Geared toward Perl users and webmasters, Perl Graphics Programming and PDF--then you'll explore the most powerful tools and Perl modules available for. Perl Graphics Programming. Shawn Wallace Part I. Raster Images and Web Graphics. 1. Creating Creating PDF Documents with Perl. Perl. Graphics. Programming. Shawn Wallace. Creating SVG, SWF (Flash), JPEG , and PNG The Perl interface consists of 14 modules in the SWF namespace.
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Graphics Programming with Perl is a guide to the graphics and imaging modules and tools available to the Perl programmer. It covers subjects ranging from. Graphics Programming with Perl - Manning pdf - Ebook download as PDF File .pdf), Text File .txt) or read book online. How to Write a Better Thesis What Is a Thesis? David Evans†, Paul Gruba, Justin Zobel · Download PDF Chapter. Page.
However, this software reaches its limits if you want advanced tasks such as combining different PDF documents into one single document or adding and adjusting the bookmarks panel for better navigation. Imagine that you want to collect all relevant Perl. In most cases you would not be satisfied by the resulting bookmarks panel, either. The following listing should be rather self explanatory.
Between those two calls, add text with the prText command. You can also draw graphics by using the low level command prAdd with plain PDF markup as parameter. Start a new page with prPage. Be aware that for the prText x,y,Text command the origin of the coordinate system is on the left bottom of the page. As an example of adding PDF markup with prAdd, the code creates a red rectangle with blue borders.
In case you would like to add more graphics or complex graphics to your PDF, you can study the examples of the PDF reference manual. The next example assembles a new file from the example material.
Omit both to add the entire document. Finally, prEnd closes the file. Suppose that you have a file customer. Now you can write a short program to add the date and the names and addresses of your customers to the letter.
Set the font size with prFontSize. The default font is Helvetica, with 12 pixel size. The rest of the code is a simple loop over the file containing the customer data to filling the template with prText.
Adding Page Numbers Sometimes you need only make a small change to a document, such as adding missing page numbers. The command-line application will interact with this package instead of directly working on PDF::Reuse.
Perl programmers naturally turn to Perl to tackle whatever challenge they have at hand, and graphics programming is no exception. Perl Graphics Programming provides all the tools you need to begin programming and designing graphics for the Web immediately. This book will change how you think about generating and manipulating graphics for the Web. About the Author: has been applying computers to graphics problems for the past fifteen years.
A programmer and artist, Shawn is managing director of the AS www.
He is also involved in the Bolero open source music notation system www. Because of Perls gluing ability, there are several interfaces to graphics manipulation libraries and programs available in the form of modules.
Other packages have been written that make use of these modules to create graphics at a higher level, for example to create charts. Together, the number of these tools has grown sufficiently to allow the tackling of many graphics programming tasks in Perl.
CHAPTER 1 Apart from the reasons just mentioned, Perl is also an attractive language with which to program, because of its flexible grammar, the large number of built-in tools and the variety of syntactical constructions. Perl can be used as a tool to quickly hack together a program that parses sets of log files, and gives some nice summaries and graphs with which to create a report. It can also be used to write large software projects, maintained by several programmers and developed over the course of a year or more.
Perl is duct tape, but it is very flexible duct tape. As a side note to the number crunching: Moores law states that every two years the average speed of electronic computers doubles. Even if you generalize that to all computing, as Ray Kurzweil does in The Age of the Spiritual Machine , this law holds remarkably well from all the way back in the nineteenth century to today.
This means that while Perl might be too slow for many tasks in computer graphics manipulation on todays computers, this will probably not hold true on computers in the not too distant future.
The demands on programs that manipulate computer graphics will probably flatten out at some point, once the resolution of what is created is higher than the resolution of the human eye. At the same time, the increase in computing power will continue. Even if you dont believe this, the other reasons already stated are more than enough to see Perl as a valid programming language in the computer graphics world, if not generally, then at least for some tasks.
Most of these modules were, in fact, born as C libraries or programs, and their original authors probably didnt have Perl in mind at all when they wrote them. All the number crunching, array manipulation and bit-shifting happens in compiled low level code, and therefore is much faster than could be achieved in pure Perl.
This does not mean that you cannot, under any circumstance, use Perl to directly manipulate pixels in an image.
Chapter 12 gives a few examples of how to do this in pure Perl, but be forewarned that it will not be blindingly fast. The same chapter also explains how to write parts of your program in C, by including the C code directly in your program.
This allows you to escape Perls slowness when you need to, without losing any of its advantages.
Summarizing: while Perl isnt particularly suitable for low-level computer graphics manipulation, there are many modules available that make the most common graphics manipulation and creation task available to a Perl programmer. In cases where the need is to jump down to a low level and do some computationally intensive programming, Perl provides access to lower-level languages without too much fuss.
Of course, if the majority of a program consists of these tasks, a language other than Perl should probably be considered. First of all there is the canvas, which is the medium that is being drawn on, or read from. In PostScript, for example, this is a page or part of a page, and for image manipulation packages such as GD this is a two-dimensional array of pixels.
It is important to note that a canvas can be part of another canvas, and that certain images can be built up of multiple canvases, such as the layers and channels in a GIMP image. A second element common to all graphics operations is a frame of reference expressed in coordinates.
This indicates where on the canvas an object is located or an operation takes place. Most commonly these coordinates are Cartesian, with a horizontal and a vertical component, but sometimes it is easier to use polar coordinates see, for example, section Thirdly, there are the objects which are being drawn or manipulated, e.
Most of the time these objects will have one or more handles, which express their center or top left corner, and some dimensions. The fourth element consists of the tools used for drawing. These can be a brush, a stamp, an eraser, a paint bucket or even a filter.
These are normally found on icon bars in interactive drawing programs, but they also exist in noninteractive programming packages.