Deprecate MarkerView / Introduce IconGenerator

[tobrun]

MarkerView

The concept of MarkerView relies on synchronising Android SDK views on top of the GL surface. At time of implementing, we were using TextureView as rendering surface but since a couple of releases, we migrated to SurfaceView for improved GL rendering performance. This introduced degraded view synchronisation for our MarkerView implementation (a.k.a MarkerView jiggling).

Besides degraded performance, MarkerViews rely on estimating the map transformation matrix, this estimation will not match the actual transformation 100%.

IconGenerator

Instead of synchronising Android SDK views on top of the GL Surface. We should look into rendering views to bitmaps instead and fallback on the base Marker Icon implementation (SymbolAnnotation in core). Code for generating a Bitmap look like this:

    public Bitmap makeIcon() {
        int measureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
        mContainer.measure(measureSpec, measureSpec);

        int measuredWidth = mContainer.getMeasuredWidth();
        int measuredHeight = mContainer.getMeasuredHeight();

        mContainer.layout(0, 0, measuredWidth, measuredHeight);

        if (mRotation == 1 || mRotation == 3) {
            measuredHeight = mContainer.getMeasuredWidth();
            measuredWidth = mContainer.getMeasuredHeight();
        }

        Bitmap r = Bitmap.createBitmap(measuredWidth, measuredHeight, Bitmap.Config.ARGB_8888);
        r.eraseColor(Color.TRANSPARENT);

        Canvas canvas = new Canvas(r);

        if (mRotation == 0) {
            // do nothing
        } else if (mRotation == 1) {
            canvas.translate(measuredWidth, 0);
            canvas.rotate(90);
        } else if (mRotation == 2) {
            canvas.rotate(180, measuredWidth / 2, measuredHeight / 2);
        } else {
            canvas.translate(0, measuredHeight);
            canvas.rotate(270);
        }
        mContainer.draw(canvas);
        return r;
    }

source

Before we would start with this migration, we will need to add some additional API to SymbolAnnotations to match the API exposed by MarkerView. Some examples of these are:

• alpha
• anchor
• TBD

cc @mapbox/android

[tobrun]

This landed in #9782