private SKImage GenerateGauge(HttpRequestHeader Header)
{
if (!Header.TryGetQueryParameter("Width", out string s) || !int.TryParse(s, out int Width))
{
Width = 480;
}
else if (Width <= 0)
{
throw new BadRequestException();
}
if (!Header.TryGetQueryParameter("Height", out s) || !int.TryParse(s, out int Height))
{
Height = 300;
}
else if (Width <= 0)
{
throw new BadRequestException();
}
using (SKSurface Surface = SKSurface.Create(Width, Height, SKImageInfo.PlatformColorType, SKAlphaType.Premul))
{
SKCanvas Canvas = Surface.Canvas;
Canvas.Clear(SKColors.White);
float NeedleX0 = Width * 0.5f;
float NeedleY0 = Height * 0.9f;
float OuterRadius = (float)Math.Min(Height * 0.8, Width * 0.4);
float LabelRadius = OuterRadius * 1.01f;
float InnerRadius = OuterRadius * 0.6f;
float NeedleRadius = OuterRadius * 0.95f;
float NutRadius = OuterRadius * 0.05f;
SKRect Rect;
SKPath Path = new SKPath();
SKShader Gradient = SKShader.CreateSweepGradient(new SKPoint(NeedleX0, NeedleY0),
new SKColor[] { (lastMotion.HasValue && lastMotion.Value ? SKColors.Green : SKColors.Black), SKColors.White },
new float[] { 0, 1 });
SKPaint GaugeBackground = new SKPaint()
{
IsAntialias = true,
Style = SKPaintStyle.Fill,
Shader = Gradient
};
SKPaint GaugeOutline = new SKPaint()
{
IsAntialias = true,
Style = SKPaintStyle.Stroke,
Color = SKColors.Black
};
Rect = new SKRect(NeedleX0 - OuterRadius, NeedleY0 - OuterRadius, NeedleX0 + OuterRadius, NeedleY0 + OuterRadius);
Path.ArcTo(Rect, -180, 180, true);
Rect = new SKRect(NeedleX0 - InnerRadius, NeedleY0 - InnerRadius, NeedleX0 + InnerRadius, NeedleY0 + InnerRadius);
Path.ArcTo(Rect, 0, -180, false);
Path.Close();
Canvas.DrawPath(Path, GaugeBackground);
Canvas.DrawPath(Path, GaugeOutline);
GaugeBackground.Dispose();
GaugeOutline.Dispose();
Gradient.Dispose();
Path.Dispose();
SKPaint Font = new SKPaint()
{
IsAntialias = true,
Color = SKColors.Black,
HintingLevel = SKPaintHinting.Full,
TextSize = Height * 0.05f
};
SKPaint Needle = new SKPaint()
{
IsAntialias = true,
Color = SKColors.Black,
Style = SKPaintStyle.Fill
};
Font.GetFontMetrics(out SKFontMetrics FontMetrics);
float TextHeight = FontMetrics.Descent - FontMetrics.Ascent;
float TextWidth;
for (int i = 0; i <= 100; i += 10)
{
s = i.ToString() + "%";
TextWidth = Font.MeasureText(s);
float LabelDeg = -90 + i * 1.8f;
float LabelRad = (float)(LabelDeg * Math.PI / 180);
float LabelX = (float)(LabelRadius * Math.Sin(LabelRad) + NeedleX0);
float LabelY = (float)(NeedleY0 - LabelRadius * Math.Cos(LabelRad));
float OuterX = (float)(OuterRadius * Math.Sin(LabelRad) + NeedleX0);
float OuterY = (float)(NeedleY0 - OuterRadius * Math.Cos(LabelRad));
float NeedleX1 = (float)(NeedleRadius * Math.Sin(LabelRad) + NeedleX0);
float NeedleY1 = (float)(NeedleY0 - NeedleRadius * Math.Cos(LabelRad));
Canvas.DrawLine(OuterX, OuterY, NeedleX1, NeedleY1, Needle);
Canvas.Translate(LabelX, LabelY);
Canvas.RotateDegrees(LabelDeg);
Canvas.Translate(-TextWidth * 0.5f, -TextHeight * 0.5f);
Canvas.DrawText(s, 0, 0, Font);
Canvas.ResetMatrix();
}
if (this.lastLight.HasValue)
{
float AngleDeg = (float)(this.lastLight.Value - 50) * 90.0f / 50;
double AngleRad = AngleDeg * Math.PI / 180;
float NeedleX1 = (float)(NeedleRadius * Math.Sin(AngleRad) + NeedleX0);
float NeedleY1 = (float)(NeedleY0 - NeedleRadius * Math.Cos(AngleRad));
Path = new SKPath();
Rect = new SKRect(NeedleX0 - NutRadius, NeedleY0 - NutRadius, NeedleX0 + NutRadius, NeedleY0 + NutRadius);
Path.ArcTo(Rect, AngleDeg - 180, -180, true);
Path.LineTo(NeedleX1, NeedleY1);
Path.Close();
Canvas.DrawPath(Path, Needle);
Path.Dispose();
Needle.Dispose();
}
return(Surface.Snapshot());
}
}
