Tk::JThumbnail - Present a list of files in a directory as a grid of icons with or without text.

- NAME
- AUTHOR
- ACKNOWLEDGEMENTS
- LICENSE AND COPYRIGHT
- SYNOPSIS
- EXAMPLE
- DESCRIPTION
- METHODS
- NOTES
- KEYWORDS
- DEPENDS
- SEE ALSO

# NAME

Tk::JThumbnail - Present a list of files in a directory as a grid of icons with or without text.

# AUTHOR

Jim Turner

(c) 2019, Jim Turner under the same license that Perl 5 itself is. All rights reserved.

# ACKNOWLEDGEMENTS

Derived from Tk::Thumbnail, by Stephen O. Lidie (Copyright (C) 2001 - 2005, Steve Lidie. All rights reserved.)

# LICENSE AND COPYRIGHT

Copyright (c) 2019 Jim Turner.

Tk::JThumbnail is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

# SYNOPSIS

            my $thumb = $parent->JThumbnail(-option => value, ... );

# EXAMPLE

            #!/usr/bin/perl -w

            use strict;
            use Tk;
            use Tk::JThumbnail;

            my $mw = MainWindow->new;
            my @list = directory($ARGV[0] || '.');  #Directory to fetch files from.

            my $thumb = $mw->Scrolled('JThumbnail',
                            -images => \@list,
                            -width => 500,
                            -scrollbars => 'osoe',
                            -highlightthickness => 1,
                            -focus => 2,
                            -nodirs => 1,
            )->pack(-side => 'top', -expand => 1, -fill => 'both');

            $thumb->Subwidget('yscrollbar')->configure(-takefocus => 0);
            $thumb->Subwidget('xscrollbar')->configure(-takefocus => 0);
            $thumb->Subwidget('corner')->Button(
                            -bitmap => $Tk::JThumbnail::CORNER,
                            -borderwidth => 1,
                            -takefocus => 0,
                            -command => [\&cornerjump, $thumb],
            )->pack;

            my $b2 = $mw->Button(
                            -text=>'E~xit',
                            -command => sub{
                                            print "ok, bye.\n";
                                            exit(0)
                            }
            )->pack(qw/-side top/);

            #EXAMPLE CALLBACK BINDING (RIGHT MOUSE-BUTTON):
            $thumb->bindImages('<ButtonRelease-3>' => [\&RighClickFunction]);

            $thumb->focus();

            MainLoop;

            exit(0);

            sub RighClickFunction  #CALLBACK BOUND TO RIGHT MOUSE-BUTTON:
            {
                    my $self = pop;

                    my $indx = $self->index('mouse');
                    my $fn = $self->get($indx);
                    print "---You right-clicked on file ($fn) at position: $indx!\n";
            }

            sub cornerjump   #CALLBACK WHEN "CORNER" BUTTON PRESSED:
            {
                    my $self = shift;

                    $self->activate($self->index('active') ? 0 : 'end');
            }

            sub directory   #FETCH LIST OF IMAGE FILES TO BE DISPLAYED:
            {
                    my ($dir) = @_;
                    chdir($dir);
                    $dir .= '/'  unless ($dir =~ m#\/#);
                    my $pwd = `pwd`; chomp $pwd;
                    $mw->title ("Directory: $pwd");
                    opendir (DIR, ".") or die "Cannot open '.': $!\n";
                    my @files = ();
                    foreach my $name (readdir(DIR)) {
                            my $st = stat($name);
                            next  unless ($st);
                            push @files, $name;
                    }
                    return sort @files;
            }

# DESCRIPTION

Tk::JThumbnail is derived from the old Tk::Thumbnail widget. The reason for this fork is to:

1) Fix some issues including an FTBFS to run in modern Perl 5.

2) Add some features needed to use in my JFM5 Filemanager to provide it with a "graphical" option of displaying files in a directory with thumbnail images (including icons based on file extension), along with the other ("text") option uses my Tk::HMListbox widget, similarly derived from the older Tk::MListbox. (JFM5 is derived from my JFM4 filemanager, but adds an icon-view using THIS module)!

The main new features are:

1) Ability to display an alternate icon for non-image files, based on their file-extension.

2) Ability to "select" images (files) for further processing (as is done in a file-manager).

3) Ability to bind both mouse and keyboard operatons to the individual images allowing for right-clicking, shift-clicking, dragging to select / unselect images, keyboard-traversal via arrow-keys, etc.

4) Added method compatability with Tk::HMListbox methods needed by a filemanager (JFM5 in particular) to allow for both to be swapped in and out with very similar code, while minimizing changes needed for giving the file-manager user the ability to display files either in line-detail mode (Tk::HMListbox) or icon-mode (Tk::JThumbnail) and interact on them in a similar fashon.

5) A "default" (fail-through) image added for display when a non-image file is encountered or an image file that can not be properly rendered. This file is in images/ and is called "failimg.png", and can be replaced with whatever default image you wish to use (must be named "failimg.png").

6) Perl can CRASH (segfault) if a .xpm image containing the C comment string "/*" is processed - OUCH! We work around this now by reading in .xpm images and converting this string to something harmless.

The original relevant Tk::Thumbnail documentation, including our additions follows below:

Create a table of thumbnail images, having a default size of 32 x 32 pixels. Once we have a Photo of an image, shrink it by copying a subsample of the original to a blank Photo. Images smaller than the thumbnail dimensions are enlarged by zooiming.

Clicking on an image displays it full-size in a separate window with a "Get Info" button. The info window shows the image's width, height, path name, size and frame count.

For multi-frame GIFs the image is shown with an extra button to play / stop the animation.

-blank

  For animated GIFs, a boolean specifying whether to blank the animation photo between movie frames. Default is now 0 (FALSE). This flag is passed to Tk::Animation's set_disposal_method().

-columns

  Number of Photos per row. The column count is computed if not specified. Default: computed to mostly form a square (columns == rows).

-command

  A Legacy callback that's executed on a <Button-1> event over a thumbnail image. It's passed 2 arguments: the thumbnail widget itself, and the index of the image clicked on (or the active image if <Return> key pressed. In Tk::Thumbnail It was passed six arguments: the Label widget reference containing the thumbnail Photo image, the file name of the Photo, a boolean indicating whether or not the the Photo is valid, the Photo's pixel width and height, and a boolean indicating whether the image is a single frame (Tk::Photo) or has multiple frames (Tk::Animation); but now this information can be fetched form the hash referenced by $self->{'data'}[$index] where $self and $index represent the two arguments passed in.

  A default callback is provided that simply displays the original image in a new Toplevel widget, along with a Get Info Button that opens another Toplevel containing information about the image. For multi-frame GIFs the image is shown with an extra button to play / stop the animation.

  To override this default <Button-1> callback, use the bindImages() function to set your own, or set -command => undef to have no <Button-1> callback.

  Example: $thumb->bindImages('<Button-1>' => [\&mycallbackfn [, args] ]);

-extimages

  JThumbnail-added feature: Optional reference to a hash of icon images to be displayed for non-image files. The hash keys are file extensions and the values image files for the icons. Default: {} (none).

  Example: {'txt' => '/usr/local/pixmaps/texticon.png', 'pdf' => '/usr/local/pixmaps/adobe.jpg' [, ...]}

  Special keys are: '' for files with no or unrecognized extension, and 'dir' for directories.

-focus

  JThumbnail-added feature: Specify the focusing model. Valid values are:

  0: Never take keyboard focus (and skip in the main window's tab-focusing order).

  1: Take focus when tabbed to from the main window (normal "-takefocus => 1" action for Tk widgets).

  2: Also take keyboard focus whenever an icon in the widget or the widget itself is clicked on.

  Default: 1.

-font

  The default font is fixed.

-highlightthickness

  Set the frame border around the images, becomes visible when widget has keyboard focus. Default 0 (none). Recommended: 1 (pixel wide).

-ilabels

  A boolean, set to TRUE if you want file names displayed under the thumbnail images. Default TRUE.

-images

  A list (reference) of file names and/or Photo widgets. JThumbnail creates temporarty Photo images from all the files, and destroys them when the JThumbnail is destroyed or when a new list of images is specified in a subsequent configure call. Already existing Photos are left untouched.

-iheight

  Pixel height of the thumbnails. Default is 32. The special value -1 means don't shrink images in the Y direction.

-iwidth

  Pixel width of the thumbnails. Default is 32. The special value -1 means don't shrink images in the X direction.

-nodirs

  JThumbnail-added feature: Do not include directories in the list. Default 0 (FALSE) - include them.

-noexpand

  JThumbnail-added feature: If set to TRUE, Do not zoom tiny images (smaller than -iwidth x -iheight) to fill those dimensions, but keep their original size. Default is 0 (FALSE) - zoom (expand) them until one dimension fills that space (aspect maintained), as Tk::Thumbnail does.

-selectbackground

  JThumbnail-added feature: Set a different background color for images that are "selected". Default: the palette's "readonlyBackground" or "highlightBackground", or, if those are the same as the current background, a different shade of gray will be used.

-selected

  JThumbnail-added feature: Optional reference to a list of boolean values corresponding to the indicies of images to be marked as currently "selected". Default: [] (none).

  Example: To select the first and fifth images: -selected => [1,0,0,0,1]

  All images beyond the fifth will not be selected.

-takefocus

  NOTE: DO NOT USE (it doesn't work properly)! Instead use the -focus option, see above:

# METHODS

$thumb->activate(index);

  JThumbnail-added feature: Sets the active element to the one indicated by index. If index is outside the range of elements in the list then undef is returned. The active element is drawn with a ridge around it, and its index may be retrieved with the index 'active'.

$thumb->bindImages(sequence, callback);

  JThumbnail-added feature: Adds the binding to all images in the widget. This is needed because normal events to the main widget itself are NOT passed down to the image subwidgets themselves.

$thumb->bindRows(sequence, callback);

  JThumbnail-added feature: Synonym for bindImages for compatability in file-managers, etc. that use both this and Tk::HMListbox interchangability for displaying directory contents. Other that that, it really has nothing to do with "rows".

$thumb->clear();

  Destroys all Frames and Labels, and deletes all the temporary Photo images, in preparation for re-populating the JThumbnail with new data.

$thumb->curselection();

  JThumbnail-added feature: Returns a list containing the numerical indices of all of the elements in the HListbox that are currently selected. If there are no elements selected in the listbox then an empty list is returned.

$thumb->get(index);

  JThumbnail-added feature: Returns the file-name of the image specified by index. index can be either a number, 'active', or 'end'.

$thumb->getRow(index)

  JThumbnail-added feature: In scalar context, returns the file-name of the image specified by index. In list context, returns an array with the following elements:

  [0]: Hash-reference to the detailed data-elements saved for each image.

  [1]: The file-name of the image.

  [2]: Directory indicator: either 'd' if image file is a directory, or '-' if not. This is from the first character of an "ls -l" list and is this way for compatability with Tk::HMListbox, as used by the JFM5 file-manager for determining whether an entry is a directory or not.

  This method is provided for convenience for creating file-managers, such as JFM5.

  The keys of the hash-reference (first argument) are:

          -index:  Index number of the image file returned.

          -label:  Widget containing the image.

          -filename:  File-name of the image.

          -bad:  True if not an image file or the image could not be rendered.

          -width:  The pixel width of the image file.

          -height:  The pixel height of the image file.

          -animated:  True if the image is an animation (animated GIF).

          -blankit:  The value of the boolean I<-blank> option.

          -row:  Row index# where the image is displayed in the widget.

          -col:  Column index# where the image is displayed in the widget.

          -photo:  The photo object of the image file.

$thumb->index(index-expression);

  JThumbnail-added feature: Returns a valid index number based in the index-expression, or -1 if invalid or out of range. index-expression can be any of the following: number, 'active', 'end', 'mouse', or '@x,y' (where x & y are the pointer[x|y] pixel coordinates of the mouse cursor in the widget). 'mouse' can be used to get the index of the widget under the mouse pointer (or just clicked on). NOTE: $thumb->index('end') returns the index of the last image in the list, so adding 1 to this gets the total count of images in the list!

$thumb->indexOf(image-filename);

  JThumbnail-added feature: Returns the index# of the image file-name, or -1 if not a valid file-name in the list.

$thumb->isFocused();

  JThumbnail-added feature: Returns TRUE if $thumb has the keyboard focus, FALSE otherwise.

$thumb->isSelected(index);

  JThumbnail-added feature: Returns TRUE if the image is currently selected or FALSE otherwise. Returns undef if index is invalid or out of range. NOTE: index must be a valid number, use $thumb->index() to get a valid index number.

$thumb->selectionSet(index [ , index ...]);

  JThumbnail-added feature: If a single index is given, that image is "selected". If two indices are given, all images between the two, inclusive are selected. If three or more are given, each image in the list is selected. index can be either a number or end.

$thumb->selectionToggle(index);

  JThumbnail-added feature: Toggles the selection state of the image given by index, then returns the selection state of the image AFTER the toggle.

$thumb->selectionClear(index [ , index ...]);

  If a single index is given, that image is "selected". If two indices are given, all images between the two, inclusive are de-selected, if selected. If three or more are given, each image in the list is de-selected. index can be either a number or end.

# NOTES

1) There are no insert, delete, or sort methods. One must "reconfigure" the widget with a new list of images in order to change the list, example:

$thumb->configure(-images => \@filelist);

which will replace all the images with the new list.

2) -takefocus does not work, use -focus instead.

3) The default for scrollbars seems to be "osow" even though I've specified "osoe" in this code. Not sure why, but to set "osoe" (SouthEast / Lower and Right), you should specify "-scrollbars => 'osoe'! "osoe" is best, if you are using the "corner button" option (see the Example in this documentation).

4) I've replaced Tk::Thumbnail's "multimedia" buttons for animated gifs in the default callback which displays the image you clicked on full-sized in it's own window since the Tk::MultiMediaControls produces floods of errors about "Tk::MasterMenu" being missing, but no such widget seems to exist anymore?! Instead, now there's a simple Play / Stop button to play the animation.

5) The default callback to display full-sized images and info. in a separate popup window is invoked whenever one clicks on an image OR now, when one presses the Return key, the active image is displayed as such. To NOT do this, specify:

-command => undef.

OR specify your own callback function for -command, OR override both <ltButtonRelease-1<gt>> and <ltReturn<gt>> key using the bindImages() function.

6) There are now TWO built-in icon images included with this package: failimg.png and info3.png in the images/ subdirectory. You can replace them with whatever you wish. failimg.png is displayed for any non-image file or image file that could not be converted properly, or for which no -extimg image exists for it's extension. info3.png is displayed for the "info" button in the popup window image by the default -command callback.

7) Tk::Animation is now an optional module (not required). Needed only if you wish to be able to "play" animated GIF images. NOTE: They are not playable from the image display screen, but only via a bound callback function, such as the default -command callback.

# KEYWORDS

jthumbnail, thumbnail, icons

# DEPENDS

Tk Tk::LabEntry Tk::JPEG Tk::PNG File::Basename

Optional: Tk::Animation (for GIF animation)

# SEE ALSO

Tk::Thumbnail Tk::Photo