OnRender
(
DrawingContext oDrawingContext,
Double dAdjustedNearValue,
Double dAdjustedNearOffset,
Double dAdjustedFarValue,
Double dAdjustedFarOffset
)
{
Debug.Assert(oDrawingContext != null);
Debug.Assert(dAdjustedNearOffset >= 0);
Debug.Assert(dAdjustedFarOffset >= 0);
AssertValid();
Rect oClientRectangle =
new Rect(0, 0, this.ActualWidth, this.ActualHeight);
Double dAxisLength = m_bIsXAxis ? this.ActualWidth : this.ActualHeight;
if (dAxisLength == 0)
{
return;
}
// If the pen is not one pixel wide, gridlines drawn on a large-font
// machine vary in width, depending on their position.
Pen oPen = WpfGraphicsUtil.CreateOnePixelPen(this,
SystemColors.WindowTextBrush);
WpfGraphicsUtil.FreezeIfFreezable(oPen);
DrawBackground(oDrawingContext, oClientRectangle, dAdjustedNearOffset,
dAdjustedFarOffset);
DrawAxisLine(oDrawingContext, oClientRectangle, oPen);
if (dAdjustedFarValue == dAdjustedNearValue)
{
// This is a degenerate case. Draw just one gridline.
DrawMajorGridlineAndValue(oDrawingContext, oClientRectangle, oPen,
dAdjustedNearValue, dAdjustedNearOffset, "N");
return;
}
if (dAdjustedNearOffset + dAdjustedFarOffset > dAxisLength)
{
return;
}
DrawLabel(oDrawingContext, oClientRectangle);
Double [] adMajorGridlineValues;
Int32 iDecimalPlacesToShow;
ChartUtil.GetAxisGridlineValues(dAdjustedNearValue, dAdjustedFarValue,
out adMajorGridlineValues, out iDecimalPlacesToShow);
String sFormatSpecifier = GetFormatSpecifier(adMajorGridlineValues,
iDecimalPlacesToShow);
// Use the point-slope equation of a line to get the major gridline
// coordinates.
Double dX1 = dAdjustedNearValue;
Double dY1 = dAdjustedNearOffset;
Double dX2 = dAdjustedFarValue;
Double dY2 = dAxisLength - dAdjustedFarOffset;
Debug.Assert(dX1 != dX2);
Double dM = (dY1 - dY2) / (dX1 - dX2);
Double dPreviousMajorGridlineOffset = Double.NaN;
foreach (Double dMajorGridlineValue in adMajorGridlineValues)
{
// Compute the major gridline's offset, then draw it.
Double dMajorGridlineOffset =
dY1 + dM * (dMajorGridlineValue - dX1);
DrawMajorGridlineAndValue(oDrawingContext, oClientRectangle, oPen,
dMajorGridlineValue, dMajorGridlineOffset, sFormatSpecifier);
if (!Double.IsNaN(dPreviousMajorGridlineOffset))
{
// Draw minor gridlines between the major gridlines.
DrawMinorGridlines(oDrawingContext, oClientRectangle, oPen,
dMajorGridlineOffset, dPreviousMajorGridlineOffset);
}
dPreviousMajorGridlineOffset = dMajorGridlineOffset;
}
}