Tk_GetImage (3)
use an image in a widget
SYNOPSIS
#include <tk.h>
Tk_Image
Tk_GetImage(interp, tkwin, name, changeProc, clientData)
Tk_RedrawImage(image, imageX, imageY, width, height, drawable, drawableX, drawableY)
Tk_SizeOfImage(image, widthPtr, heightPtr)
Tk_FreeImage(image)
ARGUMENTS
Tk_ImageChangedProc *changeProc
Tcl_Interp *interp in
Place to leave error message.
Tk_Window tkwin in
Window in which image will be used.
char *name in
Name of image.
Tk_ImageChangedProc *changeProc in
Procedure for Tk to invoke whenever image content or size changes.
ClientData clientData in
One-word value for Tk to pass to changeProc.
Tk_Image image in
Token for image instance; must have been returned by a previous
call to Tk_GetImage.
int imageX in
X-coordinate of upper-left corner of region of image to redisplay
(measured in pixels from the image's upper-left corner).
int imageY in
Y-coordinate of upper-left corner of region of image to redisplay
(measured in pixels from the image's upper-left corner).
"int" width (in)
Width of region of image to redisplay.
"int" height (in)
Height of region of image to redisplay.
Drawable drawable in
Where to display image. Must either be window specified to
Tk_GetImage or a pixmap compatible with that window.
int drawableX in
Where to display image in drawable: this is the x-coordinate
in drawable where x-coordinate imageX of the image
should be displayed.
int drawableY in
Where to display image in drawable: this is the y-coordinate
in drawable where y-coordinate imageY of the image
should be displayed.
"int" widthPtr out
Store width of image (in pixels) here.
"int" heightPtr out
Store height of image (in pixels) here.
DESCRIPTION
These procedures are invoked by widgets that wish to display images.
Tk_GetImage is invoked by a widget when it first decides to
display an image.
name gives the name of the desired image and tkwin
identifies the window where the image will be displayed.
Tk_GetImage looks up the image in the table of existing
images and returns a token for a new instance of the image.
If the image doesn't exist then Tk_GetImage returns NULL
and leaves an error message in interp->result.
When a widget wishes to actually display an image it must
call Tk_RedrawWidget, identifying the image (image),
a region within the image to redisplay (imageX, imageY,
width, and height), and a place to display the
image (drawable, drawableX, and drawableY).
Tk will then invoke the appropriate image manager, which will
display the requested portion of the image before returning.
A widget can find out the dimensions of an image by calling
Tk_SizeOfImage: the width and height will be stored
in the locations given by widthPtr and heightPtr,
respectively.
When a widget is finished with an image (e.g., the widget is
being deleted or it is going to use a different image instead
of the current one), it must call Tk_FreeImage to
release the image instance.
The widget should never again use the image token after passing
it to Tk_FreeImage.
There must be exactly one call to Tk_FreeImage for each
call to Tk_GetImage.
If the contents or size of an image changes, then any widgets
using the image will need to find out about the changes so that
they can redisplay themselves.
The changeProc and clientData arguments to
Tk_GetImage are used for this purpose.
changeProc will be called by Tk whenever a change occurs
in the image; it must match the following prototype:
typedef void Tk_ImageChangedProc(
ClientData clientData,
int x,
int y,
int width,
int height,
int imageWidth,
int imageHeight);
The clientData argument to changeProc is the same as the
clientData argument to Tk_GetImage.
It is usually a pointer to the widget record for the widget or
some other data structure managed by the widget.
The arguments x, y, width, and height
identify a region within the image that must be redisplayed;
they are specified in pixels measured from the upper-left
corner of the image.
The arguments imageWidth and imageHeight give
the image's (new) size.
SEE ALSO
KEYWORDS
images, redisplay
'\"
'\" Copyright (c) 1995-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
'\" RCS: @(#) $Id: StrictMotif.3,v 1.2 1998/09/14 18:22:54 stanton Exp $
'\"
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\" Start paragraph describing an argument to a library procedure.
'\" type is type of argument (int, etc.), in/out is either "in", "out",
'\" or "in/out" to describe whether procedure reads or modifies arg,
'\" and indent is equivalent to second arg of .IP (shouldn't ever be
'\" needed; use .AS below instead)
'\"
'\" .AS ?type? ?name?
'\" Give maximum sizes of arguments for setting tab stops. Type and
'\" name are examples of largest possible arguments that will be passed
'\" to .AP later. If args are omitted, default tab stops are used.
'\"
'\" .BS
'\" Start box enclosure. From here until next .BE, everything will be
'\" enclosed in one large box.
'\"
'\" .BE
'\" End of box enclosure.
'\"
'\" .CS
'\" Begin code excerpt.
'\"
'\" .CE
'\" End code excerpt.
'\"
'\" .VS ?version? ?br?
'\" Begin vertical sidebar, for use in marking newly-changed parts
'\" of man pages. The first argument is ignored and used for recording
'\" the version when the .VS was added, so that the sidebars can be
'\" found and removed when they reach a certain age. If another argument
'\" is present, then a line break is forced before starting the sidebar.
'\"
'\" .VE
'\" End of vertical sidebar.
'\"
'\" .DS
'\" Begin an indented unfilled display.
'\"
'\" .DE
'\" End of indented unfilled display.
'\"
'\" .SO
'\" Start of list of standard options for a Tk widget. The
'\" options follow on successive lines, in four columns separated
'\" by tabs.
'\"
'\" .SE
'\" End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
'\" Start of description of a specific option. cmdName gives the
'\" option's name as specified in the class command, dbName gives
'\" the option's name in the option database, and dbClass gives
'\" the option's class in the option database.
'\"
'\" .UL arg1 arg2
'\" Print arg1 underlined, then print arg2 normally.
'\"
'\" RCS: @(#) $Id: man.macros,v 1.2 1998/09/14 18:39:54 stanton Exp $
'\"
'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
t .wh -1.3i ^B
^l \n(.l
b
'\" # Start an argument description
AP
!"\\$4"" .TP \\$4
\{\
!"\\$2"" .TP \\n()Cu
.TP 15
|
