Silverlight 引路蜂二维图形库示例:动画Beziers曲线

类Path为一条几何路径，可以通过直线，二次曲线，三次曲线来构成任意路径。Path提供了moveTo, lineTo, curveTo, curveToCubic, closePath方法来构成路径。

下面的例子动态显示一条Bezier曲线。

/** * The animation thread. */ Thread _thread; bool _drawn; /** * The random number generator. */ readonly Random _random = new Random(); /** * The animated path */ readonly Path _path = new Path(); /** * Red brush used to fill the path. */ readonly SolidBrush _brush = new SolidBrush(Color.Red); const int Numpts = 6; readonly int[] _animpts = new int[Numpts * 2]; readonly int[] _deltas = new int[Numpts * 2]; private void Beziers() { Reset(screenWidth, screenHeight); _thread = new Thread(RunBeziers); _thread.Start(); } private void RunBeziers() { Thread me = Thread.CurrentThread; if (!_drawn) { lock (this) { graphics2D.Clear(Color.White); graphics2D.Fill(_brush, _path); _drawn = true; } } while (_thread == me) { DrawDemo(screenWidth, screenHeight); } } /** * Generates new points for the path. */ private void Animate(int[] pts, int[] deltas, int i, int limit) { int newpt = pts[i] + deltas[i]; if (newpt <= 0) { newpt = -newpt; deltas[i] = (_random.Next() & 0x00000003) + 2; } else if (newpt >= limit) { newpt = 2 * limit - newpt; deltas[i] = -((_random.Next() & 0x00000003) + 2); } pts[i] = newpt; } /** * Resets the animation data. */ private void Reset(int w, int h) { for (int i = 0; i < _animpts.Length; i += 2) { _animpts[i + 0] = (_random.Next() & 0x00000003) * w / 2; _animpts[i + 1] = (_random.Next() & 0x00000003) * h / 2; _deltas[i + 0] = (_random.Next() & 0x00000003) * 6 + 4; _deltas[i + 1] = (_random.Next() & 0x00000003) * 6 + 4; if (_animpts[i + 0] > w / 2) { _deltas[i + 0] = -_deltas[i + 0]; } if (_animpts[i + 1] > h / 2) { _deltas[i + 1] = -_deltas[i + 1]; } } } /** * Sets the points of the path and draws and fills the path. */ private void DrawDemo(int w, int h) { for (int i = 0; i < _animpts.Length; i += 2) { Animate(_animpts, _deltas, i + 0, w); Animate(_animpts, _deltas, i + 1, h); } //Generates the new pata data. _path.Reset(); int[] ctrlpts = _animpts; int len = ctrlpts.Length; int prevx = ctrlpts[len - 2]; int prevy = ctrlpts[len - 1]; int curx = ctrlpts[0]; int cury = ctrlpts[1]; int midx = (curx + prevx) / 2; int midy = (cury + prevy) / 2; _path.MoveTo(midx, midy); for (int i = 2; i <= ctrlpts.Length; i += 2) { int x1 = (curx + midx) / 2; int y1 = (cury + midy) / 2; prevx = curx; prevy = cury; if (i < ctrlpts.Length) { curx = ctrlpts[i + 0]; cury = ctrlpts[i + 1]; } else { curx = ctrlpts[0]; cury = ctrlpts[1]; } midx = (curx + prevx) / 2; midy = (cury + prevy) / 2; int x2 = (prevx + midx) / 2; int y2 = (prevy + midy) / 2; _path.CurveTo(x1, y1, x2, y2, midx, midy); } _path.ClosePath(); // clear the clipRect area before production graphics2D.Clear(Color.White); graphics2D.Fill(_brush, _path); RefreshBitmap(); }

其中实时更新图像需要CompositionTarget.Rendering事件来处理。CompositionTarget.Rendering += CompositionTargetRendering;

private void CompositionTargetRendering(object sender, EventArgs e) { bmp.Invalidate(); }