Decode PPI face payloads

src/assets/image_pixels.cpp

@@ -0,0 +1,94 @@
+#include "assets/image_pixels.h"
+
+#include "assets/image_metadata.h"
+
+#include <limits>
+#include <utility>
+
+#define STB_IMAGE_STATIC
+#define STB_IMAGE_IMPLEMENTATION
+#include <stb/stb_image.h>
+
+namespace pp::assets {
+
+namespace {
+
+[[nodiscard]] pp::foundation::Result<std::size_t> rgba_byte_size(
+    std::uint32_t width,
+    std::uint32_t height) noexcept
+{
+    const auto pixels = static_cast<std::uint64_t>(width) * static_cast<std::uint64_t>(height);
+    constexpr auto channels = 4ULL;
+    if (pixels > std::numeric_limits<std::uint64_t>::max() / channels) {
+        return pp::foundation::Result<std::size_t>::failure(
+            pp::foundation::Status::out_of_range("RGBA byte size overflows"));
+    }
+
+    const auto bytes = pixels * channels;
+    if (bytes > static_cast<std::uint64_t>(std::numeric_limits<std::size_t>::max())) {
+        return pp::foundation::Result<std::size_t>::failure(
+            pp::foundation::Status::out_of_range("RGBA byte size exceeds addressable memory"));
+    }
+
+    return pp::foundation::Result<std::size_t>::success(static_cast<std::size_t>(bytes));
+}
+
+}
+
+pp::foundation::Result<Rgba8Image> decode_png_rgba8(std::span<const std::byte> bytes)
+{
+    const auto metadata = parse_png_metadata(bytes);
+    if (!metadata) {
+        return pp::foundation::Result<Rgba8Image>::failure(metadata.status());
+    }
+
+    if (bytes.size() > static_cast<std::size_t>(std::numeric_limits<int>::max())) {
+        return pp::foundation::Result<Rgba8Image>::failure(
+            pp::foundation::Status::out_of_range("PNG payload is too large for the decoder"));
+    }
+
+    int width = 0;
+    int height = 0;
+    int source_components = 0;
+    auto* decoded = stbi_load_from_memory(
+        reinterpret_cast<const stbi_uc*>(bytes.data()),
+        static_cast<int>(bytes.size()),
+        &width,
+        &height,
+        &source_components,
+        4);
+    if (decoded == nullptr) {
+        return pp::foundation::Result<Rgba8Image>::failure(
+            pp::foundation::Status::invalid_argument("PNG payload could not be decoded"));
+    }
+
+    const auto cleanup = [decoded]() noexcept {
+        stbi_image_free(decoded);
+    };
+
+    if (width <= 0 || height <= 0
+        || static_cast<std::uint32_t>(width) != metadata.value().width
+        || static_cast<std::uint32_t>(height) != metadata.value().height) {
+        cleanup();
+        return pp::foundation::Result<Rgba8Image>::failure(
+            pp::foundation::Status::invalid_argument("decoded PNG dimensions are inconsistent"));
+    }
+
+    const auto byte_count = rgba_byte_size(metadata.value().width, metadata.value().height);
+    if (!byte_count) {
+        cleanup();
+        return pp::foundation::Result<Rgba8Image>::failure(byte_count.status());
+    }
+
+    Rgba8Image image {
+        .width = metadata.value().width,
+        .height = metadata.value().height,
+        .pixels = {},
+    };
+    image.pixels.assign(decoded, decoded + byte_count.value());
+    cleanup();
+
+    return pp::foundation::Result<Rgba8Image>::success(std::move(image));
+}
+
+}

src/assets/image_pixels.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "foundation/result.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <span>
+#include <vector>
+
+namespace pp::assets {
+
+struct Rgba8Image {
+    std::uint32_t width = 0;
+    std::uint32_t height = 0;
+    std::vector<std::uint8_t> pixels;
+};
+
+[[nodiscard]] pp::foundation::Result<Rgba8Image> decode_png_rgba8(
+    std::span<const std::byte> bytes);
+
+}

src/assets/ppi_header.cpp

@@ -561,4 +561,59 @@ pp::foundation::Result<PpiProjectIndex> parse_ppi_project_index(std::span<const
     });
 }
 
+pp::foundation::Result<PpiDecodedProjectImages> decode_ppi_project_images(std::span<const std::byte> bytes)
+{
+    auto project = parse_ppi_project_index(bytes);
+    if (!project) {
+        return pp::foundation::Result<PpiDecodedProjectImages>::failure(project.status());
+    }
+
+    PpiDecodedProjectImages decoded {
+        .project = project.value(),
+        .faces = {},
+    };
+    decoded.faces.reserve(decoded.project.body.summary.rgba_face_payload_count);
+
+    const auto body = bytes.subspan(decoded.project.layout.body_offset, decoded.project.layout.body_bytes);
+    for (std::size_t layer_index = 0; layer_index < decoded.project.body.layers.size(); ++layer_index) {
+        const auto& layer = decoded.project.body.layers[layer_index];
+        for (std::size_t frame_index = 0; frame_index < layer.frames.size(); ++frame_index) {
+            const auto& frame = layer.frames[frame_index];
+            for (std::size_t face_index = 0; face_index < frame.faces.size(); ++face_index) {
+                const auto& face = frame.faces[face_index];
+                if (!face.has_data) {
+                    continue;
+                }
+
+                if (face.body_payload_offset > body.size()
+                    || face.payload_bytes > body.size() - face.body_payload_offset) {
+                    return pp::foundation::Result<PpiDecodedProjectImages>::failure(
+                        pp::foundation::Status::out_of_range("PPI face payload range is outside the body"));
+                }
+
+                const auto image = decode_png_rgba8(
+                    body.subspan(face.body_payload_offset, face.payload_bytes));
+                if (!image) {
+                    return pp::foundation::Result<PpiDecodedProjectImages>::failure(image.status());
+                }
+
+                if (image.value().width != face.png_width || image.value().height != face.png_height) {
+                    return pp::foundation::Result<PpiDecodedProjectImages>::failure(
+                        pp::foundation::Status::invalid_argument("decoded PPI face payload dimensions changed"));
+                }
+
+                decoded.faces.push_back(PpiDecodedFacePayload {
+                    .layer_index = static_cast<std::uint32_t>(layer_index),
+                    .frame_index = static_cast<std::uint32_t>(frame_index),
+                    .face_index = static_cast<std::uint32_t>(face_index),
+                    .descriptor = face,
+                    .image = image.value(),
+                });
+            }
+        }
+    }
+
+    return pp::foundation::Result<PpiDecodedProjectImages>::success(std::move(decoded));
+}
+
 }

src/assets/ppi_header.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "assets/image_pixels.h"
 #include "foundation/result.h"
 
 #include <array>
@@ -104,6 +105,19 @@ struct PpiProjectIndex {
     PpiBodyIndex body;
 };
 
+struct PpiDecodedFacePayload {
+    std::uint32_t layer_index = 0;
+    std::uint32_t frame_index = 0;
+    std::uint32_t face_index = 0;
+    PpiFacePayloadSummary descriptor;
+    Rgba8Image image;
+};
+
+struct PpiDecodedProjectImages {
+    PpiProjectIndex project;
+    std::vector<PpiDecodedFacePayload> faces;
+};
+
 [[nodiscard]] pp::foundation::Result<PpiHeaderInfo> parse_ppi_header(
     std::span<const std::byte> bytes) noexcept;
 
@@ -126,4 +140,7 @@ struct PpiProjectIndex {
 [[nodiscard]] pp::foundation::Result<PpiProjectIndex> parse_ppi_project_index(
     std::span<const std::byte> bytes);
 
+[[nodiscard]] pp::foundation::Result<PpiDecodedProjectImages> decode_ppi_project_images(
+    std::span<const std::byte> bytes);
+
 }