I need to draw charts in my application. For that i use RGraph ( http://www.rgraph.net/ ) ; it allows to draw interactive charts with Javascript. I put my javascript code in a HTML document in assets of application, and i call it from a fragment in a ViewPager.
Here is the HTML and javascript code :
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<html>
<head>
<script src="./libraries/RGraph.common.core.js" ></script>
<script src="./libraries/RGraph.common.dynamic.js" ></script>
<script src="./libraries/RGraph.common.tooltips.js" ></script>
<script src="./libraries/RGraph.common.effects.js" ></script>
<script src="./libraries/RGraph.pie.js" ></script>
</head>
<body background="../transparent.png">
<canvas id="cvs" width="420" height="400">[No canvas support]</canvas>
<script>
function CreateGradient (obj, color)
{
return RGraph.RadialGradient(obj, 200, 150, 95, 200, 150, 125, color, color)
}
function isCanvasSupported(){
var test_canvas = document.createElement("canvas");
var canvascheck=(test_canvas.getContext) ? true : false ;
return canvascheck;
}
window.onload = function ()
{
if(isCanvasSupported)
DrawPieChart();
else
document.write("hheheheheh");
}
function DrawPieChart ()
{
var canvas = document.getElementById('cvs');
var ctx = canvas.getContext('2d');
var pie = new RGraph.Pie('cvs', [2,3,6,7,82]);
pie.Set('chart.colors', [
CreateGradient(pie, '#580600'),
CreateGradient(pie, '#AEAEAE'),
CreateGradient(pie, '#860100'),
CreateGradient(pie, '#C7C7C7'),
CreateGradient(pie, '#A70000')
]);
pie.Set('chart.labels.sticks', true);
pie.Set('chart.labels.sticks.length', 5);
pie.Set('chart.tooltips', ['Autres',
'Italie',
'Royaume-Uni',
'Espagne',
'France']);
pie.Set('chart.labels', ['2%','3%','6%','7%','82%']);
pie.Set('chart.radius', 150);
pie.Set('chart.shadow', true);
pie.Set('chart.shadow.offsetx', 0);
pie.Set('chart.shadow.offsety', 0);
pie.Set('chart.shadow.blur', 25);
pie.Draw();
}
</script>
</body>
</html>
and here is the code of a fragment :
@Override
public void onActivityCreated(Bundle savedInstanceState) {
mWebView = (WebView)getActivity().findViewById(R.id.group_fragment_one_webView);
mWebView.setFocusable(false);
mWebView.loadUrl("file:///android_asset/graphs/graph1.html");
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setDefaultZoom(ZoomDensity.FAR);
mWebView.getSettings().setDefaultFontSize(24);
mWebView.getSettings().setBuiltInZoomControls(false);
mWebView.setBackgroundColor(0);
mWebView.setHorizontalScrollBarEnabled(false);
mWebView.setVerticalScrollBarEnabled(false);
mWebView.getSettings().setSupportZoom(false);
mWebView.getSettings().setRenderPriority(RenderPriority.HIGH);
String TAG = "HTML 5";
WebSettings ws = mWebView.getSettings();
ws.setJavaScriptEnabled(true);
ws.setAllowFileAccess(true);
if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.ECLAIR) {
try {
Method m1 = WebSettings.class.getMethod("setDomStorageEnabled", new Class[]{Boolean.TYPE});
m1.invoke(ws, Boolean.TRUE);
Method m2 = WebSettings.class.getMethod("setDatabaseEnabled", new Class[]{Boolean.TYPE});
m2.invoke(ws, Boolean.TRUE);
Method m3 = WebSettings.class.getMethod("setDatabasePath", new Class[]{String.class});
m3.invoke(ws, "/data/data/" + getActivity().getApplicationContext().getPackageName() + "/databases/");
Method m4 = WebSettings.class.getMethod("setAppCacheMaxSize", new Class[]{Long.TYPE});
m4.invoke(ws, 1024*1024*8);
Method m5 = WebSettings.class.getMethod("setAppCachePath", new Class[]{String.class});
m5.invoke(ws, "/data/data/" + getActivity().getApplicationContext().getPackageName() + "/cache/");
Method m6 = WebSettings.class.getMethod("setAppCacheEnabled", new Class[]{Boolean.TYPE});
m6.invoke(ws, Boolean.TRUE);
Log.d(TAG, "Enabled HTML5-Features");
}
catch (NoSuchMethodException e) {
Log.e(TAG, "Reflection fail", e);
}
catch (InvocationTargetException e) {
Log.e(TAG, "Reflection fail", e);
}
catch (IllegalAccessException e) {
Log.e(TAG, "Reflection fail", e);
}
}
mTextView1 = (TextView)getActivity().findViewById(R.id.group_fragment_one_textview1);
mTextView1.setText(getActivity().getResources().getString(R.string.group_fragment_one_text1));
Spannable spanSize = new SpannableString(mTextView1.getText());
spanSize.setSpan(new RelativeSizeSpan(2.0f),
0,
mTextView1.getText().toString().indexOf("millions"),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
mTextView1.setText(spanSize);
Spannable colorSpan = new SpannableString(mTextView1.getText());
colorSpan.setSpan(new ForegroundColorSpan(getActivity().getResources().getColor(R.color.red_ribbon)),
0,
mTextView1.getText().toString().indexOf("millions"),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
mTextView1.setText(colorSpan);
mTextView1.setTypeface(Utils.getTextFont(getActivity().getApplicationContext()));
mTextView2 = (TextView)getActivity().findViewById(R.id.group_fragment_one_textview2);
mTextView2.setText(getActivity().getResources().getString(R.string.group_fragment_one_text2));
spanSize = new SpannableString(mTextView2.getText());
spanSize.setSpan(new RelativeSizeSpan(2.0f),
0,
mTextView2.getText().toString().indexOf("du chiffre"),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
mTextView2.setText(spanSize);
colorSpan = new SpannableString(mTextView2.getText());
colorSpan.setSpan(new ForegroundColorSpan(getActivity().getResources().getColor(R.color.red_ribbon)),
0,
mTextView2.getText().toString().indexOf("du chiffre"),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
mTextView2.setText(colorSpan);
mTextView2.setTypeface(Utils.getTextFont(getActivity().getApplicationContext()));
super.onActivityCreated(savedInstanceState);
}
It works fine on the emulator and on the Eclipse browser… But when I want to see it on a smartphone i have a bug with Canvas. sometimes the chart is correctly displayed, sometimes "No canvas support" is displayed. In the ViewPager, only the fragment n, the fragment n-1 and n+1 are simultaneously instantiated. Other fragments are instantiated when the user scroll on another fragment. So each time the user scroll, a HTML is loaded. and sometimes the canvas is supported, sometimes not…
I tried to get the support of canvas in javascript, but it always returns that the canvas is supported whereas it’s not true…
Any idea ?
Try to load the webview on the onResume() method: