更新 PDF 中的链接

以下代码片段也适用于 Aspose.PDF.Drawing 库。

更新 PDF 文件中的链接

如在《在 PDF 文件中添加超链接》中所讨论的， LinkAnnotation 类使得在 PDF 文件中添加链接成为可能。还有一个类似的类用于获取 PDF 文件中的现有链接。如果您需要更新现有链接，请使用此类。要更新现有链接：

1. 加载 PDF 文件。
2. 转到 PDF 文件中的特定页面。
3. 使用 GoToAction 对象的 Destination 属性指定链接目标。
4. 使用 XYZExplicitDestination 构造函数指定目标页面。

将链接目标设置为同一文档中的页面

以下代码片段演示如何在 PDF 文件中更新链接并将其目标设置为文档的第二页。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf"))
    {
        // Get the first link annotation from first page of document
        var linkAnnot = (Aspose.Pdf.Annotations.LinkAnnotation)document.Pages[1].Annotations[1];

        // Modification link: change link destination
        var goToAction = (Aspose.Pdf.Annotations.GoToAction)linkAnnot.Action;

        // Specify the destination for link object
        // The first parameter is document object, second is destination page number.
        // The 5ht argument is zoom factor when displaying the respective page. When using 2, the page will be displayed in 200% zoom
        goToAction.Destination = new Aspose.Pdf.Annotations.XYZExplicitDestination(1, 1, 2, 2);

        // Save PDF document
        document.Save(dataDir + "UpdateLinks_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf");

    // Get the first link annotation from first page of document
    var linkAnnot = (Aspose.Pdf.Annotations.LinkAnnotation)document.Pages[1].Annotations[1];

    // Modification link: change link destination
    var goToAction = (Aspose.Pdf.Annotations.GoToAction)linkAnnot.Action;

    // Specify the destination for link object
    // The first parameter is document object, second is destination page number.
    // The 5ht argument is zoom factor when displaying the respective page. When using 2, the page will be displayed in 200% zoom
    goToAction.Destination = new Aspose.Pdf.Annotations.XYZExplicitDestination(1, 1, 2, 2);

    // Save PDF document
    document.Save(dataDir + "UpdateLinks_out.pdf");
}

将链接目标设置为网页地址

要更新超链接以指向网页地址，请实例化 GoToURIAction 对象并将其传递给 LinkAnnotation 的 Action 属性。以下代码片段演示如何在 PDF 文件中更新链接并将其目标设置为网页地址。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf"))
    {
        // Get the first link annotation from first page of document
        var linkAnnot = (Aspose.Pdf.Annotations.LinkAnnotation)document.Pages[1].Annotations[1];

        // Modification link: change link action and set target as web address
        linkAnnot.Action = new Aspose.Pdf.Annotations.GoToURIAction("www.aspose.com");

        // Save PDF document
        document.Save(dataDir + "SetDestinationLink_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf");

    // Get the first link annotation from first page of document
    var linkAnnot = (Aspose.Pdf.Annotations.LinkAnnotation)document.Pages[1].Annotations[1];

    // Modification link: change link action and set target as web address
    linkAnnot.Action = new Aspose.Pdf.Annotations.GoToURIAction("www.aspose.com");

    // Save PDF document
    document.Save(dataDir + "SetDestinationLink_out.pdf");
}

将链接目标设置为另一个 PDF 文件

以下代码片段演示如何在 PDF 文件中更新链接并将其目标设置为另一个 PDF 文件。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf"))
    {
        var linkAnnot = (Aspose.Pdf.Annotations.LinkAnnotation)document.Pages[1].Annotations[1];
        var goToR = (Aspose.Pdf.Annotations.GoToRemoteAction)linkAnnot.Action;

        // Next line update destination, do not update file
        goToR.Destination = new Aspose.Pdf.Annotations.XYZExplicitDestination(2, 0, 0, 1.5);

        // Next line update file
        goToR.File = new Aspose.Pdf.FileSpecification(dataDir + "input.pdf");

        // Save PDF document
        document.Save(dataDir + "SetTargetLink_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf");

    var linkAnnot = (Aspose.Pdf.Annotations.LinkAnnotation)document.Pages[1].Annotations[1];
    var goToR = (Aspose.Pdf.Annotations.GoToRemoteAction)linkAnnot.Action;

    // Next line update destination, do not update file
    goToR.Destination = new Aspose.Pdf.Annotations.XYZExplicitDestination(2, 0, 0, 1.5);

    // Next line update file
    goToR.File = new Aspose.Pdf.FileSpecification(dataDir + "input.pdf");

    // Save PDF document
    document.Save(dataDir + "SetTargetLink_out.pdf");
}

更新 LinkAnnotation 文本颜色

链接注释不包含文本。相反，文本放置在注释下方页面的内容中。因此，要更改文本的颜色，请替换页面文本的颜色，而不是尝试更改注释的颜色。以下代码片段演示如何在 PDF 文件中更新链接注释的颜色。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf"))
    {
        foreach (var annotation in document.Pages[1].Annotations)
        {
            if (annotation is Aspose.Pdf.Annotations.LinkAnnotation)
            {
                // Search the text under the annotation
                var ta = new Aspose.Pdf.Text.TextFragmentAbsorber();
                var rect = annotation.Rect;
                rect.LLX -= 10;
                rect.LLY -= 10;
                rect.URX += 10;
                rect.URY += 10;
                ta.TextSearchOptions = new Aspose.Pdf.Text.TextSearchOptions(rect);
                ta.Visit(document.Pages[1]);

                // Change color of the text.
                foreach (var textFragment in ta.TextFragments)
                {
                    textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.Red;
                }
            }
        }

        // Save PDF document
        document.Save(dataDir + "UpdateLinkTextColor_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void UpdateLinkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_LinksActions();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "UpdateLinks.pdf");

    foreach (var annotation in document.Pages[1].Annotations)
    {
        if (annotation is Aspose.Pdf.Annotations.LinkAnnotation)
        {
            // Search the text under the annotation
            var ta = new Aspose.Pdf.Text.TextFragmentAbsorber();
            var rect = annotation.Rect;
            rect.LLX -= 10;
            rect.LLY -= 10;
            rect.URX += 10;
            rect.URY += 10;
            ta.TextSearchOptions = new Aspose.Pdf.Text.TextSearchOptions(rect);
            ta.Visit(document.Pages[1]);

            // Change color of the text.
            foreach (var textFragment in ta.TextFragments)
            {
                textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.Red;
            }
        }
    }

    // Save PDF document
    document.Save(dataDir + "UpdateLinkTextColor_out.pdf");
}