图形变换

用于变换的方法：

Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             //first,draw a non-scaled rectangle and circle             g.DrawRectangle(Pens.Black, 10, 10, 50, 50);             g.DrawEllipse(Pens.Black,10, 10, 10, 10);             //now apply the scaling transformation             //this will scale subsequent operations by 2x in horizontally             //and 3x vertically             g.ScaleTransform(2.0f, 3.0f);             //now drawthe same rectangle and circle             //but with the scaliing transformation             g.DrawRectangle(Pens.Black, 10, 10, 50, 50);             g.DrawEllipse(Pens.Black, 10, 10, 10, 10);

头两次绘图操作向绘图表面绘制了一个正方形和一个圆，当调用这两次操作时，没有指定变换，所以GDI+采用的是默认的通用变换--把通用坐标系映射到页坐标系，映射通用坐标系中的（0,0）到页坐标系中的（0,0），不应用缩放、平移或者错位变换，后两次应用了缩放的效果，注意：同时还缩放了用来绘制图形的钢笔的宽度。

平移：

private void Form1_Paint(object sender, PaintEventArgs e)         {             Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             Font f = new Font("Times New Roman", 24);             //draw text to the surface             g.DrawString("Translation", f, Brushes.Black, 0, 0);             //translate the text 150 pixels horizontally and 75 vertically             g.TranslateTransform(150, 75);             //draw the translated text             g.DrawString("Translation", f, Brushes.Black, 0, 0);         }

累积变换

private void Form1_Paint(object sender, PaintEventArgs e)         {             Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             for (int i = 1; i <= 5; ++i)             {                 //first,draw a rectangle with the current translation                 g.DrawRectangle(Pens.Black, 10, 10, 30, 50);                 //add a translation to the existing transformation                 g.TranslateTransform(10, 20);             }

如果想要应用非累积变换，那么我们可以调用ResetTransform方法。

旋转变换

旋转变换执行一次顺时针方向的旋转，以度为单位，旋转的中心是坐标系的当前原点。

private void Form1_Paint(object sender, PaintEventArgs e)         {             Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             Font f = new Font("Times New Roman", 24);             //draw text to thesurface             g.DrawString("Rotation", f, Brushes.Black, 0, 0);             //rotate the text through 45 degrees             g.RotateTransform(45);             //draw the rotated text             g.DrawString("Rotation", f, Brushes.Black, 0, 0);         }

一个小例子：

private void Form1_Paint(object sender, PaintEventArgs e)         {             Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             Font f = new Font("Times New Roman", 24);             for (float angle = 0; angle < 360; angle += 45)             {                 g.ResetTransform();                 g.TranslateTransform(ClientRectangle.Width / 2, ClientRectangle.Height / 2);                 g.RotateTransform(angle);                 g.DrawString("Hello,World!", f, Brushes.Black, 50, 0);              }         }
        private void Form1_Load(object sender, EventArgs e)         {             this.ResizeRedraw = true;         }

注：沿着x轴缩放一个负值，结果是y轴的一个反射；沿着y轴缩放一个负值，结果是x抽的一个反射。

错位变换

private void Form1_Paint(object sender, PaintEventArgs e)         {             Graphics g = e.Graphics;             g.FillRectangle(Brushes.White, this.ClientRectangle);             Matrix m = new Matrix();             //the following method call sets up the shear in the matrix             //the first argument is the shear factor in the x direction             //the secong argument is the shear factor in the y direction             m.Shear(.6f, 0);             g.DrawRectangle(Pens.Black, 10, 10, 50, 50);             g.MultiplyTransform(m);             g.DrawRectangle(Pens.Black, 70, 10, 50, 50);         }