ClemensFischer/XAML-Map-Control
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Avoid unnecessary Location and Point allocations

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ClemensFischer 2025-12-12 21:28:45 +01:00
parent f44d2207e5
commit e268be2948
20 changed files with 205 additions and 172 deletions
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47
MapControl/Shared/MapGraticule.cs
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@ -80,7 +80,7 @@ namespace MapControl
private void SetLineDistance()
{
var minDistance = MinLineDistance / PixelPerLongitudeDegree(ParentMap.Center);
var minDistance = MinLineDistance / PixelPerLongitudeDegree(ParentMap.Center.Latitude, ParentMap.Center.Longitude);
var scale = minDistance < 1d / 60d ? 3600d : minDistance < 1d ? 60d : 1d;
minDistance *= scale;
@ -98,11 +98,12 @@ namespace MapControl
: lineDistance < 1d ? "{0} {1}°{2:00}'" : "{0} {1}°";
}
private double PixelPerLongitudeDegree(Location location)
private double PixelPerLongitudeDegree(double latitude, double longitude)
{
var scale = ParentMap.GetScale(latitude, longitude);
return Math.Max(1d, // a reasonable lower limit
ParentMap.GetScale(location).X *
Math.Cos(location.Latitude * Math.PI / 180d) * MapProjection.Wgs84MeterPerDegree);
scale.X * Math.Cos(latitude * Math.PI / 180d) * MapProjection.Wgs84MeterPerDegree);
}
private string GetLabelText(double value, string hemispheres)
@ -121,7 +122,7 @@ namespace MapControl
labelFormat, hemisphere, seconds / 3600, seconds / 60 % 60, seconds % 60);
}
private void AddLabel(List<Label> labels, Location location, Point position, double? rotation = null)
private void AddLabel(List<Label> labels, double latitude, double longitude, Point position, double? rotation = null)
{
if (position.X >= 0d && position.X <= ParentMap.ActualWidth &&
position.Y >= 0d && position.Y <= ParentMap.ActualHeight)
@ -130,8 +131,7 @@ namespace MapControl
{
// Get rotation from second location with same latitude.
//
var pos = ParentMap.LocationToView(
new Location(location.Latitude, location.Longitude + 10d / PixelPerLongitudeDegree(location)));
var pos = ParentMap.LocationToView(latitude, longitude + 10d / PixelPerLongitudeDegree(latitude, longitude));
if (pos.HasValue)
{
@ -142,8 +142,8 @@ namespace MapControl
if (rotation.HasValue)
{
labels.Add(new Label(
GetLabelText(location.Latitude, "NS"),
GetLabelText(Location.NormalizeLongitude(location.Longitude), "EW"),
GetLabelText(latitude, "NS"),
GetLabelText(Location.NormalizeLongitude(longitude), "EW"),
position.X, position.Y, rotation.Value));
}
}
@ -177,8 +177,8 @@ namespace MapControl
for (var lat = latLabelStart; lat <= boundingBox.North; lat += lineDistance)
{
var p1 = ParentMap.LocationToView(new Location(lat, boundingBox.West));
var p2 = ParentMap.LocationToView(new Location(lat, boundingBox.East));
var p1 = ParentMap.LocationToView(lat, boundingBox.West);
var p2 = ParentMap.LocationToView(lat, boundingBox.East);
if (p1.HasValue && p2.HasValue)
{
@ -188,8 +188,8 @@ namespace MapControl
for (var lon = lonLabelStart; lon <= boundingBox.East; lon += lineDistance)
{
var p1 = ParentMap.LocationToView(new Location(boundingBox.South, lon));
var p2 = ParentMap.LocationToView(new Location(boundingBox.North, lon));
var p1 = ParentMap.LocationToView(boundingBox.South, lon);
var p2 = ParentMap.LocationToView(boundingBox.North, lon);
if (p1.HasValue && p2.HasValue)
{
@ -198,12 +198,11 @@ namespace MapControl
for (var lat = latLabelStart; lat <= boundingBox.North; lat += lineDistance)
{
var location = new Location(lat, lon);
var position = ParentMap.LocationToView(location);
var position = ParentMap.LocationToView(lat, lon);
if (position.HasValue)
{
AddLabel(labels, location, position.Value, ParentMap.ViewTransform.Rotation);
AddLabel(labels, lat, lon, position.Value, ParentMap.ViewTransform.Rotation);
}
}
}
@ -257,14 +256,13 @@ namespace MapControl
{
var lat = minLat + i * lineDistance;
var lon = minLon;
var location = new Location(lat, lon);
var points = new List<Point>();
var position = ParentMap.LocationToView(location);
var position = ParentMap.LocationToView(lat, lon);
if (position.HasValue)
{
points.Add(position.Value);
AddLabel(labels, location, position.Value);
AddLabel(labels, lat, lon, position.Value);
}
for (int j = 0; j < lonSegments; j++)
@ -272,8 +270,7 @@ namespace MapControl
for (int k = 1; k <= interpolationCount; k++)
{
lon = minLon + j * lineDistance + k * interpolationDistance;
location = new Location(lat, lon);
position = ParentMap.LocationToView(location);
position = ParentMap.LocationToView(lat, lon);
if (position.HasValue)
{
@ -283,7 +280,7 @@ namespace MapControl
if (position.HasValue)
{
AddLabel(labels, location, position.Value);
AddLabel(labels, lat, lon, position.Value);
}
}
@ -302,7 +299,7 @@ namespace MapControl
for (int i = 0; i <= numPoints; i++)
{
var p = ParentMap.LocationToView(new Location(startLatitude + i * deltaLatitude, longitude));
var p = ParentMap.LocationToView(startLatitude + i * deltaLatitude, longitude);
if (p.HasValue)
{
@ -326,8 +323,8 @@ namespace MapControl
{
var width = ParentMap.ActualWidth;
var height = ParentMap.ActualHeight;
var northPole = ParentMap.LocationToView(new Location(90d, 0d));
var southPole = ParentMap.LocationToView(new Location(-90d, 0d));
var northPole = ParentMap.LocationToView(90d, 0d);
var southPole = ParentMap.LocationToView(-90d, 0d);
if (northPole.HasValue &&
northPole.Value.X >= 0d && northPole.Value.X <= width &&