.NET DataVisualization for Creating PDF, PostScript Charts

Overview

As you may know, .NET provides nice Data Visualization features.

But, .NET Data Visualization only supports RGB raster image charts(.png, .jpg, etc) and creating high-resolution images takes much time. Also, does not supoort PDF and PostScript outputs for volume printing.

• Why PDF and PostScript outputs
  • The size of PDF/PostScript charts in high-resolution output is normally 10kb ~ 50kb per chart, but the size of raster image charts(.png, .jpg, .tif formats) may have 1mb ~ 5mb size.
  • Much faster creation, comparing to bitmap charts.
  • Let’s assume we create a chart with 2x2-inch (600 dpi resultion). Drawing raster chart image needs to handle 1,200x1,200=1,440,000 pixels and each pixel contains 3 or 4 bytes of memory, this will cause slow and huge outputs. But, for vector outputs like PDF/PostScript, drawing lines/circles/stroke/fill commands just need few bytes and creating rasterized images that requires much computing power and memory will be done by PDF viewers(like Adobe Acrobat PDF Reader) or printers.
  • PostScript and PDF also support CMYK, printing color images requires CMYK color-space for precise colors.
• PDF, PostScript Chart Features
  • Support CMYK color-space
  • 100% vector graphics
  • Fonts and reusable objects(images) are not duplicated in PDF and PostScript output
  • iTextSharp(PDF) and custom PostScript libraries are used
  • Features above result faster speed and smaller outputs

• Source code for .NET 8 Data Visualization with PDF and PostScript

• Chart Designer

  

Implementation of PDF & PostScript Charts

.NET Data Visualization library uses GDI+ for drawing chart’s components like X-Y axis lines, ellipses and label texts. So, I’ve implemented PDF and PostScript warappers to replace all GDI+ drawing methods that are used in chart drawing.

Performance Comparisons: PDF vs PostScript vs Image Charts

• Creating 1,000 pages(A4, each page has 2 charts) outputs

  	PDF Chart (CMYK Color-Space)	PostScript Chart	Image Chart
  Creation Time	14 seconds	10 seconds	35 minutes
  File Size	7,362 kb	2,641 kb	430 mb

• PDF Chart Sample - CMYK Color-Space

  

• PostScript Chart Sample

  

• Image Chart Sample - 600x600 dpi in PNG format

  

Entry Points to Create PDF, PostScript Charts

• SavePDF(), SavePS() methods in ChartWinControls.cs are the entry points for PDF, PostScript charts creation. And, these methods initialize the rendering information of PDF and PostScript.

• SavePDF() Method

    // -ChartPDF
  
    public void SavePDF(string lsPdfFile, System.Windows.Point chartLocation, PdfGraphicsInfo.EnumColorSpace lColorSpace, OrionX2.OrionFont.FontManagerConfig fontMgr, bool lbUseKValueCMYKEqual)
    {
        using (FileStream lfsPdf = new FileStream(lsPdfFile, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite))
        {
            SavePDF(lfsPdf, chartLocation, lColorSpace, fontMgr, lbUseKValueCMYKEqual);
            lfsPdf.Close();
        }
          
    }
  
    public void SavePDF(Stream lStrm, System.Windows.Point chartLocation, PdfGraphicsInfo.EnumColorSpace colorSpace, OrionX2.OrionFont.FontManagerConfig fontMgr, bool lbUseKValueCMYKEqual)
    {
        try
        {
            iTextSharp.text.FontFactory.RegisterDirectory(@"C:\Windows\Fonts");
            iTextSharp.text.Rectangle pdfPageSize = new iTextSharp.text.Rectangle(0, 0, 
                (float)OrionX2.ConfigInfo.UCNV.GetPointFromPixel(this.Width, renderingDpiX),
                (float)OrionX2.ConfigInfo.UCNV.GetPointFromPixel(this.Height, renderingDpiY), 0);
            using (iTextSharp.text.Document pdfDoc = new iTextSharp.text.Document(pdfPageSize))
            {
  
                iTextSharp.text.pdf.PdfWriter pdfWrt = iTextSharp.text.pdf.PdfWriter.GetInstance(pdfDoc, lStrm);
                pdfDoc.Open();
                pdfDoc.NewPage();
  
                SavePDF(chartLocation, pdfDoc, pdfWrt, colorSpace, fontMgr, lbUseKValueCMYKEqual);
                pdfDoc.Close();
            }
        }
        finally
        {
  
        }
    }
  
    public void SavePDF(System.Windows.Point chartLocation, iTextSharp.text.Document pdfDoc, iTextSharp.text.pdf.PdfWriter pdfWrt, PdfGraphicsInfo.EnumColorSpace colorSpace, OrionX2.OrionFont.FontManagerConfig fontMgr, bool lbUseKValueCMYKEqual)
    {
        PdfGraphicsInfo lPdfInfo = new PdfGraphicsInfo(fontMgr,  new System.Windows.Rect(chartLocation.X, chartLocation.Y, this.Width, this.Height), 
            RenderingDpiX, RenderingDpiY, lbUseKValueCMYKEqual);
        PSGraphicsInfo lPSInfo = new PSGraphicsInfo(null, null, fontMgr,
            new System.Windows.Rect(chartLocation.X, chartLocation.Y, this.Width, this.Height), RenderingDpiX, RenderingDpiY);
        try
        {
            lPdfInfo.cPdfDoc = pdfDoc;
            lPdfInfo.cPdfWrt = pdfWrt;
            lPdfInfo.ceColorSpace = colorSpace;
            lPdfInfo.DpiX = RenderingDpiX;
            lPdfInfo.DpiY = RenderingDpiY;
  
            SavePDF(lPdfInfo);
  
        }
        finally
        {
  
        }
    }
  
    public void SavePDF(PdfGraphicsInfo lPdfInfo)
    {
        this.chartPicture.isSavingAsImage = true;
        this.chartPicture.GetPDF(lPdfInfo);
        this.chartPicture.isSavingAsImage = false;
    }
    // ChartPDF-
  

• SavePS() Method

    // -ChartPS
  
    public void SavePS(System.Windows.Point chartLocation, PdfGraphicsInfo.EnumColorSpace colorSpace, OrionX2.OrionFont.FontManagerConfig fontMgr, Dictionary<string, PSFontData> ldctPSFonts, Stream lStrmHeader, Stream lStrmBody)
    {
        PSGraphicsInfo lPSInfo = new PSGraphicsInfo(lStrmHeader, lStrmBody, fontMgr,
            new System.Windows.Rect(chartLocation.X, chartLocation.Y, this.Width, this.Height), RenderingDpiX, RenderingDpiY);
        PdfGraphicsInfo lPdfInfo = new PdfGraphicsInfo(fontMgr, new System.Windows.Rect(chartLocation.X, chartLocation.Y, this.Width, this.Height),
            RenderingDpiX, RenderingDpiY, true);//lbUseKValueCMYKEqual);
        lPSInfo.cdctFontData = ldctPSFonts;
        try
        {
            lPSInfo.ceColorSpace = colorSpace;
            lPSInfo.DpiX = RenderingDpiX;
            lPSInfo.DpiY = RenderingDpiY;
  
            SavePS(lPSInfo);
        }
        finally
        {
  
        }
    }
  
    public void SavePS(PSGraphicsInfo lPSInfo)
    {
        this.chartPicture.isSavingAsImage = true;
        this.chartPicture.GetPS(lPSInfo);
        this.chartPicture.isSavingAsImage = false;
    }
    // ChartPS-
  

GDI+, PDF, PostScript Rendering Code

• RenderGDI Code

  • _graphics is GDI+ System.Drawing.Graphics object and it calls GDI+ DrawLine() methods.

    ...
    public void DrawLine(
                Pen pen,
                PointF pt1,
                PointF pt2
                )
    {
        _graphics.DrawLine(pen.ToGdiPen(), pt1, pt2);
    }
    ...
  

• RenderingGraphicsPDF Code

  • this.cPdfCnts is iTextSharp’s PdfContentsBytes object and it draws a line on PDF page.

    ...
    public void DrawLine(
        Pen pen,
        PointF pt1px,
        PointF pt2px
        )
    {
        if (pen.Color.IsEmpty || pen.Color.A == 0)
            return;
        float x1Pt = (float)UCNV.GetPointFromPixel(pt1px.X, this.DpiX);
        float y1Pt = (float)(this.ChartHeightPt - UCNV.GetPointFromPixel(pt1px.Y, this.DpiY));
        float x2Pt = (float)UCNV.GetPointFromPixel(pt2px.X, this.DpiX);
        float y2Pt = (float)(this.ChartHeightPt - UCNV.GetPointFromPixel(pt2px.Y, this.DpiY));
        this.cPdfCnts.MoveTo(x1Pt, y1Pt);
        this.cPdfCnts.LineTo(x2Pt, y2Pt);
        pen.ToPdfPen(this);
        this.cPdfCnts.Stroke();
    }
    ...
  

• PSGraphicsInfo Code

  • PS_moveto()/PS_lineto() methods create PostScript commands to draw a line.

    ...
    internal static string csPSmoveto = "m";
    internal static string csPSlineto = "l";
    ...
    public void DrawLine(
        Pen pen,
        PointF pt1px,
        PointF pt2px
        )
    {
        if (pen.Color.IsEmpty || pen.Color.A == 0)
            return;
        float x1Pt = (float)UCNV.GetPointFromPixel(pt1px.X, this.DpiX);
        float y1Pt = (float)(this.ChartHeightPt - UCNV.GetPointFromPixel(pt1px.Y, this.DpiY));
        float x2Pt = (float)UCNV.GetPointFromPixel(pt2px.X, this.DpiX);
        float y2Pt = (float)(this.ChartHeightPt - UCNV.GetPointFromPixel(pt2px.Y, this.DpiY));
        this.PS_moveto(x1Pt, y1Pt);
        this.PS_lineto(x2Pt, y2Pt);
        pen.ToPSPen(this);
        this.PS_stroke();
    }
    ...
    internal void PS_moveto(float lfX, float lfY)
    {
        WriteTo_LF(String.Format("{0:0.###} {1:0.###} {2}", lfX, lfY, csPSmoveto));
    }
    internal void PS_lineto(float lfX, float lfY)
    {
        WriteTo_LF(String.Format("{0:0.###} {1:0.###} {2}", lfX, lfY, csPSlineto));
    }