Friday, 20 September 2013

[Android] Displaying Graphical Chart and Playing Video

In this article, we will talk about how to display a graphical chart and play mp4 video in Android app.

1) Display Graphical Chart from XML data

Imagine you receive the XML data from Web Service, as shown below:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<FahrenheitToCelsiusResponse xmlns="http://tempuri.org/">
<FahrenheitToCelsiusResult>-11.6666666666667</FahrenheitToCelsiusResult>
</FahrenheitToCelsiusResponse>
</soap:Body>
</soap:Envelope>

Now you will call the web service, receive the XML data, parse the XML data, and display a graphical chart based on the data received through the web service.

  • Calling the web service:
private static String URL1 = "http://xxxx/webservice/service";
private String SOAP_ACTION = "http://192.168.10.1/methods/soap-api";
...
HttpTransportSE androidHttpTransport = new HttpTransportSE(URL1);
androidHttpTransport.debug = true;
androidHttpTransport.call(SOAP_ACTION, envelope);

  • Receiving the data:

String Data = androidHttpTransport.responseDump;

  • Parsing the data:
A few important points is highlighted below.
the start element and end element are FahrenheitToCelsiusResponse.
the tag comparison is using FahrenheitToCelsiusResult.
use the javax xml parsers and org xml sax helpers.

import javax.xml.parsers.SAXParser;
import org.xml.sax.helpers.DefaultHandler;

List<TemperatureData> Data_List;

String DataStr="";
InputStream is = new ByteArrayInputStream(Data.getBytes("UTF-8"));
Data_List = SAXParseXML.readXML(is);

  • Copy the parsed data to a string:

        for(int i =0;i<Data_List.size();i++) {                                                    
            //use integer i as the index
            Index = Integer.toString(i);
            //Get Fahrenheit from the edit text field
            //Fahrenheit = Data_List.get(i).Fahrenheit;
            Fahrenheit = txtFar.getText().toString();
            Celsius = Data_List.get(i).Celsius;                                             
            DataStr+= "["+Index+","+Fahrenheit+","+Celsius+"]";
            if (i!=Data_List.size()-1)
               DataStr+= ",\n";
            else
               break;
       }

  • Format the string into html format, plot the chart using Google Charts:

final String chartHtml = getChartHtml(DataStr);

public static String getChartHtml(String Data)

{
         String chartHtml = null;
         try{
              // Generating html content.
              chartHtml = URLDecoder.decode(
                     "<html><head>" +
                     "<script type=\"text/javascript\" src=\"https://www.google.com/jsapi\"></script>\n" +
                    "<script type=\"text/javascript\">\n" +
                    "google.load(\"visualization\",\"1\", {packages:[\"corechart\"]});\n" +
                    "google.setOnLoadCallback(drawChart);\n" +
                    "function drawChart() {\n" +
                    "var data = google.visualization.arrayToDataTable([\n" +
                    "[\'Index\',\'Fahrenheit\',\'Celsius\'],\n" +
                    Data +                         // the data
                    "]);\n" +
                    "var options = { title: \'Record\',focusTarget:\'category\',pointSize:\'5\' };\n" +   // Set options and point size=5.
                    "var chart = new google.visualization.LineChart(document.getElementById(\'chart_div\'));\n" +
                    "chart.draw(data,options);" +
                    "}</script>\n" +
                         "</head><body><div id=\"chart_div\" style=\"width: 640px; height: 420px;\"></div>" +                                     //  Chart frame size
                    "</body></html>", "utf-8");
         } catch (Exception e){
              e.printStackTrace();
         }
         return chartHtml;
 }

  • Within the thread, use the runOnUiThread() to update the UI:

Use the android webkit to draw graph.

import android.webkit.WebView;
import android.webkit.WebSettings;

runOnUiThread(new Runnable() {
      public void run() {
             //stuff that updates ui   
             //web view load data.
             setContentView(R.layout.get_measurement_record_online);
             mWebView = (WebView)findViewById(R.id.chartWebView);
       WebSettings webSettings = mWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
       webSettings.setSupportZoom(true);
             webSettings.setLoadWithOverviewMode(true);
             mWebView.setScrollBarStyle
                       (View.SCROLLBARS_OUTSIDE_OVERLAY);
             // the function call to display chart
             mWebView.loadDataWithBaseURL(null,chartHtml,"text/html","utf-8",null);
      }
});

2) Play mp4 Video

Here is a simple example of clicking a button and playing a video from sdcard. we cannot use it in a separate thread. The actual video playback takes place in runOnUiThread().

public class GatsbyDemoActivity extends Activity
{
....
  public void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    // save the context for use later
    context = this;
    btnVideo = (Button)findViewById(R.id.btnVideo);
    ...
    btnVideo.setOnClickListener(new View.OnClickListener()
    {                
          @Override
          public void onClick(View v)
          {
               vv = (VideoView) findViewById(R.id.videoView);
               // get the Activity context for use within button OnClickListener
               mc = new MediaController(context);
               //System.out.println("video="+"play video1");
               runOnUiThread(new Runnable() {
                 public void run() {
                   //stuff that updates ui
                  getWindow().setFormat(PixelFormat.TRANSLUCENT);  
                  setContentView(R.layout.get_video);
                   mVideobackBtn =(
                      Button)findViewById(R.id.videoBackBtn);
                   mVideobackBtn
                     .setOnClickListener(btnBackOnClkLis);
                                  
                   //System.out.println("video="+"play video3");
                   vv=(VideoView)findViewById(R.id.videoView);
    vv.setVideoPath("/sdcard/DCIM/Camera/GATSBY_MOVING_RUBBER.mp4");
                   mc.setMediaPlayer(vv);
                  vv.setMediaController(mc);
                  vv.requestFocus();
                  vv.start();                              
               } //run


               private Button.OnClickListener btnBackOnClkLis = new

                Button.OnClickListener(){
               @Override
               public void onClick(View arg0) {
// TODO Auto-generated method stub
// Back to the home menu
Intent intent = new Intent(vv.getContext(), GatsbyDemoActivity.class);
                startActivity(intent);
                   }
               }; //OnClickListener                             
               }); //runOnUiThread                                     
            } //onClick
       });
    }
}

After that, you can play mp4 video, and click on the back button to go back to previous screen.

3) Screen orientation

In AndroidManifest.xml file, in activity section, set
   android:screenOrientation="landscape"
to fix the display in landscape mode.

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