Bugger, just noticed you'd found a more elegant version of the same
solution! That'll teach me to catch up with my e-mail forwards not
backwards.
Sorry for the noise!
Paul
On 6 Jul 2006, at 19:43, Paul Russell wrote:
James,
I've done this before, for exactly the same reason. My solution was
as follows:
I wrote a component that sat in the form, and every 0.25 seconds
set the value of a hidden field to the current scroll position
using Javascript, and then output Javascript that when the form was
redisplayed as part of the next request, auto-scrolled it to the
correct location.
Sounds absolutely hideous, but it worked beautifully, and wasn't
that tricky to implement -- think it was a few tens of lines of
real code to write the component, and then it was just a case of
embedding it in the relevant forms. The user experience was
sufficiently good (over a fast connection) to prompt people to
believe I was using AJAX.
The code and JWC I used is below (packages declarations removed
from both files to protect the innocent!). The .html was just empty
since the component renders itself in code. Literally all you have
to do to use it is embed the component within your form.
Hope that helps...
Paul
=====--------
= Scroller.Java
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.PageRenderSupport;
import org.apache.tapestry.TapestryUtils;
import org.apache.tapestry.form.AbstractFormComponent;
public abstract class Scroller extends AbstractFormComponent {
public abstract int getCurrentX();
public abstract void setCurrentX(int pX);
public abstract int getCurrentY();
public abstract void setCurrentY(int pY);
public abstract boolean isScrollingInformationAvailable();
public abstract void setScrollingInformationAvailable(boolean
pScrollingInformationAvailable);
protected void renderFormComponent(IMarkupWriter pWriter,
IRequestCycle pRC) {
PageRenderSupport lPRS = TapestryUtils.getPageRenderSupport
(pRC,this);
StringBuffer lBodyScript = new StringBuffer();
lBodyScript.append("function updateScrollLocation" + getName() +
"() {\n");
lBodyScript.append("\tif (document.documentElement &&
document.documentElement.scrollTop) {\n");
lBodyScript.append("\t\tx = document.documentElement.scrollLeft;
\n");
lBodyScript.append("\t\ty =
document.documentElement.scrollTop;\n");
lBodyScript.append("\t} else if (document.body) {\n");
lBodyScript.append("\t\tx = document.body.scrollLeft;\n");
lBodyScript.append("\t\ty = document.body.scrollTop;\n");
lBodyScript.append("\t} else {\n");
lBodyScript.append("\t\tvar x = window.pageXOffset;\n");
lBodyScript.append("\t\tvar y = window.pageYOffset;\n");
lBodyScript.append("\t}\n");
lBodyScript.append("\tdocument.getElementsByName('" + getName() +
"')[0].value=x + ',' + y;\n");
lBodyScript.append("\treturn true;");
lBodyScript.append("}\n");
lPRS.addBodyScript(lBodyScript.toString());
lPRS.addInitializationScript("setInterval('updateScrollLocation"
+ getName() + "()',250);updateScrollLocation" + getName() + "();\n");
if ( isScrollingInformationAvailable() ) {
lPRS.addInitializationScript("window.scrollTo(" + getCurrentX()
+ "," + getCurrentY() + ");\n");
}
pWriter.begin("input");
pWriter.attribute("type","hidden");
pWriter.attribute("value","0,0");
pWriter.attribute("name",this.getName());
pWriter.end();
}
protected void rewindFormComponent(IMarkupWriter pWriter,
IRequestCycle pRC) {
String lValue = pRC.getParameter(getName());
if ( lValue != null ) {
int lPivot = lValue.indexOf(",");
setCurrentX(Integer.parseInt(lValue.substring(0,lPivot)));
setCurrentY(Integer.parseInt(lValue.substring(lPivot +
1)));
setScrollingInformationAvailable(true);
} else {
setScrollingInformationAvailable(false);
}
}
}
=====--------
= Scroller.jwc
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE component-specification
PUBLIC "-//Apache Software Foundation//Tapestry Specification
4.0//EN"
"http://jakarta.apache.org/tapestry/dtd/Tapestry_4_0.dtd";>
<component-specification class="Scroller" allow-body="no" allow-
informal-parameters="no">
</component-specification>
On 6 Jul 2006, at 15:42, James Carman wrote:
All,
Does anyone know how to get Tapestry to "stay put" on a screen
when you
submit the form and reshow it? I have a form that is somewhat
long. When I
use an event (like selecting something in a drop-down box) that
forces a
form submit to refresh some other parts of the screen, the screen
goes back
up to the top. I would like it to just stay where it is
(somewhere near the
originating drop-down). Any ideas?
James
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