This might be the way DirectFB is supposed to work but I was surprised to find
the following:
1) I blit the subrect 0, 0, 100, 100 of a surface to position 100, 0 in the
same surface
2) I blit the subrect 100, 0, 100, 100 of a surface to position 100, 100 in the
same surface
Contrary to my expections I found that the content now found in 100, 100, 100,
100 is what used to be in 100, 0, 100, 100 before the first blit rather than
after it. If I put a Flip in between 1 and 2 it works as expected.
E.g. think of each letter as a 100x100 square with a certain color in my window
surface:
rg
by
12
34
I blit 1 onto 2 expecting this to be the contents:
rr
by
I blit 2 onto 4 expecting this to be the contents:
rr
br
instead it's this:
rr
bg
This application reproduces the problem.
This is running DirectFB 1.2.8 using X11.
#include <directfb.h>
#include <unistd.h>
#define TEST(call) { result = call; if (result != DFB_OK) { func = #call; goto
end; } }
int main(int argc, char **argv)
{
const char *func = 0;
DFBResult result = DFB_OK;
IDirectFB *dfb = 0;
IDirectFBSurface *windowSurface = 0;
IDirectFBDisplayLayer *layer = 0;
IDirectFBWindow *window = 0;
DFBWindowDescription windowDescription;
DFBRectangle rect = { 0, 0, 100, 100 };
TEST(DirectFBInit(&argc, &argv));
TEST(DirectFBCreate(&dfb));
TEST(dfb->GetDisplayLayer(dfb, DLID_PRIMARY, &layer));
windowDescription.width = windowDescription.height = 200;
windowDescription.posx = windowDescription.posy = 200;
windowDescription.caps = DWCAPS_DOUBLEBUFFER;
windowDescription.flags =
DWDESC_WIDTH|DWDESC_HEIGHT|DWDESC_POSX|DWDESC_POSY|DWDESC_CAPS;
TEST(layer->CreateWindow(layer, &windowDescription, &window));
TEST(window->SetOpacity(window, 255));
TEST(window->GetSurface(window, &windowSurface));
TEST(windowSurface->SetColor(windowSurface, 255, 0, 0, 255));
TEST(windowSurface->FillRectangle(windowSurface, 0, 0, 100, 100));
TEST(windowSurface->SetColor(windowSurface, 0, 255, 0, 255));
TEST(windowSurface->FillRectangle(windowSurface, 100, 0, 100, 100));
TEST(windowSurface->SetColor(windowSurface, 0, 0, 255, 255));
TEST(windowSurface->FillRectangle(windowSurface, 0, 100, 100, 100));
TEST(windowSurface->SetColor(windowSurface, 255, 0, 255, 255));
TEST(windowSurface->FillRectangle(windowSurface, 100, 100, 100, 100));
TEST(windowSurface->Flip(windowSurface, 0, DSFLIP_BLIT));
TEST(windowSurface->Blit(windowSurface, windowSurface, &rect, 100, 0));
rect.x = 100;
TEST(windowSurface->Blit(windowSurface, windowSurface, &rect, 100, 100));
TEST(windowSurface->Flip(windowSurface, 0, DSFLIP_BLIT));
sleep(5);
end:
if (result != DFB_OK)
DirectFBError(func, result);
if (windowSurface)
windowSurface->Release(windowSurface);
if (window)
window->Release(window);
if (layer)
layer->Release(layer);
if (dfb)
dfb->Release(dfb);
if (result != DFB_OK)
DirectFBError(func, result);
return 0;
}
Maybe I am doing something wrong here.
regards
--
Qt Development Frameworks, Nokia, http://qt.nokia.com
Anders Bakken
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