How to pass a Drawable to a QML element?

[a.burks]

The requirement is to show Android app icons for a launcher. I tried the following JNI approach: First I transfer the Drawable to a Bitmap and from a Bitmapto a base64 encoded string:

public static String drawableToBase64 (Drawable drawable) {
    Bitmap bitmap = null;

    if (drawable instanceof BitmapDrawable) {
        BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
        if(bitmapDrawable.getBitmap() != null) {
            bitmap = bitmapDrawable.getBitmap();
        }
    }

    if (bitmap == null) {
        if (drawable.getIntrinsicWidth() <= 0 || drawable.getIntrinsicHeight() <= 0) {
            bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888); // Single color bitmap will be created of 1x1 pixel
        } else {
            bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        }

        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        drawable.draw(canvas);
    }

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
    byte[] imageBytes = baos.toByteArray();

    return Base64.encodeToString(imageBytes, Base64.DEFAULT);
}

In my QML file, I use the following paramter for the icon of a Button

Button {
    icon.source: "data:image/png;base64," + base64string
    icon.width: parent.width * 0.35
    icon.height: parent.width * 0.35
    display: AbstractButton.TextUnderIcon
    ...
}

Some icons are working. For the most icons, I just can see a white square. I'm afraid converting images is a complex topic. Has someone a solution?

Maybe I can write the Drawable into a temp directory and read them with a URL in the QML code.

[a.burks]

I have the solution. I was only a single line. Everything was correct. I just had to add the following line to for the button:

icon.color: "transparent"

Crazy.