rosenbergr@abo.fi (Robin Rosenberg, Computer Science, ]bo Akademi) (02/22/89)
A simple question: What is the best way of doing clipping. I.e
I would like to render some text and images into a part of a window. If
the object goes outside the required borders (a rectangle) I want that part
chopped of. I know the ROMS have a InstallClipRect() function but how do
I use it?
Could anyone give me an example of how to do this the right way?
---
Robin Rosenberg, ]bo Akademi, FINLAND
Address: Finn|, 22340 Geta, ]LAND - FINLAND
or Studentbyn 40A3, 20510 ]BO, FINLAND
Translation: ']' is an 'A' with a ring on top, '|' is an 'o' with two dots.ksp@anuck.UUCP (p.s.kasten) (02/24/89)
In article <5379@abo.fi>, rosenbergr@abo.fi (Robin Rosenberg, Computer Science, ]bo Akademi) writes: > A simple question: What is the best way of doing clipping. I.e > Robin Rosenberg, ]bo Akademi, FINLAND > Address: Finn|, 22340 Geta, ]LAND - FINLAND > or Studentbyn 40A3, 20510 ]BO, FINLAND > Translation: ']' is an 'A' with a ring on top, '|' is an 'o' with two dots. I am working on a CAD package in which I was hoping to have one window with 3 different clipping regions. When I used InstallClipRect() (or whatever it is called!), the rendering was noticably slower than when I have 3 separate windows. I never looked into it further, but was always puzzled. Any clues to this mystery, as well as the answer to Robin's question? Phil Kasten AT&T Bell Labs !att!mvuxi!ksp
scott@applix.UUCP (Scott Evernden) (02/26/89)
In article <5379@abo.fi> rosenbergr@abo.fi (Robin Rosenberg, Computer Science, ]bo Akademi) writes: >A simple question: What is the best way of doing clipping. I.e >I would like to render some text and images into a part of a window. If >the object goes outside the required borders (a rectangle) I want that part >chopped of. I know the ROMS have a InstallClipRect() function but how do >I use it? >Could anyone give me an example of how to do this the right way? Sure. It's really not too hard... As part of your init code do: struct Library *LayersBase; struct Region *region; LayersBase = OpenLibrary("layers.library", 0L); region = NewRegion(); Then, when you want clipping within (xmin,ymin)-(xmax,ymax): struct Rectangle rect; rect.MinX = minx; rect.MinY = miny; rect.MaxX = maxx; rect.MaxY = maxy; ClearRegion(region); OrRectRegion(region, &rect); InstallClipRegion(window->RPort->Layer, region); There are lots of region operations, and you can create clip areas that are not necessarily rectangular by using combinations of And/Or/XorRectRegion() and -RegionRegion(). Finally, at cleanup time: DisposeRegion(region); InstallClipRegion(window->RPort->Layer, (struct Region *) NULL); CloseLibrary(LayersBase); -scott
gay@elde.epfl.ch (David Gay) (02/27/89)
In article <911@applix.UUCP> scott@applix.uucp (Scott Evernden) writes: > >In article <5379@abo.fi> rosenbergr@abo.fi (Robin Rosenberg, Computer Science, > ]bo Akademi) writes: >>A simple question: What is the best way of doing clipping. I.e >>I would like to render some text and images into a part of a window. If >>the object goes outside the required borders (a rectangle) I want that part >>chopped of. I know the ROMS have a InstallClipRect() function but how do >>I use it? >>Could anyone give me an example of how to do this the right way? > >Sure. It's really not too hard... Well, if this worked it wouldn't be too hard, but ... it doesn't (at least not with simple refresh windows). I found this out the hard way, as this was my initial approach, and then I had to fool around to find a way that worked. [...] >Then, when you want clipping within (xmin,ymin)-(xmax,ymax): [...] > InstallClipRegion(window->RPort->Layer, region); [...] >Finally, at cleanup time: > > DisposeRegion(region); > InstallClipRegion(window->RPort->Layer, (struct Region *) NULL); > >-scott > This creates problems as soon as your window gets a damage list (eg if you display a requester in the window, or if your window is behind another). I had to do the following to get everything working: Setup clipping region: /* Save old damage list */ oldRegion = win->WLayer->DamageList; /* New clip region is old region AND my clipping region */ if (oldRegion == NULL || oldRegion->RegionRectangle == NULL) success = TRUE; else /* Argh ! */ success = AndRegionRegion(win->WLayer->DamageList, region); if (success) InstallClipRegion(win->WLayer, region); And the following to clean up: InstallClipRegion(win->WLayer, oldRegion); DisposeRegion(region); This works, but I have grave doubts about it working in future releases ... (if the xxRegion routines are changed for instance). Anybody have a better method ? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ David Gay 6 x 9 = 42 GAY@ELDE.EPFL.CH, or GAY%ELDE.EPFL.CH@CLSEPF51.bitnet ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dale@boing.UUCP (Dale Luck) (02/27/89)
In article <911@applix.UUCP> scott@applix.UUCP (Scott Evernden) writes: Unless The code is broke somewhere that we don't know InstallClipRegion returns a ptr to the original ClipRegion. It should be restored. struct Region * OldRegion; > ClearRegion(region); > OrRectRegion(region, &rect); > InstallClipRegion(window->RPort->Layer, region); OldRegion = InstallClipRegion(window->RPort->Layer, region); > >Finally, at cleanup time: > > InstallClipRegion(window->RPort->Layer, (struct Region *) NULL); InstallClipRegion(window->RPort->Layer, OldRegion ); >-scott -- Dale Luck GfxBase/Boing, Inc. {uunet!cbmvax|pyramid}!amiga!boing!dale
c60c-1ea@web-1d.berkeley.edu (Yen Yuanchi Hsieh) (02/28/89)
>Finally, at cleanup time: > > DisposeRegion(region); > InstallClipRegion(window->RPort->Layer, (struct Region *) NULL); ** Please, don't DisposeRegion BEFORE it's been removed from it's Layer, that's asking for trouble. > CloseLibrary(LayersBase); > >-scott Remember that clipping=slow graphics rendering speeds. I have found it useful to clip on graphic demand, that way Intuition runs at normal non-snail speeds when I'm not drawing Icons. Remember to trap and handle window-resizing if you're going to keep a static clipping rectangle hanging around. David Navas, hiding at c60c-1ea@WEB.Berkeley.Edu