Hello Developers…
I’m handling map based on raw-data.
I’d like to create a big map image which size is (6403, 4803 pixels).
This map image is consisted of a lot of lines and polygons.
The size of visible screen is only (640, 480).
I would like to scroll this big image horizontally and vertically when
pressing arrow keys.
After completing to draw the image in the memory context,
this should be dumped and displayed to the visible screen.
I used function.
But there’s a problem.
When I did scroll, I just changed position data, <PhPoint_t pos>.
However, whenever scrolling, the all image is dumped, even if visible screen
is
(640, 480). Because I create (6403, 480*3) size Memory Context.
In this program, scroll works well.
But, scroll speed is so slow.
I think that’s because function dumped all image.
I don’t know the reason why exactly.
Please, correct my thinking. If there are any other methods, please let me
know…
Are there any methods of copying rectangle area from memory to memory?
or from memory to visible screen?
or image transfer?
Thanx in advance and best regards,
KJ
ppojung@yahoo.co.kr
ps/
I got a demonstration code.
This code used scroll bar.
Firstly it loads big image. When I resize the window, scroll bar shows.
In this code, big image is scrolled very fast by scroll bar.
This code is different from my code.
But it work very similar.
Thanks…
Hi KJ,
I have spoken to a developer and suggests using shared memory. If you use
shared memory for the image data you will notice a dramatic improvement.
When the image data is in shared memory, the app only has to pass a
handle to the shared memory object within the drawstream. Otherwise all
of the data has to be inlined into the drawstream, which takes a lot
longer (especially for an image as big as yours)
Ensure that you use PgShmemCreate() to create your buffer is a good
place to start.
I hope this helps.
Thanks,
Brenda
Previously, ppojung wrote in qdn.public.qnx4.photon:
Hello Developers…
I’m handling map based on raw-data.
I’d like to create a big map image which size is (6403, 4803 pixels).
This map image is consisted of a lot of lines and polygons.
The size of visible screen is only (640, 480).
I would like to scroll this big image horizontally and vertically when
pressing arrow keys.
After completing to draw the image in the memory context,
this should be dumped and displayed to the visible screen.
I used function.
But there’s a problem.
When I did scroll, I just changed position data, <PhPoint_t pos>.
However, whenever scrolling, the all image is dumped, even if visible screen
is
(640, 480). Because I create (6403, 480*3) size Memory Context.
In this program, scroll works well.
But, scroll speed is so slow.
I think that’s because function dumped all image.
I don’t know the reason why exactly.
Please, correct my thinking. If there are any other methods, please let me
know…
Are there any methods of copying rectangle area from memory to memory?
or from memory to visible screen?
or image transfer?
Thanx in advance and best regards,
KJ
ppojung@yahoo.co.kr
ps/
I got a demonstration code.
This code used scroll bar.
Firstly it loads big image. When I resize the window, scroll bar shows.
In this code, big image is scrolled very fast by scroll bar.
This code is different from my code.
But it work very similar.
Thanks…
\
Have you looked into using a PtScrollArea widget?
Markus
“Brenda Merpaw” <gui@qnx.com> wrote in message
news:Voyager.010424111211.528398A@bmerpaw…
Hi KJ,
I have spoken to a developer and suggests using shared memory. If you use
shared memory for the image data you will notice a dramatic improvement.
When the image data is in shared memory, the app only has to pass a
handle to the shared memory object within the drawstream. Otherwise all
of the data has to be inlined into the drawstream, which takes a lot
longer (especially for an image as big as yours)
Ensure that you use PgShmemCreate() to create your buffer is a good
place to start.
I hope this helps.
Thanks,
Brenda
Previously, ppojung wrote in qdn.public.qnx4.photon:
Hello Developers…
I’m handling map based on raw-data.
I’d like to create a big map image which size is (6403, 4803 pixels).
This map image is consisted of a lot of lines and polygons.
The size of visible screen is only (640, 480).
I would like to scroll this big image horizontally and vertically when
pressing arrow keys.
After completing to draw the image in the memory context,
this should be dumped and displayed to the visible screen.
I used function.
But there’s a problem.
When I did scroll, I just changed position data, <PhPoint_t pos>.
However, whenever scrolling, the all image is dumped, even if visible
screen
is
(640, 480). Because I create (6403, 480*3) size Memory Context.
In this program, scroll works well.
But, scroll speed is so slow.
I think that’s because function dumped all image.
I don’t know the reason why exactly.
Please, correct my thinking. If there are any other methods, please let
me
know…
Are there any methods of copying rectangle area from memory to memory?
or from memory to visible screen?
or image transfer?
Thanx in advance and best regards,
KJ
ppojung@yahoo.co.kr
ps/
I got a demonstration code.
This code used scroll bar.
Firstly it loads big image. When I resize the window, scroll bar shows.
In this code, big image is scrolled very fast by scroll bar.
This code is different from my code.
But it work very similar.
Thanks…
\