tk_imagechanged(3) [redhat man page]

Tk_ImageChanged(3)					       Tk Library Procedures						Tk_ImageChanged(3)

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NAME

       Tk_ImageChanged - notify widgets that image needs to be redrawn

SYNOPSIS

       #include <tk.h>

       Tk_ImageChanged(imageMaster, x, y, width, height, imageWidth, imageHeight)

ARGUMENTS

       Tk_ImageMaster imageMaster (in)		Token for image, which was passed to image's createProc when the image was created.

       int x (in)				X-coordinate  of upper-left corner of region that needs redisplay (measured from upper-left corner
						of image).

       int y (in)				Y-coordinate of upper-left corner of region that needs redisplay (measured from upper-left  corner
						of image).

       int width (in)				Width of region that needs to be redrawn, in pixels.

       int height (in)				Height of region that needs to be redrawn, in pixels.

       int imageWidth (in)			Current width of image, in pixels.

       int imageHeight (in)			Current height of image, in pixels.
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DESCRIPTION

       An  image manager calls Tk_ImageChanged for an image whenever anything happens that requires the image to be redrawn.  As a result of call-
       ing Tk_ImageChanged, any widgets using the image are notified so that they can redisplay themselves appropriately.  The	imageMaster  argu-
       ment  identifies the image, and x, y, width, and height specify a rectangular region within the image that needs to be redrawn.	imageWidth
       and imageHeight specify the image's (new) size.

       An image manager should call Tk_ImageChanged during its createProc to specify the image's initial size and to force redisplay if there  are
       existing  instances  for the image.  If any of the pixel values in the image should change later on, Tk_ImageChanged should be called again
       with x, y, width, and height values that cover all the pixels that changed.  If the size of the image should change,  then  Tk_ImageChanged
       must be called to indicate the new size, even if no pixels need to be redisplayed.

SEE ALSO

       Tk_CreateImageType

KEYWORDS

       images, redisplay, image size changes

Tk									4.0							Tk_ImageChanged(3)

Tk_GetImage(3)						       Tk Library Procedures						    Tk_GetImage(3)

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NAME

       Tk_GetImage, Tk_RedrawImage, Tk_SizeOfImage, Tk_FreeImage - 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

       Tcl_Interp *interp (in)			     Place to leave error message.

       Tk_Window tkwin (in)			     Window in which image will be used.

       const 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 compati-
						     ble 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.
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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  does  not  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_RedrawImage, 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

       Tk_CreateImageType

KEYWORDS

       images, redisplay

Tk									4.0							    Tk_GetImage(3)