//// This code is part of Document Solutions for PDF .NET demos.// Copyright (c) MESCIUS inc. All rights reserved.//using System.IO;using System.Drawing;using GrapeCity.Documents.Pdf;using GrapeCity.Documents.Pdf.Graphics;using GrapeCity.Documents.Text;using GrapeCity.Documents.Drawing;using GCTEXT = GrapeCity.Documents.Text;using GCDRAW = GrapeCity.Documents.Drawing;
namespace DsPdfWeb.Demos{    // This sample demonstrates how to use GcPdfGraphics.SoftMask    // to draw semi-transparently and specify clipping.    public class SoftMask1    {        public int CreatePDF(Stream stream)        {            var doc = new GcPdfDocument();            var page = doc.NewPage();            var g = page.Graphics;
            var rc = Common.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);
            var rMask = new RectangleF(0, 0, 72 * 5, 72 * 2);            var rDoc = new RectangleF(rc.Left, rc.Bottom + 36, rMask.Width, rMask.Height);
            var softMask = SoftMask.Create(doc, rDoc);            var smGraphics = softMask.FormXObject.Graphics;            smGraphics.FillEllipse(rMask, Color.FromArgb(128, Color.Black));            smGraphics.DrawString("SOLID TEXT",                new TextFormat() { Font = StandardFonts.HelveticaBold, FontSize = 52, ForeColor = Color.Black },                new RectangleF(rMask.X, rMask.Y, rMask.Width, rMask.Height),                TextAlignment.Center, ParagraphAlignment.Center, false);            var 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 = softMask;            g.DrawImage(GCDRAW.Image.FromFile(Path.Combine("Resources", "Images", "reds.jpg")), rDoc, null, 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 (int alpha = 16; alpha <= 255; alpha += 32)            {                softMask = SoftMask.Create(doc, rDoc);                smGraphics = softMask.FormXObject.Graphics;                smGraphics.DrawString($"Text drawn on mask with alpha {alpha}.",                    new TextFormat() { 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 = softMask;                g.DrawImage(GCDRAW.Image.FromFile(Path.Combine("Resources", "Images", "reds.jpg")), rDoc, null, ImageAlign.StretchImage);                g.SoftMask = SoftMaskBase.None;                rDoc.Offset(0, rDoc.Height);            }
            // Done:            doc.Save(stream);            return doc.Pages.Count;        }    }}