Java tutorial
/* * Copyright 2012 The Stanford MobiSocial Laboratory * * 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 mobisocial.musubi.service; import gnu.trove.list.array.TByteArrayList; import java.lang.ref.SoftReference; import java.util.Arrays; import java.util.LinkedList; import java.util.Random; import mobisocial.musubi.R; import mobisocial.musubi.objects.AppStateObj; import mobisocial.musubi.util.Util; import android.app.Service; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.ServiceConnection; import android.graphics.Bitmap; import android.graphics.Bitmap.Config; import android.graphics.Canvas; import android.graphics.Picture; import android.os.Binder; import android.os.IBinder; import android.support.v4.util.LruCache; import android.util.DisplayMetrics; import android.view.View.MeasureSpec; import android.webkit.WebView; import android.webkit.WebView.PictureListener; import android.webkit.WebViewClient; import android.widget.ImageView; import android.widget.LinearLayout; //TODO: use this to measure public class WebRenderService extends Service { public static final String TAG = "WebRenderService"; public interface SizeReceiver { //note this is the size on the local phone and generally //we should be processing it and sending it with something that //understands any relevant scaling aspect ratio public void onSizeComputed(int width, int height); } WebView mWebView; RenderWebViewClient mWebViewClient; static WebRenderService sService = null; //this is a cheap way to workaround the fact that our current system is calling bind view twice //per object when it loads. we would like to cache these rendered images offline, but for now //i would like to avoid additional sources of space usage. LruCache<TByteArrayList, SoftReference<Bitmap>> mWebViewCache = new LruCache<TByteArrayList, SoftReference<Bitmap>>( 8); public static class WebRenderRequest { // input String mHtml; ImageView mDestionationView; int targetWidth; int targetHeight; // output int mWidth; int mHeight; } static LinkedList<WebRenderRequest> sToProcess = new LinkedList<WebRenderRequest>(); class RenderWebViewClient extends WebViewClient { WebRenderRequest mCurrent; private boolean mPending; public RenderWebViewClient() { mWebView.setPictureListener(new PictureListener() { @Override public void onNewPicture(WebView view, Picture picture) { if (mCurrent == null || picture.getWidth() == 0 || picture.getHeight() == 0) { return; } mCurrent.mWidth = picture.getWidth(); mCurrent.mHeight = picture.getHeight(); float scale = (float) mCurrent.targetHeight / picture.getHeight(); Bitmap bitmap = Bitmap.createBitmap((int) (scale * mCurrent.mWidth), (int) (scale * mCurrent.mHeight), Bitmap.Config.RGB_565); Canvas canvas = new Canvas(bitmap); canvas.scale(scale, scale); picture.draw(canvas); mWebViewCache.put(new TByteArrayList(Util.sha256(mCurrent.mHtml.getBytes())), new SoftReference<Bitmap>(bitmap)); if (mCurrent.mDestionationView != null) { setImageViewBitmapAndLayout(mCurrent.mDestionationView, bitmap); } mCurrent = null; mPending = false; WebRenderRequest item = sToProcess.peek(); if (item != null) { kickoffJob(item); } } }); } public void addItem(WebRenderRequest item) { sToProcess.add(item); if (!mPending) { kickoffJob(item); } } @Override public void onPageFinished(WebView view, String url) { mCurrent = sToProcess.poll(); } @Override public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) { } @Override public void onPageStarted(WebView view, String url, Bitmap favicon) { } @Override public void onScaleChanged(WebView view, float oldScale, float newScale) { } boolean lastWasSpacer = false; void kickoffJob(WebRenderRequest item) { mWebView.clearView(); mWebView.clearHistory(); //otherwise this leaks cached copies of the page in memory mPending = true; mWebView.measure(MeasureSpec.makeMeasureSpec((int) (1), MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(AppStateObj.MAX_HEIGHT, MeasureSpec.UNSPECIFIED)); mWebView.layout(0, 0, 1, 1); if (!lastWasSpacer) { WebRenderRequest dummy = new WebRenderRequest(); dummy.mHtml = "<html><body>" + new Random().nextLong() + "</body></html>"; dummy.targetHeight = 1; dummy.targetWidth = 1; sToProcess.add(0, dummy); lastWasSpacer = true; mWebView.loadData(dummy.mHtml, "text/html", "UTF-8"); } else { lastWasSpacer = false; mWebView.loadData(item.mHtml, "text/html", "UTF-8"); } } } static class WebRenderServiceConnection implements ServiceConnection { @Override public void onServiceDisconnected(ComponentName name) { sService = null; } @Override public void onServiceConnected(ComponentName name, IBinder service) { sService = ((WebRenderServiceBinder) service).getService(); if (sToProcess.size() > 0) { sService.mWebViewClient.kickoffJob(sToProcess.peek()); } } } static void bindAndSaveService(Context owner) { owner.bindService(new Intent(owner, WebRenderService.class), new WebRenderServiceConnection(), BIND_AUTO_CREATE); } public static ImageView newLazyImageWeb(Context context, String html, int targetWidth, int targetHeight) { ImageView iv = new ImageView(context); //try the short cache if (sService != null) { SoftReference<Bitmap> srb = sService.mWebViewCache .get(new TByteArrayList(Util.sha256(html.getBytes()))); if (srb != null) { Bitmap b = srb.get(); if (b != null) { sService.setImageViewBitmapAndLayout(iv, b); return iv; } } } //set a default? iv.setImageBitmap(Bitmap.createBitmap(1, 1, Config.RGB_565)); WebRenderRequest req = new WebRenderRequest(); req.targetHeight = targetHeight; req.targetWidth = targetWidth; req.mDestionationView = iv; req.mHtml = html; if (sService != null) { sService.mWebViewClient.addItem(req); } else { sToProcess.add(req); } return iv; } public void measureAndLayout() { //fake pump the layout mWebView.measure(MeasureSpec.makeMeasureSpec(1, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(AppStateObj.MAX_HEIGHT, MeasureSpec.UNSPECIFIED)); mWebView.layout(0, 0, 1, AppStateObj.MAX_HEIGHT); } @Override public void onCreate() { super.onCreate(); mWebView = new WebView(this); //set the size before we start measureAndLayout(); mWebViewClient = new RenderWebViewClient(); mWebView.setWebViewClient(mWebViewClient); } @Override public void onDestroy() { mWebView.destroy(); mWebView = null; mWebViewClient = null; super.onDestroy(); } public class WebRenderServiceBinder extends Binder { public WebRenderService getService() { return WebRenderService.this; } } private final IBinder mBinder = new WebRenderServiceBinder(); @Override public IBinder onBind(Intent intent) { return mBinder; } private void setImageViewBitmapAndLayout(ImageView imageView, Bitmap bitmap) { float scaleFactor; if (getResources().getBoolean(R.bool.is_tablet)) { scaleFactor = 3.0f; } else { scaleFactor = 2.0f; } DisplayMetrics dm = getResources().getDisplayMetrics(); int pixels = dm.widthPixels; if (dm.heightPixels < pixels) { pixels = dm.heightPixels; } int width = (int) (pixels / scaleFactor); int height = (int) ((float) width / bitmap.getWidth() * bitmap.getHeight()); int max_height = (int) (AppStateObj.MAX_HEIGHT * dm.density); if (height > max_height) { width = width * max_height / height; height = max_height; } imageView.setLayoutParams(new LinearLayout.LayoutParams(width, height)); imageView.setImageBitmap(bitmap); } }