Minimal Template - scale line problem

MaciejGolebiewski — Sat, 11 Dec 2021 19:16:07 GMT

Hi all!
I'm using OpenStreetMap in my app based on Minimal Template the problem is it's not viewing the scale line (and the zoom stack, but that's less important): http://samantha.mazury.pl/Map2/ as you can see a scale line added into MainPage.xaml work perfect, but the one in the right globe-wing just doesn't (as you probably know it should look like this: http://help.arcgis.com/en/webapi/silverlight/samples/TemplateGalleryWeb/Samples/Customized_Templates/Minimal/Web/Default.htm)
I think code used by scale line is inside Navigator.cs and in my opinion it's that part:

#region ScaleBar Helper Functions

        private void refreshScalebar()
        {
            Visibility viz = Visibility.Collapsed;
            bool canDisplay = true;
            if (ScaleBar != null)
            {
                viz = ScaleBar.Visibility;
                if (Map == null || double.IsNaN(Map.Resolution) ||
                    MapUnit == ScaleBarUnit.DecimalDegrees && Math.Abs(Map.Extent.GetCenter().Y) >= 90)
                {
                    viz = Visibility.Collapsed;
                    canDisplay = false;
                }
                if (ScaleBar != null) ScaleBar.Visibility = viz;
            }
            if (!canDisplay) return;

            ScaleBarUnit outUnit = ScaleBarUnit.Undefined;
            double outResolution;

            #region KiloMeters/Meters
            double roundedKiloMeters = getBestEstimateOfValue(Map.Resolution, ScaleBarUnit.Kilometers, out outUnit, out outResolution);
            double widthMeters = roundedKiloMeters / outResolution;
            bool inMeters = outUnit == ScaleBarUnit.Meters;

            if (PaddingLeftForScaleBarTextMeters != null)
                PaddingLeftForScaleBarTextMeters.Width = widthMeters;
            if (PaddingLeftTopNotch != null)
                PaddingLeftTopNotch.Width = widthMeters;
            if (ScaleBarTextForMeters != null)
            {
                ScaleBarTextForMeters.Text = string.Format("{0}{1}", roundedKiloMeters, (inMeters ? "m" : "km"));
                ScaleBarTextForMeters.Width = widthMeters;
            }
            #endregion

            #region Miles
            double roundedMiles = getBestEstimateOfValue(Map.Resolution, ScaleBarUnit.Miles, out outUnit, out outResolution);
            double widthMiles = roundedMiles / outResolution;
            bool inFeet = outUnit == ScaleBarUnit.Feet;

            if (PaddingLeftForScaleBarTextMiles != null)
                PaddingLeftForScaleBarTextMiles.Width = widthMiles;
            if (PaddingLeftBottomNotch != null)
                PaddingLeftBottomNotch.Width = widthMiles;
            if (ScaleBarTextForMiles != null)
            {
                ScaleBarTextForMiles.Text = string.Format("{0}{1}", roundedMiles, inFeet ? "ft" : "mi");
                ScaleBarTextForMiles.Width = widthMiles;
            }
            #endregion

            double widthOfNotches = 4; // 2 for left notch, 2 for right notch
            double scaleBarBlockWidth = (widthMiles > widthMeters) ? widthMiles : widthMeters;
            scaleBarBlockWidth += widthOfNotches;

            if (!double.IsNaN(scaleBarBlockWidth) && ScaleBarBlock != null)
                ScaleBarBlock.Width = scaleBarBlockWidth;

        }

        private double getBestEstimateOfValue(double resolution, ScaleBarUnit displayUnit, out ScaleBarUnit unit, out double outResolution)
        {
            unit = displayUnit;
            double rounded = 0;
            double originalRes = resolution;
            while (rounded < 0.5)
            {
                resolution = originalRes;
                if (MapUnit == ScaleBarUnit.DecimalDegrees)
                {
                    resolution = getResolutionForGeographic(Map.Extent, resolution);
                    resolution = resolution * (int)ScaleBarUnit.Meters / (int)unit;
                }
                else if (MapUnit != ScaleBarUnit.Undefined)
                {
                    resolution = resolution * (int)MapUnit / (int)unit;
                }

                double val = TargetWidth * resolution;
                val = roundToSignificant(val, resolution);
                double noFrac = Math.Round(val); // to get rid of the fraction
                if (val < 0.5)
                {
                    ScaleBarUnit newUnit = ScaleBarUnit.Undefined;
                    // Automatically switch unit to a lower one
                    if (unit == ScaleBarUnit.Kilometers)
                        newUnit = ScaleBarUnit.Meters;
                    else if (unit == ScaleBarUnit.Miles)
                        newUnit = ScaleBarUnit.Feet;
                    if (newUnit == ScaleBarUnit.Undefined) { break; } //no lower unit
                    unit = newUnit;
                }
                else if (noFrac > 1)
                {
                    rounded = noFrac;
                    var len = noFrac.ToString().Length;
                    if (len <= 2)
                    {
                        // single/double digits ... make it a multiple of 5 ..or 1,2,3,4
                        if (noFrac > 5)
                        {
                            rounded -= noFrac % 5;
                        }
                        while (rounded > 1 && (rounded / resolution) > TargetWidth)
                        {
                            // exceeded maxWidth .. decrement by 1 or by 5
                            double decr = noFrac > 5 ? 5 : 1;
                            rounded = rounded - decr;
                        }
                    }
                    else if (len > 2)
                    {
                        rounded = Math.Round(noFrac / Math.Pow(10, len - 1)) * Math.Pow(10, len - 1);
                        if ((rounded / resolution) > TargetWidth)
                        {
                            // exceeded maxWidth .. use the lower bound instead
                            rounded = Math.Floor(noFrac / Math.Pow(10, len - 1)) * Math.Pow(10, len - 1);
                        }
                    }
                }
                else
                { // anything between 0.5 and 1
                    rounded = Math.Floor(val);
                    if (rounded == 0)
                    {
                        //val >= 0.5 but < 1 so round up
                        rounded = (val == 0.5) ? 0.5 : 1;
                        if ((rounded / resolution) > TargetWidth)
                        {
                            // exceeded maxWidth .. re-try by switching to lower unit 
                            rounded = 0;
                            ScaleBarUnit newUnit = ScaleBarUnit.Undefined;
                            // Automatically switch unit to a lower one
                            if (unit == ScaleBarUnit.Kilometers)
                                newUnit = ScaleBarUnit.Meters;
                            else if (unit == ScaleBarUnit.Miles)
                                newUnit = ScaleBarUnit.Feet;
                            if (newUnit == ScaleBarUnit.Undefined) { break; } //no lower unit
                            unit = newUnit;
                        }
                    }
                }
            }
            outResolution = resolution;
            return rounded;
        }

        double roundToSignificant(double value, double resolution)
        {
            var round = Math.Floor(-Math.Log(resolution));
            if (round > 0)
            {
                round = Math.Pow(10, round);
                return Math.Round(value * round) / round;
            }
            else { return Math.Round(value); }
        }


        /// <summary>
        /// Calculates horizontal scale at center of extent
        /// for geographic / Plate Carrée projection.
        /// Horizontal scale is 0 at the poles.
        /// </summary>
        double toRadians = 0.017453292519943295769236907684886;
        double earthRadius = 6378137; //Earth radius in meters (defaults to WGS84 / GRS80)
        double degreeDist;
        private double getResolutionForGeographic(ESRI.ArcGIS.Client.Geometry.Envelope extent, double resolution)
        {
            degreeDist = earthRadius * toRadians;
            MapPoint center = extent.GetCenter();
            double y = center.Y;
            if (Math.Abs(y) > 90) { return 0; }
            return Math.Cos(y * toRadians) * resolution * degreeDist;
        }
        #endregion

I think there is a problem with a map units (OSM is in meters), but I'm really new to .NET and C#, I tried to figure it out by myself but no success.
Please help me... 🙂

Re: Minimal Template - scale line problem

DominiqueBroux — Thu, 19 Apr 2012 09:03:53 GMT

Try by setting the MapUnit of the Navigator control:

<localtoolkit:Navigator x:Name="nav" Map="{Binding ElementName=Map}" MapUnit="Meters" HorizontalAlignment="Left" VerticalAlignment="Top" Loaded="nav_Loaded" />

Re: Minimal Template - scale line problem

MaciejGolebiewski — Thu, 19 Apr 2012 14:05:22 GMT

OK - it works, but there is a problem still - the values seems to be multiplied by ~2, see the link: http://samantha.mazury.pl/Map2/
So there still is something to sort out in an algorithm calculating rounded values...
I don't have time right now to play with it, so if you have some ideas please post them! 🙂

Re: Minimal Template - scale line problem

DominiqueBroux — Fri, 20 Apr 2012 05:44:38 GMT

OK - it works, but there is a problem still - the values seems to be multiplied by ~2

The scale bar inside the custom navigator is not taking care of the Web Mercator distorsion.

I would recommend to replace it by the toolkit ScaleLine control, which is taking care of that.

I did it in the KML Viewer sample. No difficulty but you might perhaps same a little time by looking at that sample.

Re: Minimal Template - scale line problem

MaciejGolebiewski — Wed, 16 May 2012 19:03:41 GMT

I've been fighting with it for long time but no luck, I think the client can't recognize the OSM resolution properly.
I divided the calculated value by 1.7 and it kinda works - the error doesn't exceed the scale line wraps actually, so I will leave it as it is now...

Thanks for all the replies anyway! 🙂

Cheers!

Re: Minimal Template - scale line problem

dotMorten_esri — Thu, 17 May 2012 13:38:39 GMT

Just note that the scaleline shows the scale at the center of the screen. In a webmercator projection there can be a LOT of difference in the scale between Equator and near the poles. You should see the scaleline change values as you pan away from Equator.

Re: Minimal Template - scale line problem

MaciejGolebiewski — Thu, 24 May 2012 09:37:21 GMT

I added some feature layers to my client with defined coordinates (Web Mercator Auxiliary Sphere) and since then both scaleline and zoomstack works perfect!
I was such a moron that I didn't do that at first...:rolleyes:
So if you encounter problems with scaleline and zoomstack in Minimal Template with OSM basemap - add some layer (even an empty one) with defined coordinate system! 😉

One again thanks for the replies 🙂

Cheers

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