[gtk/doc-chapters-markdown] docs: Convert question index to markdown
- From: Matthias Clasen <matthiasc src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [gtk/doc-chapters-markdown] docs: Convert question index to markdown
- Date: Sun, 24 May 2020 18:28:38 +0000 (UTC)
commit d76d8f8b0bab78594a64495e022b3462b7339a4d
Author: Matthias Clasen <mclasen redhat com>
Date: Sun May 24 14:25:25 2020 -0400
docs: Convert question index to markdown
With this, the expand_content_files list has been
completely converted to markdown files. Whats left
in content_files is man pages, and a few special
cases.
docs/reference/gtk/gtk4-docs.xml | 2 +-
docs/reference/gtk/meson.build | 7 +-
docs/reference/gtk/question_index.md | 557 +++++++++++++++++++
docs/reference/gtk/question_index.xml | 973 ----------------------------------
4 files changed, 559 insertions(+), 980 deletions(-)
---
diff --git a/docs/reference/gtk/gtk4-docs.xml b/docs/reference/gtk/gtk4-docs.xml
index 6629c184ec..2943a6286a 100644
--- a/docs/reference/gtk/gtk4-docs.xml
+++ b/docs/reference/gtk/gtk4-docs.xml
@@ -23,7 +23,7 @@
<xi:include href="overview.xml"/>
<xi:include href="getting_started.xml"/>
<xi:include href="resources.xml" />
- <xi:include href="xml/question_index.xml" />
+ <xi:include href="question_index.xml" />
</part>
<part id="concepts">
diff --git a/docs/reference/gtk/meson.build b/docs/reference/gtk/meson.build
index e59469aae1..50efd83eb7 100644
--- a/docs/reference/gtk/meson.build
+++ b/docs/reference/gtk/meson.build
@@ -352,14 +352,9 @@ content_files = [
'gtk4-widget-factory.xml',
'other_software.xml',
'overview.xml',
- 'question_index.xml',
'visual_index.xml',
]
-expand_content_files = [
- 'question_index.xml',
-]
-
expand_content_md_files = [
'broadway.md',
'osx.md',
@@ -380,6 +375,7 @@ expand_content_md_files = [
'css-properties.md',
'section-text-widget.md',
'section-tree-widget.md',
+ 'question_index.md',
]
types_conf = configuration_data()
@@ -439,7 +435,6 @@ if get_option('gtk_doc')
'--extra-dir=../gsk',
],
content_files: content_files + expand_md_targets,
- expand_content_files: expand_content_files,
html_assets: images,
install: true)
endif
diff --git a/docs/reference/gtk/question_index.md b/docs/reference/gtk/question_index.md
new file mode 100644
index 0000000000..dcc7d92c55
--- /dev/null
+++ b/docs/reference/gtk/question_index.md
@@ -0,0 +1,557 @@
+# Common Questions {#gtk-question-index}
+
+This is an "index" of the reference manual organized by common "How do
+I..." questions. If you aren't sure which documentation to read for
+the question you have, this list is a good place to start.
+
+## General Questions
+
+1. How do I get started with GTK?
+
+ The GTK [website](https://www.gtk.org) offers some
+ [tutorials](https://www.gtk.org/documentation.php) and other documentation
+ (most of it about GTK 2.x and 3.x, but still somewhat applicable). This
+ reference manual also contains a introductory
+ [Getting Started](#gtk-getting-started) part.
+
+ More documentation ranging from whitepapers to online books can be found at
+ the [GNOME developer's site](https://developer.gnome.org). After studying these
+ materials you should be well prepared to come back to this reference manual for details.
+
+2. Where can I get help with GTK, submit a bug report, or make a feature request?
+
+ See the [documentation](#gtk-resources) on this topic.
+
+3. How do I port from one GTK version to another?
+
+ See the [migration guide](#migrating). You may also find useful information in
+ the documentation for specific widgets and functions. If you have a question not
+ covered in the manual, feel free to ask, and please
+ [file a bug report](https://gitlab.gnome.org/GNOME/gtk/issues/new) against the
+ documentation.
+
+4. How does memory management work in GTK? Should I free data returned from functions?
+
+ See the documentation for #GObject and #GInitiallyUnowned. For #GObject note
+ specifically g_object_ref() and g_object_unref(). #GInitiallyUnowned is a
+ subclass of #GObject so the same points apply, except that it has a "floating"
+ state (explained in its documentation).
+
+ For strings returned from functions, they will be declared "const" if they should
+ not be freed. Non-const strings should be freed with g_free(). Arrays follow the
+ same rule. If you find an undocumented exception to the rules, please
+ [file a bug report.](https://gitlab.gnome.org/GNOME/gtk/issues/new).
+
+ The transfer annotations for gobject-introspection that are part of the
+ documentation can provide useful hints for memory handling semantics as well.
+
+5. Why does my program leak memory, if I destroy a widget immediately
+ after creating it ?
+
+ If `GtkFooi` isn't a toplevel window, then
+
+ foo = gtk_foo_new ();
+ g_object_unref (foo);
+
+ is a memory leak, because no one assumed the initial floating reference
+ (you will get a warning about this too). If you are using a widget and
+ you aren't immediately packing it into a container, then you probably
+ want standard reference counting, not floating reference counting.
+
+ To get this, you must acquire a reference to the widget and drop the
+ floating reference (_ref and sink_ in GObject parlance) after creating it:
+
+ foo = gtk_foo_new ();
+ g_object_ref_sink (foo);
+
+ When you immediately add a widget to a container, it takes care of assuming
+ the initial floating reference and you don't have to worry about reference
+ counting at all ... just remove the widget from the container to get rid of it.
+
+6. How do I use GTK with threads?
+
+ GTK requires that all GTK API calls are made from the same thread in which
+ gtk_init() was called (the _main thread_).
+
+ If you want to take advantage of multi-threading in a GTK application,
+ it is usually best to send long-running tasks to worker threads, and feed
+ the results back to the main thread using g_idle_add() or GAsyncQueue. GIO
+ offers useful tools for such an approach such as GTask.
+
+7. How do I internationalize a GTK program?
+
+ Most people use <[GNU gettext](https://www.gnu.org/software/gettext/),
+ already required in order to install GLib. On a UNIX or Linux system with
+ gettext installed, type `info gettext` to read the documentation.
+
+ The short checklist on how to use gettext is: call bindtextdomain() so
+ gettext can find the files containing your translations, call textdomain()
+ to set the default translation domain, call bind_textdomain_codeset() to
+ request that all translated strings are returned in UTF-8, then call
+ gettext() to look up each string to be translated in the default domain.
+
+ `gi18n.h` provides the following shorthand macros for convenience.
+ Conventionally, people define macros as follows for convenience:
+
+ #define _(x) gettext (x)
+ #define N_(x) x
+ #define C_(ctx,x) pgettext (ctx, x)
+
+ You use N_() (N stands for no-op) to mark a string for translation in
+ a location where a function call to gettext() is not allowed, such as
+ in an array initializer. You eventually have to call gettext() on the
+ string to actually fetch the translation. _() both marks the string for
+ translation and actually translates it. The C_() macro (C stands for
+ context) adds an additional context to the string that is marked for
+ translation, which can help to disambiguate short strings that might
+ need different translations in different parts of your program.
+
+ Code using these macros ends up looking like this:
+
+ #include <gi18n.h>
+
+ static const char *global_variable = N_("Translate this string");
+
+ static void
+ make_widgets (void)
+ {
+ GtkWidget *label1;
+ GtkWidget *label2;
+
+ label1 = gtk_label_new (_("Another string to translate"));
+ label2 = gtk_label_new (_(global_variable));
+ ...
+
+ Libraries using gettext should use dgettext() instead of gettext(),
+ which allows them to specify the translation domain each time they
+ ask for a translation. Libraries should also avoid calling textdomain(),
+ since they will be specifying the domain instead of using the default.
+
+ With the convention that the macro `GETTEXT_PACKAGE` is defined to hold
+ your libraries translation domain, `gi18n-lib.h` can be included to provide
+ the following convenience:
+
+ #define _(x) dgettext (GETTEXT_PACKAGE, x)
+
+8. How do I use non-ASCII characters in GTK programs ?
+
+ GTK uses [Unicode](http://www.unicode.org) (more exactly UTF-8) for all text.
+ UTF-8 encodes each Unicode codepoint as a sequence of one to six bytes and
+ has a number of nice properties which make it a good choice for working with
+ Unicode text in C programs:
+
+ - ASCII characters are encoded by their familiar ASCII codepoints.
+ - ASCII characters never appear as part of any other character.
+ - The zero byte doesn't occur as part of a character, so that UTF-8
+ string can be manipulated with the usual C library functions for
+ handling zero-terminated strings.
+
+ More information about Unicode and UTF-8 can be found in the
+ [UTF-8 and Unicode FAQ](https://www.cl.cam.ac.uk/~mgk25/unicode.html).
+ GLib provides functions for converting strings between UTF-8 and other
+ encodings, see g_locale_to_utf8() and g_convert().
+
+ Text coming from external sources (e.g. files or user input), has to be
+ converted to UTF-8 before being handed over to GTK. The following example
+ writes the content of a IS0-8859-1 encoded text file to `stdout`:
+
+ char *text, *utf8_text;
+ gsize length;
+ GError *error = NULL;
+
+ if (g_file_get_contents (filename, &text, &length, NULL))
+ {
+ utf8_text = g_convert (text, length, "UTF-8", "ISO-8859-1",
+ NULL, NULL, &error);
+ if (error != NULL)
+ {
+ fprintf ("Couldn't convert file %s to UTF-8\n", filename);
+ g_error_free (error);
+ }
+ else
+ g_print (utf8_text);
+ }
+ else
+ fprintf (stderr, "Unable to read file %s\n", filename);
+
+ For string literals in the source code, there are several alternatives
+ for handling non-ASCII content:
+
+ - Direct UTF-8
+
+ If your editor and compiler are capable of handling UTF-8 encoded
+ sources, it is very convenient to simply use UTF-8 for string literals,
+ since it allows you to edit the strings in "wysiwyg". Note that choosing
+ this option may reduce the portability of your code.
+
+ - Escaped UTF-8
+
+ Even if your toolchain can't handle UTF-8 directly, you can still
+ encode string literals in UTF-8 by using octal or hexadecimal escapes
+ like `\\212` or `\\xa8` to encode each byte. This is portable, but
+ modifying the escaped strings is not very convenient. Be careful when
+ mixing hexadecimal escapes with ordinary text; `"\\xa8abcd" is a string
+ of length 1 !
+
+ - Runtime conversion
+
+ If the string literals can be represented in an encoding which your
+ toolchain can handle (e.g. IS0-8859-1), you can write your source
+ files in that encoding and use g_convert() to convert the strings
+ to UTF-8 at runtime. Note that this has some runtime overhead, so
+ you may want to move the conversion out of inner loops.
+
+ Here is an example showing the three approaches using the copyright
+ sign © which has Unicode and ISO-8859-1 codepoint 169 and is represented
+ in UTF-8 by the two bytes 194, 169, or `"\\302\\251"` as a string literal:
+
+ g_print ("direct UTF-8: ©");
+ g_print ("escaped UTF-8: \302\251");
+ text = g_convert ("runtime conversion: ©", -1,
+ "ISO-8859-1", "UTF-8", NULL, NULL, NULL);
+ g_print (text);
+ g_free (text);
+
+ If you are using gettext() to localize your application, you need
+ to call bind_textdomain_codeset() to ensure that translated strings
+ are returned in UTF-8 encoding.
+
+9. How do I use GTK with C++?
+
+ There are two ways to approach this. The GTK header files use the subset
+ of C that's also valid C++, so you can simply use the normal GTK API
+ in a C++ program. Alternatively, you can use a "C++ binding" such as
+ [gtkmm](https://www.gtkmm.org/) which provides a native C++ API.
+
+ When using GTK directly, keep in mind that only functions can be
+ connected to signals, not methods. So you will need to use global
+ functions or "static" class functions for signal connections.
+
+ Another common issue when using GTK directly is that C++ will not
+ implicitly convert an integer to an enumeration. This comes up when
+ using bitfields; in C you can write the following code:
+
+ gdk_surface_set_events (gdk_surface,
+ GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
+
+ while in C++ you must write:
+
+ gdk_surface_set_events (gdk_surface,
+ (GdkEventMask) GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
+
+ There are very few functions that require this cast, however.
+
+10. How do I use GTK with other non-C languages?
+
+ See the list of [language bindings](https://www.gtk.org/language-bindings.php)
+ on the GTK [website](https://www.gtk.org).
+
+11. How do I load an image or animation from a file?
+
+ To load an image file straight into a display widget, use
+ gtk_image_new_from_file(). To load an image for another purpose, use
+ gdk_texture_new_from_file(). To load a video from a file, use
+ gtk_media_file_new_for_file().
+
+12. How do I draw text?
+
+ To draw a piece of text onto a cairo surface, use a Pango layout and
+ pango_cairo_show_layout().
+
+ layout = gtk_widget_create_pango_layout (widget, text);
+ fontdesc = pango_font_description_from_string ("Luxi Mono 12");
+ pango_layout_set_font_description (layout, fontdesc);
+ pango_cairo_show_layout (cr, layout);
+ pango_font_description_free (fontdesc);
+ g_object_unref (layout);
+
+ See also the [Cairo Rendering](https://developer.gnome.org/pango/stable/pango-Cairo-Rendering.html)
+ section of the [Pango documentation](https://developer.gnome.org/pango/stable/).
+
+ To draw a piece of text in a widget snapshot() implementation, use
+ gtk_snapshot_append_layout().
+
+13. How do I measure the size of a piece of text?
+
+ To obtain the size of a piece of text, use a Pango layout and
+ pango_layout_get_pixel_size(), using code like the following:
+
+ layout = gtk_widget_create_pango_layout (widget, text);
+ fontdesc = pango_font_description_from_string ("Luxi Mono 12");
+ pango_layout_set_font_description (layout, fontdesc);
+ pango_layout_get_pixel_size (layout, &width, &height);
+ pango_font_description_free (fontdesc);
+ g_object_unref (layout);
+
+ See also the [Layout Objects](https://developer.gnome.org/pango/stable/pango-Layout-Objects.html)
+ section of the [Pango documentation](https://developer.gnome.org/pango/stable/).
+
+14. Why are types not registered if I use their `GTK_TYPE_BLAH` macro?
+
+ The %GTK_TYPE_BLAH macros are defined as calls to gtk_blah_get_type(), and
+ the `_get_type()` functions are declared as %G_GNUC_CONST which allows the
+ compiler to optimize the call away if it appears that the value is not
+ being used.
+
+ GLib provides the g_type_ensure() function to work around this problem.
+
+ g_type_ensure (GTK_TYPE_BLAH);
+
+15. How do I create a transparent toplevel window?
+
+ Any toplevel window can be transparent. It is just a matter of setting a
+ transparent background in the CSS style for it.
+
+## Which widget should I use...
+
+16. ...for lists and trees?
+
+ This question has different answers, depending on the size of the dataset
+ and the required formatting flexibility.
+
+ If you want to display a large amount of data in a uniform way, your best
+ option is a #GtkTreeView widget. See the [tree widget overview](#TreeWidget).
+ A list is just a tree with no branches, so the treeview widget is used for
+ lists as well.
+
+ If you want to display a small amount of items, but need flexible formatting
+ and widgetry inside the list, then you probably want to use a #GtkListBox,
+ which uses regular widgets for display.
+
+17. ...for multi-line text display or editing?
+
+ See the [text widget overview](#TextWidget) -- you should use the
+ #GtkTextView widget.
+
+ If you only have a small amount of text, #GtkLabel may also be appropriate
+ of course. It can be made selectable with gtk_label_set_selectable(). For a
+ single-line text entry, see #GtkEntry.
+
+18. ...to display an image or animation?
+
+ GTK has two widgets that are dedicated to displaying images. #GtkImage, for
+ small, fixed-size icons and #GtkPicture for content images.
+
+ Both can display images in just about any format GTK understands.
+ You can also use #GtkDrawingArea if you need to do something more complex,
+ such as draw text or graphics over the top of the image.
+
+ Both GtkImage and GtkPicture can display animations and videos as well.
+ To show an webm file, load it with the GtkMediaFile API and then use
+ it as a paintable:
+
+ mediafile = gtk_media_file_new_for_filename ("example.webm");
+ picture = gtk_picture_new_for_paintable (GDK_PAINTABLE (mediafile));
+
+19. ...for presenting a set of mutually-exclusive choices, where Windows
+ would use a combo box?
+
+ With GTK, a #GtkComboBox is the recommended widget to use for this use case.
+ If you need an editable text entry, use the #GtkComboBox:has-entry property.
+
+## Questions about GtkWidget
+
+20. How do I change the color of a widget?
+
+ The background color of a widget is determined by the CSS style that applies
+ to it. To change that, you can set style classes on the widget, and provide
+ custom CSS to change the appearance. Such CSS can be loaded with
+ gtk_css_provider_load_from_file() and its variants.
+ See gtk_style_context_add_provider().
+
+21. How do I change the font of a widget?
+
+ If you want to make the text of a label larger, you can use
+ gtk_label_set_markup():
+
+ gtk_label_set_markup (label, "<big>big tex</big>");
+
+ This is preferred for many apps because it's a relative size to the
+ user's chosen font size. See g_markup_escape_text() if you are
+ constructing such strings on the fly.
+
+ You can also change the font of a widget by putting
+
+ .my-widget-class {
+ font: Sans 30;
+ }
+
+ in a CSS file, loading it with gtk_css_provider_load_from_file(), and
+ adding the provider with gtk_style_context_add_provider_for_display().
+ To associate this style information with your widget, set a style class
+ on its #GtkStyleContext using gtk_style_context_add_class(). The advantage
+ of this approach is that users can then override the font you have chosen.
+ See the #GtkStyleContext documentation for more discussion.
+
+22. How do I disable/ghost/desensitize a widget?
+
+ In GTK a disabled widget is termed _insensitive_.
+ See gtk_widget_set_sensitive().
+
+## GtkTextView questions
+
+23. How do I get the contents of the entire text widget as a string?
+
+ See gtk_text_buffer_get_bounds() and gtk_text_buffer_get_text()
+ or gtk_text_iter_get_text().
+
+ GtkTextIter start, end;
+ GtkTextBuffer *buffer;
+ char *text;
+
+ buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view));
+ gtk_text_buffer_get_bounds (buffer, &start, &end);
+ text = gtk_text_iter_get_text (&start, &end);
+ /* use text */
+ g_free (text);
+
+24. How do I make a text widget display its complete contents in a specific font?
+
+ If you use gtk_text_buffer_insert_with_tags() with appropriate tags to
+ select the font, the inserted text will have the desired appearance, but
+ text typed in by the user before or after the tagged block will appear in
+ the default style.
+
+ To ensure that all text has the desired appearance, use
+ gtk_widget_override_font() to change the default font for the widget.
+
+25. How do I make a text view scroll to the end of the buffer automatically ?
+
+ A good way to keep a text buffer scrolled to the end is to place a
+ [mark](#GtkTextMark) at the end of the buffer, and give it right gravity.
+ The gravity has the effect that text inserted at the mark gets inserted
+ *before*, keeping the mark at the end.
+
+ To ensure that the end of the buffer remains visible, use
+ gtk_text_view_scroll_to_mark() to scroll to the mark after
+ inserting new text.
+
+ The gtk-demo application contains an example of this technique.
+
+## GtkTreeView questions
+
+26. How do I associate some data with a row in the tree?
+
+ Remember that the #GtkTreeModel columns don't necessarily have to be
+ displayed. So you can put non-user-visible data in your model just
+ like any other data, and retrieve it with gtk_tree_model_get().
+ See the [tree widget overview](#TreeWidget).
+
+27. How do I put an image and some text in the same column?
+
+ You can pack more than one #GtkCellRenderer into a single #GtkTreeViewColumn
+ using gtk_tree_view_column_pack_start() or gtk_tree_view_column_pack_end().
+ So pack both a #GtkCellRendererPixbuf and a #GtkCellRendererText into the
+ column.
+
+28. I can set data easily on my #GtkTreeStore/#GtkListStore models using
+ gtk_list_store_set() and gtk_tree_store_set(), but can't read it back?
+
+ Both the #GtkTreeStore and the #GtkListStore implement the #GtkTreeModel
+ interface. Consequentially, you can use any function this interface
+ implements. The easiest way to read a set of data back is to use
+ gtk_tree_model_get().
+
+29. How do I change the way that numbers are formatted by #GtkTreeView?
+
+ Use gtk_tree_view_insert_column_with_data_func() or
+ gtk_tree_view_column_set_cell_data_func() and do the conversion
+ from number to string yourself (with, say, g_strdup_printf()).
+
+ The following example demonstrates this:
+
+ enum
+ {
+ DOUBLE_COLUMN,
+ N_COLUMNS
+ };
+
+ GtkListStore *mycolumns;
+
+ GtkTreeView *treeview;
+
+ void
+ my_cell_double_to_text (GtkTreeViewColumn *tree_column,
+ GtkCellRenderer *cell,
+ GtkTreeModel *tree_model,
+ GtkTreeIter *iter,
+ gpointer data)
+ {
+ GtkCellRendererText *cell_text = (GtkCellRendererText *)cell;
+ double d;
+ char *text;
+
+ /* Get the double value from the model. */
+ gtk_tree_model_get (tree_model, iter, (int)data, &d, -1);
+ /* Now we can format the value ourselves. */
+ text = g_strdup_printf ("%.2f", d);
+ g_object_set (cell, "text", text, NULL);
+ g_free (text);
+ }
+
+ void
+ set_up_new_columns (GtkTreeView *myview)
+ {
+ GtkCellRendererText *renderer;
+ GtkTreeViewColumn *column;
+ GtkListStore *mycolumns;
+
+ /* Create the data model and associate it with the given TreeView */
+ mycolumns = gtk_list_store_new (N_COLUMNS, G_TYPE_DOUBLE);
+ gtk_tree_view_set_model (myview, GTK_TREE_MODEL (mycolumns));
+
+ /* Create a GtkCellRendererText */
+ renderer = gtk_cell_renderer_text_new ();
+
+ /* Create a new column that has a title ("Example column"),
+ * uses the above created renderer that will render the double
+ * value into text from the associated model's rows.
+ */
+ column = gtk_tree_view_column_new ();
+ gtk_tree_view_column_set_title (column, "Example column");
+ renderer = gtk_cell_renderer_text_new ();
+ gtk_tree_view_column_pack_start (column, renderer, TRUE);
+
+ /* Append the new column after the GtkTreeView's previous columns. */
+ gtk_tree_view_append_column (GTK_TREE_VIEW (myview), column);
+ /* Since we created the column by hand, we can set it up for our
+ * needs, e.g. set its minimum and maximum width, etc.
+ */
+ /* Set up a custom function that will be called when the column content
+ * is rendered. We use the func_data pointer as an index into our
+ * model. This is convenient when using multi column lists.
+ */
+ gtk_tree_view_column_set_cell_data_func (column, renderer,
+ my_cell_double_to_text,
+ (gpointer)DOUBLE_COLUMN, NULL);
+ }
+
+30. How do I hide the expander arrows in my tree view?
+
+ Set the expander-column property of the tree view to a hidden column.
+ See gtk_tree_view_set_expander_column() and gtk_tree_view_column_set_visible().
+
+## Using cairo with GTK
+
+31. How do I use cairo to draw in GTK applications?
+
+ Use gtk_snapshot_append_cairo() in your #GtkWidgetClass.snapshot() vfunc
+ to obtain a cairo context and draw with that.
+
+32. Can I improve the performance of my application by using another backend
+ of cairo (such as GL)?
+
+ No. Most drawing in GTK is not done via cairo anymore (but instead
+ by the GL or Vulkan renderers of GSK).
+
+ If you use cairo for drawing your own widgets, gtk_snapshot_append_cairo()
+ will choose the most appropriate surface type for you.
+
+ If you are interested in using GL for your own drawing, see #GtkGLArea.
+
+33. Can I use cairo to draw on a #GdkPixbuf?
+
+ No. The cairo image surface does not support the pixel format used by GdkPixbuf.
+
+ If you need to get cairo drawing into a format that can be displayed efficiently
+ by GTK, you may want to use an image surface and gdk_memory_texture_new().
[
Date Prev][
Date Next] [
Thread Prev][
Thread Next]
[
Thread Index]
[
Date Index]
[
Author Index]
