| 1 | """DrawingML <p:pic> -> SVG <image> conversion. |
| 2 | |
| 3 | Reverse of svg_to_pptx convert_image. |
| 4 | |
| 5 | DrawingML structure: |
| 6 | <p:pic> |
| 7 | <p:blipFill> |
| 8 | <a:blip r:embed="rIdRaster"> |
| 9 | <a:extLst>...<asvg:svgBlip r:embed="rIdSvg"/>...</a:extLst> |
| 10 | </a:blip> |
| 11 | <a:srcRect l/t/r/b="1/100000"/> (optional crop) |
| 12 | <a:stretch><a:fillRect/></a:stretch> (default: fill the shape) |
| 13 | </p:blipFill> |
| 14 | <p:spPr> |
| 15 | <a:xfrm/> |
| 16 | <a:prstGeom prst="rect"/> (usually rect; can be other) |
| 17 | </p:spPr> |
| 18 | </p:pic> |
| 19 | |
| 20 | Strategy: |
| 21 | - Prefer the editable SVG relationship in asvg:svgBlip when Office also stores |
| 22 | a raster compatibility preview on a:blip; retain the raster as fallback. |
| 23 | - Default (no srcRect, plain stretch) -> a single <image> filling the box, |
| 24 | preserveAspectRatio="none". |
| 25 | - With srcRect, or with a single oversized tile that covers the frame -> wrap |
| 26 | the <image> in a nested <svg viewBox> in the unit rectangle [0,1] x [0,1], |
| 27 | with overflow hidden so cropping is expressed identically in browsers and |
| 28 | PowerPoint. |
| 29 | - Repeating tile fills still use the legacy plain-image fallback; a repeated |
| 30 | pattern cannot be represented by the project's native picture-crop subset. |
| 31 | - Image bytes are written through the result; the slide assembler decides |
| 32 | the href format (external file vs base64). |
| 33 | """ |
| 34 | |
| 35 | from __future__ import annotations |
| 36 | |
| 37 | import base64 |
| 38 | import hashlib |
| 39 | import io |
| 40 | import math |
| 41 | import mimetypes |
| 42 | import shutil |
| 43 | import subprocess |
| 44 | import tempfile |
| 45 | from dataclasses import dataclass, field |
| 46 | from pathlib import Path |
| 47 | from xml.etree import ElementTree as ET |
| 48 | |
| 49 | try: |
| 50 | from PIL import Image, ImageEnhance |
| 51 | except ImportError: # pragma: no cover - optional visual enhancement dependency |
| 52 | Image = None |
| 53 | ImageEnhance = None |
| 54 | |
| 55 | from .emu_units import NS, Xfrm, emu_to_px, fmt_num, format_ooxml_alpha |
| 56 | from .ooxml_loader import OoxmlPackage, PartRef, blip_embed_relationship_ids |
| 57 | |
| 58 | |
| 59 | @dataclass(frozen=True) |
| 60 | class PictureDiagnostic: |
| 61 | """Recoverable loss while converting one DrawingML picture.""" |
| 62 | |
| 63 | code: str |
| 64 | message: str |
| 65 | fallback: str |
| 66 | |
| 67 | |
| 68 | @dataclass |
| 69 | class PictureResult: |
| 70 | """Resolved picture: SVG element string + extracted media bytes.""" |
| 71 | |
| 72 | svg: str = "" |
| 73 | # Map of {filename: bytes} that the assembler should emit alongside |
| 74 | # the SVG. Filename is the basename inside the package's media dir. |
| 75 | media: dict[str, bytes] = field(default_factory=dict) |
| 76 | diagnostics: tuple[PictureDiagnostic, ...] = () |
| 77 | |
| 78 | |
| 79 | class MediaResolutionError(RuntimeError): |
| 80 | """Raised when a PPTX media relationship cannot be reproduced as SVG.""" |
| 81 | |
| 82 | |
| 83 | def convert_blip_fill( |
| 84 | blip_fill_elem: ET.Element, |
| 85 | xfrm: Xfrm, |
| 86 | slide_part: PartRef, |
| 87 | pkg: OoxmlPackage, |
| 88 | *, |
| 89 | media_subdir: str = "assets", |
| 90 | embed_inline: bool = False, |
| 91 | asset_name_map: dict[str, str] | None = None, |
| 92 | strict: bool = False, |
| 93 | ) -> PictureResult: |
| 94 | """Convert an <a:blipFill> element to SVG <image>. |
| 95 | |
| 96 | Handles image fill for both: |
| 97 | - <p:pic><p:blipFill> (standard picture elements) |
| 98 | - <p:sp><p:spPr><a:blipFill> (shape with image fill, e.g. Canva exports) |
| 99 | """ |
| 100 | blip = blip_fill_elem.find("a:blip", NS) |
| 101 | if blip is None: |
| 102 | return PictureResult() |
| 103 | |
| 104 | relationship_ids = blip_embed_relationship_ids(blip) |
| 105 | linked_rid = blip.attrib.get(f"{{{NS['r']}}}link") |
| 106 | if not relationship_ids: |
| 107 | if linked_rid: |
| 108 | raise MediaResolutionError( |
| 109 | "Linked image relationships are not supported; embed the image in PowerPoint first" |
| 110 | ) |
| 111 | return PictureResult() |
| 112 | |
| 113 | target: str | None = None |
| 114 | img_bytes: bytes | None = None |
| 115 | failures: list[str] = [] |
| 116 | for rel_id in relationship_ids: |
| 117 | candidate = slide_part.resolve_rel(rel_id) |
| 118 | if not candidate: |
| 119 | failures.append(f"{rel_id}: unresolved") |
| 120 | continue |
| 121 | candidate_bytes = pkg.read_media(candidate) |
| 122 | if candidate_bytes is None: |
| 123 | failures.append(f"{rel_id}: missing {candidate}") |
| 124 | continue |
| 125 | if Path(candidate).suffix.lower() == ".svg" and not _is_valid_svg_media(candidate_bytes): |
| 126 | failures.append(f"{rel_id}: invalid SVG media {candidate}") |
| 127 | continue |
| 128 | target = candidate |
| 129 | img_bytes = candidate_bytes |
| 130 | break |
| 131 | if target is None or img_bytes is None: |
| 132 | details = "; ".join(failures) |
| 133 | raise MediaResolutionError( |
| 134 | f"No embedded image relationship can be read in {slide_part.path}: {details}" |
| 135 | ) |
| 136 | |
| 137 | filename = (asset_name_map or {}).get(target, pkg.media_filename(target)) |
| 138 | filename, img_bytes = _normalize_office_media(filename, img_bytes) |
| 139 | tile_source_bytes = img_bytes |
| 140 | diagnostics = list(_unsupported_blip_effect_diagnostics(blip)) |
| 141 | filename, img_bytes, effect_diagnostics = _apply_blip_image_effects( |
| 142 | filename, |
| 143 | img_bytes, |
| 144 | blip, |
| 145 | ) |
| 146 | diagnostics.extend(effect_diagnostics) |
| 147 | opacity_attr, opacity_diagnostics = _blip_opacity_attr(blip) |
| 148 | diagnostics.extend(opacity_diagnostics) |
| 149 | if strict and diagnostics: |
| 150 | details = "; ".join(item.message for item in diagnostics) |
| 151 | raise ValueError(f"Cannot reproduce DrawingML picture effects: {details}") |
| 152 | href = _build_href(filename, img_bytes, media_subdir, embed_inline) |
| 153 | |
| 154 | # srcRect: l/t/r/b in 1/100000ths (so 50000 = 50%). |
| 155 | src_rect = blip_fill_elem.find("a:srcRect", NS) |
| 156 | crop = _parse_src_rect(src_rect) |
| 157 | |
| 158 | # A tile larger than its frame is visually a crop, not a stretch. Preserve |
| 159 | # that common PowerPoint background construction through the same nested |
| 160 | # SVG transport used for srcRect. True repeated patterns retain the legacy |
| 161 | # plain-image fallback because native export has no registered tile subset. |
| 162 | tile = blip_fill_elem.find("a:tile", NS) |
| 163 | if crop is None and tile is not None: |
| 164 | crop = _single_cover_tile_crop( |
| 165 | tile, |
| 166 | blip_fill_elem, |
| 167 | xfrm, |
| 168 | tile_source_bytes, |
| 169 | ) |
| 170 | |
| 171 | if crop is None: |
| 172 | # Plain unclipped image |
| 173 | svg = ( |
| 174 | f'<image href="{href}" x="{fmt_num(xfrm.x)}" y="{fmt_num(xfrm.y)}" ' |
| 175 | f'width="{fmt_num(xfrm.w)}" height="{fmt_num(xfrm.h)}" ' |
| 176 | f'preserveAspectRatio="none"{opacity_attr}/>' |
| 177 | ) |
| 178 | else: |
| 179 | # Crop expressed as a unit-rectangle viewBox on a nested <svg>. |
| 180 | vb_l, vb_t, vb_w, vb_h = crop |
| 181 | svg = ( |
| 182 | f'<svg x="{fmt_num(xfrm.x)}" y="{fmt_num(xfrm.y)}" ' |
| 183 | f'width="{fmt_num(xfrm.w)}" height="{fmt_num(xfrm.h)}" ' |
| 184 | f'viewBox="{fmt_num(vb_l, 5)} {fmt_num(vb_t, 5)} ' |
| 185 | f'{fmt_num(vb_w, 5)} {fmt_num(vb_h, 5)}" ' |
| 186 | f'preserveAspectRatio="none" overflow="hidden">' |
| 187 | f'<image href="{href}" x="0" y="0" width="1" height="1" ' |
| 188 | f'preserveAspectRatio="none"{opacity_attr}/>' |
| 189 | f"</svg>" |
| 190 | ) |
| 191 | |
| 192 | media: dict[str, bytes] = {} |
| 193 | if not embed_inline: |
| 194 | media[filename] = img_bytes |
| 195 | return PictureResult( |
| 196 | svg=svg, |
| 197 | media=media, |
| 198 | diagnostics=tuple(diagnostics), |
| 199 | ) |
| 200 | |
| 201 | |
| 202 | def convert_picture( |
| 203 | pic_elem: ET.Element, |
| 204 | xfrm: Xfrm, |
| 205 | slide_part: PartRef, |
| 206 | pkg: OoxmlPackage, |
| 207 | *, |
| 208 | media_subdir: str = "assets", |
| 209 | embed_inline: bool = False, |
| 210 | asset_name_map: dict[str, str] | None = None, |
| 211 | strict: bool = False, |
| 212 | ) -> PictureResult: |
| 213 | """Translate <p:pic> to SVG <image> (or nested <svg>+<image> for cropping).""" |
| 214 | blip_fill = pic_elem.find("p:blipFill", NS) |
| 215 | if blip_fill is None: |
| 216 | return PictureResult() |
| 217 | |
| 218 | return convert_blip_fill( |
| 219 | blip_fill, xfrm, slide_part, pkg, |
| 220 | media_subdir=media_subdir, |
| 221 | embed_inline=embed_inline, |
| 222 | asset_name_map=asset_name_map, |
| 223 | strict=strict, |
| 224 | ) |
| 225 | |
| 226 | |
| 227 | # --------------------------------------------------------------------------- |
| 228 | # Helpers |
| 229 | # --------------------------------------------------------------------------- |
| 230 | |
| 231 | |
| 232 | def _blip_opacity_attr( |
| 233 | blip: ET.Element, |
| 234 | ) -> tuple[str, tuple[PictureDiagnostic, ...]]: |
| 235 | """Translate DrawingML fixed image alpha to an SVG opacity attribute.""" |
| 236 | alpha_effects = blip.findall("a:alphaModFix", NS) |
| 237 | if not alpha_effects: |
| 238 | return "", () |
| 239 | if len(alpha_effects) > 1: |
| 240 | return "", ( |
| 241 | _effect_diagnostic( |
| 242 | "duplicate a:alphaModFix effects cannot be reproduced safely" |
| 243 | ), |
| 244 | ) |
| 245 | alpha = alpha_effects[0] |
| 246 | try: |
| 247 | opacity = float(alpha.attrib.get("amt", "100000")) / 100000.0 |
| 248 | except ValueError: |
| 249 | return "", ( |
| 250 | _effect_diagnostic( |
| 251 | f"invalid a:alphaModFix amt={alpha.attrib.get('amt')!r}" |
| 252 | ), |
| 253 | ) |
| 254 | if not math.isfinite(opacity) or not 0.0 <= opacity <= 1.0: |
| 255 | return "", ( |
| 256 | _effect_diagnostic( |
| 257 | f"out-of-range a:alphaModFix amt={alpha.attrib.get('amt')!r}" |
| 258 | ), |
| 259 | ) |
| 260 | if opacity >= 1.0: |
| 261 | return "", () |
| 262 | return f' opacity="{format_ooxml_alpha(opacity)}"', () |
| 263 | |
| 264 | |
| 265 | def _effect_diagnostic(message: str) -> PictureDiagnostic: |
| 266 | return PictureDiagnostic( |
| 267 | code="image-effect-omitted", |
| 268 | message=message, |
| 269 | fallback="retain the source image and omit only this image effect", |
| 270 | ) |
| 271 | |
| 272 | |
| 273 | def _unsupported_blip_effect_diagnostics( |
| 274 | blip: ET.Element, |
| 275 | ) -> tuple[PictureDiagnostic, ...]: |
| 276 | """Report direct a:blip effects outside the implemented subset.""" |
| 277 | supported_tags = { |
| 278 | f"{{{NS['a']}}}lum", |
| 279 | f"{{{NS['a']}}}alphaModFix", |
| 280 | f"{{{NS['a']}}}extLst", |
| 281 | } |
| 282 | unsupported = sorted({ |
| 283 | child.tag.rsplit("}", 1)[-1] |
| 284 | for child in blip |
| 285 | if child.tag not in supported_tags |
| 286 | }) |
| 287 | diagnostics = ( |
| 288 | [ |
| 289 | _effect_diagnostic( |
| 290 | "unsupported direct a:blip effect(s): " |
| 291 | + ", ".join(f"a:{name}" for name in unsupported) |
| 292 | ) |
| 293 | ] |
| 294 | if unsupported |
| 295 | else [] |
| 296 | ) |
| 297 | if len(blip.findall("a:lum", NS)) > 1: |
| 298 | diagnostics.append( |
| 299 | _effect_diagnostic( |
| 300 | "duplicate a:lum effects cannot be reproduced safely" |
| 301 | ) |
| 302 | ) |
| 303 | return tuple(diagnostics) |
| 304 | |
| 305 | _OFFICE_VECTOR_EXTS = {".emf", ".wmf"} |
| 306 | |
| 307 | |
| 308 | def _is_valid_svg_media(data: bytes) -> bool: |
| 309 | """Return whether one media part is a namespaced SVG document.""" |
| 310 | try: |
| 311 | root = ET.fromstring(data) |
| 312 | except ET.ParseError: |
| 313 | return False |
| 314 | return root.tag == "{http://www.w3.org/2000/svg}svg" |
| 315 | |
| 316 | |
| 317 | def _normalize_office_media(filename: str, img_bytes: bytes) -> tuple[str, bytes]: |
| 318 | """Convert Office-only vector image formats to browser-renderable PNG. |
| 319 | |
| 320 | PPTX can contain EMF/WMF assets that PowerPoint renders natively but SVG |
| 321 | viewers generally do not. Keep the original asset in the manifest layer; |
| 322 | the SVG view uses a PNG preview when the local system can make one. |
| 323 | """ |
| 324 | suffix = Path(filename).suffix.lower() |
| 325 | if suffix not in _OFFICE_VECTOR_EXTS: |
| 326 | return filename, img_bytes |
| 327 | |
| 328 | converted = _convert_office_vector_to_png(filename, img_bytes) |
| 329 | if converted is None: |
| 330 | return filename, img_bytes |
| 331 | stem = Path(filename).stem |
| 332 | return f"{stem}_preview.png", converted |
| 333 | |
| 334 | |
| 335 | def _convert_office_vector_to_png(filename: str, img_bytes: bytes) -> bytes | None: |
| 336 | magick = shutil.which("magick") |
| 337 | if not magick: |
| 338 | return None |
| 339 | suffix = Path(filename).suffix.lower() or ".bin" |
| 340 | with tempfile.TemporaryDirectory() as tmp: |
| 341 | tmp_dir = Path(tmp) |
| 342 | src = tmp_dir / f"source{suffix}" |
| 343 | dst = tmp_dir / "preview.png" |
| 344 | src.write_bytes(img_bytes) |
| 345 | try: |
| 346 | subprocess.run( |
| 347 | [magick, str(src), str(dst)], |
| 348 | check=True, |
| 349 | stdout=subprocess.DEVNULL, |
| 350 | stderr=subprocess.DEVNULL, |
| 351 | ) |
| 352 | except (OSError, subprocess.CalledProcessError): |
| 353 | return None |
| 354 | if not dst.exists(): |
| 355 | return None |
| 356 | return dst.read_bytes() |
| 357 | |
| 358 | def _parse_src_rect(elem: ET.Element | None) -> tuple[float, float, float, float] | None: |
| 359 | """Convert <a:srcRect l t r b="1/100000"/> to (x, y, w, h) in unit space.""" |
| 360 | if elem is None: |
| 361 | return None |
| 362 | if not (elem.attrib.keys() & {"l", "t", "r", "b"}): |
| 363 | return None |
| 364 | l = _pct_attr(elem, "l") |
| 365 | t = _pct_attr(elem, "t") |
| 366 | r = _pct_attr(elem, "r") |
| 367 | b = _pct_attr(elem, "b") |
| 368 | # All zero -> equivalent to no crop |
| 369 | if l == 0 and t == 0 and r == 0 and b == 0: |
| 370 | return None |
| 371 | vb_x = l |
| 372 | vb_y = t |
| 373 | vb_w = max(0.0, 1.0 - l - r) |
| 374 | vb_h = max(0.0, 1.0 - t - b) |
| 375 | if vb_w <= 0 or vb_h <= 0: |
| 376 | return None |
| 377 | return vb_x, vb_y, vb_w, vb_h |
| 378 | |
| 379 | |
| 380 | def _single_cover_tile_crop( |
| 381 | tile: ET.Element, |
| 382 | blip_fill: ET.Element, |
| 383 | xfrm: Xfrm, |
| 384 | img_bytes: bytes, |
| 385 | ) -> tuple[float, float, float, float] | None: |
| 386 | """Map one oversized DrawingML tile to a unit-image crop window. |
| 387 | |
| 388 | The closed SVG/PPTX crop transport cannot express a repeating pattern. It |
| 389 | can, however, reproduce a tile when the aligned first tile alone covers the |
| 390 | complete frame. This is how PowerPoint commonly stores full-page bitmap |
| 391 | backgrounds without distorting their aspect ratio. |
| 392 | """ |
| 393 | if Image is None or xfrm.w <= 0 or xfrm.h <= 0: |
| 394 | return None |
| 395 | if tile.attrib.get("flip", "none") != "none": |
| 396 | return None |
| 397 | |
| 398 | natural_size = _image_size_at_96_dpi(img_bytes, blip_fill) |
| 399 | if natural_size is None: |
| 400 | return None |
| 401 | natural_w, natural_h = natural_size |
| 402 | scale_x = _pct_attr_default(tile, "sx", 1.0) |
| 403 | scale_y = _pct_attr_default(tile, "sy", 1.0) |
| 404 | tile_w = natural_w * scale_x |
| 405 | tile_h = natural_h * scale_y |
| 406 | if tile_w <= 0 or tile_h <= 0: |
| 407 | return None |
| 408 | |
| 409 | align_x, align_y = _tile_alignment(tile.attrib.get("algn", "tl")) |
| 410 | tile_x = ( |
| 411 | xfrm.x |
| 412 | + (xfrm.w - tile_w) * align_x |
| 413 | + emu_to_px(tile.attrib.get("tx")) |
| 414 | ) |
| 415 | tile_y = ( |
| 416 | xfrm.y |
| 417 | + (xfrm.h - tile_h) * align_y |
| 418 | + emu_to_px(tile.attrib.get("ty")) |
| 419 | ) |
| 420 | |
| 421 | tolerance = 1e-4 |
| 422 | if ( |
| 423 | tile_x > xfrm.x + tolerance |
| 424 | or tile_y > xfrm.y + tolerance |
| 425 | or tile_x + tile_w < xfrm.x + xfrm.w - tolerance |
| 426 | or tile_y + tile_h < xfrm.y + xfrm.h - tolerance |
| 427 | ): |
| 428 | return None |
| 429 | |
| 430 | crop = ( |
| 431 | (xfrm.x - tile_x) / tile_w, |
| 432 | (xfrm.y - tile_y) / tile_h, |
| 433 | xfrm.w / tile_w, |
| 434 | xfrm.h / tile_h, |
| 435 | ) |
| 436 | if all( |
| 437 | abs(actual - expected) <= 1e-7 |
| 438 | for actual, expected in zip(crop, (0.0, 0.0, 1.0, 1.0)) |
| 439 | ): |
| 440 | return None |
| 441 | return crop |
| 442 | |
| 443 | |
| 444 | def _image_size_at_96_dpi( |
| 445 | img_bytes: bytes, |
| 446 | blip_fill: ET.Element, |
| 447 | ) -> tuple[float, float] | None: |
| 448 | """Return the bitmap's physical size in the SVG canvas' 96-DPI pixels.""" |
| 449 | try: |
| 450 | with Image.open(io.BytesIO(img_bytes)) as image: |
| 451 | pixel_w, pixel_h = image.size |
| 452 | embedded_dpi = image.info.get("dpi") |
| 453 | except (OSError, ValueError): |
| 454 | return None |
| 455 | |
| 456 | configured_dpi = _positive_float(blip_fill.attrib.get("dpi")) |
| 457 | if configured_dpi is not None: |
| 458 | dpi_x = dpi_y = configured_dpi |
| 459 | else: |
| 460 | dpi_x, dpi_y = _dpi_pair(embedded_dpi) |
| 461 | return pixel_w * 96.0 / dpi_x, pixel_h * 96.0 / dpi_y |
| 462 | |
| 463 | |
| 464 | def _dpi_pair(value: object) -> tuple[float, float]: |
| 465 | if isinstance(value, (tuple, list)) and len(value) >= 2: |
| 466 | dpi_x = _positive_float(value[0]) or 96.0 |
| 467 | dpi_y = _positive_float(value[1]) or 96.0 |
| 468 | return dpi_x, dpi_y |
| 469 | dpi = _positive_float(value) or 96.0 |
| 470 | return dpi, dpi |
| 471 | |
| 472 | |
| 473 | def _positive_float(value: object) -> float | None: |
| 474 | try: |
| 475 | parsed = float(value) |
| 476 | except (TypeError, ValueError): |
| 477 | return None |
| 478 | return parsed if parsed > 0 else None |
| 479 | |
| 480 | |
| 481 | def _pct_attr_default(elem: ET.Element, name: str, default: float) -> float: |
| 482 | value = elem.attrib.get(name) |
| 483 | if value is None: |
| 484 | return default |
| 485 | try: |
| 486 | return float(value) / 100000.0 |
| 487 | except ValueError: |
| 488 | return default |
| 489 | |
| 490 | |
| 491 | def _tile_alignment(value: str) -> tuple[float, float]: |
| 492 | alignments = { |
| 493 | "tl": (0.0, 0.0), |
| 494 | "t": (0.5, 0.0), |
| 495 | "tr": (1.0, 0.0), |
| 496 | "l": (0.0, 0.5), |
| 497 | "ctr": (0.5, 0.5), |
| 498 | "r": (1.0, 0.5), |
| 499 | "bl": (0.0, 1.0), |
| 500 | "b": (0.5, 1.0), |
| 501 | "br": (1.0, 1.0), |
| 502 | } |
| 503 | return alignments.get(value, alignments["tl"]) |
| 504 | |
| 505 | |
| 506 | def _apply_blip_image_effects( |
| 507 | filename: str, |
| 508 | img_bytes: bytes, |
| 509 | blip: ET.Element, |
| 510 | ) -> tuple[str, bytes, tuple[PictureDiagnostic, ...]]: |
| 511 | """Bake supported DrawingML blip effects into extracted image bytes. |
| 512 | |
| 513 | Brightness and contrast are pixel operations, not picture-shape |
| 514 | shadow/glow effects, so preserve them in the extracted bitmap. |
| 515 | """ |
| 516 | lum_effects = blip.findall("a:lum", NS) |
| 517 | if not lum_effects: |
| 518 | return filename, img_bytes, () |
| 519 | if len(lum_effects) > 1: |
| 520 | return filename, img_bytes, () |
| 521 | lum = lum_effects[0] |
| 522 | |
| 523 | values: dict[str, float | None] = {} |
| 524 | for name in ("bright", "contrast"): |
| 525 | raw_value = lum.attrib.get(name) |
| 526 | if raw_value is None: |
| 527 | values[name] = None |
| 528 | continue |
| 529 | try: |
| 530 | value = float(raw_value) / 100000.0 |
| 531 | except ValueError: |
| 532 | return filename, img_bytes, ( |
| 533 | _effect_diagnostic(f"invalid a:lum {name}={raw_value!r}"), |
| 534 | ) |
| 535 | if not math.isfinite(value) or not -1.0 <= value <= 1.0: |
| 536 | return filename, img_bytes, ( |
| 537 | _effect_diagnostic( |
| 538 | f"out-of-range a:lum {name}={raw_value!r}" |
| 539 | ), |
| 540 | ) |
| 541 | values[name] = value |
| 542 | bright = values["bright"] |
| 543 | contrast = values["contrast"] |
| 544 | if bright is None and contrast is None: |
| 545 | return filename, img_bytes, () |
| 546 | if Image is None or ImageEnhance is None: |
| 547 | return filename, img_bytes, ( |
| 548 | _effect_diagnostic( |
| 549 | "a:lum requires Pillow, but Pillow is unavailable" |
| 550 | ), |
| 551 | ) |
| 552 | |
| 553 | try: |
| 554 | with Image.open(io.BytesIO(img_bytes)) as source_image: |
| 555 | if getattr(source_image, "is_animated", False): |
| 556 | return filename, img_bytes, ( |
| 557 | _effect_diagnostic( |
| 558 | "a:lum on an animated image would flatten its frames" |
| 559 | ), |
| 560 | ) |
| 561 | output_format = ( |
| 562 | source_image.format or _pil_format_from_filename(filename) |
| 563 | ) |
| 564 | image = source_image.copy() |
| 565 | if image.mode not in ("RGB", "RGBA"): |
| 566 | image = image.convert("RGBA" if "A" in image.getbands() else "RGB") |
| 567 | if bright is not None: |
| 568 | image = ImageEnhance.Brightness(image).enhance(max(0.0, 1.0 + bright)) |
| 569 | if contrast is not None: |
| 570 | image = ImageEnhance.Contrast(image).enhance(max(0.0, 1.0 + contrast)) |
| 571 | |
| 572 | out = io.BytesIO() |
| 573 | save_format = output_format or "PNG" |
| 574 | save_kwargs = {"quality": 95} if save_format.upper() in {"JPEG", "JPG"} else {} |
| 575 | image.save(out, format=save_format, **save_kwargs) |
| 576 | effect_key = f"lum-{bright}-{contrast}".encode("ascii") |
| 577 | digest = hashlib.sha1(effect_key).hexdigest()[:8] |
| 578 | return ( |
| 579 | _effect_filename(filename, digest, save_format), |
| 580 | out.getvalue(), |
| 581 | (), |
| 582 | ) |
| 583 | except (KeyError, OSError, ValueError) as exc: |
| 584 | return filename, img_bytes, ( |
| 585 | _effect_diagnostic(f"a:lum could not be rendered: {exc}"), |
| 586 | ) |
| 587 | |
| 588 | |
| 589 | def _pil_format_from_filename(filename: str) -> str | None: |
| 590 | ext = filename.rsplit(".", 1)[-1].lower() if "." in filename else "" |
| 591 | if ext in {"jpg", "jpeg"}: |
| 592 | return "JPEG" |
| 593 | if ext == "png": |
| 594 | return "PNG" |
| 595 | if ext == "gif": |
| 596 | return "GIF" |
| 597 | if ext == "webp": |
| 598 | return "WEBP" |
| 599 | return None |
| 600 | |
| 601 | |
| 602 | def _effect_filename(filename: str, digest: str, image_format: str) -> str: |
| 603 | stem, sep, ext = filename.rpartition(".") |
| 604 | if not sep: |
| 605 | ext = (image_format or "png").lower() |
| 606 | stem = filename |
| 607 | if ext.lower() == "jpg": |
| 608 | ext = "jpeg" |
| 609 | return f"{stem}_fx_{digest}.{ext}" |
| 610 | |
| 611 | |
| 612 | def _pct_attr(elem: ET.Element, name: str) -> float: |
| 613 | val = elem.attrib.get(name) |
| 614 | if val is None: |
| 615 | return 0.0 |
| 616 | try: |
| 617 | return float(val) / 100000.0 |
| 618 | except ValueError: |
| 619 | return 0.0 |
| 620 | |
| 621 | |
| 622 | def _build_href(filename: str, img_bytes: bytes, subdir: str, embed: bool) -> str: |
| 623 | """Build an <image href=...> value (relative path or data URI). |
| 624 | |
| 625 | The path is relative to the SVG file's location. The slide assembler writes |
| 626 | SVGs to <output>/svg/, so media files in <output>/<subdir>/ resolve via |
| 627 | a leading "../". |
| 628 | """ |
| 629 | if embed: |
| 630 | mime = ( |
| 631 | mimetypes.guess_type(filename)[0] |
| 632 | or _sniff_mime(img_bytes) |
| 633 | or "application/octet-stream" |
| 634 | ) |
| 635 | encoded = base64.b64encode(img_bytes).decode("ascii") |
| 636 | return f"data:{mime};base64,{encoded}" |
| 637 | rel = f"../{subdir}/{filename}" if subdir else f"../{filename}" |
| 638 | return rel |
| 639 | |
| 640 | |
| 641 | def _sniff_mime(data: bytes) -> str | None: |
| 642 | """Best-effort MIME sniffing for embedded images.""" |
| 643 | if data.startswith(b"\x89PNG\r\n\x1a\n"): |
| 644 | return "image/png" |
| 645 | if data.startswith(b"\xff\xd8\xff"): |
| 646 | return "image/jpeg" |
| 647 | if data.startswith(b"GIF87a") or data.startswith(b"GIF89a"): |
| 648 | return "image/gif" |
| 649 | if data.startswith(b"<svg") or data.startswith(b"<?xml"): |
| 650 | return "image/svg+xml" |
| 651 | if data[:4] == b"RIFF" and data[8:12] == b"WEBP": |
| 652 | return "image/webp" |
| 653 | return None |
| 654 |