Silverlight 引路蜂二维图形库示例:绘制各种几何图形

这个例子说明如何使用Graphics2D对象来绘制各种几何图形。引路蜂二维图形库中定义里多种基本几何图形，如，点，线段，曲线和矩形等。接口PathIterator定义了从Path中获取路径元素的方法。接口IShape定义了描述几何图形公用的方法。

点

类Point定义了二维空间位置在(x,y)一个点。Point point = new Point (x, y); 创建一个点对象。此外Point类也提供了计算两点之间距离的方法等。

线段

类Line定义了平面上一条线段。下面代码绘制一条线段。

// draw Line2D.Double
graphics2D.draw (pen, new Line(x1, y1, x2, y2));

图形库中类Pen可以用来定义绘制线段的线型，线宽等参数。

二次曲线

类QuadCurve实现了IShape接口，它定义了平面上一条二次曲线。二次曲线可以通过曲线的两个端点和一个控制点来定义。

// create new QuadCurve
QuadCurve q = new QuadCurve();
// draw QuadCurve2D with set coordinates
graphics2D.draw(pen,q.setCurve(x1, y1, ctrlx, ctrly, x2,y2));

三次曲线

类CubicCurve同样实现了IShape接口，它定义了平面上一条三次曲线。和二次曲线类似，三次曲线可以通过曲线的两个端点和两个控制点来定义。

// create new CubicCurve
CubicCurve c = new CubicCurve();
// draw CubicCurve with set coordinates
graphics2D.draw(pen, c.setCurve(x1, y1, ctrlx1,ctrly1, ctrlx2, ctrly2, x2, y2));

矩形

类Rectangle是RectangleShape的子类。RectangleShape同样实现了IShape接口。 Rectangle可以通过一个点(x,y)和大小(Dimsension)来定义。

// draw Rectangle
graphics2D.draw(pen,new Rectangle(x, y,rectwidth,rectheight));

类RoundRectangle定义了带圆角的矩形。圆角矩形可以由下列参数来定义：位置，宽度，长度，圆角宽度，圆角长度。

// draw RoundRectangle
graphics2D.draw(pen,new RoundRectangle(x, y,rectwidth,rectheight,10, 10));

椭圆

类Ellipse通过椭圆的外接矩形来定义其大小。

// draw Ellipse
graphics2D.draw(pen, new Ellipse(x, y,rectwidth,rectheight));

圆弧

类Arc通过外接矩形，起始角度，角度，封闭类型来定义。

// draw Arc
graphics2D.draw(pen,new Arc(x, y,rectwidth,rectheight,90, 135,Arc.OPEN));

下面代码显示了多种几何图形。

private void SharpsDemo2D()
{
 Color bg = Color.White;
 Color fg = Color.Black;
 Color red = Color.Red;
 Color white = Color.White;
 Pen pen = new Pen(fg, 1);
 SolidBrush brush = new SolidBrush(red);
 //Clear the canvas with white color.
 graphics2D.Clear(bg);
 Dimension d = new Dimension(screenWidth, screenHeight);
 int gridWidth = d.Width / 2;
 int gridHeight = d.Height / 6;

 int x = 5;
 int y = 7;
 int rectWidth = gridWidth - 2 * x;
 int stringY = gridHeight - 3 - 2 - 16;
 int rectHeight = stringY - y - 2;
 graphics2D.Draw(pen, new Line(x, y + rectHeight - 1,
  x + rectWidth, y));
 x += gridWidth;
 graphics2D.Draw(pen, new Rectangle(x, y, rectWidth,
  rectHeight));
 x += gridWidth;
 x = 5;
 y += gridHeight;
 stringY += gridHeight;
 graphics2D.Draw(pen, new RoundRectangle(x, y, rectWidth,
   rectHeight, 10, 10));
 x += gridWidth;
 graphics2D.Draw(pen, new Arc(x, y, rectWidth, rectHeight, 90,
   135, Arc.Open));
 x = 5;
 y += gridHeight;
 stringY += gridHeight;
 graphics2D.Draw(pen, new Ellipse(x, y, rectWidth, rectHeight));
 x += gridWidth;
 // draw GeneralPath (polygon)
 int[] x1Points = { x, x + rectWidth, x, x + rectWidth };
 int[] y1Points = { y, y + rectHeight, y + rectHeight, y };
 Path polygon = new Path(Path.WindEvenOdd,
   x1Points.Length);
 polygon.MoveTo(x1Points[0], y1Points[0]);
 for (int index = 1; index < x1Points.Length; index++)
 {
  polygon.LineTo(x1Points[index], y1Points[index]);
 }
 polygon.ClosePath();
 graphics2D.Draw(pen, polygon);
 x = 5;
 y += gridHeight;
 stringY += gridHeight;
 int[] x2Points = { x, x + rectWidth, x, x + rectWidth };
 int[] y2Points = { y, y + rectHeight, y + rectHeight, y };
 Path polyline = new Path(Path.WindEvenOdd,
   x2Points.Length);
 polyline.MoveTo(x2Points[0], y2Points[0]);
 for (int index = 1; index < x2Points.Length; index++)
 {
  polyline.LineTo(x2Points[index], y2Points[index]);
 }
 graphics2D.Draw(pen, polyline);
 x += gridWidth;
 graphics2D.SetPenAndBrush(pen, brush);
 graphics2D.Fill(null,
  new Rectangle(x, y, rectWidth, rectHeight));
 graphics2D.Draw(null,
  new Rectangle(x, y, rectWidth, rectHeight));
 x = 5;
 y += gridHeight;
 stringY += gridHeight;
 Color[] colors = new Color[] { red, white };
 int[] fractions = new int[] { 0, 255 };
 LinearGradientBrush redtowhite =
   new LinearGradientBrush(x, y, x + rectWidth, y,
   fractions, colors, Brush.NoCycle);
 graphics2D.SetPenAndBrush(pen, redtowhite);
 graphics2D.Fill(null, new RoundRectangle(x, y,
  rectWidth,rectHeight, 10, 10));
 graphics2D.Draw(null, new RoundRectangle(x, y,
  rectWidth,rectHeight, 10, 10));
 x += gridWidth;
 graphics2D.SetPenAndBrush(pen, brush);
 graphics2D.Fill(null, new Arc(x, y, rectWidth,
  rectHeight, 90,135, Arc.Chord));
 graphics2D.Draw(null, new Arc(x, y, rectWidth,
  rectHeight, 90,135, Arc.Chord));
 x = 5;
 y += gridHeight;
 stringY += gridHeight;
 int[] x3Points = { x, x + rectWidth, x, x + rectWidth };
 int[] y3Points = { y, y + rectHeight, y + rectHeight, y };
 Path filledPolygon = new Path(Path.WindEvenOdd,
   x3Points.Length);
 filledPolygon.MoveTo(x3Points[0], y3Points[0]);
 for (int index = 1; index < x3Points.Length; index++)
 {
  filledPolygon.LineTo(x3Points[index], y3Points[index]);
 }
 filledPolygon.ClosePath();
 graphics2D.SetPenAndBrush(pen, brush);
 graphics2D.Fill(null, filledPolygon);
 graphics2D.Draw(null, filledPolygon);

}