Google Maps API v2 Android add shape drawable as m

问题:

I've been trying to add a shape drawable as the marker icon for a marker I want to add on the map.

shape looks like this (res/drawable/blue_circle.xml):

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval" >
    <size
        android:width="15dp"
        android:height="15dp" />
    <solid
        android:color="@color/Blue" />
</shape>

and I try to add the marker like this:

markerOptions.icon(BitmapDescriptorFactory.fromResource(R.drawable.blue_circle));

Apparently I get a NullPointer exception.

Must the marker icon be a bitmap? Am I allowed to add shapes drawables as marker icons? And if yes what am I doing wrong?

回答1:

Create a drawable for your marker (res/drawable/map_dot_red.xml):

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval" >

    <gradient
        android:angle="90"
        android:endColor="#f58383"
        android:startColor="#ee6464" />

    <stroke
        android:width="1dp"
        android:color="#a13939" />

</shape>

Create a bitmap from the drawable:

int px = getResources().getDimensionPixelSize(R.dimen.map_dot_marker_size);
mDotMarkerBitmap = Bitmap.createBitmap(px, px, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(mDotMarkerBitmap);
Drawable shape = getResources().getDrawable(R.drawable.map_dot_red);
shape.setBounds(0, 0, mDotMarkerBitmap.getWidth(), mDotMarkerBitmap.getHeight());
shape.draw(canvas);

Create your marker, using the bitmap:

Marker marker = mMap.addMarker(new MarkerOptions()
    .position(point)
    .anchor(.5f, .5f)
    .icon(BitmapDescriptorFactory.fromBitmap(mDotMarkerBitmap)));

Set the size of your marker in dimens (res/values/dimens.xml):

<resources>
    <dimen name="map_dot_marker_size">12dp</dimen>
</resources>

回答2:

Here's an answer if you're using the com.google.maps.android:android-maps-utils library.

Create a Bitmap using IconGenerator

IconGenerator iconGen = new IconGenerator(context);

// Define the size you want from dimensions file
int shapeSize = getResources().getDimensionPixelSize(R.dimen.shape_size);

Drawable shapeDrawable = ResourcesCompat.getDrawable(getResources(), R.drawable.my_shape, null);
iconGen.setBackground(shapeDrawable);

// Create a view container to set the size
View view = new View(context);
view.setLayoutParams(new ViewGroup.LayoutParams(shapeSize, shapeSize));
iconGen.setContentView(view);

// Create the bitmap
Bitmap bitmap = iconGen.makeIcon();

Then use the bitmap like you would when setting the marker icon BitmapDescriptorFactory.fromBitmap(bitmap)

回答3:

My way to deal with shape (xml) drawables as marker icons (based on saxman answer).

I have a lot of objects (markers) to show on map. They have both kinds of drawables – bitmap and shape. The same icon my used for multiple markers. Thus, I have added some caching for bitmap descriptors and drawable type detection.

SparseArray<BitmapDescriptor> iconCache = new SparseArray<>();
for (MyObject object : objects) {
    int iconResId = object.icon;

    BitmapDescriptor icon = iconCache.get(iconResId);
    if (icon == null) {
        Drawable drawable;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            drawable = getResources().getDrawable(iconResId, null);
        } else {
            drawable = getResources().getDrawable(iconResId);
        }
        if (drawable instanceof GradientDrawable) {
            Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmap);
            drawable.setBounds(0, 0, bitmap.getWidth(), bitmap.getHeight());
            drawable.draw(canvas);
            icon = BitmapDescriptorFactory.fromBitmap(bitmap);
            bitmap.recycle();
        } else {
            icon = BitmapDescriptorFactory.fromResource(iconResId);
        }
        iconCache.put(iconResId, icon);

        map.addMarker(new MarkerOptions()
            .icon(icon)
            .position(position));
    }
}

My shape drawable have set size, thus, I can query drawable for desired size for bitmap.

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <size android:width="12dp" android:height="12dp" />
    <solid android:color="@color/transit_bus" />
</shape>