Ext-GWT / GXT (Not So) Simple Layout Issue?

I have posted this question on the Ext-GWT forums, I am just hoping that someone here might have an answer for me!

I am struggling to do something I initially thought was simple but am beginning to believe is impossible...

I have got a "layout template" of sorts - simply consisting of a few GWT DockLayoutPanel's within each other and finally ending in LayoutPanels. GWT's LayoutPanel is designed to size the widget (or Composite) that's added to it to its full size and does so perfectly with pure GWT widgets.

The idea of my "layout template" is that I don't know the EXACT height and width 开发者_如何学运维of the very inner LayoutPanel's because I may set certain panels sizes (of the outer DockLayoutPanels) differently when instantiating this template. All I would like is to add a Grid component to one of the inner most LayoutPanels and have it size itself (height AND width) to fit as normal GWT widgets do (works perfectly with a GWT Label for instance).

I am VERY new to GXT (as in I started using it earlier today) and I do realize that GXT builds its Components differently to the way GWT builds its Widgets on the DOM.

Is there anyway to achieve the desired result? I have tried adding the grid to a ContentPanel with a Layout of FitLayout, I have tried AnchorLayout, I have tried adding the grid directly... Nothing seems to work... Any advice or even a push in the right direction would be greatly appreciated!

Thanks in advance!

Xandel

Just a note on this post and the direction I have taken. When I started my GWT project and I was learning the basics and reading through others posts and concerns and advice, the one bit of advice I overlooked initially was quite simple - when using the GWT framework use pure 100% GWT components only.

I initially ignored these fair warnings of fellow developers because in the age of open source tools, and open source projects, one develops the mind set of "Instead of building a tool which will give me certain functionality, let me rather see if someone else has done it already". This mindset speeds up development and almost standardizes projects and methods of implementation.

However, I have found over the last two months, that when working with GWT it is best to not follow this principle. Maybe because its not as widely spread as other frameworks, or demands a very certain type of coding style but non the less my search for a (simple, sortable, JSON loadable) grid component and (validating, neatly styled) form component has been nothing short of a nightmare.

This isn't because they don't exist. They do. I tried ext-gwt, gwt-ext, gwt-mosaic, and gwt-incubator. It is because many of the components break away from the very simple layout foundation that GWT provides (in other words, the panels that you place the widgets on mostly need to be the panels provided with the tools). This in turn makes mixing components and getting the desired result near impossible. Which in turn breaks away from the let-me-find-a-useful-component mindset.

Just an interesting and final point which I think might be worth mentioning. So due to my realisation of the above mentioned point, I set about to write my own grid and form components. Which I have completed and are working fine for me (obviously, because I wrote them , I don't suspect they will be useful to everybody else). But in the process of writing the grid component, and needing the columns to size and space themselves out automatically once drawn in their parent panel, I found that knowledge of the panels final width is not known until finally being drawn (this happens long after all your code executes). So ironically I set about building a set of panels that communicate to each other, from the parent panel (who ultimately NEEDS to have knowledge of its size) right down to the most inner panels so that when my grid component finally gets drawn, I can fire a method called onSizeKnown(int width, int height) and do whatever sizing is required.

After I completed this I could do nothing but laugh. Because it suddenly became clear to me why all the other GWT components out there require their own panels. I in essence had to do the same to get what I needed working.

So in short, if you are a newbie GWT developer like I was and are (is?) looking for cool stuff to make your project look awesome - this is my advice - if you are going to use an external framework such as some of the above mentioned - use ONLY that framework. Do not mix its components with other frameworks. Learn to love that framework, and build your project from the bottom up using their panels and design methods. If this scares you and makes you feel nervous and limited then do what I did and write your own using pure vanilla GWT components. You will save yourself A LOT of time in the long run by following this advice.

Xandel

• This solution is for GXT 2.2.0 and GWT 2.0.4 *

While the original poster has since moved on I recently ran into this issue and thought I would post my solution in case anyone else stumbles on this.

There is no reason you can't add a GXT Grid directly to a GWT LayoutPanel. The problem is that the styling/positioning approach of the two libraries conflicts. Basically it boils down to the fact that the Grid is sized based on its parent's height attribute, which is not set meaning that the grid's body get assigned a height of 0 and the grid itself gets a height equal to that of the grid header (if present).

So the solution is to undo what GXT does once flow has passed back to GWT. Here is a template solution:

class MyGridWrapper extends Composite {

  private LayoutPanel widget;
  private Grid<?> grid;

  public MyGridWrapper(Grid<? extends ModelData> grid) {
    this.grid = grid;

    widget = new LayoutPanel();
    initWidget(widget);

    widget.add(grid);
    // Set the grid's vertical and horizontal constraints

    // ... populate the rest of the panel
  }

  @Override
  protected void onLoad() {
    // onLoad is called after GXT is finished so we can do what we need to

    // Redo what the LayoutPanel did originally
    grid.el().setStyleAttribute("position", "absolute");
    grid.el().setStyleAttribute("top", "0");
    grid.el().setStyleAttribute("bottom", "0");
    grid.el().setStyleAttribute("left", "0");
    grid.el().setStyleAttribute("right", "0");

    // Undo any height settings on the .x-grid3 element
    El mainWrap = grid.el().firstChild();
    assert mainWrap.hasStyleName("x-grid3") : "Wrong Element: " + mainWrap.getStyleName();
    mainWrap.setStyleAttribute("height", "auto");

    // Undo any height settings on the .x-grid3-scroller element
    El scroller = grid.el().firstChild().firstChild().getChild(1); // FUN!
    assert scroller.hasStyleName("x-grid3-scroller") : "Wrong Element: " + scroller.getStyleName();
    scroller.setStyleAttribute("height", "auto");
  }
}

The assertions are there to help protect against what is obviously very fragile code so beware that this is a GIANT, GIANT hack.

--

• Just in case you're wondering where the GXT Grid's structure is defined, you can find it in a template file in the GXT JAR under com/extjs/gxt/ui/client/widget/grid/GridTemplates#master.html

• Have a look at com.extjs.gxt.ui.client.widget.grid.GridView#renderUI() to get an idea of how the grid is built.