TermuxHelpActivity.java

package com.termux.app;

import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.ViewGroup;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;

/** Basic embedded browser for viewing help pages. */
public final class TermuxHelpActivity extends Activity {

    WebView mWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        final RelativeLayout progressLayout = new RelativeLayout(this);
        RelativeLayout.LayoutParams lParams = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        lParams.addRule(RelativeLayout.CENTER_IN_PARENT);
        ProgressBar progressBar = new ProgressBar(this);
        progressBar.setIndeterminate(true);
        progressBar.setLayoutParams(lParams);
        progressLayout.addView(progressBar);

        mWebView = new WebView(this);
        WebSettings settings = mWebView.getSettings();
        settings.setCacheMode(WebSettings.LOAD_NO_CACHE);
        settings.setAppCacheEnabled(false);
        setContentView(progressLayout);
        mWebView.clearCache(true);

        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                if (url.startsWith("https://termux.com")) {
                    // Inline help.
                    setContentView(progressLayout);
                    return false;
                }

                try {
                    startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK));
                } catch (ActivityNotFoundException e) {
                    // Android TV does not have a system browser.
                    setContentView(progressLayout);
                    return false;
                }
                return true;
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                setContentView(mWebView);
            }
        });
        mWebView.loadUrl("https://termux.com/help.html");
    }

    @Override
    public void onBackPressed() {
        if (mWebView.canGoBack()) {
            mWebView.goBack();
        } else {
            super.onBackPressed();
        }
    }

}