resolve method

Implementation

PdfImage resolve(Context context, PdfPoint size, {double? dpi}) {
  final effectiveDpi = dpi ?? this.dpi;

  if (effectiveDpi != null) {
    final width = (size.x / PdfPageFormat.inch * effectiveDpi).toInt();
    final height = (size.y / PdfPageFormat.inch * effectiveDpi).toInt();

    // Never resample above the source resolution: upscaling adds no detail
    // but discards the original (possibly better compressed) image data.
    // For rotated orientations the axis buildImage resizes depends on
    // whether decoding bakes the rotation into the pixels, so only an
    // upper bound is checked here; buildImage itself skips the resample
    // when the target is at or above the decoded pixel width. An unknown
    // source width keeps the original: it cannot be proven a downsample.
    final sourceWidth = _width;
    final resampleBound = sourceWidth == null
        ? null
        : orientation.index >= 4
        ? (sourceWidth > _height ? sourceWidth : _height)
        : sourceWidth;

    if (resampleBound != null && width > 0 && width < resampleBound) {
      if (!_cache.containsKey(width)) {
        _cache[width] ??= buildImage(context, width: width, height: height);
      }

      if (_cache[width]!.pdfDocument != context.document) {
        _cache[width] = buildImage(context, width: width, height: height);
      }

      return _cache[width]!;
    }
  }

  _cache[0] ??= buildImage(context);

  if (_cache[0]!.pdfDocument != context.document) {
    _cache[0] = buildImage(context);
  }

  return _cache[0]!;
}