在今天的数据驱动的世界中,通过图表和图表进行复杂信息的可视化已成为必不可少的,虽然Excel提供强大的图表功能,但有无数的场景需要将这些视觉元素作为单独图像提取出来:

  • 将图表纳入报告和演示文稿
  • 在网页应用中嵌入视觉
  • 分享洞察力,而不分发整个分布板
  • 用图形图像创建文档
  • 创建商业智能板的动态视觉内容

Aspose.Cells for .NET 提供了一个可靠的解决方案,以便在不需要 Microsoft Excel 安装的情况下将 Excel 图表编程转换为高品质的图像。

為什麼選擇 Aspose.Cells 為圖形轉換?

传统的 Excel 自动化方法在生产环境中可能有问题,因为:

  • 安全漏洞
  • 部署复杂性
  • 许可挑战
  • 性能瓶装
  • 稳定问题

Aspose.Cells 提供一个专门设计的 API,用于服务器侧处理 Excel 文件,提供优秀的性能和可靠性。

开始使用

在进入例子之前,请确保您有:

  • 下载和安装 Aspose.Cells 为 .NET
  • 添加了一个参考 Aspose.Cells.dll 在你的项目中
  • 进口所需的名称空间:
using Aspose.Cells;
using Aspose.Cells.Charts;
using Aspose.Cells.Rendering;

基本图为图像转换

让我们从一个简单的例子开始,将一个工作表中的所有图表转换为图像,使用 C# Excel Chart to Image:

// Load the Excel file containing charts
Workbook workbook = new Workbook("SalesReport.xlsx");

// Access the worksheet containing charts
Worksheet sheet = workbook.Worksheets[0];

// Initialize counter for unique filenames
int chartIndex = 1;

// Process each chart in the worksheet
foreach (Chart chart in sheet.Charts)
{
    // Define the output path for the image
    string outputPath = $"Chart_{chartIndex}.png";
    
    // Convert the chart to an image
    chart.ToImage(outputPath, ImageFormat.Png);
    
    Console.WriteLine($"Successfully converted chart {chartIndex} to {outputPath}");
    chartIndex++;
}

增强图像质量与自定义选项

对于专业应用程序,您将经常需要控制出口图像的质量和外观,这可以通过 Java Excel 图表到图片 技术实现:

// Load the workbook containing charts
Workbook workbook = new Workbook("FinancialDashboard.xlsx");
Worksheet sheet = workbook.Worksheets["Performance Metrics"];

// Create image options with high resolution
ImageOrPrintOptions imageOptions = new ImageOrPrintOptions
{
    HorizontalResolution = 300,
    VerticalResolution = 300,
    ImageFormat = ImageFormat.Jpeg,
    Quality = 95 // Higher quality JPEG compression
};

// Access a specific chart (e.g., the first chart)
Chart revenueChart = sheet.Charts[0];

// Convert with custom options
revenueChart.ToImage("Revenue_Trends_HQ.jpg", imageOptions);

用不同的格式转换多个图表

不同使用案例可能需要不同的图像格式. 这里是如何将图表出口到不同的格式:

// Load the Excel workbook
Workbook workbook = new Workbook("QuarterlyReport.xlsx");
Worksheet sheet = workbook.Worksheets["Sales Analysis"];

// Initialize counter for unique filenames
int idx = 0;

// Process each chart with custom options for different formats
foreach (Chart chart in sheet.Charts)
{
    // Create image options
    ImageOrPrintOptions imgOpts = new ImageOrPrintOptions();
    
    // Configure different settings based on chart index
    switch (idx % 3)
    {
        case 0: // PNG format with transparency
            imgOpts.ImageFormat = ImageFormat.Png;
            chart.ToImage($"Chart_{idx}_transparent.png", imgOpts);
            break;
            
        case 1: // JPEG format with high quality
            imgOpts.ImageFormat = ImageFormat.Jpeg;
            imgOpts.Quality = 100;
            chart.ToImage($"Chart_{idx}_high_quality.jpg", imgOpts);
            break;
            
        case 2: // SVG format for vector graphics
            imgOpts.ImageFormat = ImageFormat.Svg;
            chart.ToImage($"Chart_{idx}_vector.svg", imgOpts);
            break;
    }
    
    ++idx;
}

先进的图表转换选项

当您需要对 rendering 过程的准确控制时,Aspose.Cells 提供广泛的定制功能:

// Load the source workbook
Workbook workbook = new Workbook("MarketingAnalytics.xlsx");
Worksheet sheet = workbook.Worksheets["Campaign Performance"];

// Get reference to a specific chart
Chart campaignChart = sheet.Charts[0];

// Create advanced rendering options
ImageOrPrintOptions renderOptions = new ImageOrPrintOptions
{
    // Set high resolution for print-quality output
    HorizontalResolution = 600,
    VerticalResolution = 600,
    
    // Control image appearance
    ImageFormat = ImageFormat.Png,
    OnlyArea = false, // Include the entire chart area
    
    // Set custom dimensions (if needed)
    CustomPrintPageWidth = 800,
    CustomPrintPageHeight = 600,
    
    // Enable text rendering hints for smoother text
    TextRenderingHint = TextRenderingHint.AntiAlias,
    
    // Apply print settings from the workbook
    PrintingPage = PrintingPageType.Default
};

// Convert chart with advanced options
campaignChart.ToImage("Campaign_Performance_Print_Quality.png", renderOptions);

来自多个工作表的Batch处理图表

在企业应用程序中,您可能需要在多个工作表中处理图表:

// Load the source Excel file
Workbook workbook = new Workbook("AnnualReport.xlsx");

// Create a directory for output images
string outputDir = "ChartImages";
Directory.CreateDirectory(outputDir);

// Process charts from all worksheets in the workbook
foreach (Worksheet sheet in workbook.Worksheets)
{
    // Skip worksheets without charts
    if (sheet.Charts.Count == 0)
        continue;
        
    Console.WriteLine($"Processing {sheet.Charts.Count} charts from worksheet '{sheet.Name}'");
    
    // Process each chart in the current worksheet
    for (int i = 0; i < sheet.Charts.Count; i++)
    {
        // Get the chart
        Chart chart = sheet.Charts[i];
        
        // Create a descriptive filename
        string sanitizedSheetName = string.Join("_", sheet.Name.Split(Path.GetInvalidFileNameChars()));
        string outputPath = Path.Combine(outputDir, $"{sanitizedSheetName}_Chart_{i+1}.png");
        
        // Define image options
        ImageOrPrintOptions imgOptions = new ImageOrPrintOptions
        {
            HorizontalResolution = 300,
            VerticalResolution = 300
        };
        
        // Convert and save the chart
        chart.ToImage(outputPath, imgOptions);
        
        Console.WriteLine($"  - Saved chart {i+1} to {outputPath}");
    }
}

将图表转换为 Web 应用程序的 SVG

SVG(Scalable Vector Graphics)是适用于网页应用的优秀格式,确保图表在任何分辨率上都看起来模糊:

// Load the workbook
Workbook workbook = new Workbook("WebDashboard.xlsx");
Worksheet sheet = workbook.Worksheets["Performance Metrics"];

// Configure SVG export options
ImageOrPrintOptions svgOptions = new ImageOrPrintOptions
{
    ImageFormat = ImageFormat.Svg,
    SaveFormat = SaveFormat.Svg
};

// Export all charts to SVG with viewBox attribute for responsive display
for (int i = 0; i < sheet.Charts.Count; i++)
{
    Chart chart = sheet.Charts[i];
    
    // Export with viewBox attribute
    chart.ToImage($"WebChart_{i+1}.svg", svgOptions);
}

对大型工作簿的转换进展的监测

当处理包含多个图表的工作簿时,有助于跟踪转换进展:

// Load a large workbook with many charts
Workbook workbook = new Workbook("EnterpriseReports.xlsx");

// Create a custom stream provider to monitor progress
class ChartConversionStreamProvider : IStreamProvider
{
    private int _totalCharts;
    private int _processedCharts = 0;
    
    public ChartConversionStreamProvider(int totalCharts)
    {
        _totalCharts = totalCharts;
    }
    
    public Stream GetStream(string chartName, StreamType streamType)
    {
        // Create output stream
        string outputPath = $"Chart_{chartName}.png";
        Stream stream = new FileStream(outputPath, FileMode.Create);
        
        // Update and report progress
        _processedCharts++;
        double progressPercentage = (_processedCharts / (double)_totalCharts) * 100;
        Console.WriteLine($"Converting chart {_processedCharts} of {_totalCharts}: {progressPercentage:F1}% complete");
        
        return stream;
    }
    
    public void CloseStream(Stream stream)
    {
        if (stream != null)
        {
            stream.Close();
        }
    }
}

// Count total charts across all worksheets
int totalCharts = 0;
foreach (Worksheet sheet in workbook.Worksheets)
{
    totalCharts += sheet.Charts.Count;
}

// Create stream provider and options
ChartConversionStreamProvider streamProvider = new ChartConversionStreamProvider(totalCharts);
ImageOrPrintOptions options = new ImageOrPrintOptions
{
    HorizontalResolution = 300,
    VerticalResolution = 300
};

// Process each chart with progress tracking
int chartIndex = 0;
foreach (Worksheet sheet in workbook.Worksheets)
{
    foreach (Chart chart in sheet.Charts)
    {
        // Generate unique chart name
        string chartName = $"{sheet.Name}_Chart_{chartIndex++}";
        
        // Convert using stream provider
        chart.ToImage(streamProvider.GetStream(chartName, StreamType.Output), options);
    }
}

图形转换的最佳做法

要在将 Excel 图表转换为图像时获得最佳结果,请考虑以下建议:

  • 根据目的调整分辨率:用于印刷材料的更高分辨率(300+DPI)和网页显示的更低分辨率。
  • 选择正确的格式:使用 PNG 用于透明图表、 JPEG 用于照片和 SVG 用于网页应用。
  • 测试不同质量设置: 平衡文件大小和图像质量,特别是对于 JPEG 压缩。
  • 清理文件名:从工作表名称中创建文件名时,删除无效的字符。
  • 实施进展跟踪:为多个图表的工作簿,向用户提供进展反馈。
  • 处理资源适当: 接近流量和对象的排放,以防止记忆泄漏。

结论

Aspose.Cells for .NET 提供了一个强大的,灵活的解决方案,以编程地将 Excel 图表转换为各种图像格式. 无论您需要高分辨率图像的印刷材料,优化图形的 Web 应用程序,或 vector SVGs for responsive designs, Aspose.Cells 提供一致的,高质量的结果,而不需要 Microsoft Excel 安装。

通过遵循本文中列出的示例和最佳做法,您可以将图形图像转换能力集成到您的 .NET 应用程序中,提高数据视觉工作流,并允许在不同平台和媒体上无缝共享基于 Excel 的视觉。

More in this category