GDI+学习笔记（待续）

 

一：在应用程序中获取一个Graphics对象

选择哪一种绘图表面？

   Windows应用程序中，一个窗体就是一个绘图表面，每个窗体都有一个与之相关联的Graohics对象。

   如何获得一个与窗口相关联的Graohics对象。

   法一：使用窗体paint事件的PaintEventArgs属性来获取Graohics对象。

   private void Form1_Paint(object sender,System.Windows.Forms.PaintEventArgs e)

                   { Graphics g = e.Graphics; }

   法二：重载OnPaint方法

protected override void OnPaint(PaintEventArgs e)

         { Graphics g = e.Graphics; }

法三：通过使用CreateGraphics方法

    Graphics. g=this.CreateGraphics();

g.Clear(this.BackColor);

g.Dispose();

二：创建钢笔和画笔

Pen redPen = new Pen(Color.Red,3);    //红色，宽度为3个像素

Pen blackPen = Pens.Black;    //黑色1个像素

 

SolidBrush greenBrush = new SolidBrush(Color.Green);   //绿色实心画笔

三：绘制图形

 

四：第一个GDI+应用程序

protected override void OnPaint(PaintEventArgs e)

         {

              // Obtain the Graphics object

              Graphics g = e.Graphics;

              // Set the composit quality and smooting mode

              // of the surface

              g.CompositingQuality = CompositingQuality.HighQuality;

              g.SmoothingMode = SmoothingMode.AntiAlias;

              // Create a rectangle from point (20, 20) to (100, 100)

              Rectangle rect = new Rectangle(20, 20, 100, 100);

              // Create two Pen objects with Red and Green color

              Pen redPen = new Pen(Color.Red, 3);

              Pen blackPen = Pens.Black;

              // Create a SolidBrush objects

              SolidBrush greenBrush = new SolidBrush(Color.Green);

              // Draw shapes and lines

              g.DrawRectangle(redPen, rect);

              g.FillEllipse(greenBrush, rect);

              g.DrawLine(blackPen, 0, 250, this.Width, 250);

              g.FillEllipse(Brushes.Blue, 70, 220, 30, 30);

              g.FillEllipse(Brushes.SkyBlue, 100, 210, 40, 40);

              g.FillEllipse(Brushes.Green, 140, 200, 50, 50);

              g.FillEllipse(Brushes.Yellow, 190, 190, 60, 60);

              g.FillEllipse(Brushes.Violet, 250, 180, 70, 70);

              g.FillEllipse(Brushes.Red, 320, 170, 80, 80);

              // Dispose objects

              greenBrush.Dispose();

              // blackPen.Dispose();

              redPen.Dispose();

              g.Dispose();

         }

 

五.Color结构体

六：Point和PointF结构

         private void menuItem2_Click(object sender, System.EventArgs e)

         {

              // Create a new Point

              Point pt = new Point(50, 50);

              // Create a new point using Point.Empty

              Point newPoint = Point.Empty;

              // Set X and Y properties of Point

              newPoint.X = 100;

              newPoint.Y = 200;

              // Create a Graphics object from the

              // current form's handle

              Graphics g = Graphics.FromHwnd(this.Handle);

              // Create a new pen with blue color

              // and with = 4

              Pen pn = new Pen(Color.Blue, 4);

              // Draw a line from point pt to

              // new point

              g.DrawLine(pn, pt, newPoint);

              // Dispose pen and graphics objects

              pn.Dispose();

              g.Dispose();

         }

 

         private void menuItem3_Click(object sender, System.EventArgs e)

         {

              // Create a new PointF

              PointF pt = new PointF(50.0F, 50.0F);

              // Create a new point using PointF.Empty

              PointF newPoint = PointF.Empty;

              // Set X and Y properties of PointF

              newPoint.X = 100.0F;

              newPoint.Y = 200.0F;

              // Create a Graphics object from the

              // current form's handle

              Graphics g = Graphics.FromHwnd(this.Handle);

              // Create a new pen with blue color

              // and with = 4

              Pen pn = new Pen(Color.Blue, 4);

              // Draw a line from point pt to

              // new point

              g.DrawLine(pn, pt, newPoint);

              // Dispose pen and graphics objects

      pn.Dispose();

              g.Dispose();      

         }

 

七．Rectangle和RectangleF结构体

private void RectCreate_Click(object sender, System.EventArgs e)

         {

              // Create a Graphics object

              Graphics g = this.CreateGraphics();

              int x = 40;

              int y = 40;

              int height = 120;

              int width = 120;

              // Create a Point

              Point pt = new Point(80, 80);

              // Create a Size

              Size sz = new Size(100, 100);

              // Create a Rectangle from Point and Size

              Rectangle rect1 = new Rectangle(pt, sz);

              // Create a Rectangel from integers

              Rectangle rect2 =

                   new Rectangle(x, y, width, height);

              // Create a Rectangle from direct integers

              Rectangle rect3 =

                   new Rectangle(10, 10, 180, 180);

              // Create pens and brushes

              Pen redPen = new Pen(Color.Red, 2);

              SolidBrush greenBrush =

                   new SolidBrush(Color.Blue);

              SolidBrush blueBrush =

                   new SolidBrush(Color.Green);

              // Draw and fill rectangles

              g.DrawRectangle(redPen, rect3);

              g.FillRectangle(blueBrush, rect2);

              g.FillRectangle(greenBrush, rect1);

              // Dispose

              redPen.Dispose();

              blueBrush.Dispose();

              greenBrush.Dispose();

              g.Dispose();

         }

         private void RectFCreate_Click(object sender, System.EventArgs e)

         {

              // Create a Graphics object

              Graphics g = this.CreateGraphics();

              float x = 40.0f;

              float y = 40.0f;

              float height = 120.0f;

              float width = 120.0f;

              // Create a Point

              PointF pt = new PointF(80.0f, 80.0f);

              // Create a Size

              SizeF sz = new SizeF(100.0f, 100.0f);

              // Create a Rectangle from Point and Size

              RectangleF rect1 = new RectangleF(pt, sz);

              // Create a Rectangel from integers

              RectangleF rect2 =

                   new RectangleF(x, y, width, height);

              // Create a Rectangle from direct integers

              RectangleF rect3 =

                   new RectangleF(10.0f, 10.0f, 180.0f, 180.0f);

              // Create pens and brushes

              Pen redPen = new Pen(Color.Red, 2);

              SolidBrush greenBrush =

                   new SolidBrush(Color.Blue);

              SolidBrush blueBrush =

                   new SolidBrush(Color.Green);

              // Draw and fill rectangles

              g.DrawRectangle(redPen, rect3.X, rect3.Y,

                                     rect3.Width, rect3.Height);

              g.FillRectangle(blueBrush, rect2);

              g.FillRectangle(greenBrush, rect1);

              // Dispose

              redPen.Dispose();

              blueBrush.Dispose();

              greenBrush.Dispose();

              g.Dispose();

         }