This post will build upon the excellent tutorial on customizing map pins in .NET MAUI by Vladislav Antonyuk, and focus on adding these specific adjustments for Android.
- Z-order: This determines the drawing order of the pins. Pins with higher Z-order values appear on top of those with lower values.
- Rotation: Controls the rotation angle of the pin in degrees.
- Anchor: Defines the point on the pin image that corresponds to the pin’s location on the map. The anchor is defined in terms of a normalized coordinate system where
(0, 0)is the top-left corner and(1, 1)is the bottom-right corner of the image.
Define the Anchor Points enum, get a method to return anchor floats
We start by defining an enum to represent the different anchor points. A helper method, GetAnchorPoint, will return the appropriate anchor coordinates based on the chosen enum value.
public enum AnchorPointType
{
TopLeft,
TopCenter,
TopRight,
Center,
BottomLeft,
BottomCenter,
BottomRight,
LeftCenter,
RightCenter
}
This method returns the normalized coordinates for each anchor point, which can then be applied to the pin’s icon.
private static (float, float) GetAnchorPoint(AnchorPointType anchor)
{
return anchor switch
{
AnchorPointType.TopLeft => (0.0f, 0.0f),
AnchorPointType.TopCenter => (0.5f, 0.0f),
AnchorPointType.TopRight => (1.0f, 0.0f),
AnchorPointType.Center => (0.5f, 0.5f),
AnchorPointType.BottomLeft => (0.0f, 1.0f),
AnchorPointType.BottomCenter => (0.5f, 1.0f),
AnchorPointType.BottomRight => (1.0f, 1.0f),
AnchorPointType.LeftCenter => (0.0f, 0.5f),
AnchorPointType.RightCenter => (1.0f, 0.5f),
_ => (0.5f, 0.5f) // Default to center if undefined
};
}
Modifications to the Custom Map Handler
Now, let’s focus on the custom map handler, where you’ll need to modify how each pin is added to the map. Following the setup from Vladislav’s tutorial, you only need to adjust the following parts in the OnMapReady method for Android:
cp.ImageSource.LoadImage(MauiContext, result =>
{
if (result?.Value is BitmapDrawable bitmapDrawable)
{
var originalBitmap = bitmapDrawable.Bitmap;
// Set the custom icon for the pin
markerOption.SetIcon(BitmapDescriptorFactory.FromBitmap(originalBitmap));
// Set the rotation of the pin
markerOption.SetRotation((float)cp.Rotation);
// Set the anchor of the pin based on the chosen AnchorPointType
var anchor = GetAnchorPoint(cp.Anchor);
markerOption.Anchor(anchor.Item1, anchor.Item2);
// Set the Z-order to bring this pin to the top
markerOption.InvokeZIndex(cp.ZOrder);
}
AddMarker(Map, pin, Markers, markerOption);
});