2) What are hypertext and hypermedia?
3) What is Mosaic and what is HTML?
4) What text editors should I use to write HTML files?
5) What is a URL?
6) Writing HTML files
7) Using IMGSNAP to capture images on screen
8) Using Xview to modify images and image formats
9) Using "assemble" to paste images together
A BROWSER is the tool that gives the user access to the web. A Browser connects one to the web, reads HTML files and converts them into the nice display you're looking at right now. A browser also handles all the file transfers that hypermedia requires. MOSAIC IS A BROWSER, but there are many others.
In an emacs window save a file as "----.html". Now the mode line should indicate that you are in emacs HTML mode. Now enter Control-h, m. This will give you help on the html mode, more specifically, it will give you shortcuts to entering the markers that HTML requires. You may find a hardcopy of this help screen useful.
Once you are through the tutorial, you know more than enough to start. However, you can read the following HTML documentation, but it's probably not necessary at this point.
Linking to another document or to another place in the same document:
To create a hyperlink to jump elsewhere, one must identify the hypertext and the hyperlink in the following manner:
<A HREF="file#destination">[text to click on]</A>The [text to click on] IS THE HYPERTEXT and will be underlined when the document is read by Mosaic. The file#destination is the place Mosaic will jump to (see below) when the hypertext is clicked upon.
The following statement must be placed at the spot where one wants Mosaic to jump to:
<A NAME="Destination">[text to jump to]</A>Note that this position was given a name Destination which was referenced in the hyperlink above. The [text to jump to] can be omitted.
When using filenames, it is always better and faster to use relative references than absolute references. For example, if the reference is to a document in the same directory, simply the filename must be specified.
If the link is to the beginning of another document, than the Destination need not be specified, and the link is simply:
<A HREF="file">[text to click on]</A>If the link is to another part of the same document, then the filename need not be specified, but the Destination must me specified. The link becomes:
<A HREF="#destination">[text to click on]</A>With the destination statement as:
<A NAME="Destination">[text to jump to]</A>
Images must be in gif format (----.gif). Creating gif formats from other formats is dealt with in Section 8 (Using Xview...). To insert an image, include the statement:
<IMG ALIGN=TOP SRC="----.gif">where the image is to be placed. Note that ALIGN=TOP is optional and the default is bottom. This means that text next to the image will either be at the top or bottom of the image.
Linking to an image from hypertext:
In this case, an image will pop up when the hypertext is clicked upon. Use:
<A HREF="----.gif">[text to click on]</A>Linking to an image from another image:
Use the following statement:
<A HREF="----.gif"><IMG ALIGN=TOP SRC="----.gif"> </A>Note that the image preceeded by HREF will pop up when the other image is clicked upon.
Linking to a film:
Films must be in mpeg format (----.mpg). Use:
<A HREF="----.mpg"><IMG ALIGN=TOP SRC="----.gif"> </A>Note that in this case, the hypermedia is as image. Clicking on the image will call up the film. If the image is replaced with text, then clicking on the text will call up the movie. For example:
<A HREF="----.mpg">Click here for film. </A>
Go to the directory where the images to be modified are. Type xv. Now an xv window pops up. Click the right button on the window, and another window should pop up. Now click on "visual schnauzer", and a third window should pop up. Double click on any image file in this third window, and shortly, the image should appear on screen. Now, the size of the image can be manipulated by clicking on "set size" in the control panel. Enter the new dimensions or the percentage change. Note the change in image size. This new image can now be saved. Click on save; MAKE SURE TO SPECIFY GIF FORMAT AS HTML DOCUMENTS REQUIRE GIF FILES; specify the appropriate path and filename, and save. Note that the image size need not be changed to save the file to a different format. That's it!!!
A small version of an image may be included in a document with a hyperlink to the actual larger image. This improves loading time, and is less cluttersome on the Mosaic screeen. Also, it's pretty fun to click on an image to get a larger version of the image.
Typing "man assemble" yields: "assemble" assembles an nx by ny array of smaller images. The catch here is that all images being assembled have to have the same x/y dimensions. The nx by ny array works like this: nx is the number of images that are going to be sitting side by side in the horizontal direction, and ny is the number of images side by side in the vertical direction. Order imgfiles so that the first image will be the one sitting in the bottom left-hand corner of outimage, with the second sitting either above it or to its right. If fewer than nx times ny images are given on the command line, the last image is used repeatedly. The format for the command is:
assemble nx ny outimage imgfiles...
So, the command:
assemble 2 2 comp.rgb a.rgb b.rgb c.rgb d.rgbwill yield a composite image called comp.rgb which is a composite of images a.rgb, b.rgb, c.rgb, and d.rgb. Now the resulting rgb file can be converted to a gif file with Xview.