photo.n

linux系统下的音频通信

'\"
'\" Copyright (c) 1994 The Australian National University
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" Author: Paul Mackerras ([e-mail]),
'\"	    Department of Computer Science,
'\"	    Australian National University.
'\"
'\" "@(#) photo.n 1.12 97/10/14 10:52:30"
'\" 
.so man.macros
.TH photo n 4.0 Tk "Tk Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
photo \- Full-color images
.SH SYNOPSIS
\fBimage create photo \fR?\fIname\fR? ?\fIoptions\fR?
.BE

.SH DESCRIPTION
.PP
A photo is an image whose pixels can display any color or be
transparent.  A photo image is stored internally in full color (24
bits per pixel), and is displayed using dithering if necessary.  Image
data for a photo image can be obtained from a file or a string, or it
can be supplied from
C code through a procedural interface.  At present, only GIF and PPM/PGM
formats are supported, but an interface exists to allow additional
image file formats to be added easily.  A photo image is transparent
in regions where no image data has been supplied.

.SH "CREATING PHOTOS"
.PP
Like all images, photos are created using the \fBimage create\fR
command.
Photos support the following \fIoptions\fR:
.TP
\fB\-data \fIstring\fR
Specifies the contents of the image as a string.  The format of the
string must be one of those for which there is an image file format
handler that will accept string data.  If both the \fB\-data\fR
and \fB\-file\fR options are specified, the \fB\-file\fR option takes
precedence.
.TP
\fB\-format \fIformat-name\fR
Specifies the name of the file format for the data specified with the
\fB\-data\fR or \fB\-file\fR option.
.TP
\fB\-file \fIname\fR
\fIname\fR gives the name of a file that is to be read to supply data
for the photo image.  The file format must be one of those for which
there is an image file format handler that can read data.
.TP
\fB\-gamma \fIvalue\fR
Specifies that the colors allocated for displaying this image in a
window should be corrected for a non-linear display with the specified
gamma exponent value.  (The intensity produced by most
CRT displays is a power function of the input value, to a good
approximation; gamma is the exponent and is typically around 2).
The value specified must be greater than zero.  The default
value is one (no correction).  In general, values greater than one
will make the image lighter, and values less than one will make it
darker.
.TP
\fB\-height \fInumber\fR
Specifies the height of the image, in pixels.  This option is useful
primarily in situations where the user wishes to build up the contents
of the image piece by piece.  A value of zero (the default) allows the
image to expand or shrink vertically to fit the data stored in it.
.TP
\fB\-palette \fIpalette-spec\fR
Specifies the resolution of the color cube to be allocated for
displaying this image, and thus the number of colors used from the
colormaps of the windows where it is displayed.  The
\fIpalette-spec\fR string may be either a single decimal number,
specifying the number of shades of gray to use, or three decimal
numbers separated by slashes (/), specifying the number of shades of
red, green and blue to use, respectively.  If the first form (a single
number) is used, the image will be displayed in monochrome (i.e.,
grayscale).
.TP
\fB\-width \fInumber\fR
Specifies the width of the image, in pixels.    This option is useful
primarily in situations where the user wishes to build up the contents
of the image piece by piece.  A value of zero (the default) allows the
image to expand or shrink horizontally to fit the data stored in it.

.SH "IMAGE COMMAND"
.PP
When a photo image is created, Tk also creates a new command
whose name is the same as the image.
This command may be used to invoke various operations
on the image.
It has the following general form:
.CS
\fIimageName option \fR?\fIarg arg ...\fR?
.CE
\fIOption\fR and the \fIarg\fRs
determine the exact behavior of the command.
.PP
Those options that write data to the image generally expand the size
of the image, if necessary, to accommodate the data written to the
image, unless the user has specified non-zero values for the
\fB\-width\fR and/or \fB\-height\fR configuration options, in which
case the width and/or height, respectively, of the image will not be
changed.
.PP
The following commands are possible for photo images:
.TP
\fIimageName \fBblank\fR
Blank the image; that is, set the entire image to have no data, so it
will be displayed as transparent, and the background of whatever
window it is displayed in will show through.
.TP
\fIimageName \fBcget\fR \fIoption\fR
Returns the current value of the configuration option given
by \fIoption\fR.
\fIOption\fR may have any of the values accepted by the
\fBimage create photo\fR command.
.TP
\fIimageName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR?
Query or modify the configuration options for the image.
If no \fIoption\fR is specified, returns a list describing all of
the available options for \fIimageName\fR (see \fBTk_ConfigureInfo\fR for
information on the format of this list).  If \fIoption\fR is specified
with no \fIvalue\fR, then the command returns a list describing the
one named option (this list will be identical to the corresponding
sublist of the value returned if no \fIoption\fR is specified).  If
one or more \fIoption\-value\fR pairs are specified, then the command
modifies the given option(s) to have the given value(s);  in
this case the command returns an empty string.
\fIOption\fR may have any of the values accepted by the
\fBimage create photo\fR command.
.TP
\fIimageName \fBcopy\fR \fIsourceImage\fR ?\fIoption value(s) ...\fR?
Copies a region from the image called \fIsourceImage\fR (which must
be a photo image) to the image called \fIimageName\fR, possibly with
pixel zooming and/or subsampling.  If no options are specified, this
command copies the whole of \fIsourceImage\fR into \fIimageName\fR,
starting at coordinates (0,0) in \fIimageName\fR.  The following
options may be specified:
.RS
.TP
\fB\-from \fIx1 y1 x2 y2\fR
Specifies a rectangular sub-region of the source image to be copied.
(\fIx1,y1\fR) and (\fIx2,y2\fR) specify diagonally opposite corners of
the rectangle.  If \fIx2\fR and \fIy2\fR are not specified, the
default value is the bottom-right corner of the source image.  The
pixels copied will include the left and top edges of the specified
rectangle but not the bottom or right edges.  If the \fB\-from\fR
option is not given, the default is the whole source image.
.TP
\fB\-to \fIx1 y1 x2 y2\fR
Specifies a rectangular sub-region of the destination image to be
affected.  (\fIx1,y1\fR) and (\fIx2,y2\fR) specify diagonally opposite
corners of the rectangle.  If \fIx2\fR and \fIy2\fR are not specified,
the default value is (\fIx1,y1\fR) plus the size of the source
region (after subsampling and zooming, if specified).  If \fIx2\fR and
\fIy2\fR are specified, the source region will be replicated if
necessary to fill the destination region in a tiled fashion.
.TP
\fB\-shrink\fR
Specifies that the size of the destination image should be reduced, if
necessary, so that the region being copied into is at the bottom-right
corner of the image.  This option will not affect the width or height
of the image if the user has specified a non-zero value for the
\fB\-width\fR or \fB\-height\fR configuration option, respectively.
.TP
\fB\-zoom \fIx y\fR