CODEWITHSUNDEEP
gwtdomprinting
tlapeg07
tlapeg07

Reputation: 103

GWT Widget not properly set in the DOM

I would like to print a GWT widget which extends Composite. This widget is composed of a grid whose cells are built with a ListDataProvider. When the user clic on a button print, the widget to print is built. Once this is done, I launch the print:

    Element element = widgetToPrint.getElement();
    String content = element.getInnerHTML();
    print(content);


    public static native boolean print(String content)
    /*-{
    var mywindow = window.open('', 'Printing', '');
    mywindow.document.write('<html><head><title>Test</title>');
    mywindow.document.write('<link rel="stylesheet" href="/public/stylesheets/ToPrintWidget.css" type="text/css" media="all"/></head><body>');
    mywindow.document.write(content);
    mywindow.document.write('</body></html>');
    mywindow.print();
    return true;
    }-*/;

So, here is my problem:

The window which is opened by this method contains the core of the widget (built by the UI Binder), but some children are missing...

If I look inside the ListDataProvider and its related FlowPanel, the data are consistent, i.e. I've got several item in my list and in the flowPanel.

Consequently, it should be visible on the printing window... I thought that maybe the problem was related to the method used to print the widget, so I also tried to add this widget into a dialogbox just before launching the print, to see if the widget was properly built... and it was.

So my widget displays well on a dialogbox, but if I try to give its innerHTML to the print method, by using getElement(), some widgets are missing... I've the feeling that the widgets which should have been built when the ListDataProvider changes are not properly set in the DOM... Somehow it works when I add the widget to a regular component, but it doesn't work when I have to give directly its innerHTML...

Do you have any idea ?

Thanks in advance.

Upvotes: 1

Views: 1046

Answers (4)

tlapeg07
tlapeg07

Reputation: 103

First thank you for your answers, it helped me to work out this problem. I've almost solve the problem:

First, I do not use ListDataProvider anymore, because it wasn't clear for me when and how the view was refreshed. Instead I add my widgets by hand, which makes sense since, they are not going to move anyway.

Then, I define the style of my widgets using a common CSS stylesheet. However, in order to do it, I can't rely on CssResource, which was the way I was used to do it with GWT. I think that this comes from the JS method which gets lost by this kind of styles... Instead, I have to specify everything in a static CSS stylesheet, and to give it to the JS.

It works perfectly well, ie, I have my widgets, with thei styles, and I can print it.

But... The color of some widgets depends on the color of the object that they represent. Consequently, I cannot write a generic CSS stylesheet... And as I said, I can't add a style using CssResource... Do you have any ideas on the way to handle that ?

To make sure I'm clear on the way I'm adding styles, here is an example:

    Label l = new Label("Here is a cell in my grid to be printed");
    l.addStyleName("PrintLineCell-kind_1");

With, in a public CSS stylesheet:

    .PrintLineCell-kind_1{
        background-color: red;
    }

I hope there is a better way than to write 300 styles to cover 300 different colors...

Upvotes: 0

Thomas Broyer
Thomas Broyer

Reputation: 64541

You might want to grab the outer HTML rather than the inner one.

GWT unfortunately has no getOuterHTML, but it's relatively easy to emulate.

  • If your widget is the only child within an element, then simply get the inner HTML of the parent element (w.getElement().getParentElement().getInnerHTML())

  • Otherwise, clone your widget's node add it to a newly created parent element, from which you'll be able to get the inner HTML: 

    DivElement temp = Document.get().createDivElement();
temp.appendChild(w.getElement().cloneNode(true));
return temp.getInnerHTML();

Upvotes: 0

SwiftMango
SwiftMango

Reputation: 15284

String content = element.toString();

This will include all hierarchy elements in the node.

Just a reminder, all the GWT handlers will not work, and you have to sink all the events using DOM.

Upvotes: 0

Colin Alworth
Colin Alworth

Reputation: 18331

Widgets are not just the sum of their elements, and DOM elements are not just the string that they are serialized to. Widgets are the element, and all events sunk to the dom to listen for any changes or interactions by the user. Elements then have callback functions or handlers they invoke when the user interacts with them.

By serializing the element (i.e. invoking getInnerHTML()), you are only reading out the structure of the dom, not the callbacks, and additionally not the styles set by CSS. This probably shouldn't be expected to work correctly, and as your experience is demonstrating, it doesn't.

As this is just a print window you are trying to create, event handling is probably not a concern. You just want the ability to see, but not interact with, the content that would be in that set of widgets. Styles are probably the main problem here then (though your question doesn't specify 'some children are missing' doesn't tell us what is missing, or give us any more clues as to why...) - you are adding one stylesheet in your JSNI code, but CellTable (which I assume you are using since you reference ListDataProvider) needs additional CssResource instances to appear correctly. I'm not sure how you can hijack those to draw in a new window.

Are you only using this to print content, not to let the user directly interact with the data? If so, consider another approach - use a SafeHtmlBuilder to create a giant, properly escaped string of content to draw in the new window.

Upvotes: 2

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