BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  How to skew an image?          BorlandTalk.com Forum Index -> Delphi Graphics View previous topic :: View next topic   Author Message Ma Xiaoguang Guest Posted: Tue Oct 04, 2005 9:32 am    Post subject: How to skew an image? Dear ladies and gentlemen, I want to skew rectangular image in any shaped quadrangle. I have thought about this function for many days. In my solution, It was a linear skew. For example, to get all the points on the left side and right side of the quadrangle, and each pairs of the two points which was from the left side and right side would be two ending points for a line. And then, we can read one line from the source bitmap, and stretch draw the source line to the dest line which was getting by ourselves. The problem of my approach is that it cannot processes all the points in a non-regular quadrangle, some of the points are ignored. I have searched the information which is about skew image by Google, but unfortunately, there are too many results from Google. I have checked out a lot of the results, but none of them has satisfied what I want. Most of them skew image in parallelogram, including the demos from Graphics32. Could you please give me some suggestions and information for this question? Thank you very much! Best regards. Xiaoguang Back to top Nils Haeck Guest Posted: Tue Oct 04, 2005 11:49 am    Post subject: Re: How to skew an image? Have a look at the transformation types in Graphics32. The TProjectiveTransformation does what you want; bilinear mapping. The name Projective transform is not correct if you ask me, not that it bothers me too much:). Quote: lot of the results, but none of them has satisfied what I want. Most of them skew image in parallelogram, including the demos from Graphics32. Nope, TProjectiveTransform does not map to a parallelogram, but really to a 4-point quadrangle. You can try out the demo of Dtpdocuments, and add a "Projective Text" shape to verify: http://www.simdesign.nl/Download/dtpdemo.zip Nils "Ma Xiaoguang" <maxiaoguang10000 (AT) sina (DOT) com> schreef in bericht news:43424b37 (AT) newsgroups (DOT) borland.com... Quote: Dear ladies and gentlemen, I want to skew rectangular image in any shaped quadrangle. I have thought about this function for many days. In my solution, It was a linear skew. For example, to get all the points on the left side and right side of the quadrangle, and each pairs of the two points which was from the left side and right side would be two ending points for a line. And then, we can read one line from the source bitmap, and stretch draw the source line to the dest line which was getting by ourselves. The problem of my approach is that it cannot processes all the points in a non-regular quadrangle, some of the points are ignored. I have searched the information which is about skew image by Google, but unfortunately, there are too many results from Google. I have checked out a lot of the results, but none of them has satisfied what I want. Most of them skew image in parallelogram, including the demos from Graphics32. Could you please give me some suggestions and information for this question? Thank you very much! Best regards. Xiaoguang Back to top John Guest Posted: Tue Oct 04, 2005 12:29 pm    Post subject: Re: How to skew an image? I think that what you need is Billinear warping. projective transform of G32 is a little bit different because it give a projective effect, billiear warping is more neutral. Pixelook supports this but unfortunately this library seems to be dead... Antigrain also seems to support it. GDI+ supports it with path also. Back to top Ma Xiaoguang Guest Posted: Wed Oct 05, 2005 1:14 am    Post subject: Re: How to skew an image? Hello Nils, Thanks for you help. I will check out the dtpdemo carefully. Best regards. Xiaoguang "Nils Haeck" <bla (AT) bla (DOT) com> дÈëÏûÏ¢ÐÂÎÅ:43426a67$1 (AT) newsgroups (DOT) borland.com... Quote: Have a look at the transformation types in Graphics32. The TProjectiveTransformation does what you want; bilinear mapping. The name Projective transform is not correct if you ask me, not that it bothers me too much:). lot of the results, but none of them has satisfied what I want. Most of them skew image in parallelogram, including the demos from Graphics32. Nope, TProjectiveTransform does not map to a parallelogram, but really to a 4-point quadrangle. You can try out the demo of Dtpdocuments, and add a "Projective Text" shape to verify: http://www.simdesign.nl/Download/dtpdemo.zip Nils "Ma Xiaoguang" <maxiaoguang10000 (AT) sina (DOT) com> schreef in bericht news:43424b37 (AT) newsgroups (DOT) borland.com... Dear ladies and gentlemen, I want to skew rectangular image in any shaped quadrangle. I have thought about this function for many days. In my solution, It was a linear skew. For example, to get all the points on the left side and right side of the quadrangle, and each pairs of the two points which was from the left side and right side would be two ending points for a line. And then, we can read one line from the source bitmap, and stretch draw the source line to the dest line which was getting by ourselves. The problem of my approach is that it cannot processes all the points in a non-regular quadrangle, some of the points are ignored. I have searched the information which is about skew image by Google, but unfortunately, there are too many results from Google. I have checked out a lot of the results, but none of them has satisfied what I want. Most of them skew image in parallelogram, including the demos from Graphics32. Could you please give me some suggestions and information for this question? Thank you very much! Best regards. Xiaoguang Back to top Ma Xiaoguang Guest Posted: Wed Oct 05, 2005 1:17 am    Post subject: Re: How to skew an image? Hello John, Thanks for your help. Best regards. Xiaoguang "John" <prout (AT) nospam (DOT) com> дÈëÏûÏ¢ÐÂÎÅ:43427533 (AT) newsgroups (DOT) borland.com... Quote: I think that what you need is Billinear warping. projective transform of G32 is a little bit different because it give a projective effect, billiear warping is more neutral. Pixelook supports this but unfortunately this library seems to be dead... Antigrain also seems to support it. GDI+ supports it with path also. 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