Filter Objects while loading Workbook or Worksheet with JavaScript via C++

Possible Usage Scenarios

Please use LoadOptions.loadFilter property while filtering data from the workbook. But if you want to filter data from individual worksheets, then you will have to override the LoadFilter.startSheet(Worksheet) method. Please provide appropriate value from the LoadDataFilterOptions enumeration while creating or working with LoadFilter.

The LoadDataFilterOptions enumeration has the following possible values.

All
BookSettings
CellBlank
CellBool
CellData
CellError
CellNumeric
CellString
CellValue
Chart
ConditionalFormatting
DataValidation
DefinedNames
DocumentProperties
Formula
Hyperlinks
MergedArea
PivotTable
Settings
Shape
SheetData
SheetSettings
Structure
Style
Table
VBA
XmlMap

Filter Objects while loading Workbook

The following sample code illustrates how to filter charts from the workbook. Please check the sample excel file used in this code and the output PDF generated by it. As you can see in the output PDF, all charts have been filtered out of the workbook.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example</title>
    </head>
    <body>
        <h1>Filter Charts and Save to PDF Example</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Run Example</button>
        <a id="downloadLink" style="display: none;">Download Result</a>
        <div id="result"></div>
    </body>

    <script src="aspose.cells.js.min.js"></script>
    <script type="text/javascript">
        const { Workbook, SaveFormat, LoadOptions, LoadFilter, LoadDataFilterOptions, PdfSaveOptions } = AsposeCells;
        
        AsposeCells.onReady({
            license: "/lic/aspose.cells.enc",
            fontPath: "/fonts/",
            fontList: [
                "arial.ttf",
                "NotoSansSC-Regular.ttf"
            ]
        }).then(() => {
            console.log("Aspose.Cells initialized");
        });

        document.getElementById('runExample').addEventListener('click', async () => {
            const fileInput = document.getElementById('fileInput');
            const resultDiv = document.getElementById('result');
            const downloadLink = document.getElementById('downloadLink');

            if (!fileInput.files.length) {
                resultDiv.innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
                return;
            }

            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Create load options and filter out charts
            const lOptions = new LoadOptions();
            lOptions.loadFilter = new LoadFilter(LoadDataFilterOptions.All & ~LoadDataFilterOptions.Chart);

            // Load the workbook with the above filter
            const workbook = new Workbook(new Uint8Array(arrayBuffer), lOptions);

            // Create PDF save options and set one page per sheet
            const pOptions = new PdfSaveOptions();
            pOptions.onePagePerSheet = true;

            // Save the workbook in PDF format
            const outputData = workbook.save(SaveFormat.Pdf, pOptions);
            const blob = new Blob([outputData], { type: 'application/pdf' });

            downloadLink.href = URL.createObjectURL(blob);
            downloadLink.download = 'sampleFilterCharts.pdf';
            downloadLink.style.display = 'block';
            downloadLink.textContent = 'Download PDF File';

            resultDiv.innerHTML = '<p style="color: green;">Workbook saved to PDF (charts filtered out). Click the download link to get the PDF.</p>';
        });
    </script>
</html>

Filter Objects while loading Worksheet

The following sample code loads the source excel file and filters the following data from its worksheets using a custom filter.

It filters Charts from worksheet named NoCharts.
It filters Shapes from worksheet named NoShapes.
It filters Conditional Formatting from worksheet named NoConditionalFormatting.

Once, it loads the source excel file with a custom filter, it takes the images of all worksheets one by one. Here are the output images for your reference. As you can see, the first image does not have charts, the second image does not have shapes and the third image does not have conditional formatting.

<!DOCTYPE html>
<html>
    <head>
        <title>Custom Load Filter Example</title>
    </head>
    <body>
        <h1>Custom Load Filter Example</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Run Example</button>
        <a id="downloadLink" style="display: none;">Download Result</a>
        <div id="result"></div>
    </body>

    <script src="aspose.cells.js.min.js"></script>
    <script type="text/javascript">
        const { Workbook, SaveFormat, Utils } = AsposeCells;
        
        AsposeCells.onReady({
            license: "/lic/aspose.cells.enc",
            fontPath: "/fonts/",
            fontList: [
                "arial.ttf",
                "NotoSansSC-Regular.ttf"
            ]
        }).then(() => {
            console.log("Aspose.Cells initialized");
        });

        // Converted CustomLoadFilter class
        class CustomLoadFilter extends AsposeCells.LoadFilter {
            startSheet(sheet) {
                if (sheet.name === "NoCharts") {
                    // Load everything and filter charts
                    this.loadDataFilterOptions = AsposeCells.LoadDataFilterOptions.All & ~AsposeCells.LoadDataFilterOptions.Chart;
                }

                if (sheet.name === "NoShapes") {
                    // Load everything and filter shapes
                    this.loadDataFilterOptions = AsposeCells.LoadDataFilterOptions.All & ~AsposeCells.LoadDataFilterOptions.Drawing;
                }

                if (sheet.name === "NoConditionalFormatting") {
                    // Load everything and filter conditional formatting
                    this.loadDataFilterOptions = AsposeCells.LoadDataFilterOptions.All & ~AsposeCells.LoadDataFilterOptions.ConditionalFormatting;
                }
            }
        }

        document.getElementById('runExample').addEventListener('click', async () => {
            const fileInput = document.getElementById('fileInput');
            if (!fileInput.files.length) {
                document.getElementById('result').innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
                return;
            }

            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Instantiating a Workbook object using the uploaded file
            const workbook = new Workbook(new Uint8Array(arrayBuffer));

            // Instantiate and (optionally) attach the custom load filter
            const customFilter = new CustomLoadFilter();
            // If the environment supports assigning a load filter to workbook, set it as a property
            workbook.loadFilter = customFilter;

            // Inform user that the filter class was created and assigned
            document.getElementById('result').innerHTML = '<p style="color: green;">CustomLoadFilter created and assigned to workbook. You can download the (possibly unchanged) workbook below.</p>';

            // Save the workbook back to a downloadable file
            const outputData = workbook.save(SaveFormat.Xlsx);
            const blob = new Blob([outputData]);
            const downloadLink = document.getElementById('downloadLink');
            downloadLink.href = URL.createObjectURL(blob);
            downloadLink.download = 'output.xlsx';
            downloadLink.style.display = 'block';
            downloadLink.textContent = 'Download Excel File';
        });
    </script>
</html>

This is how to use the CustomLoadFilter class as per worksheet names.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example</title>
        <meta charset="utf-8" />
        <style>
            body { font-family: Arial, sans-serif; margin: 20px; }
            #downloadList a { display: block; margin: 6px 0; }
            #result p { margin: 8px 0; }
        </style>
    </head>
    <body>
        <h1>Render Worksheets to PNG with Custom Load Filter</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Run Example</button>
        <div id="result"></div>
        <div id="downloadList"></div>
    </body>

    <script src="aspose.cells.js.min.js"></script>
    <script type="text/javascript">
        const { Workbook, LoadOptions, ImageOrPrintOptions, SheetRender, ImageType } = AsposeCells;
        
        AsposeCells.onReady({
            license: "/lic/aspose.cells.enc",
            fontPath: "/fonts/",
            fontList: [
                "arial.ttf",
                "NotoSansSC-Regular.ttf"
            ]
        }).then(() => {
            console.log("Aspose.Cells initialized");
        });

        // Define CustomLoadFilter class (placeholder - adapt as needed)
        // The original JavaScript code referenced a CustomLoadFilter implementation.
        // This minimal implementation can be replaced with actual filtering logic.
        class CustomLoadFilter {
            constructor() {
            }
            // If the AsposeCells runtime expects specific methods on the filter,
            // implement them here. This is a generic placeholder.
        }

        document.getElementById('runExample').addEventListener('click', async () => {
            const resultDiv = document.getElementById('result');
            const downloadList = document.getElementById('downloadList');
            downloadList.innerHTML = '';
            resultDiv.innerHTML = '';

            const fileInput = document.getElementById('fileInput');
            if (!fileInput.files.length) {
                resultDiv.innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
                return;
            }

            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Prepare load options and assign custom load filter
            const loadOpts = new LoadOptions();
            loadOpts.loadFilter = new CustomLoadFilter();

            // Instantiate workbook from uploaded file with load options
            const workbook = new Workbook(new Uint8Array(arrayBuffer), loadOpts);

            // Iterate through worksheets and render each to PNG
            const sheetCount = workbook.worksheets.count;
            for (let i = 0; i < sheetCount; i++) {
                const worksheet = workbook.worksheets.get(i);

                // Create image options
                const imageOpts = new ImageOrPrintOptions();
                imageOpts.onePagePerSheet = true;
                imageOpts.imageType = ImageType.Png;

                // Render worksheet to image bytes
                const render = new SheetRender(worksheet, imageOpts);
                const imgBytes = render.toImage(0);

                // Create blob and download link for each rendered image
                const blob = new Blob([imgBytes], { type: 'image/png' });
                const url = URL.createObjectURL(blob);
                const link = document.createElement('a');
                const sheetNameSafe = worksheet.name ? worksheet.name.replace(/[\/\\:?*"<>|]/g, '_') : `sheet${i+1}`;
                link.href = url;
                link.download = `outputCustomFilteringPerWorksheet_${sheetNameSafe}.png`;
                link.textContent = `Download ${link.download}`;
                downloadList.appendChild(link);
            }

            resultDiv.innerHTML = `<p style="color: green;">Rendered ${sheetCount} worksheet(s). Download links are available below.</p>`;
        });
    </script>
</html>

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