//// This code is part of Document Solutions for Imaging demos.// Copyright (c) MESCIUS inc. All rights reserved.//using System.IO;using System.Drawing;using GrapeCity.Documents.Drawing;using GrapeCity.Documents.Text;using GrapeCity.Documents.Imaging;using GCTEXT = GrapeCity.Documents.Text;
namespace DsImagingWeb.Demos{    // This sample demonstrates the use of TransparencyMaskBitmap    // when drawing on a bitmap. The transparency mask used is    // created on the fly by filling an intermediary bitmap    // with a linear gradient brush from 0 (black, transparent)    // to 255 (white, opaque).    public class TransparencyMask    {        public GcBitmap GenerateImage(Size pixelSize, float dpi, bool opaque, string[] sampleParams = null)        {            var h2 = pixelSize.Width / 2;
            // Prepare a linear gradient transparency mask,            // from 0 (transparent) to 255 (opaque):            using var mask = new GcBitmap(h2, h2, true);            using var gmask = mask.CreateGraphics();            var grad = new LinearGradientBrush(Color.Black, Color.White);            gmask.FillRectangle(new RectangleF(0, 0, mask.Width, mask.Height), grad);            // Convert to GrayscaleBitmap to be used as Renderer.TransparencyMaskBitmap:            using var gsb = mask.ToGrayscaleBitmap();
            // Create a bitmap to draw on, fill it with yellow background:            using var bmp1 = new GcBitmap(h2, h2, true);            using var g = bmp1.CreateGraphics(Color.Yellow);
            // Apply the transparency mask:            g.Renderer.TransparencyMaskBitmap = gsb;
            // Fill 3 circles, note how the fill gradually changes            // from transparent to opaque (left to right) along with the gradient:            var d = h2 / 25f;            var rc = new RectangleF(0, 0, h2 * 0.7f, h2 * 0.7f);
            var bmp = new GcBitmap(pixelSize.Width, pixelSize.Height, true, dpi, dpi);            bmp.Clear(Color.White);            FillCircles(g, rc, h2, d);            bmp.BitBlt(bmp1, 0, 0);
            g.Renderer.TransparencyMaskBitmap = null;            FillCircles(g, rc, h2, d);            bmp.BitBlt(bmp1, h2, 0);
            // Add some explanatory texts below the images:            var gg = bmp.CreateGraphics();            rc = new RectangleF(0, h2 + d, h2 - d * 2, h2 - d * 2);            var tf = new TextFormat()            {                Font = GCTEXT.Font.FromFile(Path.Combine("Resources", "Fonts", "FreeMono.ttf")),                FontSize = 16            };            gg.DrawString(                "The circles in the image above were rendered with TransparencyMaskBitmap " +                "on the target graphics set to a linear gradient from transparent to opaque.",                tf, rc, TextAlignment.Center, ParagraphAlignment.Near);
            rc.Offset(h2, 0);            gg.DrawString(                "The circles in the image above were rendered with no TransparencyMaskBitmap " +                "on the target graphics.",                tf, rc, TextAlignment.Center, ParagraphAlignment.Near);
            return bmp;        }
        void FillCircles(GcBitmapGraphics g, RectangleF rc, float h2, float d)        {            var r = rc;            r.Offset((h2 - rc.Width) / 2, 0);            r.Inflate(-d, -d);            g.FillEllipse(r, Color.Red);            r = rc;            r.Offset(h2 - rc.Width, h2 - rc.Height);            r.Inflate(-d, -d);            g.FillEllipse(r, Color.Green);            r = rc;            r.Offset(0, h2 - rc.Height);            r.Inflate(-d, -d);            g.FillEllipse(r, Color.Blue);        }    }}