/// <inheritdoc cref="MapDecoration.OnRender(Graphics, MapViewport)"/>
protected override void OnRender(Graphics g, MapViewport mvp)
{
var image = NorthArrowImage ?? DefaultNorthArrowBitmap;
var mapSize = mvp.Size;
//Get rotation
var ptTop = mvp.ImageToWorld(new PointF(mapSize.Width / 2f, 0f), true);
var ptBottom = mvp.ImageToWorld(new PointF(mapSize.Width / 2f, mapSize.Height * 0.5f), true);
var dx = ptTop.X - ptBottom.X;
var dy = ptBottom.Y - ptTop.Y;
var length = Math.Sqrt(dx * dx + dy * dy);
var cos = dx / length;
var rot = -90 + (dy > 0 ? -1 : 1) * Math.Acos(cos) / GeoSpatialMath.DegToRad;
var halfSize = new Size((int)(0.5f * Size.Width), (int)(0.5f * Size.Height));
//var oldTransform = g.Transform;
var clip = g.ClipBounds;
var newTransform = new Matrix(1f, 0f, 0f, 1f,
clip.Left + halfSize.Width,
clip.Top + halfSize.Height);
newTransform.Rotate((float)rot);
// Setup image attributes
var ia = new ImageAttributes();
var cmap = new [] {
new ColorMap {
OldColor = Color.Transparent, NewColor = OpacityColor(BackgroundColor)
},
new ColorMap {
OldColor = Color.Black, NewColor = OpacityColor(ForeColor)
}
};
ia.SetRemapTable(cmap);
g.Transform = newTransform;
var rect = new Rectangle(-halfSize.Width, -halfSize.Height, Size.Width, Size.Height);
g.DrawImage(image, rect, 0, 0, image.Size.Width, image.Size.Height, GraphicsUnit.Pixel, ia);
//g.Transform = oldTransform;
}