Question

我正在制作Android TV应用。我想使用BackgroundManager将网址中的图片加载到Picasso drawable中。

在Glide中，使用以下代码完成：

Glide.with(getActivity())
    .load(uri)
    .centerCrop()
    .error(mDefaultBackground)
    .into(new SimpleTarget<GlideDrawable>(width, height) {
        @Override
        public void onResourceReady(GlideDrawable resource, 
            GlideAnimation<? super GlideDrawable> glideAnimation) {
            mBackgroundManager.setDrawable(resource);
        }
    });

如何使用Picasso做同样的事情？

Answer 1

这是我找到的解决方案。

public class PicassoBackgroundManager {

    private static final String TAG = PicassoBackgroundManager.class.getSimpleName();

    private static int BACKGROUND_UPDATE_DELAY = 500;
    private final int DEFAULT_BACKGROUND_RES_ID = R.drawable.default_background;
    private static Drawable mDefaultBackground;
    // Handler attached with main thread
    private final Handler mHandler = new Handler(Looper.getMainLooper());

    private Activity mActivity;
    private BackgroundManager mBackgroundManager = null;
    private DisplayMetrics mMetrics;
    private URI mBackgroundURI;
    private PicassoBackgroundManagerTarget mBackgroundTarget;

    Timer mBackgroundTimer; // null when no UpdateBackgroundTask is running.

    public PicassoBackgroundManager (Activity activity) {
        mActivity = activity;
        mDefaultBackground = activity.getDrawable(DEFAULT_BACKGROUND_RES_ID);
        mBackgroundManager = BackgroundManager.getInstance(activity);
        mBackgroundManager.attach(activity.getWindow());
        mBackgroundTarget = new PicassoBackgroundManagerTarget(mBackgroundManager);
        mMetrics = new DisplayMetrics();
        activity.getWindowManager().getDefaultDisplay().getMetrics(mMetrics);

    }

    /**
     * if UpdateBackgroundTask is already running, cancel this task and start new task.
     */
    private void startBackgroundTimer() {
        if (mBackgroundTimer != null) {
            mBackgroundTimer.cancel();
        }
        mBackgroundTimer = new Timer();
        /* set delay time to reduce too much background image loading process */
        mBackgroundTimer.schedule(new UpdateBackgroundTask(), BACKGROUND_UPDATE_DELAY);
    }


    private class UpdateBackgroundTask extends TimerTask {
        @Override
        public void run() {
            /* Here is TimerTask thread, not UI thread */
            mHandler.post(new Runnable() {
                @Override
                public void run() {
                     /* Here is main (UI) thread */
                    if (mBackgroundURI != null) {
                        updateBackground(mBackgroundURI);
                    }
                }
            });
        }
    }

    public void updateBackgroundWithDelay(String url) {
        try {
            URI uri = new URI(url);
            updateBackgroundWithDelay(uri);
        } catch (URISyntaxException e) {
            /* skip updating background */
            Log.e(TAG, e.toString());
        }
    }

    /**
     * updateBackground with delay
     * delay time is measured in other Timer task thread.
     * @param uri
     */
    public void updateBackgroundWithDelay(URI uri) {
        mBackgroundURI = uri;
        startBackgroundTimer();
    }

    private void updateBackground(URI uri) {
        try {
            Picasso.with(mActivity)
                    .load(uri.toString())
                    .resize(mMetrics.widthPixels, mMetrics.heightPixels)
                    .centerCrop()
                    .error(mDefaultBackground)
                    .into(mBackgroundTarget);
        } catch (Exception e) {
            Log.e(TAG, e.toString());
        }
    }

    /**
     * Copied from AOSP sample code.
     * Inner class
     * Picasso target for updating default_background images
     */
    public class PicassoBackgroundManagerTarget implements Target {
        BackgroundManager mBackgroundManager;

        public PicassoBackgroundManagerTarget(BackgroundManager backgroundManager) {
            this.mBackgroundManager = backgroundManager;
        }

        @Override
        public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom loadedFrom) {
            this.mBackgroundManager.setBitmap(bitmap);
        }

        @Override
        public void onBitmapFailed(Drawable drawable) {
            this.mBackgroundManager.setDrawable(drawable);
        }

        @Override
        public void onPrepareLoad(Drawable drawable) {
            // Do nothing, default_background manager has its own transitions
        }

        @Override
        public boolean equals(Object o) {
            if (this == o)
                return true;
            if (o == null || getClass() != o.getClass())
                return false;

            PicassoBackgroundManagerTarget that = (PicassoBackgroundManagerTarget) o;

            if (!mBackgroundManager.equals(that.mBackgroundManager))
                return false;

            return true;
        }

        @Override
        public int hashCode() {
            return mBackgroundManager.hashCode();
        }
    }

}

然后在您的活动或片段中使用下面的代码段

PicassoBackgroundManager picassoBackgroundManager = new PicassoBackgroundManager(getActivity());
picassoBackgroundManager.updateBackgroundWithDelay("some.image.url");

如何使用Picasso加载到BackgroundManager drawable中？

1 个答案: