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Thread Developing EWB Visual Components.
Thu, Apr 12 2012 9:15 PMPermanent Link

Steve Gill

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Hi Tim,

How much control do we have, and how deep can we go, if we want to develop visual components for EWB?  For instance, I've had a look through the framework units and haven't seen any canvas properties or paint/draw methods, so I imagine this is all handled at a lower level that we don't have access to.

I suspect that, because it's all got to convert into Javascript somehow, we are limited to extending and customizing existing controls, or is it possible to create controls from a fairly low level?

Thanks.

Steve
Mon, Apr 16 2012 8:27 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Steve,

<< How much control do we have, and how deep can we go, if we want to
develop visual components for EWB?  For instance, I've had a look through
the framework units and haven't seen any canvas properties or paint/draw
methods, so I imagine this is all handled at a lower level that we don't
have access to. >>

The main issue is the design-time environment.  The web browser side of
things uses an entirely different method of displaying themed visual
controls than the desktop-based, design-time environment:  the web browser
side uses DOM elements, while the design-time environment uses normal
Windows controls with painting, etc.

<< I suspect that, because it's all got to convert into Javascript somehow,
we are limited to extending and customizing existing controls, or is it
possible to create controls from a fairly low level? >>

As long as you create custom controls at runtime dynamically, you can do so
without requiring anything extra.  To get the same controls working at
design-time will require me to add them to the framework as "official"
components.  This is certainly possible to do, but hopefully I can have the
extensibility of the design-time environment worked out soon so that you can
just add such controls yourself in the IDE.

In general, check out the WebCtrls unit, specifically the base TControl
component that serves as the descendant for all visual controls.  It
illustrates how EWB uses DOM elements to construct the controls.

--
Tim Young
Elevate Software
www.elevatesoft.com
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