public void HighlightElement(View viewToHighlight, SKCanvasView skCanvasView, Layout <View> formLayout)
{
IList <View> layoutChildren = formLayout.Children;
if (_highlightState == null)
{
var path = HighlightPath.Create(skCanvasView, layoutChildren, _highlightSettings.StrokeWidth);
_highlightState = new HighlightState()
{
HighlightPath = path
};
}
HighlightPath highlightPath = _highlightState.HighlightPath;
int currHighlightViewId = _highlightState.CurrHighlightedViewId;
int iViewIdToHighlight = highlightPath.GetViewId(layoutChildren, viewToHighlight);
if (currHighlightViewId == iViewIdToHighlight)
{
return;
}
StrokeDash fromDash;
if (currHighlightViewId != -1)
{
fromDash = _highlightState.StrokeDash;
}
else
{
fromDash = new StrokeDash(highlightPath.GetDashForView(layoutChildren, iViewIdToHighlight));
}
_highlightState.CurrHighlightedViewId = iViewIdToHighlight;
StrokeDash toDash = new StrokeDash(highlightPath.GetDashForView(layoutChildren, viewToHighlight));
DrawDash(skCanvasView, fromDash, toDash);
}
public static HighlightPath Create(SKCanvasView skCanvasView, IList <View> layoutChildren, double strokeWidth)
{
var path = new SKPath();
var highlightPath = new HighlightPath()
{
Path = path
};
strokeWidth = (float)skCanvasView.FromPixels(new Point(0, strokeWidth)).Y;
foreach (View view in layoutChildren)
{
int iStrokeDashCount = highlightPath.DashCount;
Rectangle viewBounds = skCanvasView.FromPixels(view.Bounds);
if (!(view is Entry) && !(view is Button))
{
continue;
}
if (path.Points.Length == 0)
{
// Move path point at the left and below of the view
path.MoveTo(
x: (float)viewBounds.X,
y: (float)viewBounds.Y + (float)viewBounds.Height + (float)strokeWidth / 2);
}
float xCurr = path.LastPoint.X;
float yCurr = path.LastPoint.Y;
// Add arch for views except first one
if (iStrokeDashCount > 0)
{
float d = iStrokeDashCount % 2 == 0 ? -1 : 1;
float arcHeight = (float)viewBounds.Y + (float)viewBounds.Height - path.LastPoint.Y + (float)strokeWidth / 2;
path.ArcTo(new SKRect(xCurr - arcHeight / 2, yCurr, xCurr + arcHeight / 2, yCurr + arcHeight), -90, 180 * d, false);
}
float dashOffset = new SKPathMeasure(path).Length;
// Add line below the view
// If it's not the first view, the start point is the end from arc end point
// and line direction is either to view start or view end
path.LineTo((float)viewBounds.X + (float)viewBounds.Width * (iStrokeDashCount % 2 == 0 ? 1 : 0), path.LastPoint.Y);
if (view is Button)
{
xCurr = path.LastPoint.X;
yCurr = path.LastPoint.Y;
// Draw arc from below button to above button
float d = iStrokeDashCount % 2 == 0 ? -1 : 1;
float arcHeight = (float)viewBounds.Height + (float)strokeWidth;
path.ArcTo(new SKRect(xCurr - arcHeight / 2, yCurr - arcHeight, xCurr + arcHeight / 2, yCurr), 90, 180 * d, false);
// Draw horizontal line above the button
path.LineTo(xCurr + (float)viewBounds.Width * d, path.LastPoint.Y);
// Draw arc pointing down
xCurr = path.LastPoint.X;
yCurr = path.LastPoint.Y;
path.ArcTo(new SKRect(xCurr - arcHeight / 2, yCurr, xCurr + arcHeight / 2, yCurr + arcHeight), -90, 180 * d, false);
}
float solidDashLength = new SKPathMeasure(path).Length - dashOffset;
var strokeDash = new StrokeDash(
intervals: new float[] { solidDashLength, 0 },
phase: -dashOffset);
highlightPath.SetDashForView(layoutChildren, view, strokeDash);
}
// Compute the 2nd value of interval, which is the length of remaining path
float pathLength = new SKPathMeasure(path).Length;
for (int i = 0; i < highlightPath.DashCount; ++i)
{
StrokeDash d = highlightPath.GetDash(i);
d.Intervals[1] = pathLength - d.Intervals[0];
}
return(highlightPath);
}
static SKPaint CreateHighlightSkPaint(SKCanvasView skCanvasView, HighlightSettings highlightSettings, HighlightPath highlightPath)
{
var skPaint = new SKPaint
{
Style = SKPaintStyle.Stroke,
Color = SKColors.Red,
StrokeWidth = (float)skCanvasView.FromPixels(new Point(0, highlightSettings.StrokeWidth)).Y
};
float firstDashIntervalOn = highlightPath.FirstDash.Intervals[0];
skPaint.Shader = SKShader.CreateLinearGradient(
start: new SKPoint(firstDashIntervalOn * 0.30f, 0),
end: new SKPoint(firstDashIntervalOn, 0),
colors: new SKColor[] {
highlightSettings.StrokeStartColor.ToSKColor(),
highlightSettings.StrokeEndColor.ToSKColor()
},
colorPos: new float[] { 0, 1 },
mode: SKShaderTileMode.Clamp);
return(skPaint);
}
