Android example source code file (PurgeableBitmap.java)

This example Android source code file (PurgeableBitmap.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

activityinfo, alertdialog, android, app, application, charsequence, complete, content, graphicsactivity, namenotfoundexception, os, out, override, packagemanager, purgeablebitmapview, refreshhandler, string, stringbuilder, yes

The PurgeableBitmap.java Android example source code

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * 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.example.android.apis.graphics;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;

/**
 * PurgeableBitmap demonstrates the effects of setting Bitmaps as being
 * purgeable.
 *
 * In the NonPurgeable case, an encoded bitstream is decoded to a different
 * Bitmap over and over again up to 200 times until out-of-memory occurs.
 * In contrast, the Purgeable case shows that the system can complete decoding
 * the encoded bitstream 200 times without hitting the out-of-memory case.
 */
public class PurgeableBitmap extends GraphicsActivity {

    private PurgeableBitmapView mView;
    private final RefreshHandler mRedrawHandler = new RefreshHandler();

    class RefreshHandler extends Handler {

        @Override
        public void handleMessage(Message msg) {
            int index = mView.update(this);
            if (index > 0) {
                showAlertDialog(getDialogMessage(true, index));
            } else if (index < 0){
                mView.invalidate();
                showAlertDialog(getDialogMessage(false, -index));
            } else {
              mView.invalidate();
            }
        }

        public void sleep(long delayMillis) {
            this.removeMessages(0);
            sendMessageDelayed(obtainMessage(0), delayMillis);
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mView = new PurgeableBitmapView(this,  detectIfPurgeableRequest());
        mRedrawHandler.sleep(0);
        setContentView(mView);
    }

    private boolean detectIfPurgeableRequest() {
        PackageManager pm = getPackageManager();
        CharSequence labelSeq = null;
        try {
          ActivityInfo info = pm.getActivityInfo(this.getComponentName(),
              PackageManager.GET_META_DATA);
          labelSeq = info.loadLabel(pm);
        } catch (NameNotFoundException e) {
          e.printStackTrace();
          return false;
        }

        String[] components = labelSeq.toString().split("/");
        if (components[components.length - 1].equals("Purgeable")) {
            return true;
        } else {
            return false;
        }
    }

    private String getDialogMessage(boolean isOutOfMemory, int index) {
         StringBuilder sb = new StringBuilder();
         if (isOutOfMemory) {
             sb.append("Out of memery occurs when the ");
             sb.append(index);
             sb.append("th Bitmap is decoded.");
         } else {
             sb.append("Complete decoding ")
               .append(index)
               .append(" bitmaps without running out of memory.");
         }
         return sb.toString();
    }

    private void showAlertDialog(String message) {
      AlertDialog.Builder builder = new AlertDialog.Builder(this);
      builder.setMessage(message)
             .setCancelable(false)
             .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                 public void onClick(DialogInterface dialog, int id) {
                                 }
             });
      AlertDialog alert = builder.create();
      alert.show();
    }


}