Image(3pm) User Contributed Perl Documentation Image(3pm)NAMETk::Image - Create and manipulate images
SYNOPSIS
$image = $widget->type(?arg arg ...?)
$image->method(?arg arg ...?)
DESCRIPTION
The image constructors and methods are used to create, delete, and
query images. It can take several different forms, depending on the
type.
The constructors require a $widget to invoke them, this is used to
locate a MainWindow. (This is because the underlying Tk code registers
the images in the data structure for the MainWindow.)
The legal forms are:
$widget->type?(?name?,?option=>value ...)?
Creates a new image and returns an object. type specifies the type
of the image, which must be one of the types currently defined
(e.g., Bitmap). name specifies the name for the image; if it is
omitted then Tk picks a name of the form imagex, where x is an
integer. There may be any number of option=>value pairs, which
provide configuration options for the new image. The legal set of
options is defined separately for each image type; see below for
details on the options for built-in image types. If an image
already exists by the given name then it is replaced with the new
image and any instances of that image will redisplay with the new
contents.
$image->delete
Deletes the image $image and returns an empty string. If there are
instances of the image displayed in widgets, the image won't
actually be deleted until all of the instances are released.
However, the association between the instances and the image
manager will be dropped. Existing instances will retain their
sizes but redisplay as empty areas. If a deleted image is
recreated (with the same name) the existing instances will use the
new image.
$image->height
Returns a decimal string giving the height of image name in pixels.
$image->inuse
Returns a boolean value indicating whether or not the image is in
use by any widgets.
$widget->imageNames
Returns a list containing all existing images for $widget's
MainWindow.
$image->type
Returns the type of $image (the value of the type method when the
image was created).
$widget->imageTypes
Returns a list whose elements are all of the valid image types
(i.e., all of the values that may be supplied for the type to
create an image).
$image->width
Returns a decimal string giving the width of image name in pixels.
BUILT-IN IMAGE TYPES
The following image types are defined by Tk so they will be available
in any Tk application. Individual applications or extensions may
define additional types.
Bitmap
Each pixel in the image displays a foreground color, a background
color, or nothing. See Tk::Bitmap for more information.
Pixmap
Pixmap is slightly more general than Bitmap, each pixel can be any
available color or "transparent" (rendered as background color of
the widget image is displayed in). Pixmap is best used for icons
and other simple graphics with only a few colors.
Pixmap is derived from Tix. See Tk::Pixmap for more information.
Photo
Displays a variety of full-color images, using dithering to
approximate colors on displays with limited color capabilities.
See Tk::Photo documentation for more information.
CAVEATS
It's necessary to use the "delete" method to delete an image object and
free memory associated with it. Just using a lexical variable for
storing the image object and letting the variable to go out of scope or
setting to "undef" is not sufficient.
SEE ALSO
Tk::Bitmap Tk::Pixmap Tk::Photo
KEYWORDS
height, image, types of images, width
perl v5.26.0 2017-07-22 Image(3pm)
