Hi,

I'm trying to render Ink (collected somewhere else) onto my custom
control. I have run across the problem that Renderer.Draw( Graphics,
Strokes ) fails to support anti-aliasing and transparency settings of
strokes. This is not the case however, when drawing on the Graphics
object that arrives in the OnPaint event (which is i.e. a screen DC).

Now I still need to be able to draw on memory DC, such as
Graphics.FromImage, because 1) I need to do manual double buffering of
my control (it's too slow to repaint every time) and also 2) I need to
record metafile snapshots from my control, where ink needs to be
vector, not raster.

I have performed a thorough search of this forum and over Internet and
found the article "Printing Ink" (http://msdn2.microsoft.com/en-us/
library/ms812505.aspx#tbconprintingink_antialiasing) that works around
a similar problem by means of an unsafe (ugh) class DibGraphicsBuffer.
However, there are still problems: 1) the background needs to be
filled with a color, it cannot be transparent and 2) I cannot use this
technique to record meta files.

Now I'd like to take the opportunity to ask you MS folks to explain
what is the difference between screen DC and memory DC that prevents
the latter from supporting the anti-aliasing properly? What is the
undelying problem? How does the Renderer do anti-aliasing for screen
DC and why it cannot do for memory DC? AFAIK, GDI (without +) doesn't
have any function that turns on anti-aliasing for DCs... How does
DibGraphicsBuffer work?

If there's a totally different approach to achieve what I want, it's
also welcome. So far I've tried to draw Stroke's Bezier curves
manually but that's too slow and still looks slightly different than
Renderer's output.

I'm using Microsoft Windows XP Tablet PC Edition SDK 1.7.2600.2181
with .NET Framework 2.0 and also going to upgrade to .NET Framework
3.5.

Thanks!

Oleg.

See this thread in the MSDN forum:
http://forums.microsoft.com/MSDN/Sho...94363&SiteID=1

Thanks,
Stefan Wick
http://blogs.msdn.com/swick/


"Ignoramus" wrote:

> Hi,
>
> I'm trying to render Ink (collected somewhere else) onto my custom
> control. I have run across the problem that Renderer.Draw( Graphics,
> Strokes ) fails to support anti-aliasing and transparency settings of
> strokes. This is not the case however, when drawing on the Graphics
> object that arrives in the OnPaint event (which is i.e. a screen DC).
>
> Now I still need to be able to draw on memory DC, such as
> Graphics.FromImage, because 1) I need to do manual double buffering of
> my control (it's too slow to repaint every time) and also 2) I need to
> record metafile snapshots from my control, where ink needs to be
> vector, not raster.
>
> I have performed a thorough search of this forum and over Internet and
> found the article "Printing Ink" (http://msdn2.microsoft.com/en-us/
> library/ms812505.aspx#tbconprintingink_antialiasing) that works around
> a similar problem by means of an unsafe (ugh) class DibGraphicsBuffer.
> However, there are still problems: 1) the background needs to be
> filled with a color, it cannot be transparent and 2) I cannot use this
> technique to record meta files.
>
> Now I'd like to take the opportunity to ask you MS folks to explain
> what is the difference between screen DC and memory DC that prevents
> the latter from supporting the anti-aliasing properly? What is the
> undelying problem? How does the Renderer do anti-aliasing for screen
> DC and why it cannot do for memory DC? AFAIK, GDI (without +) doesn't
> have any function that turns on anti-aliasing for DCs... How does
> DibGraphicsBuffer work?
>
> If there's a totally different approach to achieve what I want, it's
> also welcome. So far I've tried to draw Stroke's Bezier curves
> manually but that's too slow and still looks slightly different than
> Renderer's output.
>
> I'm using Microsoft Windows XP Tablet PC Edition SDK 1.7.2600.2181
> with .NET Framework 2.0 and also going to upgrade to .NET Framework
> 3.5.
>
> Thanks!
>
> Oleg.
>