BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Smooth diagonal Lines Goto page 1, 2  Next          BorlandTalk.com Forum Index -> Delphi Graphics View previous topic :: View next topic   Author Message John Guest Posted: Wed Sep 06, 2006 7:53 pm    Post subject: Smooth diagonal Lines Hello, I have to draw on B&W picture some diagonal lines. Unfortunately using Moveto lineTo produce very sharp lines. I cannot use Antialiasing since I use only 2 colors (Blaco or white). Do someone has a code for making better line aspect ? thanks John Back to top Finn Tolderlund Guest Posted: Wed Sep 06, 2006 8:08 pm    Post subject: Re: Smooth diagonal Lines "John" <nospam (AT) nospam (DOT) com> skrev i en meddelelse news:44fee0e1 (AT) newsgroups (DOT) borland.com... Quote: I have to draw on B&W picture some diagonal lines. Unfortunately using Moveto lineTo produce very sharp lines. That is not possible to avoid when you are using only black and white. Quote: I cannot use Antialiasing since I use only 2 colors (Blaco or white). Do someone has a code for making better line aspect ? You could try to use the Bresenham line algorithm and see if that works better for you. You can find a Delphi implementation on my website -- Finn Tolderlund http://www.tolderlund.eu/delphi/ Back to top Mike Williams (TeamB) Guest Posted: Wed Sep 06, 2006 9:04 pm    Post subject: Re: Smooth diagonal Lines John wrote: Quote: I have to draw on B&W picture some diagonal lines. Unfortunately using Moveto lineTo produce very sharp lines. I cannot use Antialiasing since I use only 2 colors (Blaco or white). Do someone has a code for making better line aspect ? My suggestion would be to open a copy of the bitmap in mspaint or your favorite drawing program and attempt to make a black and white line look better there. I think you'll find that it will make no difference. The pixels are either on or off. It may be that a wider line will look less jagged than a narrow line but I don't know what sizes you're dealing with. The main advantage of the algorithm that Finn referenced is that it's fast because it uses only integer arithmetic. However, I would think that the low level GDI code would also be efficient and may very well use the same algorithm but in hand coded assembly. Your post doesn't make it sound like performance is the problem and that it's only appearance that you're concerned about. -- -Mike (TeamB) Back to top Nils Haeck Guest Posted: Wed Sep 06, 2006 9:16 pm    Post subject: Re: Smooth diagonal Lines Search for "WU antialiased line". You'll have to do a lot of low-level coding though. Also check out Graphics32, it can render polygons (a "smooth line" is actually a rectangle at high precision). FWIW, I have created a new library, called Pyro, that you can use to draw any shapes (paths, beziers, lines, circles, roundrects, etc), with many useful features: - 256 levels of AA - partial transparency on fill and stroke - dashed strokes - 3 different linecaps - fillrules and many more You can check the library out here: http://www.simdesign.nl/forum/viewtopic.php?t=648 It is not free; DCU version is Eur 99, Source version is Eur 449. You can also use it to render SVG, a very powerful vector format. That requires the SVG plugin. Nils Haeck www.simdesign.nl "John" <nospam (AT) nospam (DOT) com> schreef in bericht news:44fee0e1 (AT) newsgroups (DOT) borland.com... Quote: Hello, I have to draw on B&W picture some diagonal lines. Unfortunately using Moveto lineTo produce very sharp lines. I cannot use Antialiasing since I use only 2 colors (Blaco or white). Do someone has a code for making better line aspect ? thanks John Back to top Mike Williams (TeamB) Guest Posted: Wed Sep 06, 2006 10:42 pm    Post subject: Re: Smooth diagonal Lines Nils Haeck wrote: Quote: Search for "WU antialiased line". How well does it work in black and white (no shades of gray)? Quote: "John" <nospam (AT) nospam (DOT) com> schreef in bericht I cannot use Antialiasing since I use only 2 colors (Blaco or white). -- -Mike (TeamB) Back to top Jens Gruschel Guest Posted: Wed Sep 06, 2006 11:08 pm    Post subject: Re: Smooth diagonal Lines Quote: How well does it work in black and white (no shades of gray)? Might be interesting to draw the line with antialiasing and then convert the result to b&w using dithering (I guess it looks worse than a simple line). -- Jens Gruschel http://www.pegtop.net Back to top Mike Williams (TeamB) Guest Posted: Wed Sep 06, 2006 11:27 pm    Post subject: Re: Smooth diagonal Lines Jens Gruschel wrote: Quote: Might be interesting to draw the line with antialiasing and then convert the result to b&w using dithering (I guess it looks worse than a simple line). I wondered about dithering as well but without knowing the line width it's hard to say if that could be helpful. -- -Mike (TeamB) Back to top Nils Haeck Guest Posted: Wed Sep 06, 2006 11:32 pm    Post subject: Re: Smooth diagonal Lines Quote: How well does it work in black and white (no shades of gray)? If you only have 2 colours (1bit pixel format) then by definition you cannot anti-alias the colours. The only thing you can then do is use a process called dithering, but that's more for surfaces, not so much for very thin lines (analogous to how newspaper photos show the dots if you look real close). Nils Back to top Mr. X Guest Posted: Wed Sep 06, 2006 11:49 pm    Post subject: Re: Smooth diagonal Lines For 2 color bitmaps (B/W), if you have diagonal lines at 45 degrees angles, you will get sharp crisp lines. Any other angle and you will need antialiasing. Best X "John" <nospam (AT) nospam (DOT) com> wrote in message news:44fee0e1 (AT) newsgroups (DOT) borland.com... Quote: Hello, I have to draw on B&W picture some diagonal lines. Unfortunately using Moveto lineTo produce very sharp lines. I cannot use Antialiasing since I use only 2 colors (Blaco or white). Do someone has a code for making better line aspect ? thanks John Back to top Mike Williams (TeamB) Guest Posted: Thu Sep 07, 2006 12:08 am    Post subject: Re: Smooth diagonal Lines Nils Haeck wrote: Quote: If you only have 2 colours (1bit pixel format) then by definition you cannot anti-alias the colours. I knew that already, as did the original poster, which is why I asked. I should have worded my response better. -- -Mike (TeamB) Back to top Nils Haeck Guest Posted: Thu Sep 07, 2006 1:00 am    Post subject: Re: Smooth diagonal Lines Yes.. and I didn't read correctly I didn't notice he actually meant to only use two colours. Nils Back to top Lord Crc Guest Posted: Thu Sep 07, 2006 1:16 am    Post subject: Re: Smooth diagonal Lines On Wed, 6 Sep 2006 16:53:25 +0200, "John" <nospam (AT) nospam (DOT) com> wrote: Quote: Do someone has a code for making better line aspect ? I have some code which can change the resolution of the monitor, which is about the only thing you can do to make it look better... - Asbjørn Back to top Jens Gruschel Guest Posted: Thu Sep 07, 2006 1:27 am    Post subject: Re: Smooth diagonal Lines Quote: I wondered about dithering as well but without knowing the line width it's hard to say if that could be helpful. Another idea is what TFTs often do: dithering in time. If you refresh the line very often you can simulate gray values and therefore antialiasing. However this might not be the solution the OP wants to hear. -- Jens Gruschel http://www.pegtop.net Back to top Rudy Velthuis [TeamB] Guest Posted: Thu Sep 07, 2006 2:29 am    Post subject: Re: Smooth diagonal Lines At 17:08:28, 06.09.2006, Finn Tolderlund wrote: Quote: You could try to use the Bresenham line algorithm What do you think MoveTo/LineTo use? -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "Our children are not born to hate, they are raised to hate." -- Thomas della Peruta Back to top Rudy Velthuis [TeamB] Guest Posted: Thu Sep 07, 2006 2:39 am    Post subject: Re: Smooth diagonal Lines At 20:08:41, 06.09.2006, Jens Gruschel wrote: Quote: How well does it work in black and white (no shades of gray)? Might be interesting to draw the line with antialiasing and then convert the result to b&w using dithering (I guess it looks worse than a simple line). But usually, AA on lines only uses one or two pixels (except for almost vertical or horizontal lines), and dithering would not make it look any better, I'd guess. It even might make the line look worse, even more ragged. -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "The fear of death is the most unjustified of all fears, for there's no risk of accident for someone who's dead." -- Albert Einstein. 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