app.py

"""SHARP Gradio demo (minimal, responsive UI).

This Space:
- Runs Apple's SHARP model to predict a 3D Gaussian scene from a single image.
- Exports a canonical `.ply` file for download.
- Optionally renders a camera trajectory `.mp4` (CUDA / ZeroGPU only).

Precompiled examples
Place precompiled examples under `assets/examples/`.

Recommended structure (matching stem):
  assets/examples/<name>.jpg|png|webp
  assets/examples/<name>.mp4
  assets/examples/<name>.ply

Optional manifest (assets/examples/manifest.json):
  [
    {"label": "Desk", "image": "desk.jpg", "video": "desk.mp4", "ply": "desk.ply"},
    ...
  ]
"""

from __future__ import annotations

import json
from dataclasses import dataclass
from pathlib import Path
from typing import Final

import gradio as gr

from model_utils import TrajectoryType, predict_and_maybe_render_gpu

# -----------------------------------------------------------------------------
# Paths & constants
# -----------------------------------------------------------------------------

APP_DIR: Final[Path] = Path(__file__).resolve().parent
OUTPUTS_DIR: Final[Path] = APP_DIR / "outputs"
ASSETS_DIR: Final[Path] = APP_DIR / "assets"
EXAMPLES_DIR: Final[Path] = ASSETS_DIR / "examples"

IMAGE_EXTS: Final[tuple[str, ...]] = (".png", ".jpg", ".jpeg", ".webp")
DEFAULT_QUEUE_MAX_SIZE: Final[int] = 32

THEME: Final = gr.themes.Soft(
    primary_hue="indigo",
    secondary_hue="blue",
    neutral_hue="slate",
)

CSS: Final[str] = """
/* Keep layout stable when scrollbars appear/disappear */
html { scrollbar-gutter: stable; }

/* Use normal document flow (no fixed-height viewport shell) */
html, body { height: auto; }
body { overflow: auto; }

/* Comfortable max width; still fills small screens */
.gradio-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0.75rem 1rem 1rem;
  box-sizing: border-box;
}

/* Make media components responsive without stretching */
#run-image, #run-video,
#examples-image, #examples-video {
  width: 100%;
}

/* Keep aspect ratio and prevent runaway vertical growth on tall viewports */
#run-image img, #examples-image img {
  width: 100%;
  height: auto;
  max-height: 70vh;
  object-fit: contain;
}
#run-video video, #examples-video video {
  width: 100%;
  height: auto;
  max-height: 70vh;
  object-fit: contain;
}

/* On very small screens, reduce max media height a bit */
@media (max-width: 640px) {
  #run-image img, #examples-image img,
  #run-video video, #examples-video video {
    max-height: 55vh;
  }
}

/* Reduce extra whitespace in markdown blocks */
.gr-markdown > :first-child { margin-top: 0 !important; }
.gr-markdown > :last-child { margin-bottom: 0 !important; }
"""

# -----------------------------------------------------------------------------
# Helpers
# -----------------------------------------------------------------------------


def _ensure_dir(path: Path) -> Path:
    path.mkdir(parents=True, exist_ok=True)
    return path


@dataclass(frozen=True, slots=True)
class ExampleSpec:
    """A precompiled example bundle (image + optional mp4 + optional ply)."""

    label: str
    image: Path
    video: Path | None
    ply: Path | None


def _normalize_key(path: str) -> str:
    """Normalize a path-like string for stable dictionary keys."""
    try:
        return str(Path(path).resolve())
    except Exception:
        return path


def _load_manifest(manifest_path: Path) -> list[dict]:
    """Load manifest.json if present; return an empty list on errors."""
    try:
        data = json.loads(manifest_path.read_text(encoding="utf-8"))
        if not isinstance(data, list):
            raise ValueError("manifest.json must contain a JSON list.")
        return [x for x in data if isinstance(x, dict)]
    except FileNotFoundError:
        return []
    except Exception as e:
        # Manifest errors should not crash the app.
        print(f"[examples] Failed to parse manifest.json: {type(e).__name__}: {e}")
        return []


def discover_examples(examples_dir: Path) -> list[ExampleSpec]:
    """Discover example bundles under assets/examples/."""
    _ensure_dir(examples_dir)

    manifest_rows = _load_manifest(examples_dir / "manifest.json")
    if manifest_rows:
        specs: list[ExampleSpec] = []
        for row in manifest_rows:
            label = str(row.get("label") or "Example").strip() or "Example"
            image_rel = row.get("image")
            if not image_rel:
                continue

            image = (examples_dir / str(image_rel)).resolve()
            if not image.exists():
                continue

            video = None
            ply = None
            if row.get("video"):
                v = (examples_dir / str(row["video"])).resolve()
                if v.exists():
                    video = v
            if row.get("ply"):
                p = (examples_dir / str(row["ply"])).resolve()
                if p.exists():
                    ply = p

            specs.append(ExampleSpec(label=label, image=image, video=video, ply=ply))
        return specs

    # Fallback: infer bundles by filename stem
    images: list[Path] = []
    for ext in IMAGE_EXTS:
        images.extend(sorted(examples_dir.glob(f"*{ext}")))

    specs = []
    for img in images:
        stem = img.stem
        video = examples_dir / f"{stem}.mp4"
        ply = examples_dir / f"{stem}.ply"
        specs.append(
            ExampleSpec(
                label=stem.replace("_", " ").strip() or stem,
                image=img.resolve(),
                video=video.resolve() if video.exists() else None,
                ply=ply.resolve() if ply.exists() else None,
            )
        )
    return specs


_ensure_dir(OUTPUTS_DIR)

EXAMPLE_SPECS: Final[list[ExampleSpec]] = discover_examples(EXAMPLES_DIR)
EXAMPLE_INDEX_BY_PATH: Final[dict[str, ExampleSpec]] = {
    _normalize_key(str(s.image)): s for s in EXAMPLE_SPECS
}
EXAMPLE_INDEX_BY_NAME: Final[dict[str, ExampleSpec]] = {
    s.image.name: s for s in EXAMPLE_SPECS
}


def load_example_assets(
    image_path: str | None,
) -> tuple[str | None, str | None, str | None, str]:
    """Return (image, video, ply_path, status) for the selected example image."""
    if not image_path:
        return None, None, None, "No example selected."

    spec = EXAMPLE_INDEX_BY_PATH.get(_normalize_key(image_path))
    if spec is None:
        spec = EXAMPLE_INDEX_BY_NAME.get(Path(image_path).name)

    if spec is None:
        return image_path, None, None, "No matching example bundle found."

    video = str(spec.video) if spec.video is not None else None
    ply_path = str(spec.ply) if spec.ply is not None else None

    missing: list[str] = []
    if video is None:
        missing.append("MP4")
    if ply_path is None:
        missing.append("PLY")

    msg = f"Loaded example: **{spec.label}**."
    if missing:
        msg += f" Missing: {', '.join(missing)}."

    return str(spec.image), video, ply_path, msg


def _validate_image(image_path: str | None) -> None:
    if not image_path:
        raise gr.Error("Upload an image first.")


def run_sharp(
    image_path: str | None,
    trajectory_type: TrajectoryType,
    output_long_side: int,
    num_frames: int,
    fps: int,
    render_video: bool,
) -> tuple[str | None, str | None, str]:
    """Run SHARP inference and return (video_path, ply_path, status_markdown)."""
    _validate_image(image_path)
    out_long_side: int | None = (
        None if int(output_long_side) <= 0 else int(output_long_side)
    )

    try:
        video_path, ply_path = predict_and_maybe_render_gpu(
            image_path,
            trajectory_type=trajectory_type,
            num_frames=int(num_frames),
            fps=int(fps),
            output_long_side=out_long_side,
            render_video=bool(render_video),
        )

        lines: list[str] = [f"**PLY:** `{ply_path.name}` (ready to download)"]
        if render_video:
            if video_path is None:
                lines.append("**Video:** not rendered (CUDA unavailable).")
            else:
                lines.append(f"**Video:** `{video_path.name}`")
        else:
            lines.append("**Video:** disabled.")

        return (
            str(video_path) if video_path is not None else None,
            str(ply_path),
            "\n".join(lines),
        )
    except gr.Error:
        raise
    except Exception as e:
        raise gr.Error(f"SHARP failed: {type(e).__name__}: {e}") from e


# -----------------------------------------------------------------------------
# UI
# -----------------------------------------------------------------------------


def build_demo() -> gr.Blocks:
    with gr.Blocks(
        title="SHARP • Single-Image 3D Gaussian Prediction",
        elem_id="sharp-root",
        fill_height=True,
    ) as demo:
        gr.Markdown("## SHARP\nSingle-image **3D Gaussian scene** prediction.")

        # Run tab components are referenced by Examples tab, so keep them in outer scope.
        with gr.Column(elem_id="tabs-shell"):
            with gr.Tabs():
                with gr.Tab("Run", id="run"):
                    with gr.Column(elem_id="run-panel"):
                        with gr.Row(equal_height=True, elem_id="run-media-row"):
                            with gr.Column(
                                scale=5, min_width=360, elem_id="run-left-col"
                            ):
                                image_in = gr.Image(
                                    label="Input image",
                                    type="filepath",
                                    sources=["upload"],
                                    elem_id="run-image",
                                )

                                with gr.Row():
                                    trajectory = gr.Dropdown(
                                        label="Trajectory",
                                        choices=[
                                            "swipe",
                                            "shake",
                                            "rotate",
                                            "rotate_forward",
                                        ],
                                        value="rotate_forward",
                                    )
                                    output_res = gr.Dropdown(
                                        label="Output long side",
                                        info="0 = match input",
                                        choices=[
                                            ("Match input", 0),
                                            ("512", 512),
                                            ("768", 768),
                                            ("1024", 1024),
                                            ("1280", 1280),
                                            ("1536", 1536),
                                        ],
                                        value=0,
                                    )

                                with gr.Row():
                                    frames = gr.Slider(
                                        label="Frames",
                                        minimum=24,
                                        maximum=120,
                                        step=1,
                                        value=60,
                                    )
                                    fps_in = gr.Slider(
                                        label="FPS",
                                        minimum=8,
                                        maximum=60,
                                        step=1,
                                        value=30,
                                    )

                                render_toggle = gr.Checkbox(
                                    label="Render MP4 (CUDA / ZeroGPU only)",
                                    value=True,
                                )

                            with gr.Column(
                                scale=5, min_width=360, elem_id="run-right-col"
                            ):
                                video_out = gr.Video(
                                    label="Trajectory video (MP4)",
                                    elem_id="run-video",
                                )
                                with gr.Row(elem_id="run-download-row"):
                                    ply_download = gr.DownloadButton(
                                        label="Download PLY (.ply)",
                                        value=None,
                                        visible=True,
                                        elem_id="run-ply-download",
                                    )
                                status_md = gr.Markdown("", elem_id="run-status")

                        with gr.Row(elem_id="run-actions-row"):
                            run_btn = gr.Button("Generate", variant="primary")
                            clear_btn = gr.ClearButton(
                                [image_in, video_out, ply_download, status_md],
                                value="Clear",
                            )

                        # Ensure clearing also clears any previous download target.
                        clear_btn.click(
                            fn=lambda: None,
                            outputs=[ply_download],
                            queue=False,
                        )

                    run_btn.click(
                        fn=run_sharp,
                        inputs=[
                            image_in,
                            trajectory,
                            output_res,
                            frames,
                            fps_in,
                            render_toggle,
                        ],
                        outputs=[video_out, ply_download, status_md],
                        api_visibility="public",
                    )

                with gr.Tab("Examples", id="examples"):
                    with gr.Column(elem_id="examples-panel"):
                        if EXAMPLE_SPECS:
                            gr.Markdown(
                                "Click an example to preview precompiled outputs. "
                                "The example image will also be loaded into the Run tab."
                            )

                            # Define preview outputs first (unrendered), so we can reference them from gr.Examples.
                            ex_img = gr.Image(
                                label="Example image",
                                type="filepath",
                                interactive=False,
                                render=False,
                                height=360,
                                elem_id="examples-image",
                            )
                            ex_vid = gr.Video(
                                label="Pre-rendered MP4",
                                render=False,
                                height=360,
                                elem_id="examples-video",
                            )
                            ex_ply = gr.DownloadButton(
                                label="Download PLY (.ply)",
                                value=None,
                                visible=True,
                                render=False,
                                elem_id="examples-ply-download",
                            )
                            ex_status = gr.Markdown(
                                render=False, elem_id="examples-status"
                            )

                            with gr.Row(equal_height=True):
                                with gr.Column(scale=4, min_width=320):
                                    gr.Examples(
                                        examples=[
                                            [str(s.image)] for s in EXAMPLE_SPECS
                                        ],
                                        example_labels=[s.label for s in EXAMPLE_SPECS],
                                        inputs=[image_in],
                                        outputs=[ex_img, ex_vid, ex_ply, ex_status],
                                        fn=load_example_assets,
                                        cache_examples=False,
                                        run_on_click=True,
                                        examples_per_page=10,
                                        label=None,
                                    )

                                with gr.Column(scale=6, min_width=360):
                                    ex_img.render()
                                    ex_vid.render()
                                    ex_ply.render()
                                    ex_status.render()

                                    gr.Markdown(
                                        "Add example bundles under `assets/examples/` "
                                        "(image + mp4 + ply) or provide a `manifest.json`."
                                    )
                        else:
                            gr.Markdown(
                                "No precompiled examples found.\n\n"
                                "Add files under `assets/examples/`:\n"
                                "- `example.jpg` (or png/webp)\n"
                                "- `example.mp4`\n"
                                "- `example.ply`\n\n"
                                "Optionally add `assets/examples/manifest.json` to define labels and filenames."
                            )

                with gr.Tab("About", id="about"):
                    with gr.Column(elem_id="about-panel"):
                        gr.Markdown(
                            """
*Sharp Monocular View Synthesis in Less Than a Second* (Apple, 2025)

```bibtex
@inproceedings{Sharp2025:arxiv,
  title      = {Sharp Monocular View Synthesis in Less Than a Second},
  author     = {Lars Mescheder and Wei Dong and Shiwei Li and Xuyang Bai and Marcel Santos and Peiyun Hu and Bruno Lecouat and Mingmin Zhen and Ama\\"{e}l Delaunoyand Tian Fang and Yanghai Tsin and Stephan R. Richter and Vladlen Koltun},
  journal    = {arXiv preprint arXiv:2512.10685},
  year       = {2025},
  url        = {https://arxiv.org/abs/2512.10685},
}
```
                            """.strip()
                        )

        demo.queue(max_size=DEFAULT_QUEUE_MAX_SIZE, default_concurrency_limit=1)
        return demo


demo = build_demo()

if __name__ == "__main__":
    demo.launch(theme=THEME, css=CSS)