Added new kb article export-charts-png-300dpi-spreadprocessing (#607)

* Added new kb article export-charts-png-300dpi-spreadprocessing

* polished

* Update export-charts-png-300dpi-spreadprocessing.md

* Update export-charts-png-300dpi-spreadprocessing.md

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Co-authored-by: KB Bot <[email protected]>
Co-authored-by: Desislava Yordanova <[email protected]>

Author: 3 people

knowledge-base/export-charts-png-300dpi-spreadprocessing.md

@@ -0,0 +1,94 @@
+---
+title: Exporting Charts from Excel Documents to PNG Images with a Specific DPI Resolution Using SpreadProcessing and PdfProcessing
+description: Learn how to export Excel charts to PNG images with a Specific DPI resolution using Telerik SpreadProcessing, PdfProcessing and UI for WinForms and WPF charting controls.
+type: how-to
+page_title: Exporting Charts from Excel Documents to PNG Images with a Specific DPI Resolution Using SpreadProcessing
+meta_title: Exporting Charts from Excel Documents to PNG Images with a Specific DPI Resolution Using SpreadProcessing
+slug: export-charts-png-300dpi-spreadprocessing
+tags: spread, processing,telerik, document ,chart, image, export, png, dpi, resolution
+res_type: kb
+ticketid: 1695547
+---
+
+## Environment
+
+| Version | Product | Author | 
+| ---- | ---- | ---- | 
+| 2025.2.520| RadSpreadProcessing & RadPdfProcessing |[Desislava Yordanova](https://www.telerik.com/blogs/author/desislava-yordanova)| 
+
+## Description
+
+Learn how to extract the [charts]({%slug radspreadprocessing-features-charts%}) from Excel documents and save them as PNG files, while specifying the desired resolution (e.g. 300 DPI).
+
+## Solution
+
+Exporting charts directly from Excel files to images is not yet supported by the [SpreadProcessing]({%slug radspreadprocessing-overview%}) library. As an alternative, you can benefit the export option to PDF format which allows you to plug into the chart rendering process, export the chart and handle the DPI settings
+
+### Suggested Workflow Using Charting Controls
+
+1. Extract the chart data from the Excel file using SpreadProcessing.
+2. Rebuild the chart using a UI component, such as [RadChartView](https://docs.telerik.com/devtools/winforms/controls/chartview/features/export) from the Telerik UI for WinForms or WPF suites.
+3. Export the chart as a PNG image with 300 DPI using RadChartView.
+
+### Alternative Approach: Exporting to PDF
+
+Export the XLSX document to PDF format using SpreadProcessing. This method internally uses a **chart renderer** for rendering charts in the PDF. Implement a custom [IPdfChartRenderer]({%slug radspreadprocessing-features-charts-pdf-export%}) to manipulate chart resolution and save the chart as a PNG image in the ongoing export process.
+
+#### Sample implementation for exporting charts as PNG with 300 DPI:
+
+```csharp
+public class WinFormsPdfChartImageRenderer : IPdfChartRenderer
+{
+    public void RenderChart(FixedContentEditor editor, FloatingChartShape chartShape)
+    {
+        string filePath = @"exportedChart.png";
+
+        // Set chart dimensions
+        System.Drawing.Size size = new System.Drawing.Size((int)(chartShape.Width), (int)(chartShape.Height + 10));
+        System.Drawing.Image chartImage = Telerik.WinForms.Controls.Spreadsheet.Layers.ChartModelToImageConverter.GetImageFromFloatingChartShape(chartShape, size);
+
+        using (var bmp = new Bitmap(chartImage))
+        {
+            // Set DPI to 300
+            bmp.SetResolution(300, 300);
+
+            // Save as PNG
+            bmp.Save(filePath, System.Drawing.Imaging.ImageFormat.Png);
+        }
+        using (FileStream fs = new FileStream(filePath, FileMode.Open))
+        {
+            editor.DrawImage(fs);
+        }
+        Process.Start(new ProcessStartInfo(filePath) { UseShellExecute = true });
+    }
+}
+```
+
+To export charts to PNG, use the custom renderer in conjunction with SpreadProcessing’s PDF export functionalities. Charts saved as PNG images can then be adjusted for resolution.
+
+#### Applying the custom renderer:
+
+```csharp
+Telerik.Windows.Documents.Spreadsheet.Model.Workbook workbook;
+IWorkbookFormatProvider formatProvider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.OpenXml.Xlsx.XlsxFormatProvider();
+string fileName = "SampleFile.xlsx";
+using (Stream inputStream = new FileStream(fileName, FileMode.Open))
+{
+    workbook = formatProvider.Import(inputStream, TimeSpan.FromSeconds(10));
+}
+
+PdfFormatProvider pdfFormatProvider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.Pdf.PdfFormatProvider();
+pdfFormatProvider.ExportSettings.ChartRenderer = new WinFormsPdfChartImageRenderer();  
+converter.PdfFormatProvider = pdfFormatProvider;
+using (Stream output = File.OpenWrite("Sample.pdf"))
+{ 
+    pdfFormatProvider.Export(workbook, output, TimeSpan.FromSeconds(10));
+}
+```
+
+Note: Recreating the chart using RadChartView may require extra effort if the charts are highly customized or complex.
+
+## See Also
+
+- [SpreadProcessing PDF Export]({%slug radspreadprocessing-features-charts-pdf-export%})
+- [Exporting Spreadsheets with Charts to PDF with RadSpreadProcessing and WinForms RadChartView]({%slug export-charts-to-pdf-radspreadprocessing%})

libraries/radspreadprocessing/features/charts/pdf-export.md

@@ -83,3 +83,4 @@ Now the chart objects in the spreadsheet will be exported along with the other c
 
 * [Using PdfFormatProvider]({%slug radspreadprocessing-formats-and-conversion-pdf-pdfformatprovider%})
 * [Exporting Spreadsheets with Charts to PDF with RadSpreadProcessing and WinForms RadChartView]({%slug export-charts-to-pdf-radspreadprocessing%})
+* [Exporting Charts from Excel Documents to PNG Images with a Specific DPI Resolution Using SpreadProcessing]({%slug export-charts-png-300dpi-spreadprocessing%})