Difference between revisions of "Icon Loading"

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(Updated (API doc links, classes, CMake))
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[[Category:KDE3]]
 
[[Category:Architecture]]
  +
[[Category:Developers]]
  +
{{Applicable to TDE}}
   
 
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<!--T:2-->
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<!--T:5-->
 
<!--T:5-->
Icons are loaded using the class [http://api.kde.org/3.5-api/kdelibs-apidocs/kdecore/html/classKIconLoader.html KIconLoader]. Every KDE
+
Icons are loaded using the class [http://trinitydesktop.org/docs/trinity/tdelibs/tdecore/html/classTDEIconLoader.html TDEIconLoader]. Every TDE
 
appliation has a global iconloader object. You can access this object with:
 
appliation has a global iconloader object. You can access this object with:
   
 
<!--T:6-->
 
<!--T:6-->
 
<syntaxhighlight lang="cpp-qt">
 
<syntaxhighlight lang="cpp-qt">
#include <kglobal.h>
+
#include <tdeglobal.h>
 
#include <kiconloader.h>
 
#include <kiconloader.h>
 
 
KIconLoader *loader = KGlobal::iconLoader();
+
TDEIconLoader *loader = TDEGlobal::iconLoader();
 
</syntaxhighlight>
 
</syntaxhighlight>
   
=== Loading icons with loadIcon === <!--T:7-->
+
=== Loading icons with loadIcon() === <!--T:7-->
   
 
<!--T:8-->
 
<!--T:8-->
 
The iconloader loads icons, transparently '''caches''' them and applies effects.
 
The iconloader loads icons, transparently '''caches''' them and applies effects.
To load an icon, use the method [http://api.kde.org/3.5-api/kdelibs-apidocs/kdecore/html/classKIconLoader.html#a3 loadIcon()], which is defined like this:
+
To load an icon, use the method [http://trinitydesktop.org/docs/trinity/tdelibs/tdecore/html/classTDEIconLoader.html#a73764006b6eaa18ee5a0ac71ee417c5a loadIcon()], which is defined like this:
   
 
<!--T:9-->
 
<!--T:9-->
 
<syntaxhighlight lang="cpp-qt">
 
<syntaxhighlight lang="cpp-qt">
QPixmap loadIcon( QString name, int group, int size=0,
+
TQPixmap loadIcon( TQString name, int group, int size=0,
int state=KIcon::DefaultState,
+
int state=TDEIcon::DefaultState,
QString *path_store=0L, bool canReturnNull=false);
+
TQString *path_store=0L, bool canReturnNull=false);
 
</syntaxhighlight>
 
</syntaxhighlight>
   
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<!--T:13-->
 
<!--T:13-->
The idea of an ''icon group'' is an important concept in the KDE icon
+
The idea of an ''icon group'' is an important concept in the TDE icon
 
scheme. The icon group denotes where on the screen the icon is going to be used.
 
scheme. The icon group denotes where on the screen the icon is going to be used.
This is relevant because the KDE user can bind icon sizes and visual effects to
+
This is relevant because the TDE user can bind icon sizes and visual effects to
 
each group. When passing the icon group to the icon loader, you are in fact telling
 
each group. When passing the icon group to the icon loader, you are in fact telling
 
it which incarnation of the icon to load. And by requiring the group argument, the
 
it which incarnation of the icon to load. And by requiring the group argument, the
 
iconloader provides the means to have a consistent and configurable icon look over
 
iconloader provides the means to have a consistent and configurable icon look over
the whole KDE desktop.
+
the whole Trinity desktop.
   
 
<!--T:14-->
 
<!--T:14-->
For example: The user can configure that he wants 32 pixel icons with 0.2
+
For example: The user can configure that (s)he wants 32 pixel icons with 0.2
 
desaturation for the main toolbars.
 
desaturation for the main toolbars.
   
 
<!--T:15-->
 
<!--T:15-->
 
The available icon groups are given below. All are defined in the
 
The available icon groups are given below. All are defined in the
[http://api.kde.org/3.5-api/kdelibs-apidocs/kdecore/html/classKIcon.html KIcon]
+
[http://trinitydesktop.org/docs/trinity/tdelibs/tdecore/html/classTDEIcon.html TDEIcon]
class, so prefix them with ''KIcon::''.
+
class, so prefix them with ''TDEIcon::''.
   
 
<!--T:16-->
 
<!--T:16-->
 
* '''Desktop''' - Icons for use on the desktop, in the filemanager and similar places.
 
* '''Desktop''' - Icons for use on the desktop, in the filemanager and similar places.
* '''Toolbar''' - Icon for in normal toolbars.
+
* '''Toolbar''' - Icon for use innormal toolbars.
* '''MainToolbar''' - Icons for in the main toolbar. An application can have multiple toolbars, of which one is allways the main toolbar. This typically has entries like "Save" and "Open" and contains larger icons than the other toolbars.
+
* '''MainToolbar''' - Icons for use in the main toolbar. An application can have multiple toolbars, of which one is always the main toolbar. This typically has entries like "Save" and "Open" and contains larger icons than the other toolbars.
 
* '''Small''' - Various small icons, like the ones in popup menus, listviews and treelists.
 
* '''Small''' - Various small icons, like the ones in popup menus, listviews and treelists.
  +
* '''Panel''' - Icons for use in Kicker panels.
 
* '''User''' - Special group for loading application specific icons. This is explained in section 3: Installing icons.
 
* '''User''' - Special group for loading application specific icons. This is explained in section 3: Installing icons.
   
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<!--T:18-->
 
<!--T:18-->
 
<syntaxhighlight lang="cpp-qt">
 
<syntaxhighlight lang="cpp-qt">
QPixmap icon;
+
TQPixmap icon;
icon = loader->loadIcon("kfind", KIcon::Desktop);
+
icon = loader->loadIcon("kfind", TDEIcon::Desktop);
 
</syntaxhighlight>
 
</syntaxhighlight>
   
=== loadIcon continued === <!--T:19-->
+
=== loadIcon() continued === <!--T:19-->
   
 
<!--T:20-->
 
<!--T:20-->
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<!--T:21-->
 
<!--T:21-->
 
# '''size''' - Override the globally configured size for the specified icon group. Effects bound to the group are still applied.
 
# '''size''' - Override the globally configured size for the specified icon group. Effects bound to the group are still applied.
# '''state''' - The icon state. The icon state is one of ''KIcon::DefaultState'', ''KIcon::ActiveState'' or ''KIcon::DisabledState''. The icon state denotes in which state the icon is. Toolbar buttons, for example, are in state ''active'' if the mouse pointer is above them, in state ''disabled'' when they are not available, and ''default'' otherwise. Each icon state can have different effects assigned to it to give the user visual feedback.
+
# '''state''' - The icon state. The icon state is one of ''TDEIcon::DefaultState'', ''TDEIcon::ActiveState'' or ''KIcon::DisabledState''. The icon state denotes in which state the icon is. Toolbar buttons, for example, are in state ''active'' if the mouse pointer is above them, in state ''disabled'' when they are not available, and ''default'' otherwise. Each icon state can have different effects assigned to it to give the user visual feedback.
# '''path_store''' - If you want to know where the icon you just loaded is in the filesystem, you can pass a pointer to a QString here and the icon path is stored there.
+
# '''path_store''' - If you want to know where the icon you just loaded is in the filesystem, you can pass a pointer to a TQString here and the icon path is stored there.
 
# '''canReturnNull''' - If the requested icon is not found, the result of ''loadIcon'' depends on this parameter. If ''canReturnNull'' is ''true'', a null pixmap will be returned, if not, the "unknown" icon is returned.
 
# '''canReturnNull''' - If the requested icon is not found, the result of ''loadIcon'' depends on this parameter. If ''canReturnNull'' is ''true'', a null pixmap will be returned, if not, the "unknown" icon is returned.
   
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Themed icons are stored in a directory hierarchy according to their
 
Themed icons are stored in a directory hierarchy according to their
 
'''1. depth''', '''2. size''' and '''3. context'''.
 
'''1. depth''', '''2. size''' and '''3. context'''.
The term ''context'' is new concept introduced by the KDE icon scheme.
+
The term ''context'' is a new concept introduced by KDE/Trinity icon schemes.
 
The context of an icon is what the icon ''means''. The standard
 
The context of an icon is what the icon ''means''. The standard
 
contexts are given below:
 
contexts are given below:
Line 139: Line 144:
 
icon. When an application wants the user to select an icon for, say, a
 
icon. When an application wants the user to select an icon for, say, a
 
toolbar, it would be very user unfriendly to show every single icon
 
toolbar, it would be very user unfriendly to show every single icon
installed in KDE. Instead, it is much better to let the user select
+
installed in Trinity. Instead, it is much better to let the user select
 
an icon from the "action" icons only. These all represent some action and
 
an icon from the "action" icons only. These all represent some action and
 
therefore are suitable for in toolbars.
 
therefore are suitable for in toolbars.
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<!--T:37-->
 
<!--T:37-->
Themed icons can be installed either globally with respect to KDE, or in
+
Themed icons can be installed either globally with respect to TDE, or in
 
application specific place. In the global case, the icon theme hierarchy
 
application specific place. In the global case, the icon theme hierarchy
resides under $KDEDIR/share/icons while in the application specific
+
resides under $TDEDIR/share/icons while in the application specific
case, it is under $KDEDIR/share/apps/$APPNAME/icons.
+
case, it is under $TDEDIR/share/apps/$APPNAME/icons.
   
 
=== Installing themed icons === <!--T:38-->
 
=== Installing themed icons === <!--T:38-->
   
 
<!--T:39-->
 
<!--T:39-->
  +
The Trinity framework has support for installing themed icons. First, you
The KDE source configuration system (specifically, am_edit) has support for
 
installing themed icons. First, you have to name your icons in a way that it
+
have to name your icons in a way that it is clear where it must be installed.
is clear where it must be installed. The naming convention is explained in
+
The naming convention is explained in
 
the table below:
 
the table below:
   
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<!--T:42-->
 
<!--T:42-->
lo22-action-open.png
+
lo22-action-open.png
 
hi48-app-kfind.png
 
hi48-app-kfind.png
   
 
<!--T:43-->
 
<!--T:43-->
  +
The icons are installed automatically when using the TDE CMake macros.
To install these icons globally, add this line to your <tt>Makefile.am</tt>.
 
  +
  +
<!--
  +
to your <tt>Makefile.am</tt>.
   
<!--T:44-->
 
 
KDE_ICON = open kfind
 
KDE_ICON = open kfind
   
<!--T:45-->
 
 
and to install them in an application specific directory, use this:
 
and to install them in an application specific directory, use this:
   
 
icondir = $(kde_datadir)/myapp/icons
<!--T:46-->
 
icondir = $(kde_datadir)/myapp/icons
 
 
icon_ICON = open kfind
 
icon_ICON = open kfind
  +
-->
   
 
=== Loading themed icons === <!--T:47-->
 
=== Loading themed icons === <!--T:47-->
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<!--T:48-->
 
<!--T:48-->
 
<syntaxhighlight lang="cpp-qt">
 
<syntaxhighlight lang="cpp-qt">
QPixmap pm;
+
TQPixmap pm;
pm = loader->loadIcon("kfind", KIcon::Desktop);
+
pm = loader->loadIcon("kfind", TDEIcon::Desktop);
 
</syntaxhighlight>
 
</syntaxhighlight>
   
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<!--T:51-->
 
<!--T:51-->
Unthemed icons are installed in $KDEDIR/share/apps/$APPNAME/pics.
+
Unthemed icons are installed in $TDEDIR/share/apps/$APPNAME/pics.
To install them, use this in you <tt>Makefile.am</tt>.
+
To install them, use this in your CMakeLists.txt:
   
  +
<code>install( FILES open.png kfind.png DESTINATION ${DATA_INSTALL_DIR}/myapp/pics )</code>
<!--T:52-->
 
  +
icondir = $(kde_datadir)/myapp/pics
 
  +
<!--
  +
in your <tt>Makefile.am</tt>.
  +
 
icondir = $(kde_datadir)/myapp/pics
 
icon_DATA = open kfind
 
icon_DATA = open kfind
  +
-->
   
 
<!--T:53-->
 
<!--T:53-->
 
You must not give the icons special names.
 
You must not give the icons special names.
Also, no further processing is done on them: no effects and size,depth selection
+
Also, no further processing is done on them: no effects and size, depth selection
 
is done.
 
is done.
   
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<!--T:55-->
 
<!--T:55-->
 
<syntaxhighlight lang="cpp-qt">
 
<syntaxhighlight lang="cpp-qt">
QPixmap pm;
+
TQPixmap pm;
pm = loader->loadIcon("myicon", KIcon::User);
+
pm = loader->loadIcon("myicon", TDEIcon::User);
 
</syntaxhighlight>
 
</syntaxhighlight>
   
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<!--T:58-->
 
<!--T:58-->
[[Category:KDE3]]
 
[[Category:Architecture]]
 

Revision as of 21:16, 22 August 2021

TDE Logo.png
Information on this page is applicable to TDE
This page contains archived KDE 3.x content from various sources which is directly applicable to (or has been updated for) the Trinity Desktop Environment.

Icons are an important user interface element in any desktop environment. Because of different user preferences and video hardware, one icon may come in different sizes and display depths. In order to make this manageable, a standard way of storing and accessing icons has been developed.

Loading icons

Accessing the iconloader

Icons are loaded using the class TDEIconLoader. Every TDE appliation has a global iconloader object. You can access this object with:

#include <tdeglobal.h>
#include <kiconloader.h>
 
TDEIconLoader *loader = TDEGlobal::iconLoader();

Loading icons with loadIcon()

The iconloader loads icons, transparently caches them and applies effects. To load an icon, use the method loadIcon(), which is defined like this:

TQPixmap loadIcon( TQString name, int group, int size=0,
                   int state=TDEIcon::DefaultState, 
                   TQString *path_store=0L, bool canReturnNull=false);

As you see, there are a lot of parameters. The first two are most important:

  1. name - The name of the icon to load. You must pass the bare icon name here, without extension.
  2. group - The icon group. This is explained below.

Icon groups

The idea of an icon group is an important concept in the TDE icon scheme. The icon group denotes where on the screen the icon is going to be used. This is relevant because the TDE user can bind icon sizes and visual effects to each group. When passing the icon group to the icon loader, you are in fact telling it which incarnation of the icon to load. And by requiring the group argument, the iconloader provides the means to have a consistent and configurable icon look over the whole Trinity desktop.

For example: The user can configure that (s)he wants 32 pixel icons with 0.2 desaturation for the main toolbars.

The available icon groups are given below. All are defined in the TDEIcon class, so prefix them with TDEIcon::.

  • Desktop - Icons for use on the desktop, in the filemanager and similar places.
  • Toolbar - Icon for use innormal toolbars.
  • MainToolbar - Icons for use in the main toolbar. An application can have multiple toolbars, of which one is always the main toolbar. This typically has entries like "Save" and "Open" and contains larger icons than the other toolbars.
  • Small - Various small icons, like the ones in popup menus, listviews and treelists.
  • Panel - Icons for use in Kicker panels.
  • User - Special group for loading application specific icons. This is explained in section 3: Installing icons.

So, to load the icon "kfind" for use in the Desktop group, you'd use:

TQPixmap icon;
icon = loader->loadIcon("kfind", TDEIcon::Desktop);

loadIcon() continued

Now lets discuss the other parameters of loadIcon.

  1. size - Override the globally configured size for the specified icon group. Effects bound to the group are still applied.
  2. state - The icon state. The icon state is one of TDEIcon::DefaultState, TDEIcon::ActiveState or KIcon::DisabledState. The icon state denotes in which state the icon is. Toolbar buttons, for example, are in state active if the mouse pointer is above them, in state disabled when they are not available, and default otherwise. Each icon state can have different effects assigned to it to give the user visual feedback.
  3. path_store - If you want to know where the icon you just loaded is in the filesystem, you can pass a pointer to a TQString here and the icon path is stored there.
  4. canReturnNull - If the requested icon is not found, the result of loadIcon depends on this parameter. If canReturnNull is true, a null pixmap will be returned, if not, the "unknown" icon is returned.

Installing icons

Icons may come in different sizes and display depths. I shall refer to these icons as themed icons. Icons that come in just one form are referred to as unthemed icons.

Default icon sizes

Themed icons come in different sizes and display depths. The standard sizes are:

40 Colors
16x16 pixels
22x22 pixels
32x32 pixels
Truecolor
22x22 pixels
32x32 pixels
48x48 pixels

Please refer to the KDE Icon Guide for information on which icon sizes are mandatory and more. Remember that each of these sizes can be bound to an icon group.

Icon context

Themed icons are stored in a directory hierarchy according to their 1. depth, 2. size and 3. context. The term context is a new concept introduced by KDE/Trinity icon schemes. The context of an icon is what the icon means. The standard contexts are given below:

  • action - The icon represents an action in a toolbar, for example "Open" or "Save".
  • application - The icon represents an application, for example "kfind".
  • device - The icon represents something related to a device, for example "floppy" or "mount".
  • filesystem - The icon represents something in the filesystem, for example "directory", "socket" or "trashcan".
  • mimetype - The icon represents an mimetype, for example "text/html".

Contexts are important in one case: selecting an icon. When an application wants the user to select an icon for, say, a toolbar, it would be very user unfriendly to show every single icon installed in Trinity. Instead, it is much better to let the user select an icon from the "action" icons only. These all represent some action and therefore are suitable for in toolbars.

Directory hierarchy

The directory hierarchy in which themed icons are stored follows. The directory names are self explanatory.

hicolor/

    22x22/
        actions/
        apps/
        devices/
        filesystems/
        mimetypes/
    32x32/
        ...
    48x48/
        ...

locolor/
    16x16/
        ...
    22x22/
        ...
    32x32/
        ...

Directory roots

Themed icons can be installed either globally with respect to TDE, or in application specific place. In the global case, the icon theme hierarchy resides under $TDEDIR/share/icons while in the application specific case, it is under $TDEDIR/share/apps/$APPNAME/icons.

Installing themed icons

The Trinity framework has support for installing themed icons. First, you have to name your icons in a way that it is clear where it must be installed. The naming convention is explained in the table below:

depth size - context - name .png
hi 16 action
lo 22 app
32 device
48 filesys
mime

Examples:

lo22-action-open.png
hi48-app-kfind.png

The icons are installed automatically when using the TDE CMake macros.


Loading themed icons

Themed icons are loaded with the iconloader, using the standard icon groups. For example:

TQPixmap pm;
pm = loader->loadIcon("kfind", TDEIcon::Desktop);

This will load the "kfind" icon, of depth and size specified for the Desktop group.

Unthemed icons

Unthemed icons are installed in $TDEDIR/share/apps/$APPNAME/pics. To install them, use this in your CMakeLists.txt:

install( FILES open.png kfind.png DESTINATION ${DATA_INSTALL_DIR}/myapp/pics )


You must not give the icons special names. Also, no further processing is done on them: no effects and size, depth selection is done.

Unthemed icons can be loaded with the iconloader using the User group. This will load a user icon:

TQPixmap pm;
pm = loader->loadIcon("myicon", TDEIcon::User);

Conclusion

There are 3 ways to install icons: global themed, application specific themed and unthemed. All types of icons can be loaded with the iconloader. You should choose a specific installation depending on your needs.


Initial Author: Geert Jansen <jansen@kde.org>