Rendering di testo utilizzando il carattere Type1 | .NET

Rendering Testo

Al fine di rendere il testo, il sottosistema di rendering richiede l’implementazione di Aspose.Font.Rendering.IGlyphOutlinePainter Interfaccia per disegnare glifo. Questo può essere ottenuto utilizzando i seguenti passaggi.

  1. Implementa i metodi IglyphoutLinePainter creando un GlyphOutlinePainter di classe che richiede oggetto di tipo System.Drawing.Drawing2d.Graphicspath per obiettivi di disegno grafico. L’implementazione è come illustrata di seguito.
 1// For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-.NET
 2class GlyphOutlinePainter : IGlyphOutlinePainter
 3{ 
 4    private System.Drawing.Drawing2D.GraphicsPath _path;
 5    private System.Drawing.PointF _currentPoint;
 6
 7    public GlyphOutlinePainter(System.Drawing.Drawing2D.GraphicsPath path)
 8    {
 9        _path = path;
10    }
11
12    public void MoveTo(MoveTo moveTo)
13    {
14        _path.CloseFigure();
15        _currentPoint.X = (float)moveTo.X;
16        _currentPoint.Y = (float)moveTo.Y;
17    }
18
19    public void LineTo(LineTo lineTo)
20    {
21        float x = (float)lineTo.X;
22        float y = (float)lineTo.Y;
23        _path.AddLine(_currentPoint.X, _currentPoint.Y, x, y);
24        _currentPoint.X = x;
25        _currentPoint.Y = y;
26    }
27
28    public void CurveTo(CurveTo curveTo)
29    {
30        float x3 = (float)curveTo.X3;
31        float y3 = (float)curveTo.Y3;
32
33        _path.AddBezier(
34                  _currentPoint.X,
35                  _currentPoint.Y,
36                  (float)curveTo.X1,
37                  (float)curveTo.Y1,
38                  (float)curveTo.X2,
39                  (float)curveTo.Y2,
40                  x3,
41                  y3);
42
43        _currentPoint.X = x3;
44        _currentPoint.Y = y3;
45    }
46
47    public void ClosePath()
48    {
49        _path.CloseFigure();
50    }
51}
  1. Crea metodo DrawText() che disegna il testo specificato in System.Drawing.Bitmap e salva la bitmap risultante sul disco. Ciò includerà i seguenti passaggi:

Passaggi ausiliari per questa strategia

L’implementazione del metodo “DrawText” è come mostrato di seguito.

 1// For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-.NET
 2static void DrawText(string text, IFont font, double fontSize,
 3            Brush backgroundBrush, Brush textBrush, string outFile)
 4{
 5    //Get glyph identifiers for every symbol in text line
 6    GlyphId[] gids = new GlyphId[text.Length];
 7    for (int i = 0; i < text.Length; i++)
 8        gids[i] = font.Encoding.DecodeToGid(text[i]);
 9    // set common drawing settings
10    double dpi = 300;
11
12    double resolutionCorrection = dpi / 72; // 72 is font's internal dpi
13    // prepare output bitmap
14    Bitmap outBitmap = new Bitmap(960, 720);
15    outBitmap.SetResolution((float)dpi, (float)dpi);
16    Graphics outGraphics = Graphics.FromImage(outBitmap);
17    outGraphics.FillRectangle(backgroundBrush, 0, 0, outBitmap.Width, outBitmap.Height);
18    outGraphics.SmoothingMode = SmoothingMode.HighQuality;
19    //declare coordinate variables and previous gid
20    GlyphId previousGid = null;
21    double glyphXCoordinate = 0;
22    double glyphYCoordinate = fontSize * resolutionCorrection;
23    //loop which paints every glyph in gids
24    foreach (GlyphId gid in gids)
25    {
26        // if the font contains the gid
27        if (gid != null)
28        {
29            Glyph glyph = font.GlyphAccessor.GetGlyphById(gid);
30            if (glyph == null)
31                continue;
32
33            // path that accepts drawing instructions
34            GraphicsPath path = new GraphicsPath();
35
36            // Create IGlyphOutlinePainter implementation
37            GlyphOutlinePainter outlinePainter = new GlyphOutlinePainter(path);
38
39            // Create the renderer
40            Aspose.Font.Renderers.IGlyphRenderer renderer = new
41                Aspose.Font.Renderers.GlyphOutlineRenderer(outlinePainter);
42
43            // get common glyph properties
44            double kerning = 0;
45
46            // get kerning value
47            if (previousGid != null)
48            {
49                kerning = (font.Metrics.GetKerningValue(previousGid, gid) /
50                           glyph.SourceResolution) * fontSize * resolutionCorrection;
51                kerning += FontWidthToImageWith(font.Metrics.GetGlyphWidth(previousGid),
52                        glyph.SourceResolution, fontSize);
53            }
54
55            // glyph positioning - increase glyph X coordinate according to kerning distance
56            glyphXCoordinate += kerning;
57
58            // Glyph placement matrix
59            TransformationMatrix glyphMatrix =
60                new TransformationMatrix(
61                    new double[]
62                            {
63                                    fontSize*resolutionCorrection,
64                                    0,
65                                    0,
66                                // negative because of bitmap coordinate system begins from the top
67                                    - fontSize*resolutionCorrection,
68                                    glyphXCoordinate,
69                                    glyphYCoordinate
70                            });
71
72            // render current glyph
73            renderer.RenderGlyph(font, gid, glyphMatrix);
74            // fill the path
75            path.FillMode = FillMode.Winding;
76            outGraphics.FillPath(textBrush, path);
77        }
78        //set current gid as previous to get correct kerning for next glyph
79        previousGid = gid;
80    }
81    //Save results
82    outBitmap.Save(outFile);
83}
  1. Crea metodo di utilità per calcolare la larghezza del carattere alla larghezza dell’immagine come mostrato nel campione di codice seguente
1// For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-.NET
2static double FontWidthToImageWith(double width, int fontSourceResulution, double fontSize, double dpi = 300)
3{
4    double resolutionCorrection = dpi / 72; // 72 is font's internal dpi
5    return (width / fontSourceResulution) * fontSize * resolutionCorrection;
6}

Chiamare la funzionalità di testo di rendering

Per utilizzare le implementazioni di cui sopra, il seguente codice di esempio può essere eseguito dal metodo principale di un’applicazione basata sulla console.

1// For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-.NET
2string fileName = dataDir + "courier.pfb"; //Font file name with full path
3
4FontDefinition fd = new FontDefinition(FontType.Type1, new FontFileDefinition("pfb", new FileSystemStreamSource(fileName)));
5Type1Font font = Aspose.Font.Font.Open(fd) as Type1Font;
6            
7
8DrawText("Hello world", font, 14, Brushes.White, Brushes.Black, dataDir + "hello1_type1_out.jpg");
9DrawText("Hello world", font, 14, Brushes.Yellow, Brushes.Red, dataDir + "hello2_type1_out.jpg");

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