Hello there,
I have the exactly same question. Did you find out the solution?
Thanks
Aaron
On Wednesday, August 18, 2010 6:40:21 AM UTC+8, Jawfish wrote:
>
> This should be a simple question, but I have read many pages of the
> Docs and examples and can't find it....
>
> Me:
> Java and Javascript beginner.
>
> Intent:
> I am making a small demo app in GWT 2.0x with charts. It intends to
> put up a chart and then redraws the chart with new data.
>
> Problem:
> Nothing happens when I use the draw method on the chart object. It
> seems that once drawn the chart object is rendered in JS, and I can't
> talk to it again. I haven't found docs, or maybe haven't understood
> the dynamic relationship between the Java GWT code and the JS code
> running in the browser. Almost all examples for charts are in JS. I
> see the Gauge visualization re-drawing itself in the example, but no
> Java source code.
>
> Thanks.
> John
>
> My code:
>
> package com.demo.gwtdemoviz1.client;
>
>
> import com.google.gwt.core.client.JavaScriptObject;
> import com.google.gwt.core.client.JavaScriptException;
>
>
> import com.google.gwt.core.client.EntryPoint;
> import com.google.gwt.core.client.JsArray;
> import com.google.gwt.user.client.Random;
> import com.google.gwt.user.client.Timer;
> import com.google.gwt.user.client.Window;
> import com.google.gwt.user.client.ui.Panel;
> import com.google.gwt.user.client.ui.RootPanel;
> import com.google.gwt.visualization.client.AbstractDataTable;
> import com.google.gwt.visualization.client.DataView;
> import com.google.gwt.visualization.client.Query;
> import com.google.gwt.visualization.client.QueryResponse;
> import com.google.gwt.visualization.client.VisualizationUtils;
> import com.google.gwt.visualization.client.DataTable;
> import com.google.gwt.visualization.client.Selection;
> import
> com.google.gwt.visualization.client.AbstractDataTable.ColumnType;
> import com.google.gwt.visualization.client.Query.Callback;
> import com.google.gwt.visualization.client.events.SelectHandler;
> import com.google.gwt.visualization.client.visualizations.BarChart;
> import
> com.google.gwt.visualization.client.visualizations.Visualization;
> import
> com.google.gwt.visualization.client.visualizations.BarChart.Options;
>
> public class GWTDemoViz1 implements EntryPoint {
>
> // stuff to randomize the data
> private static final int REFRESH_INTERVAL = 5000; // ms
> // randomize the variables
> private void randomData(Visualization<Options> bar) {
> // do something here to change data
>
> /////////////////////////////// this is where it
> fails //////////////////////////////////////
> bar.draw( updateTable() );
> // updateTable() is called and it runs, the changed values can be
> seen
> // in the browser; further it can instantiate a fresh barchart if I
> swap it for
> // createTable(), but used as a refresh, the chart never redraws.
> ///////////////////////////////////////////////////////////////////////////////////////////////////////
>
>
> }
>
>
> public void onModuleLoad() {
> // Create a callback to be called when the visualization API
> // has been loaded.
> Runnable onLoadCallback = new Runnable() {
> public void run() {
> Panel panel = RootPanel.get();
>
> // Create a pie chart visualization.
> BarChart bar = new BarChart(createTable(),
> createOptions());
>
> bar.addSelectHandler(createSelectHandler(bar));
> panel.add(bar);
>
> }
>
> };
> // Setup timer to refresh data automatically.
> Timer refreshTimer = new Timer() {
> @Override
> public void run() {
> randomData(null);
> }
> };
> refreshTimer.scheduleRepeating( REFRESH_INTERVAL );
>
> // Load the visualization api, passing the onLoadCallback to be
> called
> // when loading is done.
> VisualizationUtils.loadVisualizationApi(onLoadCallback,
> BarChart.PACKAGE);
> }
>
> private Options createOptions() {
> Options options = Options.create();
> options.setWidth(400);
> options.setHeight(240);
> options.set3D(true);
> options.setTitle("My Daily Activities");
> return options;
> }
>
> private SelectHandler createSelectHandler(final BarChart bar) {
> */... just the selecthandler from the simpleviz demo .... */
> }
> }
>
> Window.alert(message);
> }
> };
> }
>
> private AbstractDataTable createTable() {
> // Underlying data
> DataTable data = DataTable.create();
> data.addColumn(ColumnType.STRING, "Item");
> data.addColumn(ColumnType.NUMBER, "item per sec");
> data.addRows(3);
> data.setValue(0, 0, "Nits");
> data.setValue(0, 1, 10);
> data.setValue(1, 0, "Gnats");
> data.setValue(1, 1, 4);
> data.setValue(2, 0, "Pits");
> data.setValue(2, 1, 8);
>
> // Data view -- read only, and no location column
> DataView result = DataView.create(data);
> result.setColumns(new int[]{0, 1});
> return result;
>
> }
>
> private AbstractDataTable updateTable() {
> // Underlying data
> DataTable data = DataTable.create();
> data.addColumn(ColumnType.STRING, "Item");
> data.addColumn(ColumnType.NUMBER, "item per sec");
>
> // now create some values
> String message = "";
> final int MAX_VALUE = 10;
> int nit = Random.nextInt(MAX_VALUE) ;
> int gnat = Random.nextInt(MAX_VALUE) ;
> int pit = Random.nextInt(MAX_VALUE) ;
>
> data.addRows(3);
> data.setValue(0, 0, "Nits");
> data.setValue(0, 1, nit);
> data.setValue(1, 0, "Gnats");
> data.setValue(1, 1, gnat);
> data.setValue(2, 0, "Pits");
> data.setValue(2, 1, pit);
> message += nit + " valu " + nit + " other " + gnat;
> //Window.alert(message);
>
> return data;
>
> }
>
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