【转帖】howto avoid flickering
 

howto avoid flickering?
howto avoid flickering?
hello
i'm using the dwgdirect c++ libraries in a c# application with windows forms (a dxf-viewer with simple interaction). the dxf-drawing is displayed using the wingdi-module which draws to the hdc of my custom windows::forms::control. the onpaint() method tells the device created by the wingdi module to update itself. the result looks good so far. but whenever i interact with the drawing (zoom, pan, show/hide layers, add comments...) it flickers. the redraw-performance while panning is the worst...
to force a redraw, i invalidate the control when an interaction occurs. panning invalidates the control on every "onmousemove()"-call.
---------------edit:
ok, the problem is solved. i had to override the ondrawbackground() method which is now empty. results look good, no more flickering.
-------------------
creating the device( once when loading new file ):
code:
....
odstring modulename = odstring(l"wingdi.gs");
odgsinitialize();
con->gicontext = odgicontextfordbdatabase::createobject();
con->gicontext->setdatabase(con->database);
con->gicontext->enablegsmodel(true);
odgsmoduleptr gsmodule = ::odrxdynamiclinker()->loadmodule( modulename, false );
if (con->database.isnull()) {
throw gcnew exception("error opening database");
}
con->gsdevice = gsmodule->createdevice();
if (con->gsdevice.isnull()) {
throw gcnew exception("error creating gdi render device");
}
odrxdictionaryptr pproperties = con->gsdevice->properties();
if (pproperties->has(dd_t("doublebufferenabled"))){
pproperties->putat(dd_t("doublebufferenabled"), odrxvariantvalue(true));
}
if (pproperties->has(dd_t("clearscreen"))){
pproperties->putat(dd_t("clearscreen"), odrxvariantvalue(false));
}
if (pproperties->has(dd_t("enablesoftwarehlr"))){
pproperties->putat(dd_t("enablesoftwarehlr"), odrxvariantvalue(false));
}
if (pproperties->has(dd_t("discardbackfaces"))){
pproperties->putat(dd_t("discardbackfaces"), odrxvariantvalue(false));
}
odcolorref bg = odrgb(0,0,0); // palette background
con->gicontext->setpalettebackground(bg);
const odcolorref* palette = odcmacadpalette(bg);
con->gsdevice->setlogicalpalette(palette, 256);
con->gsdevice = oddbgsmanager::setupactivelayoutviews(con->gsdevice, con->gicontext);
drawable = true;
zoomextents();
return nullptr;
...onpaint() method in custom control:
code:
virtual void onpaint(system::windows::forms::painteventargs^ e) override{
control::onpaint(e);
// "g" is an instance of system::drawing::graphics
intptr hdc = e->graphics->gethdc();
ctx->draw( hdc, this->width, this->height );
}updating the device (call from onpaint() ):
code:
void draw( intptr hdc, int width, int height ){
try{
if( this->isdrawable() ){
odint32 handlevalue = (odint32)hdc.toint32();
odrxdictionaryptr pproperties = con->gsdevice->properties();
if (pproperties->has(dd_t("windowhdc"))){
pproperties->putat(dd_t("windowhdc"), odrxvariantvalue(handlevalue));
}
// code to render the drawing
odgsdcrect gsrect(0, width, height, 0); // you'll have to provide the dimensions of the output device
con->gsdevice->onsize(gsrect);
con->gsdevice->ondisplaychange(16, width, height);
odgsviewptr pview = con->gsdevice->viewat(0);
pview->setviewportborderproperties(odrgb(0x00, 0x00, 0x00), 0);
pview->setviewportbordervisibility(false);
pview->setviewport(gsrect);
con->gsdevice->update();
}
}catch( oderror e ){
odstring err = e.description();
}
}do you have any suggestions how to avoid the flickering? i tried to enable doublebuffering in the device-properties but haven't noticed any differences.
thanks for hints and ideas.
last edited by martin.affolter@ntb.ch; 16th december 2008 at 09:40 amfff">.
maybe override the onerasebackground to do nothing. (i didn't see your edit, i know this problem also happens when you use wxwidgets)
last edited by billyaraujo@gmail.com; 17th december 2008 at 02:21 amfff">.