Line data    Source code

       1              : // Copyright 2026 The Authors.
       2              : //
       3              : // Licensed under the Apache License, Version 2.0 (the "License");
       4              : // you may not use this file except in compliance with the License.
       5              : // You may obtain a copy of the License at
       6              : //
       7              : //     https://www.apache.org/licenses/LICENSE-2.0
       8              : //
       9              : // Unless required by applicable law or agreed to in writing, software
      10              : // distributed under the License is distributed on an "AS IS" BASIS,
      11              : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12              : // See the License for the specific language governing permissions and
      13              : // limitations under the License.
      14              : 
      15              : /// The intrinsic size of a PDF page, measured in PDF user units (points).
      16              : ///
      17              : /// One PDF user unit equals 1/72 inch. This is a storage-level measurement
      18              : /// independent of any rendering resolution. Use [sizeForDpi] to convert to
      19              : /// pixel dimensions at a target DPI for rendering.
      20              : ///
      21              : /// ## Example
      22              : ///
      23              : /// ```dart
      24              : /// final size = await doc.getPageSize(0);
      25              : /// // Convert to pixels at 150 DPI:
      26              : /// final pixelSize = size.sizeForDpi(150);
      27              : /// final image = await doc.renderPageToBytes(
      28              : ///   0,
      29              : ///   pixelSize.width.round(),
      30              : ///   pixelSize.height.round(),
      31              : /// );
      32              : /// ```
      33              : class PdfPageSize {
      34              :   /// Creates a [PdfPageSize] with the given [widthPt] and [heightPt] in points.
      35              :   ///
      36              :   /// Both values must be positive. A value of zero or negative indicates a
      37              :   /// malformed page in the PDF; callers should guard against this before
      38              :   /// passing dimensions to [PdfDocument.renderPageToBytes].
      39            4 :   const PdfPageSize({required this.widthPt, required this.heightPt});
      40              : 
      41              :   /// The page width in PDF user units (points, 1/72 inch).
      42              :   final double widthPt;
      43              : 
      44              :   /// The page height in PDF user units (points, 1/72 inch).
      45              :   final double heightPt;
      46              : 
      47              :   /// The aspect ratio of the page (width / height).
      48              :   ///
      49              :   /// Returns `1.0` when [heightPt] is zero to avoid division-by-zero on
      50              :   /// malformed pages. Callers should still guard against zero-sized pages
      51              :   /// before rendering.
      52           12 :   double get aspectRatio => heightPt > 0 ? widthPt / heightPt : 1.0;
      53              : 
      54              :   /// Returns the page size in pixels at the given [dpi] as a named record.
      55              :   ///
      56              :   /// Multiply [widthPt] and [heightPt] (both in points, 1/72 inch) by
      57              :   /// [dpi] / 72 to obtain pixel dimensions suitable for passing to
      58              :   /// [PdfDocument.renderPageToBytes].
      59              :   ///
      60              :   /// Example: an A4 page (595 × 842 pt) at 150 DPI yields
      61              :   /// approximately 1239 × 1754 pixels.
      62              :   ///
      63              :   /// [dpi] must be positive. Returns `(width: 0.0, height: 0.0)` when [dpi]
      64              :   /// is zero or negative.
      65            2 :   ({double width, double height}) sizeForDpi(double dpi) {
      66            2 :     if (dpi <= 0) return (width: 0.0, height: 0.0);
      67            2 :     final scale = dpi / 72.0;
      68            8 :     return (width: widthPt * scale, height: heightPt * scale);
      69              :   }
      70              : 
      71            1 :   @override
      72            3 :   String toString() => 'PdfPageSize(widthPt: $widthPt, heightPt: $heightPt)';
      73              : 
      74            2 :   @override
      75              :   bool operator ==(Object other) =>
      76              :       identical(this, other) ||
      77            1 :       other is PdfPageSize &&
      78            3 :           other.widthPt == widthPt &&
      79            3 :           other.heightPt == heightPt;
      80              : 
      81            1 :   @override
      82            3 :   int get hashCode => Object.hash(widthPt, heightPt);
      83              : }