How to adjust height of richtextbox dynamically based on inner content?

Question

public class AutoResizeBox extends RichTextArea
{
    public AutoResizeBox()
    {
       set(getElement());
    }

   public static native void set(Element f) /*-{
       console.log(f.tagName) ;
         // console.log(f.document.body.scrollHeight + 'px');
   }-*/;
}

---

RichTextBox is based on iframe,I tried to use JSNI.For above code,"console.log(f.tagName)" will print out "IFRAME",but "console.log(f.document.body.scrollHeight + 'px');" will preduce a compilation error:" com.google.gwt.core.client.JavaScriptException: (TypeError): f.document is undefined",　can anybody tell me reasons?

Answer 1

Blow is a worked version

import com.google.gwt.dom.client.BodyElement;
import com.google.gwt.event.dom.client.BlurEvent;
import com.google.gwt.event.dom.client.BlurHandler;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.ui.RichTextArea;
import com.google.inject.Inject;

public class AutoResizeTextArea extends RichTextArea implements ClickHandler,
     BlurHandler
{
private static final int margin = 6;
private BodyElement body;
private String defaultText;
private int minHeight = 25;
private String title;

@Inject
public AutoResizeTextArea()
{
    addBlurHandler(this);
    addClickHandler(this);
    setHeight(minHeight + "px");
    setStyleName("textArea");
    sinkEvents(Event.ONKEYUP | Event.ONKEYPRESS);
}

private void adjustHeight()
{
    // NP remove blow will cause auto-grow doesn't work
    if (body != null)
    {
        int offsetHeight = body.getOffsetHeight();
        if (offsetHeight != body.getClientHeight())
        {
            int height = (offsetHeight < minHeight ? minHeight : offsetHeight);
            boolean breaking = height > minHeight;
            if (breaking)
            {
                height = height + margin * 2;
            }
            setHeight(height + "px");
        }
    }
}

public void clean()
{
    setText(defaultText);
    setHeight(minHeight + "px");
    setBodyStyle(true);
}

@Override
public String getHTML()
{
    // AP RichTextArea.getHTML will return "<br>",even no html exists
    // within it,report this issue to gwt team;
    String html = super.getHTML();
    return html.equals("<br>") || html.equals(defaultText) ? "" : html;
}

@Override
public String getText()
{
    String text = super.getText();
    return text.equals(defaultText) ? "" : text;
}

@Override
public void onBlur(BlurEvent event)
{
    if (defaultText != null && "".equals(getText()))
    {
        setDefaultText(defaultText);
        setBodyStyle(true);
    }
}

@Override
public void onBrowserEvent(Event event)
{
    super.onBrowserEvent(event);
    int eventType = DOM.eventGetType(event);
    if (eventType == Event.ONKEYUP || eventType == Event.ONKEYPRESS)
    {
        adjustHeight();
    }
}

@Override
public void onClick(ClickEvent event)
{

    super.setText(null);
    setBodyStyle(false);
}

private native void registerOnCut(BodyElement element) /*-{
    var that = this;
    console.log("registerOnCut");
    element.oncut = $entry(function(event) {
        [email protected]::adjustHeight()();
        return false;
    });
    element.onpaste = $entry(function(event) {
        [email protected]::adjustHeight()();
        return false;
    });
}-*/;

private void setBodyStyle(boolean useDefaultTextStyle)
{
    if (body != null)
    {
        body.setAttribute(  "style",
                            (useDefaultTextStyle ? "color: gray;font-style: italic;" : "")
                                    + "word-wrap:break-word;overflow:hidden;margin: "
                                    + margin
                                    + "px;padding: 0;font-size: 13px;font-family: arial,\"Microsoft YaHei\", Verdana, Tahoma, Arial, STHeiTi,sans-serif, Simsun;");
    }
}

public void setDefaultText(String defaultText)
{
    super.setText(this.defaultText = defaultText);
}


@Override
public void setHTML(String html)
{
    super.setHTML(html);
    if (html == null || "".equals(html))
    {
        setDefaultText(defaultText);
    }
    adjustHeight();
}


public void setMinHeight(int minHeight)
{
    setHeight((this.minHeight = minHeight) + "px");
}

@Override
public void setText(String text)
{
    super.setText(text);
    if (text == null || "".equals(text))
    {
        setDefaultText(defaultText);
    }
}

@Override
public void setTitle(String title)
{
    this.title = title;
}
}