Heinenen
commented
1 month ago If you could formulate a question (best in English, but I can use Google Translate too), I can try to help you.
I tried formatting your code a little better:
use lopdf::{Document, Object, Stream, content::Content, content::Operation, Dictionary, dictionary};
use std::fs::File;
use std::io::Read;
use std::f64::consts::PI;
use hex::ToHex;
fn add_watermark_to_existing_pdf(input_path: &str, output_path: &str, watermark_texts: &Vec<String>, font_path: &str, opacity: f32) {
let mut doc = Document::load(input_path).unwrap();
// 加载字体文件
let mut font_file = Vec::new();
File::open(font_path).unwrap().read_to_end(&mut font_file).unwrap();
let font_stream = Stream::new(dictionary! { "Length1" => font_file.len() as i64 }, font_file);
let font_stream_id = doc.add_object(font_stream);
// 创建FontDescriptor字典
let font_descriptor = dictionary! {
"Type" => "FontDescriptor",
"FontName" => "SourceHanSansCN-Normal",
"FontFile2" => font_stream_id,
"Flags" => 4, // Symbolic
"FontBBox" => vec![Object::Integer(-1000), Object::Integer(-500), Object::Integer(2000), Object::Integer(1000)],
"ItalicAngle" => Object::Integer(0),
"Ascent" => Object::Integer(1000),
"Descent" => Object::Integer(-200),
"CapHeight" => Object::Integer(750),
"StemV" => Object::Integer(80),
};
let font_descriptor_id = doc.add_object(font_descriptor);
// 创建CIDFontType2字体字典
let cid_font_dict = dictionary! {
"Type" => "Font",
"Subtype" => "CIDFontType2",
"BaseFont" => "SourceHanSansCN-Normal",
"CIDSystemInfo" => dictionary! {
"Registry" => "Adobe",
"Ordering" => "Identity",
"Supplement" => 0,
},
"FontDescriptor" => font_descriptor_id,
"DW" => 1000,
};
let cid_font_id = doc.add_object(cid_font_dict);
// 创建Type0字体字典
let font_dict = dictionary! {
"Type" => "Font",
"Subtype" => "Type0",
"BaseFont" => "SourceHanSansCN-Normal",
"Encoding" => "Identity-H",
"DescendantFonts" => vec![cid_font_id.into()],
"ToUnicode" => create_to_unicode_cmap(),
};
let font_id = doc.add_object(font_dict);
// 创建ExtGState字典用于透明度设置
let ext_gstate = dictionary! {
"Type" => "ExtGState",
"ca" => Object::Real(opacity), // 字体透明度
"CA" => Object::Real(opacity), // 图像透明度
"BM" => "Normal",
};
let ext_gstate_id = doc.add_object(ext_gstate);
// 计算旋转角度和位置
let angle = 45.0 * PI / 180.0; // 45度旋转
let (cos_theta, sin_theta) = (angle.cos() as f32, angle.sin() as f32);
let page_width = 595.0;
let page_height = 842.0;
// 遍历每个页面，将水印添加到每个页面的内容流中
for (_, page_id) in doc.get_pages() {
let page_content = doc.get_page_content(page_id).unwrap();
let mut watermark_operations = vec![
Operation::new("q", vec![]), // 保存图形状态
Operation::new("BT", vec![]), // 开始文本块
Operation::new("gs", vec![ext_gstate_id.into()]), // 设置透明度
Operation::new("Tf", vec![font_id.into(), Object::Real(24.0)]), // 设置字体和大小
Operation::new("0.65 0.65 0.65 rg", vec![]), // 设置浅灰色（RGB各0.65）
];
let font_size = 24.0;
let line_height = font_size * 1.5; // 行高
// 计算整个水印块的中心点
let center_x = page_width / 2.0;
let center_y = page_height / 2.0;
for (i, text) in watermark_texts.iter().enumerate() {
let text_width = text.len() as f32 * font_size * 0.5;
// 计算每行文本相对于水印中心的偏移
let offset_y = (i as f32 - (watermark_texts.len() - 1) as f32 / 2.0) * line_height;
// 应用旋转并移动到正确的位置
let rotated_x = -offset_y * sin_theta;
let rotated_y = offset_y * cos_theta;
watermark_operations.push(Operation::new("Tm", vec![
Object::Real(cos_theta), Object::Real(sin_theta),
Object::Real(-sin_theta), Object::Real(cos_theta),
Object::Real(center_x + rotated_x), Object::Real(center_y + rotated_y)
]));
// 移动文本起始点，使其居中
watermark_operations.push(Operation::new("Td", vec![
Object::Real(-text_width / 2.0), Object::Real(0.0)
]));
let text = "中";
let utf16be = text.encode_utf16().flat_map(|c| c.to_be_bytes()).collect::<Vec<u8>>();
watermark_operations.push(Operation::new("Tj", vec![Object::String(utf16be, lopdf::StringFormat::Literal)]));
}
watermark_operations.push(Operation::new("ET", vec![])); // 结束文本块
watermark_operations.push(Operation::new("Q", vec![])); // 恢复图形状态
let mut watermark_content = Content {
operations: watermark_operations,
};
let watermark_encoded = watermark_content.encode().unwrap();
let new_content = [watermark_encoded.as_slice(), &page_content].concat(); // 先绘制水印，再添加原内容
doc.change_page_content(page_id, new_content);
}
doc.save(output_path).unwrap();
}
fn utf16be_hex_encode(text: &str) -> String {
text.encode_utf16()
.flat_map(|c| c.to_be_bytes())
.map(|b| format!("{:02X}", b))
.collect()
}
// 创建ToUnicode映射
fn create_to_unicode_cmap() -> Object {
let cmap = b"/CIDInit /ProcSet findresource begin
12 dict begin
begincmap
/CIDSystemInfo << /Registry (Adobe) /Ordering (Identity) /Supplement 0 >> def
/CMapName /Adobe-Identity-UCS def
/CMapType 2 def
1 begincodespacerange
<0000> <FFFF>
endcodespacerange
1 beginbfchar
<4E2D> <4E2D>
endbfchar
endcmap
CMapName currentdict /CMap defineresource pop
end
end";
let stream = Stream::new(dictionary!{}, cmap.to_vec());
Object::Stream(stream)
}
// PDF水印居中
fn main() {
let input_pdf = "input-01.pdf";
let output_pdf = "output.pdf";
let watermark_texts = vec!["2024/08/23 17:30".to_string(),"6002008".to_string(),"中文".to_string()];
let font_path = "./font/SourceHanSansCN-Normal.otf"; // 确保字体文件路径正确
let opacity = 0.5; // 透明度, 范围为 0.0 (完全透明) 到 1.0 (完全不透明)
add_watermark_to_existing_pdf(input_pdf, output_pdf, &watermark_texts, font_path, opacity);
}
this is my code: `use lopdf::{Document, Object, Stream, content::Content, content::Operation, Dictionary, dictionary}; use std::fs::File; use std::io::Read; use std::f64::consts::PI; use hex::ToHex;
fn add_watermark_to_existing_pdf(input_path: &str, output_path: &str, watermark_texts: &Vec, font_path: &str, opacity: f32) {
let mut doc = Document::load(input_path).unwrap();
}; let cid_font_id = doc.add_object(cid_font_dict);
} fn utf16be_hex_encode(text: &str) -> String { text.encode_utf16() .flat_map(|c| c.to_be_bytes()) .map(|b| format!("{:02X}", b)) .collect() } // 创建ToUnicode映射 fn create_to_unicode_cmap() -> Object { let cmap = b"/CIDInit /ProcSet findresource begin 12 dict begin begincmap /CIDSystemInfo << /Registry (Adobe) /Ordering (Identity) /Supplement 0 >> def /CMapName /Adobe-Identity-UCS def /CMapType 2 def 1 begincodespacerange
<0000>