'''' This code is part of Document Solutions for PDF .NET demos.'' Copyright (c) MESCIUS inc. All rights reserved.''Imports System.IOImports System.DrawingImports GrapeCity.Documents.PdfImports GrapeCity.Documents.Pdf.GraphicsImports GrapeCity.Documents.TextImports GrapeCity.Documents.DrawingImports GCDRAW = GrapeCity.Documents.Drawing
'' This sample demonstrates how to use GcPdfGraphics.SoftMask'' to draw semi-transparently and specify clipping.Public Class SoftMask1    Function CreatePDF(ByVal stream As Stream) As Integer        Dim doc = New GcPdfDocument()        Dim page = doc.NewPage()        Dim g = page.Graphics
        Dim rc = Util.AddNote(            "GcPdfGraphics has a SoftMask property, which allows creating a mask with a FormXObject, " +            "draw on that object's Graphics using any supported drawing methods " +            "(including semi-transparent drawing), and then use the result as a mask when drawing " +            "on the document's pages. Only the alpha channel from the mask is used. " +            "Solid areas do not mask, transparent areas mask completely, " +            "semi-transparent areas mask in inverse proportion to the alpha value.",            page)
        Dim rMask = New RectangleF(0, 0, 72 * 5, 72 * 2)        Dim rDoc = New RectangleF(rc.Left, rc.Bottom + 36, rMask.Width, rMask.Height)
        Dim sMask = SoftMask.Create(doc, rDoc)        Dim smGraphics = sMask.FormXObject.Graphics        smGraphics.FillEllipse(rMask, Color.FromArgb(128, Color.Black))        smGraphics.DrawString("SOLID TEXT",            New TextFormat() With {.Font = StandardFonts.HelveticaBold, .FontSize = 52, .ForeColor = Color.Black},            New RectangleF(rMask.X, rMask.Y, rMask.Width, rMask.Height),            TextAlignment.Center, ParagraphAlignment.Center, False)        Dim rt = rMask        rt.Inflate(-8, -8)        '' Color on the mask does not matter, only alpha channel is important:        smGraphics.DrawEllipse(rt, Color.Red)
        g.SoftMask = sMask        g.DrawImage(GCDRAW.Image.FromFile(Path.Combine("Resources", "Images", "reds.jpg")), rDoc, Nothing, ImageAlign.StretchImage)        '' NOTE: it looks like some PDF viewers (such as built-in browser viewers)        '' do not handle changing soft masks correctly unless the mask is reset prior        '' to assigning a new one, hence this:        g.SoftMask = SoftMaskBase.None
        rDoc.Offset(0, rDoc.Height + 12)        rDoc.Width = rc.Width        rDoc.Height = 36        rMask.Height = rDoc.Height        '' Draw a string on mask with increasing alpha values:        For alpha = 16 To 255 Step 32            sMask = SoftMask.Create(doc, rDoc)            smGraphics = sMask.FormXObject.Graphics            smGraphics.DrawString($"Text drawn on mask with alpha {alpha}.",                New TextFormat() With {.Font = StandardFonts.HelveticaBold, .FontSize = 24, .ForeColor = Color.FromArgb(alpha, Color.Black)},                New RectangleF(rMask.X, rMask.Y, rMask.Width, rMask.Height),                TextAlignment.Leading, ParagraphAlignment.Center, False)            g.SoftMask = sMask            g.DrawImage(GCDRAW.Image.FromFile(Path.Combine("Resources", "Images", "reds.jpg")), rDoc, Nothing, ImageAlign.StretchImage)            g.SoftMask = SoftMaskBase.None            rDoc.Offset(0, rDoc.Height)        Next
        '' Done:        doc.Save(stream)        Return doc.Pages.Count    End FunctionEnd Class