使用C++实现给PDF文档添加文字水印

#include "Spire.Pdf.o.h";
 
using namespace std;
using namespace Spire::Pdf;
 
int main()
{
 
    //创建PdfDocument对象
    intrusive_ptr <PdfDocument> doc = new PdfDocument();
 
    //加载PDF文件
    doc->LoadFromFile(L"协议.pdf");
 
    //创建TrueType字体
    intrusive_ptr <PdfTrueTypeFont> font = new PdfTrueTypeFont(L"黑体", 60.0f, PdfFontStyle::Bold, true);
 
    //创建笔刷
    intrusive_ptr <PdfBrush> brush = PdfBrushes::GetSkyBlue();
 
    //指定水印文本
    wstring text = L"内部文件";
 
    //测量水印文本大小
    SizeF textSize = font->MeasureString(text.c_str());
 
    //计算两个偏移量，用于计算坐标系的平移量
    float offset1 = (float)(textSize.GetWidth() * sqrt(2) / 4);
    float offset2 = (float)(textSize.GetHeight() * sqrt(2) / 4);
 
    //遍历文档中的页面
    for (size_t i = 0; i < doc->GetPages()->GetCount(); i++)
    {
        //获取指定页面
        intrusive_ptr <PdfPageBase> page = doc->GetPages()->GetItem(i);
 
        //设置透明度
        page->GetCanvas()->SetTransparency(0.8);
 
        //将页面坐标系平移至指定位置
        page->GetCanvas()->TranslateTransform(page->GetCanvas()->GetSize()->GetWidth() / 2 - offset1 - offset2, page->GetCanvas()->GetSize()->GetHeight() / 2 + offset1 - offset2);
 
        //逆时针旋转坐标系45度
        page->GetCanvas()->RotateTransform(-45);
 
        //在页面上绘制水印
        page->GetCanvas()->DrawString(text.c_str(), font, brush, 0, 0, new PdfStringFormat(PdfTextAlignment::Left));
    }
 
    //保存结果文档
    doc->SaveToFile(L"Output\\文字水印.pdf");
    doc->Close();
}

#include "Spire.Pdf.o.h";
 
using namespace std;
using namespace Spire::Pdf;
 
static void InsertTiledTextWatermark(intrusive_ptr <PdfPageBase> page, wstring watermarkText, intrusive_ptr <PdfTrueTypeFont> font, int rowNum, int columnNum)
{
    //测量水印文本大小
    SizeF textSize = font->MeasureString(watermarkText.c_str());
 
    //计算两个偏移量，用于计算坐标系的平移量
    float offset1 = (float)(textSize.GetWidth() * sqrt(2) / 4);
    float offset2 = (float)(textSize.GetHeight() * sqrt(2) / 4);
 
    //获取页面高度和宽度
    float height = page->GetActualSize()->GetHeight();
    float width = page->GetActualSize()->GetWidth();
 
    //创建平铺笔刷
    intrusive_ptr <PdfTilingBrush> brush = new PdfTilingBrush(new SizeF(width / columnNum, height / rowNum));
    brush->GetGraphics()->SetTransparency(0.3f);
    brush->GetGraphics()->TranslateTransform(brush->GetSize()->GetWidth() / 2 - offset1 - offset2, brush->GetSize()->GetHeight() / 2 + offset1 - offset2);
    brush->GetGraphics()->RotateTransform(-45);
 
    //在笔刷上绘制水印文字
    brush->GetGraphics()->DrawString(watermarkText.c_str(), font, PdfBrushes::GetRed(), 0, 0, new PdfStringFormat(PdfTextAlignment::Left));
 
    //使用平铺笔刷绘制一个覆盖整个页面的矩形
    page->GetCanvas()->DrawRectangle(brush, new RectangleF(new PointF(0, 0), page->GetActualSize()));
}
 
int main()
{
 
    //创建PdfDocument对象
    intrusive_ptr <PdfDocument> doc = new PdfDocument();
 
    //加载PDF文件
    doc->LoadFromFile(L"协议.pdf");
 
    //指定水印文本
    wstring text = L"内部文件";
 
    //创建TrueType字体
    intrusive_ptr <PdfTrueTypeFont> font = new PdfTrueTypeFont(L"黑体", 30.0f, PdfFontStyle::Bold, true);
 
    //遍历文档中的页面
    for (size_t i = 0; i < doc->GetPages()->GetCount(); i++)
    {
        //调用自定义方法来插入多行文本水印
        InsertTiledTextWatermark(doc->GetPages()->GetItem(i), text.c_str(), font, 3, 3);
    }
 
    //保存结果文件
    doc->SaveToFile(L"Output\\多行水印.pdf");
    doc->Close();
}