GetBounds()
{
AssertValid();
if (m_oEdge.IsSelfLoop)
{
Debug.Assert(false);
throw new InvalidOperationException("Edge is self-loop.");
}
// Start with a rectangle that has the same dimensions as the edge, but
// that starts at the origin and has an angle of zero.
Point oVertex1Location = WpfGraphicsUtil.PointFToWpfPoint(
m_oEdge.Vertex1.Location);
Point oVertex2Location = WpfGraphicsUtil.PointFToWpfPoint(
m_oEdge.Vertex2.Location);
Double dLength = WpfGraphicsUtil.GetDistanceBetweenPoints(
oVertex1Location, oVertex2Location);
Double dAngleDegrees = MathUtil.RadiansToDegrees(
WpfGraphicsUtil.GetAngleBetweenPointsRadians(
oVertex1Location, oVertex2Location));
Double dHalfWidth = m_dWidth / 2.0;
Point[] ao4BoundingPoints = new Point[4] {
new Point(0, -dHalfWidth),
new Point(dLength, -dHalfWidth),
new Point(dLength, dHalfWidth),
new Point(0, dHalfWidth),
};
// Rotate the rectangle so it is at the same angle as the edge.
TransformPoints(new RotateTransform(dAngleDegrees), ao4BoundingPoints);
// Translate the rotated rectangle to the location of the edge's first
// endpoint.
TransformPoints(
new TranslateTransform(oVertex1Location.X, oVertex1Location.Y),
ao4BoundingPoints);
// Create a PathGeometry from the bounding points.
return(WpfPathGeometryUtil.GetPathGeometryFromPoints(
ao4BoundingPoints[0],
ao4BoundingPoints[1],
ao4BoundingPoints[2],
ao4BoundingPoints[3]
));
}
GetBezierControlPoint
(
GraphDrawingContext oGraphDrawingContext,
Point oEndpoint1,
Point oEndpoint2,
Double dBezierDisplacementFactor
)
{
Debug.Assert(oGraphDrawingContext != null);
Debug.Assert(dBezierDisplacementFactor >= 0);
AssertValid();
// This method finds the midpoint of the straight line between the two
// endpoints, then calculates a point that is displaced from the
// midpoint at a right angle. This is analagous to pulling a taut
// string at its midpoint.
//
// The calculations are based on the anonymous post "How Can I
// Calculate The Cartesian Coordinates Of A The Third Corner Of A
// Triangle If I Have The Lengths Of All Three Sides And The
// Coordinates Of The First Two Corners?" at
// http://www.blurtit.com/q9044151.html.
// Point a, the first endpoint, is one vertex of a right triangle.
Double dPointAX = oEndpoint1.X;
Double dPointAY = oEndpoint1.Y;
// Point b, the midpoint of the line between the two endpoints, is
// another vertex of the right triangle. The angle at b is 90 degrees.
Double dPointBX = dPointAX + (oEndpoint2.X - dPointAX) / 2.0;
Double dPointBY = dPointAY + (oEndpoint2.Y - dPointAY) / 2.0;
// Side C connects points a and b.
Double dSideCLength = WpfGraphicsUtil.GetDistanceBetweenPoints(
new Point(dPointBX, dPointBY), oEndpoint1);
// Side A connects points b and c, where c is the point we need to
// calculate. Make the length of A, which is the displacement
// mentioned above, proportional to the length of the line between the
// two endpoints, so that a longer line gets displaced more than a
// shorter line.
Double dSideALength = dSideCLength * dBezierDisplacementFactor;
// Calculate the angle of the line between the two endpoints.
Double dAbsAtan2 = Math.Abs(Math.Atan2(
Math.Max(oEndpoint2.Y, dPointAY) - Math.Min(oEndpoint2.Y, dPointAY),
Math.Max(oEndpoint2.X, dPointAX) - Math.Min(oEndpoint2.X, dPointAX)
));
Rect oGraphRectangle = oGraphDrawingContext.GraphRectangle;
if (dAbsAtan2 >= Math.PI / 4.0 && dAbsAtan2 <= 3.0 * Math.PI / 4.0)
{
// The line between the two endpoints is closer to vertical than
// horizontal.
//
// As explained in the post mentioned above, the length of side A
// can be negative or positive, depending on which direction point
// c should be displaced. The following adjustments to
// dSideALength were determined experimentally.
if (oEndpoint2.Y > dPointAY)
{
dSideALength *= -1.0;
}
if (dPointBX - oGraphRectangle.Left <
oGraphRectangle.Right - dPointBX)
{
dSideALength *= -1.0;
}
}
else
{
// The line between the two endpoints is closer to horizontal than
// vertical.
if (oEndpoint2.X < dPointAX)
{
dSideALength *= -1.0;
}
if (dPointBY - oGraphRectangle.Top <
oGraphRectangle.Bottom - dPointBY)
{
dSideALength *= -1.0;
}
}
// Calculate point c.
Double dPointCX = dPointBX +
(dSideALength * (dPointAY - dPointBY)) / dSideCLength;
Double dPointCY = dPointBY +
(dSideALength * (dPointBX - dPointAX)) / dSideCLength;
// Don't let point c fall outside the graph's margins.
return(WpfGraphicsUtil.MovePointWithinBounds(
new Point(dPointCX, dPointCY),
oGraphDrawingContext.GraphRectangleMinusMargin));
}
DrawLabel
(
DrawingContext oDrawingContext,
GraphDrawingContext oGraphDrawingContext,
Point oEdgeEndpoint1,
Point oEdgeEndpoint2,
String sLabel,
Color oColor
)
{
Debug.Assert(oDrawingContext != null);
Debug.Assert(oGraphDrawingContext != null);
Debug.Assert(sLabel != null);
AssertValid();
if (sLabel.Length == 0)
{
return;
}
sLabel = TruncateLabel(sLabel);
if (oEdgeEndpoint2.X < oEdgeEndpoint1.X)
{
// Don't let text be drawn upside-down.
Point oTemp = oEdgeEndpoint2;
oEdgeEndpoint2 = oEdgeEndpoint1;
oEdgeEndpoint1 = oTemp;
}
Double dEdgeAngleDegrees = MathUtil.RadiansToDegrees(
WpfGraphicsUtil.GetAngleBetweenPoints(
oEdgeEndpoint1, oEdgeEndpoint2));
Double dEdgeLength = WpfGraphicsUtil.GetDistanceBetweenPoints(
oEdgeEndpoint1, oEdgeEndpoint2);
// To avoid trigonometric calculations, use a RotateTransform to make
// the edge look as if it is horizontal, with oEdgeEndpoint2 to the
// right of oEdgeEndpoint1.
RotateTransform oRotateTransform = new RotateTransform(
dEdgeAngleDegrees, oEdgeEndpoint1.X, oEdgeEndpoint1.Y);
oEdgeEndpoint2 = oRotateTransform.Transform(oEdgeEndpoint2);
oRotateTransform.Angle = -dEdgeAngleDegrees;
oDrawingContext.PushTransform(oRotateTransform);
FormattedText oFormattedText = CreateFormattedText(sLabel, oColor);
oFormattedText.Trimming = TextTrimming.CharacterEllipsis;
if (sLabel.IndexOf('\n') == -1)
{
// Unless the label includes line breaks, don't allow the
// FormattedText class to break the text into multiple lines.
oFormattedText.MaxLineCount = 1;
}
Double dTextWidth = oFormattedText.Width;
// The ends of the label text are between one and two "buffer units"
// from the ends of the edge. The buffer unit is the width of an
// arbitrary character.
Double dBufferUnit = CreateFormattedText("i", oColor).Width;
Double dEdgeLengthMinusBuffers = dEdgeLength - 2 * dBufferUnit;
if (dEdgeLengthMinusBuffers <= 0)
{
return;
}
// Determine where to draw the label text, and where to draw a
// translucent rectangle behind the text. The translucent rectangle
// serves to obscure, but not completely hide, the underlying edge.
Point oLabelOrigin = oEdgeEndpoint1;
Rect oTranslucentRectangle;
if (dTextWidth > dEdgeLengthMinusBuffers)
{
// The label text should start one buffer unit from the first
// endpoint, and terminate with ellipses approximately one buffer
// length from the second endpoint.
oLabelOrigin.Offset(dBufferUnit, 0);
oFormattedText.MaxTextWidth = dEdgeLengthMinusBuffers;
// The translucent rectangle should be the same width as the text.
oTranslucentRectangle = new Rect(oLabelOrigin,
new Size(dEdgeLengthMinusBuffers, oFormattedText.Height));
}
else
{
// The label should be centered along the edge's length.
oLabelOrigin.Offset(dEdgeLength / 2.0, 0);
oFormattedText.TextAlignment = TextAlignment.Center;
// The translucent rectangle should extend between zero and one
// buffer units beyond the ends of the text. This provides a
// margin between the text and the unobscured edge, if there is
// enough space.
oTranslucentRectangle = new Rect(oLabelOrigin,
new Size(
Math.Min(dTextWidth + 2 * dBufferUnit,
dEdgeLengthMinusBuffers),
oFormattedText.Height)
);
oTranslucentRectangle.Offset(
-oTranslucentRectangle.Width / 2.0, 0);
}
// The text and rectangle should be vertically centered on the edge.
oDrawingContext.PushTransform(
new TranslateTransform(0, -oFormattedText.Height / 2.0));
// Draw the translucent rectangle, then the text.
//
// Note: Don't make the rectangle any more opaque than the edge, which
// might be translucent itself.
oDrawingContext.DrawRectangle(GetBrush(
WpfGraphicsUtil.SetWpfColorAlpha(oGraphDrawingContext.BackColor,
Math.Min(LabelBackgroundAlpha, oColor.A))
),
null, oTranslucentRectangle);
oDrawingContext.DrawText(oFormattedText, oLabelOrigin);
oDrawingContext.Pop();
oDrawingContext.Pop();
}