Custom Shape component: What code actually paints the component?

rbuser

Hi all,

I'm trying to create my own descendant from TppShape to draw a specific shape
based on same pipeline value.
I've studied the MyCheckbox example, and got lots of information from it
regarding creating the component and its associated classes.
But I can't find where i have to implement the actual drawing of the component.

Can anybody help or direct me to an example which can teach me this?

Thanks
Bas Schouten

rbuser

Think i'v found the structure in all this, please confirm i'm on the right
path here:

The drawcommand associated with a Component is used when the comp has to
be drawn, by calling TppDrawCommand.Draw(TppDevice)
This in turns calls TppDevice.Draw(TppDrawcommand), which calls the device
specific draw-methods bsaed on the drawcommand type like DrawShape and Drawtext.

So if i want to draw my own shape (consisting of a few lines) i have to create
a new DrawCommand and override TppDrawCommand.Draw(aDevice).
In this implementation of the Draw method, i have to create several TppDrawLine
objects each representing one of the lines to draw, and call each of their
Drawmethods, relaying the device supplied in the original call

nicocizik

Hi Bas,


This is one way to do it. You can also directly draw the shape to the
canvas similar to the way it currently works in ReportBuilder. Take a look
at the TppScreenDevice.DrawShape routine in ppViewer.pas or
TppPrinterDevice.DrawShape in ppPrnDev.pas. When creating custom
components, this code will obviously be inside the DrawCommand.Draw routine,
however looking at the device code may be helpful.

--
Regards,

Nico Cizik
Digital Metaphors
http://www.digital-metaphors.com

rbuser

Hello Nico,

thanks for the tips.

I got it working now, by repeately calling the Draw command of a runtime-generated
TLineDrawcommand object, with changing top, left, widht and heights. I think
i'm working more "device indpendent" this way.

greetings
bas