Vec<u8> {
+    let image = image::RgbaImage::from_pixel(width, height, image::Rgba([64, 128, 192, 255]));
+    let mut out = Cursor::new(Vec::new());
+    image.write_to(&mut out, ImageFormat::Png).unwrap();
+    out.into_inner()
+}
+#[test]
+fn texture_input_preserves_channels_and_explicit_map_interpretation() {
+    for role in [MapRole::BaseColor, MapRole::NormalOpenGl, MapRole::Roughness, MapRole::Metallic, MapRole::AmbientOcclusion] {
+        let source = TextureSource::new(png(3, 2), role).unwrap();
+        let decoded = source.decode(|| false).unwrap();
+        assert_eq!((decoded.info().width, decoded.info().height, decoded.info().rgba_bytes), (3, 2, 24));
+        assert_eq!(decoded.info().interpretation, if role == MapRole::BaseColor { Interpretation::Srgb } else { Interpretation::Data });
+        assert!(decoded.rgba().as_chunks::<4>().0.iter().all(|p| *p == [64, 128, 192, 255]));
+    }
+}
+#[test]
+fn texture_input_rejects_dimensions_formats_and_corrupt_pixels() {
+    assert!(TextureSource::new(png(MAX_TEXTURE_EDGE + 1, 1), MapRole::BaseColor).is_err());
+    assert!(TextureSource::new(Vec::new(), MapRole::BaseColor).is_err());
+    assert!(TextureSource::new(b"#?RADIANCE\nFORMAT=32-bit_rle_rgbe\n\n-Y 1 +X 2\nabcdefgh".to_vec(), MapRole::BaseColor).is_err());
+    let bytes = png(3, 2);
+    for n in 0..bytes.len() {
+        if let Ok(source) = TextureSource::new(bytes.get(..n).unwrap().to_vec(), MapRole::BaseColor) {
+            assert!(source.decode(|| false).is_err(), "truncated PNG accepted at {n}");
+        }
+    }
+}
+#[test]
+fn texture_input_cancellation_never_publishes_partial_pixels() {
+    let source = TextureSource::new(png(3, 2), MapRole::NormalOpenGl).unwrap();
+    assert!(source.decode(|| true).is_err());
+    let calls = std::cell::Cell::new(0);
+    assert!(
+        source
+            .decode(|| {
+                calls.set(calls.get() + 1);
+                calls.get() == 2
+            })
+            .is_err()
+    );
+    assert!(source.clone().decode(|| false).is_ok());
+}
+#[test]
+fn texture_input_jpeg_is_supported_without_hdr_feature_confusion() {
+    let image = image::RgbImage::from_pixel(2, 2, image::Rgb([64, 128, 192]));
+    let mut out = Cursor::new(Vec::new());
+    image.write_to(&mut out, ImageFormat::Jpeg).unwrap();
+    let source = TextureSource::new(out.into_inner(), MapRole::BaseColor).unwrap();
+    assert_eq!(source.decode(|| false).unwrap().rgba().len(), 16);
+}
+
+#[test]
+fn texture_input_caps_encoded_storage_and_refuses_precision_loss() {
+    let mut bytes = Vec::with_capacity(MAX_TEXTURE_BYTES + 1);
+    bytes.extend(png(1, 1));
+    assert!(TextureSource::new(bytes, MapRole::Roughness).is_err());
+    assert!(TextureSource::new(vec![0; MAX_TEXTURE_BYTES + 1], MapRole::BaseColor).is_err());
+    let image = image::DynamicImage::ImageLuma16(image::ImageBuffer::from_pixel(1, 1, image::Luma([32768u16])));
+    let mut out = Cursor::new(Vec::new());
+    image.write_to(&mut out, ImageFormat::Png).unwrap();
+    assert!(TextureSource::new(out.into_inner(), MapRole::NormalOpenGl).is_err());
+}

docs/render-texture-input.md

@@ -0,0 +1,74 @@
+# Bounded texture input (resource admission)
+
+`solidcraft_render::texture_input` is an independent input utility for #900, coordinated
+with #792 and #813. It accepts in-memory PNG/JPEG bytes and supplies completed RGBA8
+pixels. It does not change a document, read files, assign materials, add a resource-pack
+format, schedule work, upload GPU data or advertise PBR/triplanar support.
+
+`TextureSource::new(bytes, role)` admits bounded headers; `decode(cancelled)` validates
+the whole image before returning `DecodedTexture`. Sources are immutable and shared.
+Header admission alone is not proof of valid pixel data. PNG/JPEG codecs run as bounded
+whole-image operations, so a host must use its own worker rather than block the UI.
+Cancellation is checked before/after decoding and conversion; it cannot interrupt a
+codec internally. This is not the cooperative row API of the separate HDR utility.
+
+Roles are `base_color`, `normal_open_gl`, `roughness`, `metallic`, `ambient_occlusion`.
+Base color declares sRGB interpretation; other roles retain data-channel values.
+The utility does not apply a transfer function, normalize normals, swap DirectX normal
+channels, unpack combined maps or infer semantics from file names. Missing maps,
+material defaults and sampling/basis choices belong to the eventual renderer adapter.
+
+Initial limits and exclusions:
+
+- Nonempty encoded storage, including Vec capacity, at most 16 MiB.
+- PNG/JPEG only, with a required final PNG IEND / JPEG EOI marker. This does not
+  constitute a complete container-framing/trailing-data validator.
+- Positive dimensions, each at most 2048; completed RGBA8 is at most 16 MiB.
+- Codec allocation limit 64 MiB, separately from retained encoded bytes and output
+  conversion. This is not a combined CPU/GPU memory guarantee.
+- Eight-bit channels only. Sixteen-bit files refuse rather than silently quantize.
+- Embedded ICC profiles and nontrivial EXIF orientation refuse. Explicit color-space
+  conversion/orientation normalization is required before admission; no ICC transform
+  or PNG gamma correction is performed here. Untagged base color is a caller-declared
+  sRGB input, not an inferred or certified source color space.
+- Third-party decoding/conversion panics are contained and partial buffers never escape.
+  GPU allocation, browser scheduling and document/session generations remain host concerns.
+
+The numerical opaque-surface contract is available in `surface`; its product consumer
+is being integrated separately in #1046 under #1004. The texture/environment adapter
+and its resource ownership are still separate work coordinated in #813.
+Wood repeat size/rotation, definition-local grain frames, durable resource identity,
+source/license receipts, document packaging and setup-owned HDR rotation/exposure must
+use that agreed consumer representation. This input utility does not reserve any of
+those fields or a document version. The scalar library from #863 remains distinct.
+
+HDR environments use existing `lighting::HdrSource` / `HdrDecodeTask`, not this PNG/JPEG
+path: Radiance RGBE, at most 16 MiB and 2048x1024, standard 2:1 lat-long, finite corrected
+radiance. See [HDR input](render-hdr-input.md). Successful decoding alone enables neither
+IBL nor GPU preview. The current CPU snapshot executor remains unchanged and must not
+claim unsupported HDRI/PBR output.
+
+## Licensed-file probe (2026-10-14)
+
+Files were downloaded outside the checkout for validation only, from the public API
+with an identifying SolidCraft User-Agent. No assets are bundled by this change.
+[Poly Haven assets are CC0](https://polyhaven.com/license); live API integration has
+separate credit/identity conditions. These results are input checks, not shaded images:
+
+| Resource | Author / source | Result |
+|---|---|---|
+| Black Oak Veneer, 1K base-color PNG | Jenelle van Heerden; [asset](https://polyhaven.com/a/black_oak_veneer) | Refused: 16-bit channel precision is outside this initial utility. |
+| Black Oak Veneer, 1K base-color JPEG | Same asset/author | Refused: embedded ICC requires explicit color conversion. |
+| Joburg Central Sunset, 1K Radiance HDR | Greg Zaal and Dimitrios Savva; [asset](https://polyhaven.com/a/sunset_jhbcentral) | Existing HDR utility fully validates 1024x512, 1,573,705 encoded bytes, 6,291,456 linear RGB bytes. No lighting result is claimed. |
+
+The refusals are deliberate evidence of remaining normalization work, not successful
+wood integration. Provider MD5 values were checked against selected downloads and local
+SHA-256 receipts retained with source/license/retrieval metadata. Neither is a claim of
+publisher authentication. Shipped assets would require per-file ATTRIBUTION.md entries;
+private/user resources need their own portable provenance records. Reuse the maintainer's
+starter set when available rather than introduce a competing set.
+
+Tests generate original small PNG/JPEG files in code and check exact channel values,
+role interpretation, dimensions/storage limits, precision rejection, truncation,
+cancellation and continued source reuse. These tests do not establish GPU performance,
+interactive browser behavior or the final resource-pack schema.