___89___GraphicsPath_GDI矩阵变幻Transform

#region Windows Form Designer generated code/// <summary>/// Required method for Designer support - do not modify/// the contents of this method with the code editor./// </summary>       private void InitializeComponent(){            //             // Form1            //             this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);            this.ClientSize = new System.Drawing.Size(392, 170);            this.Name = "Form1";            this.Text = "Transform";        }#endregion/// <summary>/// The main entry point for the application./// </summary>[STAThread]static void Main() {Application.Run(new Form1());}        protected override void OnPaint(PaintEventArgs pe)         {             const float offsetValue = 80.0f; // used to translate the diagram            //Graphics类，封装一个 GDI+ 绘图图面。此类不能被继承            Graphics g = pe.Graphics ;             //矩形，一个矩形的有位置和大小信息            Rectangle rect = this.ClientRectangle;             //LinearGradientBrush 使用线性渐变封装 Brush。此类不能被继承。            LinearGradientBrush lBrush = new LinearGradientBrush(rect, Color.Yellow, Color.Lime,                                                                     LinearGradientMode.BackwardDiagonal);             g.FillRectangle(lBrush, rect);             // create a graphics path            GraphicsPath gp = new GraphicsPath();            /*             GraphicsPath对象             它由一系列相互连接的直线、曲线连接起来组成的开放（非闭合）图形。             创建路径时就会隐式创建一个新图形（由上面的直线、曲线等组成）。也可以             显示地声明StartFigure。            */            // 在当前图形中添加一段立方贝塞尔曲线             gp.AddBezier(110, 110, 110, 115, 120, 115, 125, 130);            // 向当前路径添加一个椭圆            gp.AddEllipse(125,130, 8,8);            // save a copy of the graphics path so we can reset             // each time we rotate it.            GraphicsPath gpOld = new GraphicsPath();            gpOld = (GraphicsPath)gp.Clone();            //Clone方法获得路径对象的指针            // offset path Matrix--C#矩阵类--封装表示几何变换的 3x3 仿射矩阵            Matrix aTransform = new Matrix(1, 0, 0, 1, 0, 0);            Matrix TranslationTransform = new Matrix(1, 0, 0, 1, 0, 0);            // PointF 表示在二维平面中定义点的浮点 x 和 y 坐标的有序对            PointF TheRotationPoint = new PointF(110.0f, 110.0f);            // cycle through 4 translated balloon wheel patterns            for (int i = 0; i < 4; i++)            {                // cycle through 360 degrees and draw a balloon at each 45 degree angle                for (float f = 0.0f; f < 359.0; f += (float)45.0)                {                    // use the translation matrix to translate the graphics path                     // to the right  将变换矩阵-TranslationTransform-应用到此 GraphicsPath。                    gp.Transform(TranslationTransform);                                          // rotate the rotation transformation matrix f degrees around TheRotationPoint                    //沿 point 参数中指定的点-TheRotationPoint-并通过预先计算该旋转f(45度)，来顺时针旋转此 Matrix                    aTransform.RotateAt(f, TheRotationPoint);                                        //Call the Transform method of the Graphics Path in order to multiply it by the rotation matrix and rotate the balloon                    //将变换矩阵-aTransform-应用到此 GraphicsPath。                    gp.Transform(aTransform);                                        // Fill the balloon with a red colored brush                    //填充 GraphicsPath 的内部                    g.FillPath(Brushes.Red, gp);                                        // Draw the balloon with a black pen                    //绘制 GraphicsPath。                    g.DrawPath(Pens.Black, gp);                                        // reset the transformation matrix                    aTransform.Dispose();                    aTransform = new Matrix(1, 0, 0, 1, 0, 0);                                        // get the original graphics path for our rotation and translation reference                    gp = (GraphicsPath)gpOld.Clone();                }                //move the translation matrix by an offset. When the matrix is then                // used in the transform method(above), it causes the balloon wheel to                 // be drawn to the right (translation in the positive X direction)                //通过预先计算转换向量，将指定的转换向量（offsetX 和 offsetY）应用到此 Matrix                TranslationTransform.Translate(offsetValue, 0);                                //  We also need to translate the point that we rotate around                 TheRotationPoint.X = TheRotationPoint.X + offsetValue;            }                        g.DrawString("Translations and Rotation Transforms in GDI+", new Font("Times New Roman", 14), Brushes.DarkBlue, 20, 20, new StringFormat());        }

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