non scroll background in subcanvas

CONTENTS DELETED

   Hi Vam, although I haven't worked with cairo yet, it seems that you
are loading the image from a file (imageSurface :=
CairoGraphics.ImageSurface pngPath: 'c:\temp\test.png') on each
redisplay. This can make your repaint process slow, specially
flickering when scrolling or changing its bounds. If that's the case I
would suggest loading the image in advance and storing it in an
instance variable of your view and just using the i.v. on the display
method.

HTH,
Andrés

   VAM <[hidden email]> ha escrito:

>
> I made MyView and using CairoGraphics for displaying (using
subCanvas).
> MyView may be scrollable.
> I should display background image. Now, my background image is
scroll with
> subcanvas view and dirty redisplay.
>
> displayOn: aGraphicsContext
>   aGraphicsContext newCairoContextWhile:
>                         [:aCairoContext |
>                         imageSurface :=
CairoGraphics.ImageSurface pngPath: 'c:\temp\test.png'.
>                         aCairoContext sourceSurface:
imageSurface x: (self bounds center x) y:
> (self bounds center y).
>                         aCairoContext paint].
>
>
> Do anybody like things?
>
>
> --
> View this message in context: 
http://old.nabble.com/non-scroll-background-in-subcanvas-tp26952338p26952338.html
> Sent from the VisualWorks mailing list archive at Nabble.com.
>
> _______________________________________________
> vwnc mailing list
> [hidden email]
> http://lists.cs.uiuc.edu/mailman/listinfo/vwnc
>



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VAM,

You might also want to look at using Assets to "preload" those images with caching methods.  Set the i.v. of your view from the asset accessor.

Cheers!
 
Tom Hawker
--------------------------
Senior Framework Developer
--------------------------
Home +1 (408) 274-4128
Office +1 (408) 576-6591
Mobile +1 (408) 835-3643
 

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Tuesday, December 29, 2009 7:07 AM
To: [hidden email]
Subject: Re: [vwnc] non scroll background in subcanvas


   Hi Vam, although I haven't worked with cairo yet, it seems that you
are loading the image from a file (imageSurface :=
CairoGraphics.ImageSurface pngPath: 'c:\temp\test.png') on each
redisplay. This can make your repaint process slow, specially
flickering when scrolling or changing its bounds. If that's the case I
would suggest loading the image in advance and storing it in an
instance variable of your view and just using the i.v. on the display
method.

HTH,
Andrés

   VAM <[hidden email]> ha escrito:

>
> I made MyView and using CairoGraphics for displaying (using
subCanvas).
> MyView may be scrollable.
> I should display background image. Now, my background image is
scroll with
> subcanvas view and dirty redisplay.
>
> displayOn: aGraphicsContext
>   aGraphicsContext newCairoContextWhile:
>                         [:aCairoContext |
>                         imageSurface :=
CairoGraphics.ImageSurface pngPath: 'c:\temp\test.png'.
>                         aCairoContext sourceSurface:
imageSurface x: (self bounds center x) y:
> (self bounds center y).
>                         aCairoContext paint].
>
>
> Do anybody like things?
>
>
> --
> View this message in context: 
http://old.nabble.com/non-scroll-background-in-subcanvas-tp26952338p26952338.html
> Sent from the VisualWorks mailing list archive at Nabble.com.
>
> _______________________________________________
> vwnc mailing list
> [hidden email]
> http://lists.cs.uiuc.edu/mailman/listinfo/vwnc
>



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Hi,
I do this kind of things with Cairo allthough not with images. My Cairo view
is scalable has inifite horizontal size and scrolls vertically with a scroll
bar.
In order to get good Cairo speed you should never draw outside the actual
View bounds. This however is not compatible with a standard scrolling view.
For this reason my Cairo View does not have any scroll bar. I keep track of
its bounds and origin point, its real size are the actual bounds of the view
(or the screen bounds upon creation).  In order to scroll I use a seperate
View of horizontal size 0, with only the scroll bar being visible. When I
scroll the separate view I change the origin point of the CairoView which
updates through invalidation of the view or through the Extra activity loop
I am using (See also the Akamura example).
My CairoView also updates from the associated dataset navigation and from
redbutton dragging (if nothing is selected). It involves quite some hacking
around to make it all work work, but the end Cairo speed is acceptable.

Hope this helps you start off.

@+Maarten,


----- Original Message -----
From: "VAM" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, December 29, 2009 9:54 AM
Subject: [vwnc] non scroll background in subcanvas




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