path: root/docs/reference/gtk/tmpl/gtkpreview.sgml

<!-- ##### SECTION Title ##### -->
GtkPreview

<!-- ##### SECTION Short_Description ##### -->
A widget to display RGB or grayscale data

<!-- ##### SECTION Long_Description ##### -->
<para>
The #GtkPreview widget provides a simple interface 
used to display images as RGB or grayscale data.
It's deprecated; just use a #GdkPixbuf displayed by a #GtkImage, or
perhaps a #GtkDrawingArea. #GtkPreview has no advantage over those 
approaches.
</para>

<!-- ##### SECTION See_Also ##### -->
<para>
<variablelist>

<varlistentry>
<term>#GdkRGB</term>
<listitem><para>the backend used by #GtkPreview.</para></listitem>
</varlistentry>

</variablelist>
</para>

<!-- ##### SECTION Stability_Level ##### -->


<!-- ##### STRUCT GtkPreview ##### -->
<para>
The #GtkPreview-struct struct contains private data only, and
should be accessed using the functions below.
</para>


<!-- ##### ARG GtkPreview:expand ##### -->
<para>

</para>

<!-- ##### STRUCT GtkPreviewInfo ##### -->
<para>
Contains information about global properties
of preview widgets.

The #GtkPreviewInfo struct contains the following fields.
(These fields should be considered read-only. They should never be set by
an application.)

<informaltable pgwide="1" frame="none" role="struct">
<tgroup cols="2"><colspec colwidth="2*"/><colspec colwidth="8*"/>
<tbody>

<row>
<entry>#GdkVisual *visual;</entry>
<entry>the visual used by all previews.</entry>
</row>

<row>
<entry>#GdkColormap *cmap;</entry>
<entry>the colormap used by all previews.</entry>
</row>

<row>
<entry>gdouble gamma;</entry>
<entry>the gamma correction value used by all previews (See gtk_preview_set_gamma()).</entry>
</row>

</tbody>
</tgroup>
</informaltable>

</para>

@lookup: 
@gamma: 

<!-- ##### UNION GtkDitherInfo ##### -->
<para>
This union not used in GTK+.
</para>


<!-- ##### FUNCTION gtk_preview_uninit ##### -->
<para>
This function is deprecated and does nothing.
</para>



<!-- ##### FUNCTION gtk_preview_new ##### -->
<para>
Create a new preview widget.
</para>

@type: the type data contained by the widget. 
(Grayscale or RGB)
@Returns: a new #GtkPreview


<!-- ##### FUNCTION gtk_preview_size ##### -->
<para>
Set the size that the preview widget will request
in response to a "size_request" signal. The 
drawing area may actually be allocated a size
larger than this depending on how it is packed
within the enclosing containers. The effect
of this is determined by whether the preview
is set to expand or not (see gtk_preview_expand())
</para>

@preview: a #GtkPreview.
@width: the new width.
@height: the new height.


<!-- ##### FUNCTION gtk_preview_put ##### -->
<para>
Takes a portion of the contents of a preview widget
and draws it onto the given drawable, @window.
</para>

@preview: a #GtkPreview.
@window: a window or pixmap.
@gc: The graphics context for the operation. Only the
     clip mask for this GC matters.
@srcx: the x coordinate of the upper left corner in the source image.
@srcy: the y coordinate of the upper left corner in the source image.
@destx: the x coordinate of the upper left corner in the destination image.
@desty: the y coordinate of the upper left corner in the destination image.
@width: the width of the rectangular portion to draw.
@height: the height of the rectangular portion to draw.


<!-- ##### FUNCTION gtk_preview_draw_row ##### -->
<para>
Sets the data for a portion of a row.
</para>

@preview: a #GtkPreview.
@data: the new data for the portion. It should contain
       @w bytes of data if the preview is of type
       GTK_TYPE_GRAYSCALE, and 3*@w bytes of data
       if the preview is of type GTK_TYPE_COLOR.
@x: the starting value on the row to set.
@y: the row to change.
@w: the number of pixels in the row to change.


<!-- ##### FUNCTION gtk_preview_set_expand ##### -->
<para>
Determines the way that the the preview widget behaves
when the size it is allocated is larger than the requested
size. If @expand is %FALSE, then the preview's window
and buffer will be no larger than the size set with 
gtk_preview_size(), and the data set will be centered
in the allocation if it is larger. If @expand is %TRUE
then the window and buffer will expand with the allocation;
the application is responsible for catching
the "size_allocate" signal and providing the data 
appropriate for this size.
</para>

@preview: a #GtkPreview.
@expand: whether the preview's window should expand or not.


<!-- ##### FUNCTION gtk_preview_set_gamma ##### -->
<para>
Set the gamma-correction value for all preview widgets.
(This function will eventually be replaced with a
function that sets a per-preview-widget gamma value).
The resulting intensity is given by:
<literal>destination_value * pow (source_value/255, 1/gamma)</literal>.
The gamma value is applied when the data is
set with gtk_preview_draw_row() so changing this
value will not affect existing data in preview
widgets.
</para>

@gamma_: the new gamma value.


<!-- ##### FUNCTION gtk_preview_set_color_cube ##### -->
<para>
This function is deprecated and does nothing. GdkRGB
automatically picks an optimium color cube for the
display.
</para>

@nred_shades: ignored
@ngreen_shades: ignored
@nblue_shades: ignored
@ngray_shades: ignored


<!-- ##### FUNCTION gtk_preview_set_install_cmap ##### -->
<para>
This function is deprecated
and does nothing. GdkRGB will automatically pick
a private colormap if it cannot allocate sufficient
colors.
</para>

@install_cmap: ignored.


<!-- ##### FUNCTION gtk_preview_set_reserved ##### -->
<para>
This function is deprecated and does nothing.
</para>

@nreserved: ignored.


<!-- ##### FUNCTION gtk_preview_set_dither ##### -->
<para>
Set the dithering mode for the display. 
</para>

@preview: a #GtkPreview.
@dither: the dithering mode.


<!-- ##### FUNCTION gtk_preview_get_visual ##### -->
<para>
Returns the visual used by preview widgets. This
function is deprecated, and you should use
gdk_rgb_get_visual() instead.
</para>

@Returns: the visual for previews.


<!-- ##### FUNCTION gtk_preview_get_cmap ##### -->
<para>
Returns the colormap used by preview widgets. This
function is deprecated, and you should use
gdk_rgb_get_cmap() instead.
</para>

@Returns: the colormap for previews.


<!-- ##### FUNCTION gtk_preview_get_info ##### -->
<para>
Return a #GtkPreviewInfo structure containing 
global information about preview widgets.
</para>

@Returns: a #GtkPreviewInfo structure. The return
 value belongs to GTK+ and must not be modified
 or freed.


<!-- ##### FUNCTION gtk_preview_reset ##### -->
<para>
This function is deprecated and does nothing. It was
once used for changing the colormap and visual on the fly.
</para>