Re: construct image from Serverside to client side in GWT

Hi Ramanan,

Few months ago I had to view different pictures within a popup widget, wich are taken from the server side.
Here is a resume about how I made it (but I am not sure the solution is very secure) :

imagePopup = new Image();
popup = new PopupPanel();
popup.setWidget(imagePopup);

.....

I discard details about the functionnality with selecting a particular row into a grid, going from the view side to the presenter side of the MVP model used with events, etc), but regarding the following line, the picture is automatically retrieved and vie<ed through the browser :
.....


imagePopup.setUrl(GWT.getHostPageBaseURL() + "photos/photo1.jpg"); // server side, from root directory of the web site, pictures are putted into a photos subdirectory

=> when you reset the url with another picture file, rerefresh of the picture occurs.
=> some people could be right by saying that pictures are not secured but perhaps it could help you

Regards,

Eddy

Le vendredi 17 juin 2016 12:08:38 UTC+2, Ramanan Nathamuni a écrit :

Hello all,

my requirement is an image getting from server to GWT client.

from the client side, I send a message through AsyncCallBack method and the server response Serializable byte[] object. when getting this object,  I am parsing as String object. but the image could get.

the steps i followed

1.client side  Asynccallback method is

CommandMessage msg = new CommandMessage(itemId, "get-image-data");

cmain.ivClient.execute(msg, new AsyncCallback<ResponseMessage>() {

                @Override
                public void onFailure(Throwable caught) {
                    //add(new Label("Problem in Getting Map"));

                }

                @Override
                public void onSuccess(ResponseMessage result) { 
                 
                        here I am getting result.data is "data:india/png;base64,parsedString"     
               
                        Image image = new Image(result.data.toString());

                        canvas.add(image);                        //but I could not getting Image
                 
                }
            });



2. parsing the byte[] object from serverside

@Override
    public cti.gwtdemo.client.rpc.ResponseMessage execute(cti.gwtdemo.client.rpc.CommandMessage commandMessage) throws Exception {
        cti.item_system.CommandMessage cmdMsg = CVT(commandMessage);
        cti.gwtdemo.client.rpc.ResponseMessage rsMsg = CVT(getItemService().execute(cmdMsg));
        byte[] bytes = (byte[]) rsMsg.data;
        String base64 = com.google.gwt.user.server.Base64Utils.toBase64(bytes); //here converting process
        String[] s = rsMsg.args[0].split(" ");
        s[0] = s[0].replace(".", "/");               // the string s[0] contains image name with type ie india.png and i replaced as india/png
        rsMsg.data="data:"+s[0]+";base64,"+base64;                                      //"data:images/png;base64," + base64; ---------------------> Actually I stuck here.  ( As per mentioned in   http://gurselkoca.blogspot.in/2010/12/construction-of-gwt-image-from-byte.html )
      
       (in rsMsg.data now contains ......... "data:india/png;base64, parsedString")
      
         return rsMsg;
    }

 protected cti.item_system.CommandMessage CVT(cti.gwtdemo.client.rpc.CommandMessage cm) {

        return new cti.item_system.CommandMessage(cm.itemId, cm.command, cm.args, cm.data);   //Server Side data
    }

    protected cti.gwtdemo.client.rpc.ResponseMessage CVT(cti.item_system.ResponseMessage rm) {

        return new cti.gwtdemo.client.rpc.ResponseMessage(rm.command, rm.itemId, rm.result, rm.args, rm.data); //after getting data it set to client side
    }

please Help me, and  what stands for "data:images/png;base64," + base64;

Thanks in Advance
Ramanan

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