iText7 C# 如何提取 (CROP/CLIP?) 大于 A4 的模板部分以与 A4 PDF 合并并生成 A4？

Question

我有一个比 A4 稍大的 PDF 模板，每个角附近都有十字线以指示页面的 A4 尺寸部分。我应该如何从超大 PDF 中提取居中的 A4 部分以与另一个 A4 PDF 合并并生成最终的 A4 PDF？

因此将其分解为模板 crop/clip 问题。我使用了改编自 Java 示例的代码。它确实如我所愿 Crop/Clip 出现......除了它仍然以原始模板页面大小（大于 A4）而不是我期望/想要的 A4 结束？然后我必须弄清楚如何与包含要与模板合并的文本的 pdf 合并，一旦它是 A4。

private void manipulatePdf(string sTemplate, string sDoc, string sOutput)
{
    PdfDocument pdfDoc = new PdfDocument(new PdfWriter(sOutput));
    Document doc = new Document(pdfDoc, PageSize.A4);
    doc.SetMargins(0f,0f,0f,0f);
    PdfDocument docTemplateA4Plus = new PdfDocument(new PdfReader(sTemplate));
    PdfDocument docTextA4 = new PdfDocument(new PdfReader(sDoc));
    PdfPage pageTemplateA4Plus = docTemplateA4Plus.GetPage(1);
    PdfPage pageTextA4 = docTextA4.GetPage(1);
    iText.Kernel.Geom.Rectangle mediaBoxTemplateA4Plus =  pageTemplateA4Plus.GetMediaBox();
    iText.Kernel.Geom.Rectangle mediaBoxTextA4 = pageTextA4.GetMediaBox();
    float template_llx = mediaBoxTemplateA4Plus.GetX();
    float template_lly = mediaBoxTemplateA4Plus.GetY();
    float template_w = mediaBoxTemplateA4Plus.GetWidth();
    float template_h = mediaBoxTemplateA4Plus.GetHeight();
    float text_llx = mediaBoxTextA4.GetX();
    float text_lly = mediaBoxTextA4.GetY();
    float text_w = mediaBoxTextA4.GetWidth();
    float text_h = mediaBoxTextA4.GetHeight();
    float llx = ((template_w - text_w) / 2);
    float lly = ((template_h - text_h) / 2);
    float w = text_w;
    float h = text_h;
    docTemplateA4Plus.CopyPagesTo(1,1,pdfDoc);
    string sCommand = "\nq " + llx.ToString() + " " + lly.ToString() + " " + w.ToString() + " " + h.ToString() + " re W n\nq\n";
    PdfPage pdfPage = pdfDoc.GetPage(1);
    new PdfCanvas(pdfPage.NewContentStreamBefore(), pdfPage.GetResources(), pdfDoc)
    .WriteLiteral(sCommand);
    new PdfCanvas(pdfPage.NewContentStreamAfter(), pdfPage.GetResources(), pdfDoc)
    .WriteLiteral("\nQ\nQ\n");
    doc.Close();
    pdfDoc.Close();
}

Answer 1

所以回答我自己的问题，我不确定它是最优雅的，但为了解决我添加的页面大小

var rect = new Rectangle(llx,lly,w,h);
pdfPage.SetMediaBox(rect);

为了合并，我在下面的完整代码中添加了与 canvas 相关的 5 条新行。

private void manipulatePdf(string sTemplate, string sDoc, string sOutput)
{
    PdfDocument pdfDoc = new PdfDocument(new PdfWriter(sOutput));
    Document doc = new Document(pdfDoc, PageSize.A4);
    doc.SetMargins(0f,0f,0f,0f);
    PdfDocument docTemplateA4Plus = new PdfDocument(new PdfReader(sTemplate));
    PdfDocument docTextA4 = new PdfDocument(new PdfReader(sDoc));
    PdfPage pageTemplateA4Plus = docTemplateA4Plus.GetPage(1);
    PdfPage pageTextA4 = docTextA4.GetPage(1);
    iText.Kernel.Geom.Rectangle mediaBoxTemplateA4Plus =  pageTemplateA4Plus.GetMediaBox();
    iText.Kernel.Geom.Rectangle mediaBoxTextA4 = pageTextA4.GetMediaBox();
    float template_llx = mediaBoxTemplateA4Plus.GetX();
    float template_lly = mediaBoxTemplateA4Plus.GetY();
    float template_w = mediaBoxTemplateA4Plus.GetWidth();
    float template_h = mediaBoxTemplateA4Plus.GetHeight();
    float text_llx = mediaBoxTextA4.GetX();
    float text_lly = mediaBoxTextA4.GetY();
    float text_w = mediaBoxTextA4.GetWidth();
    float text_h = mediaBoxTextA4.GetHeight();
    float llx = ((template_w - text_w) / 2);
    float lly = ((template_h - text_h) / 2);
    float w = text_w;
    float h = text_h;
    var rect = new Rectangle(llx,lly,w,h);
    docTemplateA4Plus.CopyPagesTo(1,1,pdfDoc);
    string sCommand = "\nq " + llx.ToString() + " " + lly.ToString() + " " + w.ToString() + " " + h.ToString() + " re W n\nq\n";
    PdfPage pdfPage = pdfDoc.GetPage(1);
    new PdfCanvas(pdfPage.NewContentStreamBefore(), pdfPage.GetResources(), pdfDoc)
    .WriteLiteral(sCommand);
    new PdfCanvas(pdfPage.NewContentStreamAfter(), pdfPage.GetResources(), pdfDoc)
    .WriteLiteral("\nQ\nQ\n");

    pdfPage.SetMediaBox(rect);

    PdfCanvas canvas = new PdfCanvas(pdfDoc.GetFirstPage().NewContentStreamBefore(), pdfDoc.GetFirstPage().GetResources(), pdfDoc);
    PdfFormXObject page;
    srcDoc = new PdfDocument(new PdfReader(path));
    page = srcDoc.GetFirstPage().CopyAsFormXObject(pdfDoc);
    canvas.AddXObject(page, 0, 0);

    doc.Close();
    pdfDoc.Close();
}

iText7 C# 如何提取 (CROP/CLIP?) 大于 A4 的模板部分以与 A4 PDF 合并并生成 A4？

iText7 C# how extract (CROP/CLIP?) part of template larger than A4 to merge with an A4 PDF and result in A4?

c#

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