Android:将WebView输出加载到App Widget中

Question

虽然我很欣赏App Widget不WebView直接支持,但是它是否可以使用ImageView(支持),以及这里描述的技术来生成图像ImageView？该WebView不会直接使用,但只在后台使用,以用于提供图像ImageView.

Answer 1

显然,这可能至少在我的设备上,尽管你的里程可能会有所不同.

在清单中,我们<receiver>正常注册Widget ,并注册我们Service处理它WebView和它的图像捕获.

<manifest ... >
    ...

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

    <application ... >
        ...

        <receiver
            android:name=".WebWidgetProvider"
            android:label="@string/widget_name" >
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            </intent-filter>

            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/widget_info" />
        </receiver>

        <service android:name=".WebShotService" />

    </application>

</manifest>

在Widget的信息文件中widget_info.xml,我将最小大小设置为4 x 2.

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:initialLayout="@layout/widget_layout"
    android:minWidth="292dip"
    android:minHeight="146dip" />

对于这个例子,Widget的布局widget_layout.xml简直就是一个ImageView.

<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/widget_image"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="fitXY"
    android:src="@drawable/ic_launcher" />

在AppWidgetProvider这个例子中仅覆盖了onUpdate()方法,因为我们使用相同的ACTION_APPWIDGET_UPDATE触发与我们自己的更新AlarmManager.请注意,只要有一个活动的Widget,示例警报将每30秒触发一次.您可能不希望在测试之外执行此操作,因为Widget更新可能相当昂贵.

public class WebWidgetProvider extends AppWidgetProvider {
    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // We can't trust the appWidgetIds param here, as we're using
        // ACTION_APPWIDGET_UPDATE to trigger our own updates, and
        // Widgets might've been removed/added since the alarm was last set.
        final int[] currentIds = appWidgetManager.getAppWidgetIds(
            new ComponentName(context, WebWidgetProvider.class));

        if (currentIds.length < 1) {
            return;
        }

        // We attach the current Widget IDs to the alarm Intent to ensure its
        // broadcast is correctly routed to onUpdate() when our AppWidgetProvider
        // next receives it.
        Intent iWidget = new Intent(context, WebWidgetProvider.class)
            .setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE)
            .putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, currentIds);
        PendingIntent pi = PendingIntent.getBroadcast(context, 0, iWidget, 0);

        ((AlarmManager) context.getSystemService(Context.ALARM_SERVICE))
            .setExact(AlarmManager.RTC, System.currentTimeMillis() + 30000, pi);

        Intent iService = new Intent(context, WebShotService.class);
        context.startService(iService);
    }
}

在Service,我们实例化a WebView,并将其添加到a FrameLayout,然后将其添加到WindowManager零的宽度和高度参数.然后我们在其中加载测试URL WebView,当页面完成时,我们强制将WebView布局设置为适当的大小,并Bitmap通过Canvas对象将其绘制到目标.这是在稍微延迟之后完成的,以便WebView完全渲染自身,以免我们最终得到一张空白的白色图像.在Bitmap随后一个上设置的RemoteViews对象来更新ImageView在控件的布局.我Toast在代码中留下了一个用于测试目的,因为我们的示例Widget可能比Stack Overflow的首页刷新更频繁地更新.

public class WebShotService extends Service {
    private WebView webView;
    private WindowManager winManager;

    public int onStartCommand(Intent intent, int flags, int startId) {
        winManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        webView = new WebView(this);
        webView.setVerticalScrollBarEnabled(false);
        webView.setWebViewClient(client);

        final WindowManager.LayoutParams params =
            new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT,
                                           WindowManager.LayoutParams.WRAP_CONTENT,
                                           WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
                                           WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
                                           PixelFormat.TRANSLUCENT);
        params.x = 0;
        params.y = 0;
        params.width = 0;
        params.height = 0;

        final FrameLayout frame = new FrameLayout(this);
        frame.addView(webView);
        winManager.addView(frame, params);

        webView.loadUrl("http://stackoverflow.com");

        return START_STICKY;
    }

    private final WebViewClient client = new WebViewClient() {
        public void onPageFinished(WebView view, String url) {
            final Point p = new Point();
            winManager.getDefaultDisplay().getSize(p);

            webView.measure(MeasureSpec.makeMeasureSpec((p.x < p.y ? p.y : p.x),
                                MeasureSpec.EXACTLY), 
                            MeasureSpec.makeMeasureSpec((p.x < p.y ? p.x : p.y),
                                MeasureSpec.EXACTLY));
            webView.layout(0, 0, webView.getMeasuredWidth(), webView.getMeasuredHeight());

            webView.postDelayed(capture, 1000);
        }
    };

    private final Runnable capture = new Runnable() {
        @Override
        public void run() {
            try {
                final Bitmap bmp = Bitmap.createBitmap(webView.getWidth(),
                    webView.getHeight(), Bitmap.Config.ARGB_8888);
                final Canvas c = new Canvas(bmp);
                webView.draw(c);

                updateWidgets(bmp);
            }
            catch (IllegalArgumentException e) {
                e.printStackTrace();
            }

            stopSelf();
        }
    };

    private void updateWidgets(Bitmap bmp) {
        final AppWidgetManager widgetManager = AppWidgetManager.getInstance(this);
        final int[] ids = widgetManager.getAppWidgetIds(
            new ComponentName(this, WebWidgetProvider.class));

        if (ids.length < 1) {
            return;
        }

        final RemoteViews views = new RemoteViews(getPackageName(), R.layout.widget_layout);
        views.setImageViewBitmap(R.id.widget_image, bmp);
        widgetManager.updateAppWidget(ids, views);

        Toast.makeText(this, "WebWidget Update", 0).show();
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

这是Widgety善的截图.