C# Context.MoveTo方法代码示例

		/// <summary>
		/// Visual test for pixel alignment and odd/even line widths
		/// </summary>
		public void Lines (Context ctx)
		{
			ctx.Save ();

			ctx.SetColor (Colors.Black);

			int nPairs = 4;
			double length = 90;
			double gap = 2;

			// set half-pixel y-coordinate for sharp single-pixel-wide line
			// on first line of Canvas, extending to match line pairs below
			ctx.SetLineWidth (1);
			double x = 0;
			double y = 0.5;
			double end = x + 2*(length - 1) + gap;
			ctx.MoveTo (x, y);
			ctx.LineTo (end, y);
			ctx.Stroke ();

			// draw pairs of lines with odd and even widths,
			// each pair aligned on half-pixel y-coordinates
			y = 4.5;
			for (int w = 1; w <= nPairs; ++w) {
				x = 0;
				ctx.SetLineWidth (w);
				ctx.MoveTo (x, y);
				ctx.RelLineTo (length-1, 0);
				ctx.Stroke ();

				ctx.SetLineWidth (w + 1);
				x += (gap + length - 1);
				ctx.MoveTo (x, y);
				ctx.RelLineTo (length-1, 0);
				ctx.Stroke ();
				y += w * 2 + gap;
			}

			ctx.Restore ();
		}

        public virtual void Curves1(Context ctx, double x, double y)
        {
            ctx.Save ();
            ctx.Translate (x, y);

            ctx.SetLineWidth (1);
            Action curve1 = () => {
                ctx.MoveTo (0, 30);
                ctx.CurveTo (20, 0, 50, 0, 60, 25);
            };
            // curve2 with lineTo; curve1 is closed
            Action curve2 = () => {
                ctx.LineTo (0, 0);
                ctx.CurveTo (20, 30, 50, 30, 60, 5);
            };
            Action paint = () => {
                curve1 ();
                curve2 ();
                ctx.ClosePath ();
                ctx.SetColor (new Color (0, 0, 0, .5));
                ctx.StrokePreserve ();
                ctx.SetColor (new Color (1, 0, 1, .5));
                ctx.Fill ();
            };
            paint ();

            ctx.Translate (0, 40);
            // curve2 with moveTo; curve1 is open
            curve2 = () => {
                ctx.MoveTo (0, 0);
                ctx.CurveTo (20, 30, 50, 30, 60, 5);
            };
            paint ();
            ctx.Restore ();

            //Todo: same stuff with arc
        }

		internal protected override void Draw (Context win, Rectangle area, long line, double x, double y)
		{
			win.Rectangle (x, y, Width, Editor.LineHeight);
			win.SetColor (Style.IconBarBg);
			win.Fill ();
			win.MoveTo (x + Width - 1, y);
			win.LineTo (x + Width - 1, y + Editor.LineHeight);
			win.SetColor (Style.IconBarSeperator);
			win.Stroke ();

			foreach (long bookmark in Data.Bookmarks) {
				if (line * Editor.BytesInRow <= bookmark && bookmark < line * Editor.BytesInRow + Editor.BytesInRow) {
					DrawBookmark (win, x, y);
					return;
				}
			}
		}

		public static void DrawRoundRectangle (Context cr, double x, double y, double r, double w, double h)
		{
			const double ARC_TO_BEZIER = 0.55228475;
			double radius_x = r;
			double radius_y = r / 4;
			
			if (radius_x > w - radius_x)
				radius_x = w / 2;
					
			if (radius_y > h - radius_y)
				radius_y = h / 2;
			
			double c1 = ARC_TO_BEZIER * radius_x;
			double c2 = ARC_TO_BEZIER * radius_y;
			
			cr.NewPath ();
			cr.MoveTo (x + radius_x, y);
			cr.RelLineTo (w - 2 * radius_x, 0.0);
			cr.RelCurveTo (c1, 0.0, radius_x, c2, radius_x, radius_y);
			cr.RelLineTo (0, h - 2 * radius_y);
			cr.RelCurveTo (0.0, c2, c1 - radius_x, radius_y, -radius_x, radius_y);
			cr.RelLineTo (-w + 2 * radius_x, 0);
			cr.RelCurveTo (-c1, 0, -radius_x, -c2, -radius_x, -radius_y);
			cr.RelLineTo (0, -h + 2 * radius_y);
			cr.RelCurveTo (0.0, -c2, radius_x - c1, -radius_y, radius_x, -radius_y);
			cr.ClosePath ();
		}

		void DrawTicks (Context ctx, TickEnumerator e, AxisPosition pos, AxisDimension ad, int tickSize, bool showLabels)
		{
			double rheight = Bounds.Height;
			
			TextLayout layout = null;
			
			if (showLabels) {
				layout = new TextLayout ();
				layout.Font = chartFont;
			}
			
			bool isX = pos == AxisPosition.Top || pos == AxisPosition.Bottom;
			bool isTop = pos == AxisPosition.Top || pos == AxisPosition.Right;
			
			double start = GetStart (ad);
			double end = GetEnd (ad);
			
			e.Init (GetOrigin (ad));
			
			while (e.CurrentValue > start)
				e.MovePrevious ();
			
			double lastPosLabel;
			double lastPos;
			double lastTw = 0;
			
			if (isX) {
				lastPosLabel = reverseXAxis ? left + width + MinLabelGapX : left - MinLabelGapX;
				lastPos = left - minTickStep*2;
			}
			else {
				lastPosLabel = reverseYAxis ? top - MinLabelGapY : rheight + MinLabelGapY;
				lastPos = top + height + minTickStep*2;
			}
			
			for ( ; e.CurrentValue <= end; e.MoveNext ())
			{
				double px, py;
				double tw = 0, th = 0;
				int tick = tickSize;
				
				GetPoint (e.CurrentValue, e.CurrentValue, out px, out py);
				
				if (showLabels) {
					layout.Text = e.CurrentLabel;
					var ts = layout.GetSize ();
					tw = ts.Width;
					th = ts.Height;
				}

				if (isX) {
					if (Math.Abs ((long)px - (long)lastPos) < minTickStep || px < left || px > left + width)
						continue;
					lastPos = px;
					
					bool labelFits = false;
					if ((Math.Abs (px - lastPosLabel) - (tw/2) - (lastTw/2)) >= MinLabelGapX) {
						lastPosLabel = px;
						lastTw = tw;
						labelFits = true;
					}
					
					if (isTop) {
						if (showLabels) {
							if (labelFits)
								ctx.DrawTextLayout (layout, px - (tw/2), top - AreaBorderWidth - th);
							else
								tick = tick / 2;
						}
						ctx.MoveTo (px, top);
						ctx.LineTo (px, top + tick);
						ctx.Stroke ();
					}
					else {
						if (showLabels) {
							if (labelFits)
								ctx.DrawTextLayout (layout, px - (tw/2), top + height + AreaBorderWidth);
							else
								tick = tick / 2;
						}
						ctx.MoveTo (px, top + height);
						ctx.LineTo (px, top + height - tick);
						ctx.Stroke ();
					}
				}
				else {
					if (Math.Abs ((long)lastPos - (long)py) < minTickStep || py < top || py > top + height)
						continue;
					lastPos = py;
					
					bool labelFits = false;
					if ((Math.Abs (py - lastPosLabel) - (th/2) - (lastTw/2)) >= MinLabelGapY) {
						lastPosLabel = py;
						lastTw = th;
						labelFits = true;
					}
					
					if (isTop) {
						if (showLabels) {
							if (labelFits)
//.........这里部分代码省略.........

        /// <summary>
        /// Draws the horizontal line plot using the Context and the x and y axes specified
        /// </summary>
        /// <param name="ctx">The Context with which to draw.</param>
        /// <param name="xAxis">The X-Axis to draw against.</param>
        /// <param name="yAxis">The Y-Axis to draw against.</param>
        public void Draw(Context ctx, PhysicalAxis xAxis, PhysicalAxis yAxis)
        {
            double xMin = xAxis.PhysicalMin.X;
            double xMax = xAxis.PhysicalMax.X;

            xMin += pixelIndent_;
            xMax -= pixelIndent_;

            double length = Math.Abs (xMax - xMin);
            double lengthDiff = length - length*scale_;
            double indentAmount = lengthDiff/2;

            xMin += indentAmount;
            xMax -= indentAmount;

            double yPos = yAxis.WorldToPhysical (value_, false).Y;

            ctx.Save ();
            ctx.SetLineWidth (1);
            ctx.SetColor (color_);
            ctx.MoveTo (xMin, yPos);
            ctx.LineTo (xMax, yPos);
            ctx.Stroke ();
            ctx.Restore ();

            // todo:  clip and proper logic for flipped axis min max.
        }

        void DrawBorder(Context ctx, double x, double y, double w, double h, double radius, double thickness)
        {
            // test limits (without using multiplication)
            if (radius > w - radius)
                radius = w / 2;
            if (radius > h - radius)
                radius = h / 2;

            // approximate (quite close) the arc using a bezier curve
            double arc = ArcToBezier * radius;

            ctx.SetLineWidth (thickness);

            // top-left corner
            ctx.NewPath ();
            ctx.MoveTo (x, y + radius);
            ctx.CurveTo (x, y + radius - arc, x + radius - arc, y, x + radius, y);
            ctx.Pattern = GetCornerGradient (x + radius, y + radius, radius, thickness / 2);
            ctx.Stroke ();

            // top edge
            ctx.NewPath ();
            ctx.MoveTo (x + radius - 0.5, y);
            ctx.LineTo (x + w - radius + 0.5, y);
            ctx.Pattern = GetTopEdgeGradient (y, thickness / 2);
            ctx.Stroke ();

            // top-right corner
            ctx.NewPath ();
            ctx.MoveTo (x + w - radius, y);
            ctx.CurveTo (x + w - radius + arc, y, x + w, y + arc, x + w, y + radius);
            ctx.Pattern = GetCornerGradient (x + w - radius, y + radius, radius, thickness / 2);
            ctx.Stroke ();

            // right edge
            ctx.NewPath ();
            ctx.MoveTo (x + w, y + radius - 0.5);
            ctx.LineTo (x + w, y + h - radius + 0.5);
            ctx.Pattern = GetRightEdgeGradient (x + w, thickness / 2);
            ctx.Stroke ();

            // bottom-right corner
            ctx.NewPath ();
            ctx.MoveTo (x + w, y + h - radius);
            ctx.CurveTo (x + w, y + h - radius + arc, x + w + arc - radius, y + h, x + w - radius, y + h);
            ctx.Pattern = GetCornerGradient (x + w - radius, y + h - radius, radius, thickness / 2);
            ctx.Stroke ();

            // bottom edge
            ctx.NewPath ();
            ctx.MoveTo (x + w - radius + 0.5, y + h);
            ctx.LineTo (x + radius - 0.5, y + h);
            ctx.Pattern = GetBottomEdgeGradient (y + h, thickness / 2);
            ctx.Stroke ();

            // bottom-left corner
            ctx.NewPath ();
            ctx.MoveTo (x + radius, y + h);
            ctx.CurveTo (x + radius - arc, y + h, x, y + h - arc, x, y + h - radius);
            ctx.Pattern = GetCornerGradient (x + radius, y + h - radius, radius, thickness / 2);
            ctx.Stroke ();

            // left edge
            ctx.NewPath ();
            ctx.MoveTo (x, y + h - radius + 0.5);
            ctx.LineTo (x, y + radius - 0.5);
            ctx.Pattern = GetLeftEdgeGradient (x, thickness / 2);
            ctx.Stroke ();
        }

        protected override void OnDraw(Context ctx, Rectangle cellArea)
        {
            ctx.Rectangle (BackgroundBounds);
            ctx.SetColor (new Color (0.9, 0.9, 0.9));
            ctx.Fill ();

            ctx.Rectangle (Bounds);
            ctx.SetColor (new Color (0.7, 0.7, 0.7));
            ctx.Fill ();

            var pct = GetValue (ValueField);
            var size = (cellArea.Width * pct.Value) / 100f;
            cellArea.Width = (int) size;

            ctx.SetLineWidth (1);
            ctx.Rectangle (cellArea.Inflate (-0.5, -0.5));
            ctx.SetColor (Selected ? Colors.Blue : Colors.LightBlue);
            ctx.FillPreserve ();
            ctx.SetColor (Colors.Gray);
            ctx.Stroke ();

            if (pct.YPos != -1) {
                ctx.MoveTo (cellArea.Right, Bounds.Y + pct.YPos);
                ctx.Arc (cellArea.Right, Bounds.Y + pct.YPos, 2.5, 0, 360);
                ctx.SetColor (Colors.Red);
                ctx.Fill ();
            }
        }

        /// <summary>
        /// Draw a tick on the axis.
        /// </summary>
        /// <param name="ctx">The Drawing Context with on which to draw.</param>
        /// <param name="w">The tick position in world coordinates.</param>
        /// <param name="size">The size of the tick (in pixels)</param>
        /// <param name="text">The text associated with the tick</param>
        /// <param name="textOffset">The Offset to draw from the auto calculated position</param>
        /// <param name="axisPhysMin">The minimum physical extent of the axis</param>
        /// <param name="axisPhysMax">The maximum physical extent of the axis</param>
        /// <param name="boundingBox">out: The bounding rectangle for the tick and tickLabel drawn</param>
        /// <param name="labelOffset">out: offset from the axies required for axis label</param>
        public virtual void DrawTick( 
			Context ctx, 
			double w,
			double size,
			string text,
			Point textOffset,
			Point axisPhysMin,
			Point axisPhysMax,
			out Point labelOffset,
			out Rectangle boundingBox )
        {
            // determine physical location where tick touches axis.
            Point tickStart = WorldToPhysical (w, axisPhysMin, axisPhysMax, true);

            // determine offset from start point.
            Point  axisDir = Utils.UnitVector (axisPhysMin, axisPhysMax);

            // rotate axisDir anti-clockwise by TicksAngle radians to get tick direction. Note that because
            // the physical (pixel) origin is at the top left, a RotationTransform by a positive angle will
            // be clockwise.  Consequently, for anti-clockwise rotations, use cos(A-B), sin(A-B) formulae
            double x1 = Math.Cos (TicksAngle) * axisDir.X + Math.Sin (TicksAngle) * axisDir.Y;
            double y1 = Math.Cos (TicksAngle) * axisDir.Y - Math.Sin (TicksAngle) * axisDir.X;

            // now get the scaled tick vector.
            Point tickVector = new Point (TickScale * size * x1, TickScale * size * y1);

            if (TicksCrossAxis) {
                tickStart.X -= tickVector.X / 2;
                tickStart.Y -= tickVector.Y / 2;
            }

            // and the end point [point off axis] of tick mark.
            Point  tickEnd = new Point (tickStart.X + tickVector.X, tickStart.Y + tickVector.Y);

            // and draw it
            ctx.SetLineWidth (1);
            ctx.SetColor (LineColor);
            ctx.MoveTo (tickStart.X+0.5, tickStart.Y+0.5);
            ctx.LineTo (tickEnd.X+0.5, tickEnd.Y+0.5);
            ctx.Stroke ();

            // calculate bounds of tick.
            double minX = Math.Min (tickStart.X, tickEnd.X);
            double minY = Math.Min (tickStart.Y, tickEnd.Y);
            double maxX = Math.Max (tickStart.X, tickEnd.X);
            double maxY = Math.Max (tickStart.Y, tickEnd.Y);
            boundingBox = new Rectangle (minX, minY, maxX-minX, maxY-minY);

            // by default, label offset from axis is 0. TODO: revise this.
            labelOffset = new Point (-tickVector.X, -tickVector.Y);

            // ------------------------

            // now draw associated text.

            // **** TODO ****
            // The following code needs revising. A few things are hard coded when
            // they should not be. Also, angled tick text currently just works for
            // the bottom x-axis. Also, it's a bit hacky.

            if (text != "" && !HideTickText) {
                TextLayout layout = new TextLayout ();
                layout.Font = tickTextFontScaled;
                layout.Text = text;
                Size textSize = layout.GetSize ();

                // determine the center point of the tick text.
                double textCenterX;
                double textCenterY;

                // if text is at pointy end of tick.
                if (!TickTextNextToAxis) {
                    // offset due to tick.
                    textCenterX = tickStart.X + tickVector.X*1.2;
                    textCenterY = tickStart.Y + tickVector.Y*1.2;

                    // offset due to text box size.
                    textCenterX += 0.5 * x1 * textSize.Width;
                    textCenterY += 0.5 * y1 * textSize.Height;
                }
                    // else it's next to the axis.
                else {
                    // start location.
                    textCenterX = tickStart.X;
                    textCenterY = tickStart.Y;

                    // offset due to text box size.
                    textCenterX -= 0.5 * x1 * textSize.Width;
//.........这里部分代码省略.........

        /// <summary>
        /// Draws the line plot using the Context and Physical Axes provided
        /// </summary>
        /// <param name="ctx">The Drawing Context with which to draw.</param>
        /// <param name="xAxis">The X-Axis to draw against.</param>
        /// <param name="yAxis">The Y-Axis to draw against.</param>
        /// <param name="drawShadow">If true draw the shadow for the line. If false, draw line.</param>
        public void DrawLineOrShadow(Context ctx, PhysicalAxis xAxis, PhysicalAxis yAxis, bool drawShadow)
        {
            SequenceAdapter data = new SequenceAdapter (DataSource, DataMember, OrdinateData, AbscissaData);

            ITransform2D t = Transform2D.GetTransformer (xAxis, yAxis);

            int numberPoints = data.Count;

            if (data.Count == 0) {
                return;
            }

            ctx.Save ();
            ctx.SetLineWidth (lineWidth_);

            // clipping is now handled assigning a clip region in the
            // graphic object before this call
            if (numberPoints == 1) {
                Point physical = t.Transform (data[0]);

                if (drawShadow) {
                    ctx.SetColor (shadowColor_);
                    ctx.MoveTo (physical.X - 0.5 + ShadowOffset.X, physical.Y + ShadowOffset.Y);
                    ctx.LineTo (physical.X + 0.5 + ShadowOffset.X, physical.Y + ShadowOffset.Y);
                    ctx.Stroke ();
                }
                else {
                    ctx.SetColor (lineColor_);
                    ctx.MoveTo (physical.X-0.5, physical.Y);
                    ctx.LineTo (physical.X+0.5, physical.Y);
                    ctx.Stroke ();
                }
            }
            else {
                // prepare for clipping
                double leftCutoff = xAxis.PhysicalToWorld (xAxis.PhysicalMin, false);
                double rightCutoff = xAxis.PhysicalToWorld (xAxis.PhysicalMax, false);
                if (leftCutoff > rightCutoff) {
                    Utils.Swap (ref leftCutoff, ref rightCutoff);
                }
                if (drawShadow) {
                    // correct cut-offs
                    double shadowCorrection =
                        xAxis.PhysicalToWorld (ShadowOffset, false) - xAxis.PhysicalToWorld (new Point(0,0), false);
                    leftCutoff -= shadowCorrection;
                    rightCutoff -= shadowCorrection;
                }

                for (int i = 1; i < numberPoints; ++i) {
                    // check to see if any values null. If so, then continue.
                    double dx1 = data[i-1].X;
                    double dx2 = data[i].X;
                    double dy1 = data[i-1].Y;
                    double dy2 = data[i].Y;
                    if (Double.IsNaN(dx1) || Double.IsNaN(dy1) || Double.IsNaN(dx2) || Double.IsNaN(dy2)) {
                        continue;
                    }

                    // do horizontal clipping here, to speed up
                    if ((dx1 < leftCutoff && dx2 < leftCutoff) || (rightCutoff < dx1 && rightCutoff < dx2)) {
                        continue;
                    }

                    // else draw line.
                    Point p1 = t.Transform (data[i-1]);
                    Point p2 = t.Transform (data[i]);

                    // when very far zoomed in, points can fall ontop of each other,
                    // and g.DrawLine throws an overflow exception
                    if (p1.Equals(p2)) {
                        continue;
                    }

                    if (drawShadow) {
                        ctx.SetColor (shadowColor_);
                        ctx.MoveTo (p1.X + ShadowOffset.X, p1.Y + ShadowOffset.Y);
                        ctx.LineTo (p2.X + ShadowOffset.X, p2.Y + ShadowOffset.Y);
                        ctx.Stroke ();
                    }
                    else {
                        ctx.SetColor (lineColor_);
                        ctx.MoveTo (p1.X, p1.Y);
                        ctx.LineTo (p2.X, p2.Y);
                        ctx.Stroke ();
                    }
                }
            }
            ctx.Restore ();
        }

        protected override void OnDraw(Context ctx, Rectangle dirtyRect)
        {
            base.OnDraw(ctx, dirtyRect);

            for (int i = 0; i < Size.Width / checkerboard.Width; i++)
            {
                for (int j = 0; j < Size.Height / checkerboard.Height; j++)
                {
                    ctx.DrawImage(checkerboard, i * checkerboard.Width, j * checkerboard.Height);
                }
            }

            ctx.SetLineWidth(1);

            ctx.SetColor(color);
            ctx.Rectangle(0, 0, Size.Width - 20, Size.Height);
            ctx.Fill();

            ctx.SetColor(DefaultColor);
            ctx.Rectangle(Size.Width - 20, 0, 20, Size.Height);
            ctx.Fill();

            ctx.SetColor(Colors.Black);
            ctx.Rectangle(0, 0, Size.Width, Size.Height);
            ctx.Stroke();

            //ctx.SetColor(Color.Brightness > .5 ? Colors.White : Colors.Black);
            ctx.SetColor(((-1 * Color.Brightness) + 1) * 1.15 + (Color.Alpha) > 1.2 ? Colors.White : Colors.Black);
            ctx.DrawTextLayout(new TextLayout(this) { Text = Color.ToHexString().ToUpper() }, 2, 3);

            if (mover && (IsDefaultColor || mx <= Size.Width - 20))
            {
                ctx.SetColor(new Color(1, 1, 1, .33));
                ctx.Rectangle(0, 0, Size.Width - (IsDefaultColor ? 0 : 20), Size.Height);
                ctx.Fill();
            }

            if (!IsDefaultColor)
            {
                if (mover && mx > Size.Width - 20)
                {
                    ctx.SetColor(new Color(1, 1, 1, .33));
                    ctx.Rectangle(Size.Width - 20, 0, 20, Size.Height);
                    ctx.Fill();
                }

                ctx.SetColor(Colors.Black);
                ctx.MoveTo(Size.Width - 19.5, 0);
                ctx.RelLineTo(0, Size.Height);
                ctx.Stroke();

                if (mover)
                    ctx.DrawImage(resetImage, Size.Width - 18, (Size.Height - 16) / 2, 16, 16);
            }
        }

 void DrawFocus(Context ctx, Point p)
 {
     // Draw a 'zoom'-style Focus at specified point
     double focusRadius = 32;
     double r = 12, w = focusRadius - 1;
     Point o = Point.Zero;	// Drawing origin
     // Align single-thickness lines on 0.5 pixel coords
     o.X += 0.5;
     o.Y += 0.5;
     ctx.Save ();
     ctx.Translate (p);	// Final translation
     // Hairlines in X-direction
     ctx.MoveTo (o.X + r, o.Y);
     ctx.LineTo (o.X + w, o.Y);
     ctx.MoveTo (o.X - r, o.Y);
     ctx.LineTo (o.X - w, o.Y);
     // Hairlines in Y-direction
     ctx.MoveTo (o.X, o.Y + r);
     ctx.LineTo (o.X, o.Y + w);
     ctx.MoveTo (o.X, o.Y - r);
     ctx.LineTo (o.X, o.Y - w);
     // Inner single-thickness circle
     ctx.MoveTo (o.X + r, o.Y);
     ctx.Arc (o.X, o.Y, r, 0, 360);
     ctx.SetColor (Colors.Black);
     ctx.SetLineWidth (1);
     ctx.Stroke ();
     // Double thickness outer arcs. Draw at (0,0) and rotate
     o = Point.Zero;
     r = 22;
     ctx.Rotate (5);
     ctx.MoveTo (r, 0);
     ctx.Arc (o.X, o.Y, r, 0, 80);
     ctx.MoveTo (o.X, r);
     ctx.Arc (o.X, o.Y, r, 90, 170);
     ctx.MoveTo (-r, o.Y);
     ctx.Arc (o.X, o.Y, r, 180, 260);
     ctx.MoveTo (o.X, -r);
     ctx.Arc (o.X, o.Y, r, 270, 350);
     ctx.SetLineWidth (2);
     ctx.Stroke ();
     ctx.Restore ();
 }

        /// <summary>
        /// Draws the arrow on a plot surface.
        /// </summary>
        /// <param name="ctx">the Drawing Context with which to draw</param>
        /// <param name="xAxis">The X-Axis to draw against.</param>
        /// <param name="yAxis">The Y-Axis to draw against.</param>
        public void Draw(Context ctx, PhysicalAxis xAxis, PhysicalAxis yAxis )
        {
            if (To.X > xAxis.Axis.WorldMax || To.X < xAxis.Axis.WorldMin) {
                return;
            }
            if (To.Y > yAxis.Axis.WorldMax || To.Y < yAxis.Axis.WorldMin) {
                return;
            }

            ctx.Save ();

            TextLayout layout = new TextLayout ();
            layout.Font = textFont_;
            layout.Text = text_;

            double angle = angle_;
            if (angle_ < 0.0) {
                int mul = -(int)(angle_ / 360.0) + 2;
                angle = angle_ + 360.0 * (double)mul;
            }

            double normAngle = (double)angle % 360.0;	// angle in range 0 -> 360.

            Point toPoint = new Point (
                xAxis.WorldToPhysical (to_.X, true).X,
                yAxis.WorldToPhysical (to_.Y, true).Y);

            double xDir = Math.Cos (normAngle * 2.0 * Math.PI / 360.0);
            double yDir = Math.Sin (normAngle * 2.0 * Math.PI / 360.0);

            toPoint.X += xDir*headOffset_;
            toPoint.Y += yDir*headOffset_;

            double xOff = physicalLength_ * xDir;
            double yOff = physicalLength_ * yDir;

            Point fromPoint = new Point(
                (int)(toPoint.X + xOff),
                (int)(toPoint.Y + yOff) );

            ctx.SetLineWidth (1);
            ctx.SetColor (arrowColor_);
            ctx.MoveTo (fromPoint);
            ctx.LineTo (toPoint);
            ctx.Stroke ();

            xOff = headSize_ * Math.Cos ((normAngle-headAngle_/2) * 2.0 * Math.PI / 360.0);
            yOff = headSize_ * Math.Sin ((normAngle-headAngle_/2) * 2.0 * Math.PI / 360.0);

            ctx.LineTo (toPoint.X + xOff, toPoint.Y + yOff);

            double xOff2 = headSize_ * Math.Cos ((normAngle+headAngle_/2) * 2.0 * Math.PI / 360.0);
            double yOff2 = headSize_ * Math.Sin ((normAngle+headAngle_/2) * 2.0 * Math.PI / 360.0);

            ctx.LineTo (toPoint.X + xOff2, toPoint.Y + yOff2);
            ctx.LineTo (toPoint);
            ctx.ClosePath ();
            ctx.SetColor (arrowColor_);
            ctx.Fill ();

            Size textSize = layout.GetSize ();
            Size halfSize = new Size (textSize.Width/2, textSize.Height/2);

            double quadrantSlideLength = halfSize.Width + halfSize.Height;

            double quadrantD = normAngle / 90.0;		// integer part gives quadrant.
            int quadrant = (int)quadrantD;				// quadrant in.
            double prop = quadrantD - (double)quadrant;	// proportion of way through this qadrant.
            double dist = prop * quadrantSlideLength;	// distance along quarter of bounds rectangle.

            // now find the offset from the middle of the text box that the
            // rear end of the arrow should end at (reverse this to get position
            // of text box with respect to rear end of arrow).
            //
            // There is almost certainly an elgant way of doing this involving
            // trig functions to get all the signs right, but I'm about ready to
            // drop off to sleep at the moment, so this blatent method will have
            // to do.
            Point offsetFromMiddle = new Point (0, 0);
            switch (quadrant) {
            case 0:
                if (dist > halfSize.Height) {
                    dist -= halfSize.Height;
                    offsetFromMiddle = new Point ( -halfSize.Width + dist, halfSize.Height );
                }
                else {
                    offsetFromMiddle = new Point ( -halfSize.Width, - dist );
                }
                break;
            case 1:
                if (dist > halfSize.Width) {
                    dist -= halfSize.Width;
                    offsetFromMiddle = new Point ( halfSize.Width, halfSize.Height - dist );
                }
//.........这里部分代码省略.........

        /// <summary>
        /// Draws the step plot using a Drawing Context against the provided x and y axes.
        /// </summary>
        /// <param name="ctx">The Drawing Context with which to draw.</param>
        /// <param name="xAxis">The X-Axis to draw against.</param>
        /// <param name="yAxis">The Y-Axis to draw against.</param>
        public virtual void Draw(Context ctx, PhysicalAxis xAxis, PhysicalAxis yAxis )
        {
            SequenceAdapter data =
                new SequenceAdapter (DataSource, DataMember, OrdinateData, AbscissaData);

            double leftCutoff = xAxis.PhysicalToWorld(xAxis.PhysicalMin, false);
            double rightCutoff = xAxis.PhysicalToWorld(xAxis.PhysicalMax, false);

            for (int i=0; i<data.Count; ++i) {
                Point p1 = data[i];
                if (Double.IsNaN(p1.X) || Double.IsNaN(p1.Y)) {
                    continue;
                }

                Point p2;
                Point p3;
                if (i+1 != data.Count) {
                    p2 = data[i+1];
                    if (Double.IsNaN(p2.X) || Double.IsNaN(p2.Y)) {
                        continue;
                    }
                    p2.Y = p1.Y;
                    p3 = data[i+1];
                }
                else {
                    // Check that we are not dealing with a DataSource of 1 point.
                    // This check is done here so it is only checked on the end
                    // condition and not for every point in the DataSource.
                    if (data.Count > 1) {
                        p2 = data[i - 1];
                    }
                    else {
                        // TODO: Once log4net is set up post a message to the user that a step-plot of 1 really does not make any sense.
                        p2 = p1;
                    }

                    double offset = p1.X - p2.X;
                    p2.X = p1.X + offset;
                    p2.Y = p1.Y;
                    p3 = p2;
                }

                if (center_) {
                    double offset = ( p2.X - p1.X ) / 2.0;
                    p1.X -= offset;
                    p2.X -= offset;
                    p3.X -= offset;
                }

                Point xPos1 = xAxis.WorldToPhysical (p1.X, false);
                Point yPos1 = yAxis.WorldToPhysical (p1.Y, false);
                Point xPos2 = xAxis.WorldToPhysical (p2.X, false);
                Point yPos2 = yAxis.WorldToPhysical (p2.Y, false);
                Point xPos3 = xAxis.WorldToPhysical (p3.X, false);
                Point yPos3 = yAxis.WorldToPhysical (p3.Y, false);

                // do horizontal clipping here, to speed up
                if ((p1.X<leftCutoff && p2.X<leftCutoff && p3.X<leftCutoff) || (p1.X>rightCutoff && p2.X>rightCutoff && p3.X>rightCutoff)) {
                    continue;
                }

                ctx.Save ();
                ctx.SetColor (Color);
                ctx.SetLineWidth (1);
                if (!this.hideHorizontalSegments_) {
                    if (scale_ != 1) {
                        double middle = (xPos2.X + xPos1.X) / 2;
                        double width = xPos2.X - xPos1.X;
                        width *= this.scale_;
                        ctx.MoveTo (middle-width/2, yPos1.Y);
                        ctx.LineTo (middle+width/2, yPos2.Y);
                    }
                    else {
                        ctx.MoveTo (xPos1.X, yPos1.Y);
                        ctx.LineTo (xPos2.X, yPos2.Y);
                    }
                    ctx.Stroke ();
                }

                if (!this.hideVerticalSegments_) {
                    ctx.MoveTo (xPos2.X, yPos2.Y);
                    ctx.LineTo (xPos3.X, yPos3.Y);
                    ctx.Stroke ();
                }
                ctx.Restore ();
            }
        }

        /// <summary>
        /// Draws the marker at the given position
        /// </summary>
        /// <param name="ctx">The Drawing Context with which to draw.</param>
        /// <param name="x">The [physical] x position to draw the marker.</param>
        /// <param name="y">The [physical] y position to draw the marker.</param>
        public void Draw(Context ctx, double x, double y )
        {
            ctx.Save ();
            ctx.SetLineWidth (lineWidth);
            ctx.SetColor (lineColor);

            switch (markerType) {
            case MarkerType.Cross1:
                ctx.MoveTo (x-h, y+h);
                ctx.LineTo (x+h, y-h);
                ctx.MoveTo (x+h, y+h);
                ctx.LineTo (x-h, y-h);
                ctx.Stroke ();
                break;

            case MarkerType.Cross2:
                ctx.MoveTo (x, y-h);
                ctx.LineTo (x, y+h);
                ctx.MoveTo (x-h, y);
                ctx.LineTo (x+h, y);
                ctx.Stroke ();
                break;

            case MarkerType.Circle:
                ctx.MoveTo (x+h,y);
                ctx.Arc (x, y, h, 0, 360);
                ctx.ClosePath ();
                if (filled ) {
                    ctx.SetColor (fillColor);
                    ctx.FillPreserve ();
                }
                ctx.SetColor (lineColor);
                ctx.Stroke ();
                break;

            case MarkerType.Square:
                ctx.Rectangle (x-h, y-h, size, size);
                ctx.ClosePath ();
                if (filled) {
                    ctx.SetColor (fillColor);
                    ctx.FillPreserve ();
                }
                ctx.SetColor (lineColor);
                ctx.Stroke ();
                break;

            case MarkerType.Triangle:
                ctx.MoveTo (x-h, y+h);
                ctx.LineTo (x, y-h);
                ctx.LineTo (x+h, y+h);
                ctx.ClosePath ();
                if (filled) {
                    ctx.SetColor (fillColor);
                    ctx.FillPreserve ();
                }
                ctx.SetColor (lineColor);
                ctx.Stroke ();
                break;

            case MarkerType.TriangleDown:
                ctx.MoveTo (x-h, y-h);
                ctx.LineTo (x, y+h);
                ctx.LineTo (x+h, y-h);
                ctx.ClosePath ();
                if (filled) {
                    ctx.SetColor (fillColor);
                    ctx.FillPreserve ();
                }
                ctx.SetColor (lineColor);
                ctx.Stroke ();
                break;

            case MarkerType.FilledCircle:
                ctx.MoveTo (x+h,y);
                ctx.Arc (x, y, h, 0, 360);
                ctx.ClosePath ();
                ctx.SetColor (fillColor);
                ctx.FillPreserve ();
                ctx.SetColor (lineColor);
                ctx.Stroke ();
                break;

            case MarkerType.FilledSquare:
                ctx.Rectangle (x-h, y-h, size, size);
                ctx.ClosePath ();
                ctx.SetColor (fillColor);
                ctx.FillPreserve ();
                ctx.SetColor (lineColor);
                ctx.Stroke ();
                break;

            case MarkerType.FilledTriangle:
                ctx.MoveTo (x-h, y+h);
                ctx.LineTo (x, y-h);
//.........这里部分代码省略.........