//// 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;using GCDRAW = GrapeCity.Documents.Drawing;
namespace DsImagingWeb.Demos{    // This sample demonstrates the use of BitmapRenderer.BackgroundBitmap    // when drawing on a bitmap.    //    // When drawing semi-transparent graphic objects, usually the resulting color    // of a pixel is a combination of the target bitmap pixel's color and the color    // of the graphic object's pixel. But if the BackgroundBitmap is set on the    // BitmapRenderer, pixels of that bitmap will be used instead of the target    // bitmap's pixels when determining the resulting color. Background bitmaps    // are used to support Isolated and Knockout transparency groups (as defined    // in the PDF specification 1.7 sections 7.3.4 and 7.3.5) when rendering PDFs    // to images.    public class BackgroundBitmap    {        public GcBitmap GenerateImage(Size pixelSize, float dpi, bool _, string[] _1 = null)        {            var hx = pixelSize.Width / 2;            var hy = pixelSize.Height / 2;
            // The spectrum image used for the backdrop:            using var bmp0 = new GcBitmap(Path.Combine("Resources", "ImagesBis", "spectrum-pastel-500x500.png"));            using var bmp1 = bmp0.Resize(hx, hy, InterpolationMode.Cubic);
            using var bmpBackdrop = new GcBitmap(hx, hy, false, dpi, dpi);            using var bmpInitial = new GcBitmap(hx, hy, false, dpi, dpi);            using var gB = bmpBackdrop.CreateGraphics();            using var gI = bmpInitial.CreateGraphics();
            gB.Renderer.Aliased = true;            gB.Renderer.BlendMode = BlendMode.Multiply;            gI.Renderer.Aliased = true;            gI.Renderer.BlendMode = BlendMode.Multiply;
            // The target bitmap will contain 4 demo quadrants:            var bmp = new GcBitmap(pixelSize.Width, pixelSize.Height, false, dpi, dpi);
            // Isolated, Knockout:            bmpBackdrop.BitBlt(bmp1, 0, 0);            bmpInitial.Clear(Color.Transparent);            gB.Renderer.BackgroundBitmap = bmpInitial;            FillCircles(gB, hx, hy);            bmp.BitBlt(bmpBackdrop, 0, 0);
            // Isolated, Non-knockout:            FillCircles(gI, hx, hy);            bmpBackdrop.BitBlt(bmp1, 0, 0);            bmpBackdrop.AlphaBlend(bmpInitial, 0, 0);            bmp.BitBlt(bmpBackdrop, hx, 0);
            // Non-isolated, Knockout:            bmpBackdrop.BitBlt(bmp1, 0, 0);            bmpInitial.BitBlt(bmp1, 0, 0);            FillCircles(gB, hx, hy);            bmp.BitBlt(bmpBackdrop, 0, hy);
            // Non-isolated, Non-knockout:            bmpBackdrop.BitBlt(bmp1, 0, 0);            gB.Renderer.BackgroundBitmap = null;            FillCircles(gB, hx, hy);            bmp.BitBlt(bmpBackdrop, hx, hy);
            // Adornments:            using var g = bmp.CreateGraphics();            g.DrawLine(0, hy, bmp.PixelWidth, hy, new GCDRAW.Pen(Color.Black));            g.DrawLine(hx, 0, hx, bmp.PixelHeight, new GCDRAW.Pen(Color.Black));            var tf = new TextFormat()            {                Font = GCTEXT.Font.FromFile(Path.Combine("Resources", "Fonts", "FreeMonoBold.ttf")),                FontSize = 16,            };            var d = 40;            g.DrawString("Isolated, Knockout", tf, new RectangleF(0, hy - d, hx, d),                TextAlignment.Center, ParagraphAlignment.Center, false);            g.DrawString("Isolated, Non-knockout", tf, new RectangleF(hx, hy - d, hx, d),                TextAlignment.Center, ParagraphAlignment.Center, false);            g.DrawString("Non-isolated, Knockout", tf, new RectangleF(0, hy * 2 - d, hx, d),                TextAlignment.Center, ParagraphAlignment.Center, false);            g.DrawString("Non-isolated, Non-knockout", tf, new RectangleF(hx, hy * 2 - d, hx, d),                TextAlignment.Center, ParagraphAlignment.Center, false);
            // Done:            return bmp;        }
        void FillCircles(GcBitmapGraphics g, float hx, float hy)        {            var dx = hx / 10;            var dy = hy / 10;            var qx = hx / 2;            var qy = hy / 2;
            g.FillEllipse(new RectangleF(dx, dy, qx, qy), Color.LightGray);            g.FillEllipse(new RectangleF(qx - dx, dy, qx, qy), Color.LightGray);            g.FillEllipse(new RectangleF(dx, qy - dy, qx, qy), Color.LightGray);            g.FillEllipse(new RectangleF(qx - dx, qy - dy, qx, qy), Color.LightGray);        }    }}