C# 绘制PDF图形——基本图形、自定义图形、色彩透明度

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.NET PDF

C#.NET Spire.PDF PDF 图形

引言

在PDF中我们可以通过C#程序代码来添加非常丰富的元素来呈现我们想要表达的内容，如绘制表格、文字，添加图形、图像等等。在本篇文章中，我将介绍如何在PDF中绘制图形，并设置图形属性的操作。

文章中将分以下要点进行介绍：

1. 绘制基本图形（线条、椭圆、圆形、矩形、三角形）

2. 绘制自定义图形

3. 绘制图形并设置图形透明度

所需工具：Spire.PDF for .NET 4.0

【示例1】绘制基本图形

【C#】

using Spire.Pdf;
using Spire.Pdf.Graphics;
using System.Drawing;

namespace DrawRectangle_PDF
{
    class Program
    {
        static void Main(string[] args)
        {        
            //新建一个PDF文档
            PdfDocument doc = new PdfDocument();
            PdfPageBase page = doc.Pages.Add();

            //设置画笔和画刷
            PdfPen pen = new PdfPen(PdfBrushes.Black, 1f);
            PdfBrush brush1 = PdfBrushes.RosyBrown;
            PdfBrush brush2 = PdfBrushes.Goldenrod;
            //绘入矩形（此处通过设置值来绘制成正方形）
            page.Canvas.DrawRectangle(pen, brush1, new Rectangle(new Point(50, 50), new Size(60, 60)));

            //绘入椭圆（此处通过设置值来绘制成圆形）
            page.Canvas.DrawEllipse(pen, brush2, 210, 50, 60, 60);

            //绘入线段
            page.Canvas.DrawLine(pen, new PointF(50, 115), new PointF(270, 115));

            //绘入多边形（此处绘制成三角形）
            PointF p1 = new PointF(130, 172);
            PointF p2 = new PointF(160, 120);
            PointF p3 = new PointF(190, 172);
            PointF[] points = new PointF[] { p1, p2, p3 };
            page.Canvas.DrawPolygon(pen, points);

            //保存并打开文档
            doc.SaveToFile("基本图形.pdf");
            System.Diagnostics.Process.Start("基本图形.pdf");
        }
    }
}

效果图：

【示例2】绘制自定义图形

【C#】

using Spire.Pdf;
using Spire.Pdf.Graphics;
using System;
using System.Drawing;


namespace DrawCustomGraphics_PDF
{
    class Program
    {
        static void Main(string[] args)
        {
            //新建一个PDF文档，添加页
            PdfDocument doc = new PdfDocument();
            PdfPageBase page = doc.Pages.Add();

            //调用DrawStar()方法绘入五角星图形
            DrawStar(page);

            //保存并打开文档
            doc.SaveToFile("自定义图形.pdf");
            System.Diagnostics.Process.Start("自定义图形.pdf");

        }

        //自定义DrawStar方法绘制几个不同样式的五角星
        private static void DrawStar(PdfPageBase page)
        {
            //设置五角星的5个顶点坐标
            PointF[] points = new PointF[5];
            for (int i = 0; i < points.Length; i++)
            {
                float x = (float)Math.Cos(i * 2 * Math.PI / 5);
                float y = (float)Math.Sin(i * 2 * Math.PI / 5);
                points[i] = new PointF(x, y);
            }

            //创建PdfPath类，在顶点之间添加线段组成五角星
            PdfPath path = new PdfPath();
            path.AddLine(points[2], points[0]);
            path.AddLine(points[0], points[3]);
            path.AddLine(points[3], points[1]);
            path.AddLine(points[1], points[4]);
            path.AddLine(points[4], points[2]);

            //保存画布状态
            PdfGraphicsState state = page.Canvas.Save();

            //实例化画笔和画刷1、画刷2
            PdfPen pen = new PdfPen(Color.DeepSkyBlue, 0.02f);
            PdfBrush brush1 = new PdfSolidBrush(Color.PaleGreen);
            PdfBrush brush2 = new PdfSolidBrush(Color.Bisque);
            //将坐标放大40倍
            page.Canvas.ScaleTransform(40f, 40f);

            //平移坐标
            page.Canvas.TranslateTransform(1f, 1.5f);

            //绘入第一个五角星
            page.Canvas.DrawPath(pen, path);

            //平移坐标并在新的位置绘入第二个五角星
            page.Canvas.TranslateTransform(2f, 0f);
            path.FillMode = PdfFillMode.Alternate;
            page.Canvas.DrawPath(pen, brush1, path);

            //平移坐标并在新的位置绘入第三个五角星
            page.Canvas.TranslateTransform(2f, 0f);
            path.FillMode = PdfFillMode.Winding;
            page.Canvas.DrawPath(pen, brush2, path);

            //实例化画刷3，平移坐标并在新的位置绘入第四个五角星
            PdfLinearGradientBrush brush3
                = new PdfLinearGradientBrush(new PointF(-2, 0), new PointF(2, 0), Color.OrangeRed, Color.Yellow);
            page.Canvas.TranslateTransform(-4f, 2f);
            path.FillMode = PdfFillMode.Alternate;
            page.Canvas.DrawPath(pen, brush3, path);

            //实例化画刷4，平移坐标并在新的位置绘入第五个五角星
            PdfRadialGradientBrush brush4
                = new PdfRadialGradientBrush(new PointF(0f, 0f), 0f, new PointF(0f, 0f), 1f, Color.Orchid, Color.LightBlue);
            page.Canvas.TranslateTransform(2f, 0f);
            path.FillMode = PdfFillMode.Winding;
            page.Canvas.DrawPath(pen, brush4, path);

            //实例化画刷5，平移坐标并在新的位置绘入第六个五角星
            PdfTilingBrush brush5 = new PdfTilingBrush(new RectangleF(0, 0, 4f, 4f));
            brush5.Graphics.DrawRectangle(brush3, 0, 0, 4f, 4f);
            page.Canvas.TranslateTransform(2f, 0f);
            path.FillMode = PdfFillMode.Winding;
            page.Canvas.DrawPath(pen, brush5, path);

            //再次保存画布状态
            page.Canvas.Restore(state);
        }
    }
}

效果图：

【示例3】设置色彩透明度

【C#】

using Spire.Pdf;
using Spire.Pdf.ColorSpace;
using Spire.Pdf.Graphics;
using System.Drawing;

namespace CrearteSpotColor_PDF
{
    class Program
    {
        static void Main(string[] args)
        {
            //新建一个PDF文档
            PdfDocument doc = new PdfDocument();
            PdfPageBase page = doc.Pages.Add();

            //初始化一个PdfSeparationColorSpace的对象，用于创建基本色
            PdfSeparationColorSpace cs1 = new PdfSeparationColorSpace("MySpotColor", Color.DarkGreen);
            PdfSeparationColorSpace cs2 = new PdfSeparationColorSpace("MySpotColor", Color.Yellow);
            PdfSeparationColorSpace cs3 = new PdfSeparationColorSpace("MySpotColor", Color.DeepPink);

            //将基本色透明度设置为1
            PdfSeparationColor color1 = new PdfSeparationColor(cs1, 1f);
            PdfSeparationColor color2 = new PdfSeparationColor(cs2, 1f);
            PdfSeparationColor color3 = new PdfSeparationColor(cs3, 1f);
            //根据颜色创建画刷
            PdfSolidBrush brush1 = new PdfSolidBrush(color1);
            PdfSolidBrush brush2 = new PdfSolidBrush(color2);
            PdfSolidBrush brush3 = new PdfSolidBrush(color3);

            //绘入图形及文字并着色
            page.Canvas.DrawPie(brush1, 10, 30, 60, 60, 360, 360);
            page.Canvas.DrawPie(brush2, 10, 120, 60, 60, 360, 360);
            page.Canvas.DrawPie(brush3, 10, 210, 60, 60, 360, 360);
            page.Canvas.DrawString("透明度=1.0", new PdfTrueTypeFont(new Font("Arial Unicode MS", 10f), true), brush1, new PointF(16, 100));

            //将基本色透明度设置为0.5,并绘入图片及文字
            color1 = new PdfSeparationColor(cs1, 0.5f);
            brush1 = new PdfSolidBrush(color1);
            page.Canvas.DrawPie(brush1, 80, 30, 60, 60, 360, 360);
            color2 = new PdfSeparationColor(cs2, 0.5f);
            brush2 = new PdfSolidBrush(color2);
            page.Canvas.DrawPie(brush2, 80, 120, 60, 60, 360, 360);
            color3 = new PdfSeparationColor(cs3, 0.5f);
            brush3 = new PdfSolidBrush(color3);
            page.Canvas.DrawPie(brush3, 80, 210, 60, 60, 360, 360);

            page.Canvas.DrawString("透明度=0.5", new PdfTrueTypeFont(new Font("Arial Unicode MS", 10f), true), brush1, new PointF(86, 100));

            //将基本色透明度设置为0.25,并绘入图片及文字
            color1 = new PdfSeparationColor(cs1, 0.25f);
            brush1 = new PdfSolidBrush(color1);
            page.Canvas.DrawPie(brush1, 150, 30, 60, 60, 360, 360);
            color2 = new PdfSeparationColor(cs2, 0.25f);
            brush2 = new PdfSolidBrush(color2);
            page.Canvas.DrawPie(brush2, 150, 120, 60, 60, 360, 360);
            color3 = new PdfSeparationColor(cs3, 0.25f);
            brush3 = new PdfSolidBrush(color3);
            page.Canvas.DrawPie(brush3, 150, 210, 60, 60, 360, 360);
            page.Canvas.DrawString("透明度=0.25", new PdfTrueTypeFont(new Font("Arial Unicode MS", 10f), true), brush1, new PointF(156, 100));

            //保存并打开文档
            doc.SaveToFile("设置透明度.pdf");
            System.Diagnostics.Process.Start("设置透明度.pdf");
        }
    }
}

效果图：