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Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1097905]

Fri, 30 August 2013 10:09

Tilak Sharma

Messages: 48
Registered: July 2009

Member

Hi,

We are extending WindowBuilder to contribute our custom UI components (like, CustomCanvas, CustomComboBox, CustomTextBox, CustomRadioButton, etc) into the Palette.

We will be having our CustomCanvas on the ViewPart by default. Now we want to restrict Users from dropping any other existing UI components (Composite, Button, Tree, etc) onto our canvas.

How can we achieve that?

I tried extending the extension point ("org.eclipse.wb.core.editPolicyFactories"), but org.eclipse.wb.core.gef.policy.layout.LayoutPolicyUtils.createLayoutEditPolicy() method returns another LayoutEditPolicy object even before it loops till editPolicyFactory I contributed.

Thanks in anticipation,
Tilak

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Re: Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1098173 is a reply to message #1097905]

Fri, 30 August 2013 18:27

Konstantin Scheglov

Messages: 555
Registered: July 2009

Senior Member

1. You probably want to rise priority for your layout factory.




<extension point="org.eclipse.wb.core.editPartFactories">
<factory class="org.eclipse.wb.internal.rcp.nebula.gef.EditPartFactory" priority="1"/>
</extension>

2. Also take a look at Designer_2.0_descriptions.pdf and GEF validators - you can put validation script into wbp-component.xml descriptor. So, you can use standard layouts, but custom limitations.

<parameter name="GEF.requestValidator.parent">true</parameter>

<parameter name="GEF.requestValidator.child"><![CDATA[
isComponentType(parent, 'org.eclipse.swt.widgets.Table') &&
parent.object.itemCount <= 2
]]></parameter>

Konstantin Scheglov,
Google, Inc.

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Re: Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1098799 is a reply to message #1098173]

Sat, 31 August 2013 18:13

Tilak Sharma

Messages: 48
Registered: July 2009

Member

Thanks for the reply , Konstantin.

After adding the priority as 1 for my extension as:
<extension
point="org.eclipse.wb.core.editPolicyFactories">
<factory
class="com.sample.policy.MyLayoutEditPolicyFactory"
priority="1">
</factory>
</extension>

I now get a callback to my MyLayoutEditPolicyFactory.createLayoutEditPolicy() method.

I understand that I need to return a class that extens LayoutEditPolicy. But it requires me to extend getCreateCommand(), getPasteCommand() and three other get*Command() methods.

What is the contract I should define for these methods? I just need a call back to the RequestValidator I return from this EditPolicy object, so that I can restrict the user from dropping any existing component based on a condition check.

Please suggest.

Thanks,
Tilak

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Re: Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1098911 is a reply to message #1098799]

Sat, 31 August 2013 22:14

Konstantin Scheglov

Messages: 555
Registered: July 2009

Senior Member

If you return null command, container with your LayoutEditPolicy will not accept this request, i.e. component.

Konstantin Scheglov,
Google, Inc.

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Re: Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1099266 is a reply to message #1098911]

Sun, 01 September 2013 11:59

Tilak Sharma

Messages: 48
Registered: July 2009

Member

Hi Konstantin,

In the class MyLayoutEditPolicyFactory, I am creating an anonymous ILayoutRequestValidator like:

ILayoutRequestValidator validator = new ILayoutRequestValidator() {

@Override
public boolean validateCreateRequest(EditPart host, CreateRequest request) {
if (((JavaInfo) request.getSelectObject()).toString().contains("com.sample.custom"))
return true;
return false;
}

.
.
.
}

When I drag any existing component onto ViewPart canvas, it is now showing Red marker on the cursor for existing components and Green marker for my custom components.

Now, when I click on the ViewPart canvas to drop the component (ex, my customComboBox), it gives me a callback to MyLayoutEditPolicyFactory.getCreateCommand(CreateRequest request).
Here I want to return a command that handles this drop and adds it to the Canvas.
That is, I want to reuse existing code or class which does that already.

I see that without my extension point definition, the drop is being handled by FlowContainerLayoutEditPolicy or AbsoluteLayoutEditPolicy. I cannot extend them as they are marked final.

Please suggest.

Thanks,
Tilak

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Re: Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1099403 is a reply to message #1099266]

Sun, 01 September 2013 17:05

Konstantin Scheglov

Messages: 555
Registered: July 2009

Senior Member

You can always use delegation instead of inheritance.

Konstantin Scheglov,
Google, Inc.

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Re: Restrict usage of few Palette objects from dropping onto ViewPart canvas [message #1110662 is a reply to message #1099403]

Tue, 17 September 2013 06:43

Tilak Sharma

Messages: 48
Registered: July 2009

Member

Hi Konstantin,

I am able to show only my Custom components in the Palette now. I achieved that by having a file org.eclipse.wb.rcp.wbp-palette-commands.xml under wbp-meta folder apart from org.eclipse.wb.rcp.wbp-palette.xml.

In this file (org.eclipse.wb.rcp.wbp-palette-commands.xml), I have the the commands to remove the existing categories, so that everytime I launch the WindowBuilder editor, I will see only the category of custom components I contributed.

Thanks,
Tilak

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