World Library  
Flag as Inappropriate
Email this Article

X PixMap

Article Id: WHEBN0000522417
Reproduction Date:

Title: X PixMap  
Author: World Heritage Encyclopedia
Language: English
Subject: Xwd, Portable Network Graphics, XPM, Picon, Vtwm
Collection: Graphics File Formats, X Window System
Publisher: World Heritage Encyclopedia
Publication
Date:
 

X PixMap

X PixMap
Some text editors, for example gvim, can display xpm images in graphical form
Filename extension .xpm
Internet media type image/x‑xpixmap[1]
Developed by BULL Research
Type of format Image file formats
Extended from XBM
Open format? yes

X PixMap (XPM) is an image file format used by the X Window System, created in 1989 by Daniel Dardailler and Colas Nahaboo working at Bull Research Center at Sophia Antipolis, France, and later enhanced by Arnaud Le Hors.[2][3]

It is intended primarily for creating icon pixmaps, and supports transparent pixels. Derived from the earlier XBM syntax, it is a plain text file in the XPM2 format or of a C programming language syntax, which can be included in a C program file.[2]

Contents

  • XPM 1
  • XPM2 2
  • XPM3 3
  • Comparison with other formats 4
  • Application support 5
  • See also 6
  • References 7

XPM

The XPM format is an array of strings composed of six different sections as follows:

static char* [] = {




};

This is a black-and-white image in the first (1989) XPM format.

#define XFACE_format 1
#define XFACE_width 48
#define XFACE_height 48
#define XFACE_ncolors 2
#define XFACE_chars_per_pixel 1
static char *XFACE_colors[] = {
"a", "#ffffff",
"b", "#000000"
};
static char *XFACE_pixels[] = {
"abaabaababaaabaabababaabaabaababaabaaababaabaaab",
// and so on for 48 rows with 48 pixels

The values section contains the width, height, number of colors, and number of characters per pixel.

XPM2

XPM2 simplifies the format by removing all C codes. An example:

! XPM2
48 4 2 1
a c #FFFFFF
b c #000000
abaabaababaaabaabababaabaabaababaabaaababaabaaab
abaabaababaaabaabababaabaabaababaabaaababaabaaab
abaabaababaaabaabababaabaabaababaabaaababaabaaab
abaabaababaaabaabababaabaabaababaabaaababaabaaab

This is an XPM2 file with width 48, height 4, 2 colors, and 1 character per pixel. One tool is known to use only a to p for 16 colors, switching to aa up to dp for 64 colors, but still reading single character encodings for 64 colors; compare Base64.

With more colors the codes use more characters, e.g. aa up to pp for 16 × 16 = 256 colors. This is less useful for text editors, because a string ab could be actually the middle of two adjacent pixels dabc. Spaces are allowed as color code, but might be a bad idea depending on the used text editor. Without control codes, space, and quote (needed in XPM1 and XPM3) 128 − 33 − 2 = 93 ASCII characters are available for single character color codes.

Simplified example: 90 US-ASCII characters could be arranged into nine non-overlapping sets of 10 characters. Thus unambiguous strings of nine characters could set the color of each pixel by its XPM palette index with up to 109 = 1000000000 colors (compare to GIF, which supports only 256).

For XPM2 it is clear how many lines belong to the image – two header lines, the second header line announcing the number of color codes (2 lines in the example above) and rows (height 4 in the example above), e.g. 2 + 2 + 4 = 8 lines.

XPM3

The other styles XPM1 and XPM3 are designed to be used as is in C source code, example:

/* XPM */
static char * XFACE[] = {
/*  */
/*    */
"48 4 2 1",
/*  */
"a c #ffffff",
"b c #000000",
/*  */
"abaabaababaaabaabababaabaabaababaabaaababaabaaab",
"abaabaababaaabaabababaabaabaababaabaaababaabaaab",
"abaabaababaaabaabababaabaabaababaabaaababaabaaab",
"abaabaababaaabaabababaabaabaababaabaaababaabaaab"
};

The latter format is XPM3, the common format used for the X Window System since about 1991. The c means "color", it's possible to add m for "monochrome" output, g for "grayscale", and s for "symbolic", explaining what a defined color is supposed to do.

In addition to the X11 color names the name none indicates transparency.[4][5]

The "symbolic" feature permits adjusting colors depending on the context where they are used. Code such as s border c blue could be adjusted on a blue background.

If the width, height, colors, and characters per pixel line contains six instead of four numbers, the additional values indicate the coordinates of a "hotspot", 0 0 is the upper left corner of a box containing the icon and the default. A "hotspot" is used for mouse pointers and similar applications.

Comparison with other formats

Blarg file opened in program window

The following code displays the same blarg file in the XBM, XPM and PBM formats.

XBM version:

#define test_width 16
#define test_height 7
static char test_bits[] = {
0x13, 0x00, 0x15, 0x00, 0x93, 0xcd, 0x55, 0xa5, 0x93, 0xc5, 0x00, 0x80,
0x00, 0x60 };

XPM3 version:

/* XPM */
static char * blarg_xpm[] = {
"16 7 2 1",
"* c #000000",
". c #ffffff",
"**..*...........",
"*.*.*...........",
"**..*..**.**..**",
"*.*.*.*.*.*..*.*",
"**..*..**.*...**",
"...............*",
".............**."
}
Blarg.xpm (XPM2) rendered by XnView

XPM2 version:

! XPM2
16 7 2 1
* c #000000
. c #ffffff
**..*...........
*.*.*...........
**..*..**.**..**
*.*.*.*.*.*..*.*
**..*..**.*...**
...............*
.............**.

PBM file:

P1
16 7
1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0
1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0
1 1 0 0 1 0 0 1 1 0 1 1 0 0 1 1
1 0 1 0 1 0 1 0 1 0 1 0 0 1 0 1
1 1 0 0 1 0 0 1 1 0 1 0 0 0 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0

Application support

ACDSee, Amaya, CorelDRAW, GIMP, ImageMagick, IrfanView (formats plugin), PaintShop Pro, Photoshop (plugins), and XnView among others support XPM.[6][7] Gravatar and picons also support XPM.[8][9]

An X11 libXpm vulnerability was fixed in 2005.[10]

See also

References

  1. ^ .xpm MIME type not registered at IANA
  2. ^ a b Le Hors, Arnaud (1996-02-01). XPM Manual: The X PixMap Format (PDF).  
  3. ^ Daniel Dardailler (1996-07-15). "The XPM Story". Colas Nahaboo and Arnaud Le Hors. Retrieved 2014-01-01. 
  4. ^ "The XPM FAQ".  
  5. ^ "XPM File Format Summary". Encyclopedia of Graphics File Formats, 2nd Edition.  
  6. ^ Nir Sofer. ".xpm Extension". Retrieved 2014-01-12. 
  7. ^ "File Type: X Windows Pixmap". Windows File Association.  
  8. ^ Gravatar unofficial, no XPM2
  9. ^  
  10. ^ "libXpm library contains multiple integer overflow vulnerabilities".  
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.