pdfluent_lopdf/font.rs
1/// This struct represents the data of a font.
2/// It contains information about the font's bounding box, ascent, descent, cap height, italic angle, and stemV.
3/// Reference: https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/pdfreference1.5_v6.pdf
4#[derive(Debug, Clone)]
5pub struct FontData {
6 /// (Required) The PostScript name of the font. This should be the same as the value of BaseFont in the font or CIDFont dictionary that refers to this font descriptor.
7 pub font_name: String,
8 /// (Required) A collection of flags defining various characteristics of the font.
9 pub flags: i64,
10 /// (Required, except for Type 3 fonts) A rectangle (see Section 3.8.4, “Rectangles”), expressed in the glyph coordinate system, specifying the font bounding box. This is the smallest rectangle enclosing the shape that would result if all of the glyphs of the font were placed with their origins coincident and then filled.
11 /// Format as: (x_min, y_min, x_max, y_max).
12 pub font_bbox: (i64, i64, i64, i64),
13 /// (Required) The angle, expressed in degrees counterclockwise from the vertical, of the dominant vertical strokes of the font. (For example, the 9-o’clock position is 90 degrees, and the 3-o’clock position is –90 degrees.) The value is negative for fonts that slope to the right, as almost all italic fonts do.
14 pub italic_angle: i64,
15 /// (Required, except for Type 3 fonts) The maximum height above the baseline reached by glyphs in this font, excluding the height of glyphs for accentedc haracters.
16 pub ascent: i64,
17 /// (Required, except for Type 3 fonts) The maximum depth below the baseline reached by glyphs in this font. The value is a negative number.
18 pub descent: i64,
19 /// (Required for fonts that have Latin characters, except for Type 3 fonts) The vertical coordinate of the top of flat capital letters, measured from the baseline.
20 pub cap_height: i64,
21 /// (Required, except for Type 3 fonts) The thickness, measured horizontally, of the dominant vertical stems of glyphs in the font.
22 pub stem_v: i64,
23 /// (Required) The name of a predefined CMap, or a stream containing a CMap program, that maps character codes to font numbers and CIDs. If the descendant is a Type 2 CIDFont whose associated TrueType font program is not embedded in the PDF file, the Encoding entry must be a predefined CMap name
24 /// Read more (page 422): https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/pdfreference1.5_v6.pdf
25 pub encoding: String,
26 /// Size of the font data in bytes.
27 /// This is used to set the `Length1` key in the font stream dictionary.
28 font: Vec<u8>,
29}
30
31/// This struct is used to store font metadata extracted from a TrueType Fonts (TTF) file.
32/// # Examples
33///
34/// ```no_run
35/// // Read a TrueType Fonts (TTF) file.
36/// let font_file = std::fs::read("./SomeFont.ttf").unwrap();
37///
38/// // Create a new FontData instance.
39/// let font_name = "SomeFont".to_string();
40/// let font_data = pdfluent_lopdf::FontData::new(&font_file, font_name);
41/// ```
42///
43/// Also provides methods to set various font properties such as bounding box, italic angle, ascent, descent, and stemV.
44/// # Examples
45///
46/// ```no_run
47/// let font_file = std::fs::read("./SomeFont.ttf").unwrap();
48///
49/// // Create a new FontData instance along custome value.
50/// let font_data = pdfluent_lopdf::FontData::new(&font_file, "SomeFont".to_string())
51/// .set_stem_v(100)
52/// .set_italic_angle(10);
53/// ```
54impl FontData {
55 /// Create a new `FontData` instance by parsing the provided TTF file.
56 /// The TTF file is expected to be in bytes.
57 pub fn new(font_file: &[u8], font_name: String) -> Self {
58 // Parse the TTF file using ttf_parser crate
59 let font = ttf_parser::Face::parse(font_file, 0).expect("Failed to parse font file");
60
61 // Extract font metadata
62 // Note: The ttf_parser crate provides methods to get font bounding box, ascent, descent, cap height, italic angle, and stemV.
63 let font_bbox = font.global_bounding_box();
64 let ascent = font.ascender();
65 let descent = font.descender();
66 let cap_height = font.capital_height().unwrap_or(ascent);
67 let italic_angle = font.italic_angle();
68 let flags = 1; // Default flags, can be modified later if needed
69
70 // Calculate stemV based on the font bounding box
71 // Reference: https://stackoverflow.com/questions/35485179/stemv-value-of-the-truetype-font
72 // The stemV is typically calculated as 13% of the font's bbox width value.
73 let stem_v = (font_bbox.width() as f64 * 0.13).round() as i64;
74
75 Self {
76 font_name,
77 flags,
78 font_bbox: (
79 font_bbox.x_min as i64,
80 font_bbox.y_min as i64,
81 font_bbox.x_max as i64,
82 font_bbox.y_max as i64,
83 ),
84 italic_angle: italic_angle.round() as i64,
85 ascent: ascent as i64,
86 descent: descent as i64,
87 cap_height: cap_height as i64,
88 stem_v,
89 encoding: "WinAnsiEncoding".to_string(), // Default encoding, can be modified later if needed
90 font: font_file.to_vec(),
91 }
92 }
93
94 pub fn set_flags(&mut self, flags: i64) -> &mut Self {
95 self.flags = flags;
96 self
97 }
98
99 pub fn set_font_bbox(&mut self, font_bbox: (i64, i64, i64, i64)) -> &mut Self {
100 self.font_bbox = font_bbox;
101 self
102 }
103
104 pub fn set_italic_angle(&mut self, italic_angle: i64) -> &mut Self {
105 self.italic_angle = italic_angle;
106 self
107 }
108
109 pub fn set_ascent(&mut self, ascent: i64) -> &mut Self {
110 self.ascent = ascent;
111 self
112 }
113
114 pub fn set_descent(&mut self, descent: i64) -> &mut Self {
115 self.descent = descent;
116 self
117 }
118
119 pub fn set_cap_height(&mut self, cap_height: i64) -> &mut Self {
120 self.cap_height = cap_height;
121 self
122 }
123
124 pub fn set_stem_v(&mut self, stem_v: i64) -> &mut Self {
125 self.stem_v = stem_v;
126 self
127 }
128
129 pub fn set_encoding(&mut self, encoding: String) -> &mut Self {
130 self.encoding = encoding;
131 self
132 }
133
134 pub fn bytes(&self) -> Vec<u8> {
135 self.font.clone()
136 }
137}