private void UpdateMinorGridLines()
{
Axis xAxis = XAxis;
Axis yAxis = YAxis;
if (xAxis != null && yAxis != null)
{
AxisScale xScale = xAxis.Scale;
AxisScale yScale = yAxis.Scale;
if (xScale != null && yScale != null)
{
double xMin = xAxis.GetPosition(xScale.Min);
double xMax = xAxis.GetPosition(xScale.Max);
double yMin = yAxis.GetPosition(yScale.Min);
double yMax = yAxis.GetPosition(yScale.Max);
// Add vertical minor lines
if (_verticalMinorLinesRenderer != null && VerticalMinorLineStyle != null)
{
using (var renderContext = _verticalMinorLinesRenderer.Open())
{
for (int i = 0; i < xAxis.MinorTicks.Length; ++i)
{
double x = xAxis.GetPosition(xAxis.MinorTicks[i]);
renderContext.DrawLine(new Point(x, yMin), new Point(x, yMax));
}
}
}
// Add horizontal minor lines
if (_horizontalMinorLinesRenderer != null && HorizontalMinorLineStyle != null)
{
using (var renderContext = _horizontalMinorLinesRenderer.Open())
{
for (int i = 0; i < yAxis.MinorTicks.Length; ++i)
{
double y = yAxis.GetPosition(yAxis.MinorTicks[i]);
renderContext.DrawLine(new Point(xMin, y), new Point(xMax, y));
}
}
}
}
}
}
protected virtual void OnUpdateLines(int startIndex, int endIndexExclusive, double[] xPositions, double[] basePositions, double[] yPositions)
{
if (Data.Count == 0)
return;
bool reversed = XAxis.Scale.Reversed;
bool horizontalStepLineVisible = HorizontalStepLineVisible;
bool verticalStepLineVisible = VerticalStepLineVisible;
bool filled = Filled;
var interpolation = EffectiveInterpolation;
// Perform the large data optimization (see below) if the line chart contains vertical lines.
bool largeDataOptimization = interpolation == ChartInterpolation.Linear
|| interpolation == ChartInterpolation.CenteredSteps && verticalStepLineVisible
|| interpolation == ChartInterpolation.LeftSteps && verticalStepLineVisible
|| interpolation == ChartInterpolation.RightSteps && verticalStepLineVisible;
double pixelSize = WindowsHelper.GetPixelSize(this).Width;
using (var lineRenderContext = _lineRenderer.Open())
using (var areaRenderContext = _areaRenderer.Open())
{
int numberOfDataPoints = Data.Count;
// Lines are drawn from index i to i+1.
startIndex = Math.Max(0, startIndex - 1);
// For centered steps one additional data point needs to be rendered.
if (interpolation == ChartInterpolation.CenteredSteps)
endIndexExclusive = Math.Min(numberOfDataPoints, endIndexExclusive + 1);
for (int i = startIndex; i < endIndexExclusive; i++)
{
if (Numeric.IsNaN(xPositions[i]) || Numeric.IsNaN(yPositions[i]))
continue;
if (largeDataOptimization)
{
// Draw a single vertical line for all data points that lie on the same pixel column.
double xPixel = WindowsHelper.RoundToDevicePixelsCenter(xPositions[i], pixelSize);
double yMin = yPositions[i];
double yMax = yPositions[i];
int overlap = 0;
for (int j = i + 1; j < endIndexExclusive; j++)
{
// ReSharper disable once CompareOfFloatsByEqualityOperator
if (Numeric.IsNaN(xPositions[j])
|| Numeric.IsNaN(yPositions[j])
|| xPixel != WindowsHelper.RoundToDevicePixelsCenter(xPositions[j], pixelSize))
{
break;
}
overlap++;
if (yPositions[j] < yMin) // Safe for NaN.
yMin = yPositions[j];
else if (yPositions[j] > yMax) // Safe for NaN.
yMax = yPositions[j];
}
if (overlap > 1)
{
lineRenderContext.DrawLine(new Point(xPixel, yMin), new Point(xPixel, yMax));
// i ............. index of first point in overlap.
// i + overlap ... index of last point in overlap.
if (filled && !Numeric.IsNaN(basePositions[i]) && !Numeric.IsNaN(basePositions[i + overlap]))
areaRenderContext.DrawPolygon(
new Point(xPositions[i], yMin),
new Point(xPositions[i + overlap], yMin),
new Point(xPositions[i + overlap], basePositions[i + overlap]),
new Point(xPositions[i], basePositions[i]));
// Jump ahead to last point in overlap.
i += overlap;
if (Numeric.IsNaN(yPositions[i]))
continue;
}
}
Point previousPoint; //, previousPointBase;
Point point, pointBase;
Point nextPoint, nextPointBase;
if (i - 1 >= 0)
{
previousPoint = new Point(xPositions[i - 1], yPositions[i - 1]);
//previousPointBase = new Point(xPositions[i - 1], basePositions[i - 1]);
}
else
{
previousPoint = new Point(double.NaN, double.NaN);
//previousPointBase = new Point(double.NaN, double.NaN);
}
point = new Point(xPositions[i], yPositions[i]);
pointBase = new Point(xPositions[i], basePositions[i]);
if (i + 1 < numberOfDataPoints)
{
nextPoint = new Point(xPositions[i + 1], yPositions[i + 1]);
nextPointBase = new Point(xPositions[i + 1], basePositions[i + 1]);
}
else
{
nextPoint = new Point(double.NaN, double.NaN);
nextPointBase = new Point(double.NaN, double.NaN);
}
// Draw lines and area from i to i+1.
if (interpolation == ChartInterpolation.Linear)
{
// Linear interpolation
if (!Numeric.IsNaN(nextPoint.X) && !Numeric.IsNaN(nextPoint.Y))
{
lineRenderContext.DrawLine(point, nextPoint);
if (filled && !Numeric.IsNaN(pointBase.Y) && !Numeric.IsNaN(nextPointBase.Y))
areaRenderContext.DrawPolygon(
point,
nextPoint,
nextPointBase,
pointBase);
}
}
else
{
if (interpolation == ChartInterpolation.CenteredSteps)
{
// Centered steps
double centerBefore, centerAfter;
GetCenteredStep(previousPoint, point, nextPoint, out centerBefore, out centerAfter);
if (horizontalStepLineVisible)
lineRenderContext.DrawLine(new Point(centerBefore, point.Y), new Point(centerAfter, point.Y));
if (verticalStepLineVisible && !Numeric.IsNaN(nextPoint.X) && !Numeric.IsNaN(nextPoint.Y))
lineRenderContext.DrawLine(new Point(centerAfter, point.Y), new Point(centerAfter, nextPoint.Y));
if (filled && !Numeric.IsNaN(pointBase.Y))
{
areaRenderContext.DrawPolygon(
new Point(centerBefore, point.Y),
new Point(centerAfter, point.Y),
new Point(centerAfter, pointBase.Y),
new Point(centerBefore, pointBase.Y));
}
}
else
{
if (interpolation == ChartInterpolation.LeftSteps && !reversed
|| interpolation == ChartInterpolation.RightSteps && reversed)
{
// LeftSteps or Reversed RightSteps
if (!Numeric.IsNaN(nextPoint.X) && !Numeric.IsNaN(nextPoint.Y))
{
if (verticalStepLineVisible)
lineRenderContext.DrawLine(point, new Point(point.X, nextPoint.Y));
if (horizontalStepLineVisible)
lineRenderContext.DrawLine(new Point(point.X, nextPoint.Y), nextPoint);
if (filled && !Numeric.IsNaN(nextPointBase.Y))
{
areaRenderContext.DrawPolygon(
new Point(point.X, nextPoint.Y),
nextPoint,
nextPointBase,
new Point(point.X, nextPointBase.Y));
}
}
}
else
{
// RightSteps or Reversed LeftSteps
if (!Numeric.IsNaN(nextPoint.X) && !Numeric.IsNaN(nextPoint.Y))
{
if (horizontalStepLineVisible)
lineRenderContext.DrawLine(point, new Point(nextPoint.X, point.Y));
if (verticalStepLineVisible)
lineRenderContext.DrawLine(new Point(nextPoint.X, point.Y), nextPoint);
if (filled && !Numeric.IsNaN(pointBase.Y) && !Numeric.IsNaN(nextPointBase.Y))
{
areaRenderContext.DrawPolygon(
point,
new Point(nextPoint.X, point.Y),
new Point(nextPointBase.X, pointBase.Y),
pointBase);
}
}
}
}
}
}
}
if (_linePath != null)
_linePath.Clip = LineClipGeometry;
if (_areaPath != null)
_areaPath.Clip = AreaClipGeometry;
// Bugfix:
// Sometimes the first line of a Path is not drawn.
// We need to explicitly call InvalidateMeasure() on the canvas.
Canvas.InvalidateMeasure();
}
