com.github.mkjensen.dml.util.LoadingHelper.java Source code

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Here is the source code for com.github.mkjensen.dml.util.LoadingHelper.java

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/*
 * Copyright 2016 Martin Kamp Jensen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.github.mkjensen.dml.util;

import android.content.Context;
import android.content.res.Resources;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.ProgressBar;

import com.github.mkjensen.dml.R;

/**
 * Helper class for showing a progress indicator when a fragment is waiting for an operation to
 * complete.
 */
public final class LoadingHelper {

    private static final String TAG = "LoadingHelper";

    private static final String LOADING_FRAGMENT_TAG = "LoadingFragment";

    private LoadingHelper() {
    }

    /**
     * Shows the progress indicator, if not already present, for the specified fragment.
     */
    public static void showLoading(@NonNull Fragment fragment) {
        FragmentManager fragmentManager = fragment.getActivity().getSupportFragmentManager();
        Fragment loadingFragment = getLoadingFragment(fragmentManager);
        if (loadingFragment != null) {
            Log.w(TAG, "Was asked to add progress indicator but it is already present, ignoring");
            return;
        }
        fragmentManager.beginTransaction().add(fragment.getId(), new LoadingFragment(), LOADING_FRAGMENT_TAG)
                .commit();
    }

    /**
     * Hides the progress indicator, if present, for the specified fragment.
     */
    public static void hideLoading(@NonNull Fragment fragment) {
        FragmentManager fragmentManager = fragment.getActivity().getSupportFragmentManager();
        Fragment loadingFragment = getLoadingFragment(fragmentManager);
        if (loadingFragment == null) {
            Log.w(TAG, "Was asked to remove nonexistent progress indicator, ignoring");
            return;
        }
        fragmentManager.beginTransaction().remove(loadingFragment).commitAllowingStateLoss(); // TODO: Is commitAllowingStateLoss okay, can it be avoided?
    }

    private static LoadingFragment getLoadingFragment(FragmentManager fragmentManager) {
        return (LoadingFragment) fragmentManager.findFragmentByTag(LOADING_FRAGMENT_TAG);
    }

    /**
     * A fragment containing a progress indicator for use when another fragment is waiting for an
     * operation to complete.
     */
    public static final class LoadingFragment extends Fragment {

        @Nullable
        @Override
        public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
                @Nullable Bundle savedInstanceState) {
            if (container == null) {
                return null;
            }
            Context context = container.getContext();
            ProgressBar progressBar = new ProgressBar(context);
            if (container instanceof FrameLayout) {
                Resources resources = context.getResources();
                int width = resources.getDimensionPixelSize(R.dimen.util_loading_width);
                int height = resources.getDimensionPixelSize(R.dimen.util_loading_height);
                FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(width, height, Gravity.CENTER);
                progressBar.setLayoutParams(layoutParams);
            }
            return progressBar;
        }
    }
}