On Oct 12, 2007, at 3:59 AM, Felipe Monteiro de Carvalho wrote:
Creating a custom control is generally the best option to avoid
flickering. It's all documented here:
http://wiki.lazarus.freepascal.org/
Developing_with_Graphics#Motion_Graphics_-_How_to_Avoid_flickering
Thanks Felipe. Writing controls is fun. Am not concerned with
flickering, just speed in the cases where direct draw makes sense.
====
On Oct 11, 2007, at 7:43 PM, Luiz Americo Pereira Camara wrote:
You can invalidate only the area that needs update using
LCLIntf.InvalidateRect. Then you can get the update rect using the
TLMPaint message. With this you can speed the drawing but will
require a more sophisticated algorithm to define what to draw.
Luiz
Thanks Luiz. That is worthy to explore if direct drawing turns out
infeasible on Carbon Lazarus.
====
On Oct 12, 2007, at 3:55 AM, Mattias Gaertner wrote:
3. LED Audio VU Meters-- [snip]
Make the LEDs controls.
I wrote audio VU Controls. But consider a mixer window with 24 or 48
VU meters, which should visually update about 15 to 30 times per
second, while also maintaining realtime views in other sequencer
windows (and of course should also play the music without staggering).
Controls I've written for heavy duplication (see screenshot link
below)-- For rows of meters, sliders or knobs. They are written as
non-windowed controls to minimize memory usage. They share imagelists
so if you have a couple of hundred knobs in a mixer, at least all the
knobs share the same image pool.
But even if you use controls, it can become a direct-draw issue- If
there is a persistent 'pixel backing store' somewhere that individual
controls can 'draw over' in small regions of the bigger canvas--
It is just plain faster to directly call the control's paint method
somehow, than to invalidate each control and let a lot of messages
percolate thru the system before the control finally decides to paint
itself.
In Carbon LCL, haven't yet figured out how to directly call an
OnPaint method and get anything to show on the screen. An object must
be invalidated and called by the LCL before anything will show on the
screen, so far.
In the past (non lazarus) it wasn't difficult to draw into a Mac
window. Duh. It was much easier before Apple worked all those years
to 'improve' it so much that it now causes permanent brain damage to
figure out (grin).
Anyway, my sales pitch is not persuasive. Will let it go.
Here is a sequencer window full of some controls. It is a 1920 wide
screenshot shrunk down. Reckon 30 times per second of invalidate-
onpaint cycles on all these controls, is really gonna cut it?
www.errnum.com/tmpimages/ptw_scrn.jpg
Thanks
jcjr
_________________________________________________________________
To unsubscribe: mail [EMAIL PROTECTED] with
"unsubscribe" as the Subject
archives at http://www.lazarus.freepascal.org/mailarchives
