/// <summary>
/// Updates position until stopDragging completes.
/// </summary>
public static async Task <IBehavior> DragRelative(this IBehavior self,
V2d initialPosition, IEvent <V2d> moves, IAwaitable stopDragging, CancellationToken ct
)
{
var obj = self as IBehaviorTransform2d;
if (obj == null)
{
throw new InvalidOperationException("DragRelative requires IBehaviorTransform2d.");
}
var lastPos = initialPosition;
await stopDragging.RepeatUntilCompleted(
async delegate
{
var p = await moves.Next.WithCancellation(ct);
obj.Transform(M33d.Translation(p - lastPos));
lastPos = p;
});
return(self);
}
/// <summary>
/// Returns a Matrix to
/// convert from pixel-center position to normalized image position [0,1][0,1].
/// (The inverse of toPixelCenter.)
/// </summary>
public static M33d PixelCenterToNormalizedImgMat(V2d imgSizeInPixel)
{
return(M33d.Scale(V2d.II / imgSizeInPixel) * M33d.Translation(V2dHalf));
}
/// <summary>
/// Returns a Matrix to
/// convert from normalized image position [0,1][0,1] to pixel-center position
/// (The inverse of toNormalizedImgPos.)
/// </summary>
public static M33d NormalizedImagePosToPixelCenterMat(V2d imgSizeInPixel)
{
return(M33d.Translation(-V2dHalf) * M33d.Scale(imgSizeInPixel));
}
public static Trafo2d Translation(double dx, double dy)
{
return(new Trafo2d(M33d.Translation(dx, dy),
M33d.Translation(-dx, -dy)));
}
public static Trafo2d Translation(V2d v)
{
return(new Trafo2d(M33d.Translation(v),
M33d.Translation(-v)));
}