GWT Custom PushButton not working with ImageResources

Question

What I need is exactly a gwt PushButton in term of behavior with the exception that I need it to have an image in addition to the text.

I use GWT, GWTP and the UiBinder

In my ui.xml file, the following code works, but I can't specify another image if I hover or click the button

<g:SimplePanel height="100%" styleName="{style.button}"
    width="100%">
    <g:HTMLPanel width="100%" height="100%">
        <table align="center">
            <tr>
                <td>
                    <g:Image styleName="{style.pane}" resource='{res.Edit}' />
                </td>
                <td>
                    <g:Label ui:field="label2" text="Edit Project Edit Project" />
                </td>
            </tr>
        </table>
    </g:HTMLPanel>
</g:SimplePanel>

After searching for a solution, I came across this code from here

package com.test.gwtptestproject.client;

import com.google.gwt.dom.client.Style;
import com.google.gwt.dom.client.Style.Float;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.ui.Image;

public class MyButton implements SafeHtml {

    private static final long serialVersionUID = 1L;
    Image img;
    private String text;
    private String innerHtml = "";

    public void setImage(ImageResource imgr) {
        this.img = new Image(imgr);
        update();
    }

    public void setText(String text) {
        this.text = text;
        update();
    }

    private void update() {
        Element d = DOM.createDiv();
        if (img != null) {
            Element di = DOM.createDiv();
            Style s = di.getStyle();
            s.setPaddingLeft(5, Unit.PX);
            s.setPaddingRight(5, Unit.PX);
            s.setFloat(Float.LEFT);
            di.appendChild(img.getElement());
            d.appendChild(di);
        }
        if (text != null) {
            Element t = DOM.createDiv();
            t.setInnerText(text);
            d.appendChild(t);
        }
        innerHtml = d.getInnerHTML();

    }

    public MyButton() {
    }

    @Override
    public String asString() {
        return innerHtml;
    }
}

Which I later used in my ui.xml like this

...
<ui:with field='res' type='com.test.gwtptestproject.resources.ImageResources' />
...
<g:PushButton>
    <g:upFace>
    <MyButton image="{res.Edit}" text="Edit"></MyButton>
    </g:upFace>
</g:PushButton>

My ImageResources package contains the following interface and this package was added to the sources in gwt.xml file

public interface ImageResources extends ClientBundle {
    public ImageResources INSTANCE = GWT.create(ImageResources.class);

    @Source("Edit.png")
    ImageResource Edit();
    
    @Source("Edit_Hover.png")
    ImageResource Edit_Hover();
    
    @Source("Edit_Click.png")
    ImageResource Edit_Click();
}

When I try to open the designer I keep having the following error and I don't know how to solve it (I get the same error if I try to access the page from a browser)

[ERROR] java.lang.String required, but {res.Edit} returns com.google.gwt.resources.client.ImageResource: <MyButton image='{res.Edit}' text='Edit'> (:110)
[ERROR] Deferred binding failed for 'com.test.gwtptestproject.client.SecondView.Binder'; expect subsequent failures

From what I understand when I write image="{res.Edit}" the application should expect an ImageResource and not a String isn't it ?

*Note : I'm pretty new to web development (school project) so don't presume I might already know some things when you'll answer unless it is obvious

spg spg · Accepted Answer · 2013-05-29T14:06:46

Don't forget to include MyButton's package as a xmnls (XML Namespace) attribute to the opening ui:Binder tag:

<ui:UiBinder xmlns:ui='urn:ui:com.google.gwt.uibinder'
             xmlns:g='urn:import:com.google.gwt.user.client.ui'
             xmlns:mybtn='urn:import:com.test.gwtptestproject.client'>

and prefix your <MyButton> tag with the xmnls' alias (here, mybtn):

<g:PushButton>
    <g:upFace>
    <mybtn:MyButton image="{res.Edit}" text="Edit"></mybtn:MyButton>
    </g:upFace>
</g:PushButton>

This way, GWT will know where to look (package com.test.gwtptestproject.client) to find the MyButton class.

GWT Custom PushButton not working with ImageResources

1 Answers