BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  RichEdit: how to know that we are at the end of the RichEdit          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message chris Guest Posted: Thu Nov 20, 2003 2:27 pm    Post subject: RichEdit: how to know that we are at the end of the RichEdit Well I guess all is in the subject. I also guess that we have to deal with SelStart.... But I suppose there will be a bug because SelStart is just an int and so if the file exceed a certain size, the int will not be able to store the value. So I want a method which answer is true when the cursor is at the end of the text without using selstart or use it with guarantee that there will be no problem if the size is greater than the int capacity. thx in advance -- chris Back to top george Guest Posted: Thu Nov 20, 2003 2:32 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich Hans Galema <dontusethis (AT) dontusethis (DOT) nl> wrote: Quote: What kind of monstruous files to you want to handle ? Do you know the maximum value an int can take ? According to 'Help' the OS will limit the max RE size somehow and I guess the OS limit will be less than or equal to the int limit, so Chris will hit his problem when he tries to overload his RE, not when he tries to find his cursor with SelStart. George Back to top Hans Galema Guest Posted: Thu Nov 20, 2003 3:19 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich chris wrote: Quote: Well I guess all is in the subject. Well that is a bad guess. Please read: http://info.borland.com/newsgroups/guide.html RULES <quote> ..... Place all of the information relevant to your post in the message body. Do not assume that everyone can see or will read the subject line. </quote> Quote: I also guess that we have to deal with SelStart.... But I suppose there will be a bug because SelStart is just an int and so if the file exceed a certain size, the int will not be able to store the value. What kind of monstruous files to you want to handle ? Do you know the maximum value an int can take ? Hans. Back to top Graham Reeds Guest Posted: Thu Nov 20, 2003 4:20 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich Quote: What kind of monstruous files to you want to handle ? Do you know the maximum value an int can take ? It's not that monstrous. The largest file I've ever made was nearly 10Gb in size. Needed to use BCB's FileRead and FileWrite functions and __int64s to get it to work. G. Back to top Remy Lebeau (TeamB) Guest Posted: Thu Nov 20, 2003 6:25 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich "george" <zombacity (AT) aol (DOT) com> wrote Quote: According to 'Help' the OS will limit the max RE size somehow By default, a RichEdit is limited to 64K of text. However, that limit can be increased programmably. Quote: and I guess the OS limit will be less than or equal to the int limit, so Chris will hit his problem when he tries to overload his RE, not when he tries to find his cursor with SelStart. SelStart is an 'int'. It can handle up to 2 billion characters positions, or 2GB of text. I seriously doubt anyone would try to load a 2GB text document into a RichEdit control, the system doesn't have that kind of memory available in the first place (unless you're really really lucky, and rich). Gambit Back to top chris Guest Posted: Fri Nov 21, 2003 3:08 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich "Remy Lebeau (TeamB)" <gambit47.no.spam (AT) no (DOT) spam.yahoo.com> a écrit dans le message de news: [email]3fbd0625 (AT) newsgroups (DOT) borland.com[/email]... Quote: "george" <zombacity (AT) aol (DOT) com> wrote in message news:3fbcdea3$1 (AT) newsgroups (DOT) borland.com... According to 'Help' the OS will limit the max RE size somehow By default, a RichEdit is limited to 64K of text. However, that limit can be increased programmably. Well I do not see this limitation ( I load file that are 25Mo) Quote: and I guess the OS limit will be less than or equal to the int limit, so Chris will hit his problem when he tries to overload his RE, not when he tries to find his cursor with SelStart. SelStart is an 'int'. It can handle up to 2 billion characters positions, or 2GB of text. I seriously doubt anyone would try to load a 2GB text document into a RichEdit control, the system doesn't have that kind of memory available in the first place (unless you're really really lucky, and rich). Well that is right that 2Go is very big but log files are sometimes very huge..... But I recognize I have make a mistake thinking that it can happen because you are right saying that only rare personn could have such memory. Nevertheless, I still do not have an answer for my question that, like Hans said, I should have written in the body (sorry, I had forgotten this rule....) So I repeat it here: How do I know that my cursor is actually positionned at the end of the RichEdit? Well I do not see how to corelate SelStart with anything else in the RichEdit. I surely missed something easy but I do not see what.... thanks for the help Back to top Hans Galema Guest Posted: Fri Nov 21, 2003 6:16 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich chris wrote: Quote: How do I know that my cursor is actually positionned at the end of the RichEdit? if ( RichEdit1->SelStart == RichEdit1->GetTextLen() ) { // the cursor is at end of the text } If you want to set the cursor at the end of the text: RichEdit1->SelStart = RichEdit1->GetTextLen(); Hans. Back to top Remy Lebeau (TeamB) Guest Posted: Fri Nov 21, 2003 8:30 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich "chris" <blin_c (AT) epita (DOT) fr> wrote Quote: Well that is right that 2Go is very big but log files are sometimes very huge..... Log files that large are not usually displayed in normal text editors. If they are, the user gets when he deserves. For such massive files, It is better to use an actual log viewer that supports large files, or just write your own viewer using a virtual ListView, which can handle billions of entries with minimal memory overhead, especially if you perform some file buffering as well so you don't instill the overhead of performing file I/O all the time.. Quote: How do I know that my cursor is actually positionned at the end of the RichEdit? That has already been answered the first time - the SelStart property is the only way to know where the caret is located. Simply test its value against the return value of the GetTextLen() method to see if the caret is at the end of the text. You will be limited to 2GB, so if that bothers you, you could always limit the RichEdit itself to 2GB as well so that it does not attempt to load more text than that. You could always pre-test the file to see what its actual file size is before you try to load it, and then warn the user if the file is too large. Gambit Back to top chris Guest Posted: Mon Nov 24, 2003 8:23 am    Post subject: Re: RichEdit: how to know that we are at the end of the Rich "Hans Galema" <dontusethis (AT) dontusethis (DOT) nl> a écrit dans le message de news: [email]3fbe55ac (AT) newsgroups (DOT) borland.com[/email]... Quote: chris wrote: How do I know that my cursor is actually positionned at the end of the RichEdit? if ( RichEdit1->SelStart == RichEdit1->GetTextLen() ) { // the cursor is at end of the text } If you want to set the cursor at the end of the text: RichEdit1->SelStart = RichEdit1->GetTextLen(); Thanks. I was sure I miss something very simple, and that something was GetTextLen(); :) Back to top chris Guest Posted: Mon Nov 24, 2003 8:25 am    Post subject: Re: RichEdit: how to know that we are at the end of the Rich "Remy Lebeau (TeamB)" <gambit47.no.spam (AT) no (DOT) spam.yahoo.com> a écrit dans le message de news: [email]3fbe7505 (AT) newsgroups (DOT) borland.com[/email]... Quote: "chris" <blin_c (AT) epita (DOT) fr> wrote in message news:3fbe29b8 (AT) newsgroups (DOT) borland.com... Well that is right that 2Go is very big but log files are sometimes very huge..... Log files that large are not usually displayed in normal text editors. If they are, the user gets when he deserves. For such massive files, It is better to use an actual log viewer that supports large files, or just write your own viewer using a virtual ListView, which can handle billions of entries with minimal memory overhead, especially if you perform some file buffering as well so you don't instill the overhead of performing file I/O all the time.. As it will be my future task (writing a log viewer), I will remember this story of virtual ListView. I do not know what it means know, but I hope it will be clearer when I do it.... Quote: How do I know that my cursor is actually positionned at the end of the RichEdit? That has already been answered the first time - the SelStart property is the only way to know where the caret is located. Simply test its value against the return value of the GetTextLen() method to see if the caret is at the end of the text. Well the function that I was seraching for was GetTextLen and this was not given in the first post. Quote: You will be limited to 2GB, so if that bothers you, you could always limit the RichEdit itself to 2GB as well so that it does not attempt to load more text than that. You could always pre-test the file to see what its actual file size is before you try to load it, and then warn the user if the file is too large. Thanks, that is what I am going to do. -- chris Back to top Remy Lebeau (TeamB) Guest Posted: Mon Nov 24, 2003 6:33 pm    Post subject: Re: RichEdit: how to know that we are at the end of the Rich "chris" <blin_c (AT) epita (DOT) fr> wrote Quote: As it will be my future task (writing a log viewer), I will remember this story of virtual ListView. I do not know what it means know, but I hope it will be clearer when I do it.... All a virtual ListView does is allows you to store the ListItem data elsewhere in memory rather than inside the TListView itself. Whenever the ListView needs to display or access a particular item, its OnData event will be triggered, and you provide the data for the requested item at that moment. You can store the data whereever you want (an in-memory buffer, a database, a file, anywhere you want. This allows you, not the ListView, to manage the memory for the ListView items. Why would you do this? Because if you let the ListView manage it, it will load *all* items into memory at one time, which for millions to billions of records, will bring the system to a crawl or even crash. But if you manage it yourself, you could buffer the data more efficiently, such as keeping a buffer that is large enough just for the items that are actually visible onscreen, and re-buffering the data only when the user actually scrolls through the ListView. 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