Rotate an ImageView

Question

I am designing (trying to learn) a simple widget for Android. I have:

public class NewAppWidget extends AppWidgetProvider {

Inside that class, I have the simple code:

public double angle(Calendar calendarDate) {
        //Earth rotation;
        int day = calendarDate.get(Calendar.DAY_OF_YEAR);
        int angle;
        angle = (day / 365) * 360;
        return angle;
    }

I then want to select an image and rotate it by that angle in ImageView, which totally does not work ...

static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
                            int appWidgetId) {



 // Construct the RemoteViews object

 ImageView image = (ImageView) findViewById(R.layout.new_app_widget);

    image.setImageResource(R.drawable.moon10);
    image.setRotation(angle);

    // Instruct the widget manager to update the widget
    appWidgetManager.updateAppWidget(appWidgetId, new_app_widget);

}

There are probably several mistakes in there - I am a beginner.

The three errors highlighted by Android studio are:

1. findViewById in red (cannot resolve method)
2. angle in red (cannot resolve symbol angle)
3. new_app_widget in last line in red (cannot resolve symbol)

Thanks for your help and have a good day.

JY

Answer 1

1. as the method is static, you will need to create view to findviewbyid(); or make void non-static
2. angle in rotation must be int, not double

Answer 2

For getting Orientation, use below function. Just pass context and Uri of Image Path

public static int getGalleryOrientation(Context context, Uri path) {
    /* it's on the external media. */
    Cursor cursor = context.getContentResolver().query(path,
            new String[]{MediaStore.Images.ImageColumns.ORIENTATION},
            null, null, null);

    if (cursor.getCount() != 1) {
        return -1;
    }

    cursor.moveToFirst();
    return cursor.getInt(0);

}

Answer 3

TL;DR

It is not possible to use the method View.setRotation(float) with any View which is part of a home screen widget, at least that's what my IDE tells me:

W/AppWidgetHostView﹕ updateAppWidget couldn't find any view, using error view android.widget.RemoteViews$ActionException: view: android.widget.ImageView can't use method with RemoteViews: setRotation(float)

That being said, let's at least get your app widget up and running :)

You need a layout file with an ImageView, let's call it new_app_widget.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:padding="@dimen/widget_margin"
            android:background="#09C">
    <ImageView
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:background="#ffffff"
        android:id="@+id/imageView"
        android:layout_gravity="center"
       />

</FrameLayout>

Change your code like this:

static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
                        int appWidgetId) {

    // Construct the RemoteViews object 
    RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.new_app_widget);

    // use the RemoteViews methods to access the children of the FrameLayout:
    views.setImageViewResource(R.id.imageView, R.drawable.moon10);


    // Instruct the widget manager to update the widget
    appWidgetManager.updateAppWidget(appWidgetId, views);

}

If you need some rotation, you will have to perform it on the Drawable and then with the rotated Drawable call setImageViewResource() like above. See also Rotating a drawable in Android

Finally, about:

angle in red (cannot resolve symbol angle)

You have defined a method angle(Calendar). If you want to use it, you need to call it with some Calendar input.