使用 WorkbookSetting.StreamProvider 控制外部资源

可能的使用场景

有时，您的 Excel 文件包含外部资源，例如链接图像等。Aspose.Cells 允许您使用以下命令控制这些外部资源工作簿.设置.StreamProvider这需要实施IStreamProvider界面。每当您尝试呈现包含外部资源（例如链接图像）的工作表时，IStreamProvider接口将被调用，这将使您能够对外部资源采取适当的操作。

使用 WorkbookSetting.StreamProvider 控制外部资源

下面的示例代码解释了工作簿.设置.StreamProvider .它加载了示例 Excel 文件包含链接图像。该代码将链接的图像替换为Aspose 徽标并使用将整个工作表渲染成单个图像图纸渲染班级。以下屏幕截图显示了示例 Excel 文件及其渲染输出图像供参考。如您所见，损坏的链接图像已替换为 Aspose 徽标。

示例代码

// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-.NET
class ControlExternalResourcesUsingWorkbookSetting_StreamProvider
{
    //Source directory
    static string sourceDir = RunExamples.Get_SourceDirectory();

    //Output directory
    static string outputDir = RunExamples.Get_OutputDirectory();

    //Implementation of IStreamProvider
    class SP : IStreamProvider
    {
        public void CloseStream(StreamProviderOptions options)
        {

        }

        public void InitStream(StreamProviderOptions options)
        {
            //string sourceDir = RunExamples.Get_SourceDirectory();

            //Open the filestream of Aspose Logo and assign it to StreamProviderOptions.Stream property
            FileStream fi = new FileStream(sourceDir + "sampleControlExternalResourcesUsingWorkbookSetting_StreamProvider.png", FileMode.OpenOrCreate, FileAccess.Read);
            options.Stream = fi;
        }
    }
    public static void Run()
    {
        //Load sample Excel file containing the external resource e.g. linked image etc.
        Workbook wb = new Workbook(sourceDir + "sampleControlExternalResourcesUsingWorkbookSetting_StreamProvider.xlsx");

        //Provide your implementation of IStreamProvider
        wb.Settings.ResourceProvider = new SP();

        //Access first worksheet
        Worksheet ws = wb.Worksheets[0];

        //Specify image or print options, we need one page per sheet and png output
        ImageOrPrintOptions opts = new ImageOrPrintOptions();
        opts.OnePagePerSheet = true;
        opts.ImageType = ImageType.Png;

        //Create sheet render by passing required parameters
        SheetRender sr = new SheetRender(ws, opts);

        //Convert your entire worksheet into png image
        sr.ToImage(0, outputDir + "outputControlExternalResourcesUsingWorkbookSetting_StreamProvider.png");

        Console.WriteLine("ControlExternalResourcesUsingWorkbookSetting_StreamProvider executed successfully.");
    }
}