在DrawingVisual上绘制圆形的进度条，类似于IOS系统风格。
1.说明：在WPF中，文件下载时需要显示下载进度，由于系统自带的条型进度条比较占用空间，改用圆形的进度条,需要在DrawingVisual上呈现。
运行的效果如图：
private Point GetPointOnCir(Point CenterPoint, double r, double angel) { Point p = new Point(); p.X = Math.Sin(angel * Math.PI / 180) * r + CenterPoint.X; p.Y = CenterPoint.Y - Math.Cos(angel * Math.PI / 180) * r; return p; } private Geometry drawingArc(Point bigCirclefirstPoint, Point bigCirclesecondPoint, Point smallCirclefirstPoint, Point smallCirclesecondPoint, double bigCircleRadius, double smallCircleRadius,bool isLargeArc) { PathFigure pathFigure = new PathFigure { IsClosed = true }; pathFigure.StartPoint = bigCirclefirstPoint; pathFigure.Segments.Add( new ArcSegment { Point = bigCirclesecondPoint, IsLargeArc = isLargeArc, Size = new Size(bigCircleRadius, bigCircleRadius), SweepDirection = SweepDirection.Clockwise }); pathFigure.Segments.Add(new LineSegment { Point = smallCirclesecondPoint }); pathFigure.Segments.Add( new ArcSegment { Point = smallCirclefirstPoint, IsLargeArc = isLargeArc, Size = new Size(smallCircleRadius, smallCircleRadius), SweepDirection = SweepDirection.Counterclockwise }); PathGeometry pathGeometry = new PathGeometry(); pathGeometry.Figures.Add(pathFigure); return pathGeometry; } //根据已保存的大小和文件总大小来计算下载进度百分比 private Geometry GetGeometry() { bool isLargeArc =false; double percent = double.Parse(Convert.ToString(savedSize)) / double.Parse(Convert.ToString(fileSize)); PercentString = string.Format("{0}%",Math.Round(percent*100,0)); double angel = percent * 360D; if(angel>180)isLargeArc=true; //double angel = 45; double bigR = 16; double smallR = 13; Point centerPoint = vl.StartPoint;//new Point(100, 300); Point firstpoint = GetPointOnCir(centerPoint, bigR, 0); Point secondpoint = GetPointOnCir(centerPoint, bigR, angel); Point thirdpoint = GetPointOnCir(centerPoint, smallR, 0); Point fourpoint = GetPointOnCir(centerPoint, smallR, angel); return drawingArc(firstp, secondpoint, thirdpoint, fourpoint, bigR, smallR, isLargeArc); }
画圆形的进度条，实际上是动态画两个同心圆，根据文件保存的百分比来计算画弧形的角度的大小，需要7个参数：大圆的半径bigR 、小圆的半径smallR 、同心圆的圆心centerPoint 、大圆的起始点firstpoint 、大圆的结束点secondpoint 、小圆的起始点thirdpoint、小圆的结束点fourpoint
最后需要使用DrawingContext把圆给画出来：
public Visual drawShape() { DrawingVisual drawingWordsVisual = new DrawingVisual(); DrawingContext drawingContext = drawingWordsVisual.RenderOpen(); try { if (savedSize != fileSize) {
drawingContext.DrawEllipse(null, new Pen(Brushes.Gray, 3), vl.StartPoint, 13, 13); drawingContext.DrawGeometry(vs.VisualBackgroundBrush, vs.VisualFramePen, GetGeometry()); FormattedText formatWords = new FormattedText(PercentString, System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface(vs.WordsFont.Name), vs.WordsFont.Size, currentStyle.VisualBackgroundBrush); formatWords.SetFontWeight(FontWeights.Bold); Point startPoint = new Point(vl.StartPoint.X - formatWords.Width / 2, vl.StartPoint.Y - formatWords.Height / 2); drawingContext.DrawText(formatWords, startPoint); } else { drawingContext.DrawEllipse(null, new Pen(Brushes.Green, 3), vl.StartPoint, 16, 16); FormattedText formatWords = new FormattedText("Open", System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface(vs.WordsFont.Name), vs.WordsFont.Size, Brushes.Red); formatWords.SetFontWeight(FontWeights.Bold); Point startPoint = new Point(vl.StartPoint.X - formatWords.Width / 2, vl.StartPoint.Y - formatWords.Height / 2); drawingContext.DrawText(formatWords, startPoint); } } catch (Exception ex) { new SaveExceptionInfo().SaveLogAsTXTInfoex(ex.Message); } finally { drawingContext.Close(); } return drawingWordsVisual; }