<!-- ##### 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, orperhaps 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, andshould be accessed using the functions below.</para><!-- ##### ARG GtkPreview:expand ##### --><para></para><!-- ##### STRUCT GtkPreviewInfo ##### --><para>Contains information about global propertiesof preview widgets.The #GtkPreviewInfo struct contains the following fields.(These fields should be considered read-only. They should never be set byan 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: <!-- ##### FUNCTION gtk_preview_size ##### --><para>Set the size that the preview widget will requestin response to a "size_request" signal. The drawing area may actually be allocated a sizelarger than this depending on how it is packedwithin the enclosing containers. The effectof this is determined by whether the previewis 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 widgetand 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 behaveswhen the size it is allocated is larger than the requestedsize. If @expand is %FALSE, then the preview's windowand buffer will be no larger than the size set with gtk_preview_size(), and the data set will be centeredin the allocation if it is larger. If @expand is %TRUEthen the window and buffer will expand with the allocation;the application is responsible for catchingthe "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 afunction 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 isset with gtk_preview_draw_row() so changing thisvalue will not affect existing data in previewwidgets.</para>@gamma_: the new gamma value.<!-- ##### FUNCTION gtk_preview_set_color_cube ##### --><para>This function is deprecated and does nothing. GdkRGBautomatically picks an optimium color cube for thedisplay.</para>@nred_shades: ignored@ngreen_shades: ignored@nblue_shades: ignored@ngray_shades: ignored<!-- ##### FUNCTION gtk_preview_set_install_cmap ##### --><para>This function is deprecatedand does nothing. GdkRGB will automatically picka private colormap if it cannot allocate sufficientcolors.</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. Thisfunction is deprecated, and you should usegdk_rgb_get_visual() instead.</para>@Returns: the visual for previews.<!-- ##### FUNCTION gtk_preview_get_cmap ##### --><para>Returns the colormap used by preview widgets. Thisfunction is deprecated, and you should usegdk_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 wasonce used for changing the colormap and visual on the fly.</para>