Converting a Drawable to a Bitmap to change the color of a Marker in Google Maps Android API v2

问题

I'm converting an old application from v1 to v2, and I'm having a problem with the color of my Marker icons. I have a basic, white icon, and It needs to be colorized.

In v1, I did it this way :

Drawable d = DrawableUtils.resizeImageToDrawable(
    MapViewFragment.mapviewActivity,
    Configuration.Display.getDrawableFix(i),
    Configuration.MapView.getWaypointIconWidth(),
    Configuration.MapView.getWaypointIconHeight());
d.setColorFilter(color, Mode.MULTIPLY);

overlay = new MyFplnFixListItimizedOverlay(d);

Since v2 Markers do not accept Drawables for their icons, I thought about converting the Drawable to a Bitmap, like this :

Drawable d = DrawableUtils.resizeImageToDrawable(
    MapViewFragment.mapviewActivity,
    Configuration.Display.getDrawableFix(i),
    Configuration.MapView.getWaypointIconWidth(),
    Configuration.MapView.getWaypointIconHeight());
d.setColorFilter(color, Mode.MULTIPLY);

Bitmap icon = ((BitmapDrawable) d).getBitmap();

Marker marker = MapViewFragment.map.addMarker(new MarkerOptions()
    .position(point)
    .title(Integer.toString(fplnType))
    .visible(true)
    .icon(BitmapDescriptorFactory.fromBitmap(icon)));

But for some reason, it's not working. The icons stay white. Anyone knows why ?

Thanks in advance.

回答1:

OK, here's how I did it at the end of the day :

Drawable d = DrawableUtils.resizeImageToDrawable(
                    MapViewFragment.mapViewActivity,
                    Configuration.Display.getDrawableFix(i),
                    Configuration.MapView.getWaypointIconWidth(),
                    Configuration.MapView.getWaypointIconHeight());
d.setColorFilter(color, Mode.MULTIPLY);

Bitmap b = ((BitmapDrawable) d).getBitmap();
Canvas myCanvas = new Canvas(b);

int myColor = b.getPixel(0,0);
ColorFilter filter = new LightingColorFilter(myColor, color);

Paint pnt = new Paint();
pnt.setColorFilter(filter);
myCanvas.drawBitmap(b,0,0,pnt);

Marker marker = MapViewFragment.map.addMarker(new MarkerOptions()
    .position(point)
    .title(Integer.toString(fplnType))
    .visible(true)
    .icon(BitmapDescriptorFactory.fromBitmap(b)));

回答2:

If your drawable is not defined in a XML, you can do it with this method:

protected Bitmap fromDrawable(final Drawable drawable, final int height, final int width) {
        final int widthDip = (int) TypedValue.applyDimension(1, width, getResources()
                .getDisplayMetrics());
            final int heightDip = (int) TypedValue.applyDimension(1, width, getResources().getDisplayMetrics());
        final Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        final Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        drawable.draw(canvas);
        return bitmap;
    }

Note that if you need to do it from OUTSIDE an Activity, you'll also need to pass a Context (in order to call context.getResources().getDisplayMetrics()). You also pass the DisplayMetrics object instead.

回答3:

I'm not sure what this DrawableUtils is doing, but you're casting it to a BitmapDrawable. Is it really a BitmapDrawable?

here's some code to extract a Bitmap out of any type of drawable:

Drawable d = // make sure it's not null
d.setBounds(0, 0, width, height);
Bitmap b = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(b);
d.draw(c);

the idea is that you create a canvas on a mutable bitmap and draw that drawable on the canvas

edit:

I've just seen the @Analizer answer and yeah, my answer is good if you don't have the Drawable as a resource. But if you do, user his answer instead.

来源：https://stackoverflow.com/questions/16037279/converting-a-drawable-to-a-bitmap-to-change-the-color-of-a-marker-in-google-maps