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.One interesting feature isthe ability to load images into a visual directory so you can see thumbnails of all images ina directory.Using the display command is easy, but you must be running the X WindowSystem.From a terminal command line, type the following:# display &This starts the program.To see a visual directory of your graphics, type the following:# display  vid:*.gif &This command line loads all.gif graphics in the current directory.Once the program starts,access its menus by pressing the left mouse button when your cursor is over the imageswindow.The display command imports and exports 58 different graphics formats.Theprogram features built-in help, and also can create slide shows of graphics (see Figure 16.2).Figure 16.2The display X11 client,included with theImageMagick softwarepackage, can be used tomake changes to manydifferent types of graphics.1 6Graphics Tools 253For more information about ImageMagick, see its manual page, and the manual pages forthe other programs in the distribution.Comprehensive hypertext documentation is underthe /usr/doc/ImageMagick directory.Using the xv Command to View GraphicsThexv command is a handy previewer used to review, crop, scale, edit, or convert graphics.This command offers many sophisticated sizing and color controls, and you also can use xv,found under the /usr/X11R6/bin directory, to capture windows of your X11 session (you1 6must run X11 in order to use the xv command).The xv command loads a single file or series of graphics if you specify the files on thecommand line:# xv *.jpgThis command line loads all files ending in.jpg in the current directory.After the files areloaded, scroll through a list of files to make your changes, or use a graphic directory to selectyour files (see Figure 16.3).Figure 16.3The xv command is anX11 client that loads,edits, captures, saves, orprints images, andfeatures sophisticatedcolor controls.The xv command can import and export 18 different graphics file formats, and also printsgraphics.For more information about using xv, see its manual page, or read the definitivedocumentation (128 pages in PostScript format, nearly as many as the xv command s 107command-line options!) found under the /usr/doc/xv directory.254 Hour 16Using the gv Command to View PostScript FilesThe gv command is a PostScript previewer used to examine or read PostScript graphics ordocuments before printing.You must run the X Window System to use this program.Thegv command, found under the /usr/X11R6/bin directory, is a much-improved previewer byJohannes Plass, and is based on the previous ghostview program by Tim Theilson (you ll finda symbolic link under /usr/X11R6/bin called ghostview, which points to gv).The gv command has more than 36 different command-line options, and uses a number ofX11 Toolkit options, such as geometry settings.You can start gv by itself, or specify a file onthe command line, along with its options:# gv -geometry 640x480 myfile.psThis command line starts the gv command in a 640 by 480 pixel window with the filemyfile.ps displayed.Another great feature of the gv command is that it reads portabledocument format, or.pdf files (see Figure 16.4).This is a handy way to read.pdf documentswithout installing an additional.pdf reader, such as Adobe Acrobat.Figure 16.4The gv X11 clientdisplays PostScript orPDF documents andgraphics, and provides aneasy-to-use interface topreviewing files beforeprinting.The gv command also uses a unique scrolling mechanism; instead of scrollbars alongside orbelow the document window, a rectangular button controls the document viewing area.Youalso can print whole documents or selected pages by using different commands.You ll find a comprehensive manual page, along with a hypertext series of.html files underthe /usr/doc/gv directory.1 6Graphics Tools 255Painting and Drawing with xpaint and xfigIf you need to create or edit simple bitmap graphics, use David Koblas xpaint program, foundunder the /usr/X11R6/bin directory.For technical drawing, you ll also find the xfig program,which uses drawing objects (with handles), rather than a flat canvas.The xpaint program features a floating control window with tools, and a separate canvaswindow with color palettes for selecting or mixing colors.The xpaint program has severaldifferent command-line options, and also can use a resource file, called.Xpaintrc (located1 6in your home directory), to customize colors and patterns.You can load graphics from thecommand line:# xpaint mygraphic.bmpThe xpaint program starts, presents the image in an editing window, and displays a floatingwindow of tools (see Figure 16.5).Xpaint imports eight and exports 10 different file formats.You also may have multiple windows with different images waiting to be edited.Figure 16.5The xpaint X11 client isa simple bitmap editingprogram with a fatbitsmode, multiple windows,and image filters.If you d rather work with a drawing program, try the xfig program (see Figure 16.6).Likexpaint, you must run X11 in order to use this program.You should have an X11 display ofat least 1024 pixels high by 768 pixels wide in order to use this program (although you canuse it with an 800-by-600 display, you ll miss some tools on the xfig window).Starting the xfig program is easy, and you can control the initial size of its drawing area byusing the -ph and -pw command-line options.For example,# xfig -ph 6 -pw 8 &256 Hour 16Figure 16.6The xfig drawingprogram, which runsunder X11, requires a1024x768 window, andcan be used to producetechnical drawings orother illustrations.This command line starts the xfig program with a canvas six inches high by eight inches wide.The xfig program features pop-up balloon help for its menus.You can use this program todraw intricate drawings or other illustrations you can later include in documents or graphics.The xfig program can import.gif,.jpeg,.pcx,.xpm and PostScript documents.Oneinteresting feature is its ability to spell check any text in your drawings.Customize xfig s default colors or keyboard commands by editing the files Fig-color and Figunder the /usr/X11/lib/X11/app-defaults directory.For more details about how to use xfig,see its manual page.A Word About ScannersAlthough Linux runs on many different computers and supports many different hardwaredevices, the state of scanner support is still in its infancy.Before you buy a scanner with theexpress purpose of using it with Linux, carefully check all Linux Internet sites for differentscanning software, and then carefully read the documentation.You ll find scanner support for many models from Nikon, Epson, Genius, Hewlett Packard,and Mustek.Although most scanners for Linux require a small computer system interface,or SCSI interface, you ll find support for the Connectix series of QuickCams using yourcomputer s parallel port.But there are variations between models of scanners even from thesame manufacturer, and not all models in a particular series of scanners may be supported [ Pobierz całość w formacie PDF ]