public void DrawChart()
{
if (_data == null || _data.Length <= 0)
{
return;
}
CanvasDevice device = CanvasDevice.GetSharedDevice();
//rendering options are calculating min & max values & value texts
RenderingOptions renderingOptions = CreateRenderingOptions(_data);
//_offscreenBackGround is created in here
DrawBackGround(device, renderingOptions);
//_offscreenChartImage is created in here
DrawCharData(device, renderingOptions, _data);
//forces re-draw
ChartWin2DCanvas.Invalidate();
}
private void MoveZoom(double changeX, double changeY)
{
if (_currentDirection == MoveDirection.Done ||
_currentDirection == MoveDirection.Determining ||
_offscreenChartImage == null)
{
//Nothing will change on drawing
return;
}
if (_currentDirection == MoveDirection.Horizontal)
{
if (changeX == 0)
{
//Nothing will change on drawing
return;
}
//we simply move the start point according to finger movement
_graphDrawingPoint.X += changeX;
//and make sure that we don't go over the actual beginning point
if (_graphDrawingPoint.X < 0)
{
_graphDrawingPoint.X = 0;
}
}
else if (_currentDirection == MoveDirection.Vertical)
{
if (changeY == 0)
{
//Nothing will change on drawing
return;
}
// use different divider to adjust the zoomefect
_zoomFactor += (int)(changeY / 2);
//and lets keep the zoom level in defined range
if (_zoomFactor < _minZoomFactor)
{
_zoomFactor = _minZoomFactor;
}
else if (_zoomFactor > 100)
{
_zoomFactor = 100;
}
//zoom efect simply changes the width part of the size what we draw
_graphDrawingSource = new Size(((_offscreenChartImage.Size.Width * _zoomFactor) / 100), _offscreenChartImage.Size.Height);
}
double maxChange = _offscreenChartImage.Size.Width - _graphDrawingSource.Width;
//the max value changes on zoom, and move value in move
//so we need to check the max value for movement after each action
if (_graphDrawingPoint.X > maxChange)
{
_graphDrawingPoint.X = maxChange;
}
//invalidate forces re-draw
ChartWin2DCanvas.Invalidate();
}