Documention for: view-html.r
Created by: btiffin
 on: 17-May-2007
Last updated by: btiffin on: 17-May-2007
Format: text/editable
Downloaded on: 30-Apr-2025

[h1 Usage document for %view-html.r
[contents
[numbering-on
[h2 Introduction to %view-html.r

[p view-html.r is an introduction to the ease of
gui creation with REBOL/View, plus the ease
and simplicity of accessing internet URLs.

[table/att/border="1px"/att/cellpadding="4px"
[row [cell **gui** [cell Graphic User Interface, usually pronounced as gooey
[row [cell **HTML** [cell Hyper Text Markup Language, usually pronounced [br H T M L
[row [cell **URL** [cell Uniform Resource Locator, usually pronounced [br U R L
[row [cell **widget** [cell Window Gadget, REBOL/View uses the term **face** for buttons, text areas and other windowing gadgets.
table]

[h2 view-html At a Glance
[p Not setup is required, just **do** it.
[asis >> do %view-html.r
asis]
[p [image http://www.rebol.org/library/arts/accessories/lf019t/view-html.png "view-html.png"
[p The above image was created running REBOL/View 2.7.5.4.2 GNU/Linux 4.0, KDE Desktop.
and has been cropped for space.

[h2 Using %view-html.r
[p Requires REBOL/View

[h3 Running %view-html.r
[p From the library with:
[asis/style/font-size:75%
>> do http://www.rebol.org/cgi-bin/cgiwrap/rebol/download-a-script.r?script-name=view-html.r
asis]
or locally with:
[asis
>> do %view-html.r
asis]

[h2 See also
[p There is another rebol.org script, very similar to this one,
[br [link http://www.rebol.org/cgi-bin/cgiwrap/rebol/view-script.r?script=webprint.r "%webprint.r"
that is more like the sample D program listed below, in that there is no gui involved.

[h2 What you can learn
[p This script is an introduction to the
**view** and **layout** functions.
[br Please see the [link http://rebol.com/docs/view-guide.html "REBOL/View Developer's Guide"

[h3 URLs
[p **http://www.rebol.com** is actually a value with a special datatype.  In REBOL
this is a **url!**.  Very powerful.  No quotes needed.  REBOL just **knows**. 

[h3 Web Server defaults
[p Web Servers have default files that are returned.  http://www.rebol.com
is actually returned as http://www.rebol.com/index.html.  This is not always the
case.  Some sites return default.htm, or index.php, or index.cgi.  No need
to worry, the REBOL **read** function and the web server will work that all out
for you.  If REBOL Technologies ever changes its web server setup, a different file
may be returned and this script will still work.

[h3 Changing what page is displayed
[p Changing the website or page that is printed is as easy as changing
the text after the http:// part following the **read** command.

[h3 Getting REBOL
[p Both REBOL/Core and REBOL/View are available
[br **free of charge** from [link http://www.rebol.com "www.rebol.com"

[h3 Super simple and powerful gui creation
[p REBOL/View gui building is **easy**.
[p **view layout** [...gui specification...]  How cool is REBOL/View?

[h3 Powerful builtin Internet Access
[p REBOL has fantastically simple builtin procedures for accessing the internet.
[br **read http://www.rebol.com** accesses and returns the HTML as text.  How cool
is that?

[h3 Compare the complexity to the simplicity
[p Please compare the **read http://www.rebol.com** 25 character sequence to this
[link http://www.digitalmars.com/d "D language" program (which doesn't have a window
by the way, just text output to a console).

[h4 D Language sample for printing HTML as text
[asis/style/font-size:75%
/*
    HTMLget written by Christopher E. Miller
    This code is public domain.
    You may use it for any purpose.
    This code has no warranties and is provided 'as-is'.
*/


//debug = HTMLGET;

import std.string, std.conv, std.stream;
import std.socket, std.socketstream;


int main(char[][] args)
{
    if(args.length < 2)
    {
        printf("Usage:\n   htmlget <web-page>\n");
        return 0;
    }
    char[] url = args[1];
    int i;
    
    i = std.string.find(url, "://");
    if(i != -1)
    {
        if(icmp(url[0 .. i], "http"))
            throw new Exception("http:// expected");
    }
    
    i = std.string.find(url, '#');
    if(i != -1) // Remove anchor ref.
        url = url[0 .. i];
    
    i = std.string.find(url, '/');
    char[] domain;
    if(i == -1)
    {
        domain = url;
        url = "/";
    }
    else
    {
        domain = url[0 .. i];
        url = url[i .. url.length];
    }
    
    uint port;
    i = std.string.find(domain, ':');
    if(i == -1)
    {
        port = 80; // Default HTTP port.
    }
    else
    {
        port = std.conv.toUshort(domain[i + 1 .. domain.length]);
        domain = domain[0 .. i];
    }
    
    debug(HTMLGET)
        printf("Connecting to " ~ domain ~ " on port " ~ std.string.toString(port) ~ "...\n");
    
    auto Socket sock = new TcpSocket(new InternetAddress(domain, port));
    Stream ss = new SocketStream(sock);
    
    debug(HTMLGET)
        printf("Connected!\nRequesting URL \"" ~ url ~ "\"...\n");
    
    if(port != 80)
        domain = domain ~ ":" ~ std.string.toString(port);
    ss.writeString("GET " ~ url ~ " HTTP/1.1\r\n"
        "Host: " ~ domain ~ "\r\n"
        "\r\n");
    
    // Skip HTTP header.
    char[] line;
    for(;;)
    {
        line = ss.readLine();
        if(!line.length)
            break;
        
        const char[] CONTENT_TYPE_NAME = "Content-Type: ";
        if(line.length > CONTENT_TYPE_NAME.length &&
            !icmp(CONTENT_TYPE_NAME, line[0 .. CONTENT_TYPE_NAME.length]))
        {
            char[] type;
            type = line[CONTENT_TYPE_NAME.length .. line.length];
            if(type.length <= 5 || icmp("text/", type[0 .. 5]))
                throw new Exception("URL is not text");
        }
    }
    
    print_lines:
    while(!ss.eof())
    {
        line = ss.readLine();
        printf("%.*s\n", line);
        
        //if(std.string.ifind(line, "</html>") != -1)
        //  break;
        size_t iw;
        for(iw = 0; iw != line.length; iw++)
        {
            if(!icmp("</html>", line[iw .. line.length]))
                break print_lines;
        }
    }
    
    return 0;
}
asis]
What would you rather type? The above or something like
[br **print read join http:// ask "Web site? " ** 
What will be easier to remember 6 months from now?

[h2 What can break
[p This particular example does not have scroll bars.
Not hard to add, but in this case, there is more text on the
**rebol.com** home page than will fit in the window.

[p You will need access to the internet and rebol.com will
have to be up and running for this script to work.  Don't
worry, **rebol.com** is always up and running.

[p REBOL/Core will not have the **view** or
**layout** functions defined.  You will need to start
up REBOL/View.

[h2 Credits

[table/att/border="1px"/att/cellpadding="4px"
[row [cell %view-html.r [cell Author: Unknown
[row [cell %webprint.r [cell Author: Unknown
[row [cell htmlget.d [cell Author Christopher E. Miller
[row [cell D Programming Language [cell Walter Bright, Digital Mars
[row [cell REBOL/View [cell Carl Sassenrath, REBOL Technologies
table]
[list
[li The rebol.org Library Team
[li Usage document by Brian Tiffin, Library Team Apprentice, [date
list]