GtkPreview: GTK+ 2 Reference Manual

## GtkPreview GtkPreview — A widget to display RGB or grayscale data |

## Functions

void | gtk_preview_uninit ()
GtkWidget * | gtk_preview_new ()
void | gtk_preview_size ()
void | gtk_preview_put ()
void | gtk_preview_draw_row ()
void | gtk_preview_set_expand ()
void | gtk_preview_set_gamma ()
void | gtk_preview_set_color_cube ()
void | gtk_preview_set_install_cmap ()
void | gtk_preview_set_reserved ()
void | gtk_preview_set_dither ()
GdkVisual * | gtk_preview_get_visual ()
GdkColormap * | gtk_preview_get_cmap ()
GtkPreviewInfo * | gtk_preview_get_info ()
void | gtk_preview_reset ()

## Properties

gboolean | expand | Read / Write

## Types and Values

struct | GtkPreview
struct | GtkPreviewInfo
union | GtkDitherInfo

## Object Hierarchy

        GObject
        ╰── GInitiallyUnowned
            ╰── GtkObject
                ╰── GtkWidget
                    ╰── GtkPreview

## Implemented Interfaces

GtkPreview implements AtkImplementorIface and GtkBuildable.

## Includes

    #include <gtk/gtk.h>

## Description

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.

## Functions

### gtk_preview_uninit ()

    void
    gtk_preview_uninit (void);

`gtk_preview_uninit` is deprecated and should not be used in newly-written code.

This function is deprecated and does nothing.

### gtk_preview_new ()

    GtkWidget *
    gtk_preview_new (GtkPreviewType type);

`gtk_preview_new` is deprecated and should not be used in newly-written code.

Create a new preview widget.

#### Parameters

type | the type data contained by the widget. (Grayscale or RGB) |

#### Returns

a new GtkPreview

### gtk_preview_size ()

    void
    gtk_preview_size (GtkPreview *preview,
                      gint width,
                      gint height);

`gtk_preview_size` is deprecated and should not be used in newly-written code.

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()`)

#### Parameters

preview | a GtkPreview. |
width | the new width. |
height | the new height. |

### gtk_preview_put ()

    void
    gtk_preview_put (GtkPreview *preview,
                     GdkWindow *window,
                     GdkGC *gc,
                     gint srcx,
                     gint srcy,
                     gint destx,
                     gint desty,
                     gint width,
                     gint height);

`gtk_preview_put` is deprecated and should not be used in newly-written code.

Takes a portion of the contents of a preview widget and draws it onto the given drawable, `window`.

#### Parameters

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. |

### gtk_preview_draw_row ()

    void
    gtk_preview_draw_row (GtkPreview *preview,
                          guchar *data,
                          gint x,
                          gint y,
                          gint w);

`gtk_preview_draw_row` is deprecated and should not be used in newly-written code.

Sets the data for a portion of a row.

#### Parameters

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. |

### gtk_preview_set_expand ()

    void
    gtk_preview_set_expand (GtkPreview *preview,
                            gboolean expand);

`gtk_preview_set_expand` is deprecated and should not be used in newly-written code.

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.

#### Parameters

preview | a GtkPreview. |
expand | whether the preview's window should expand or not. |

### gtk_preview_set_gamma ()

    void
    gtk_preview_set_gamma (double gamma_);

`gtk_preview_set_gamma` is deprecated and should not be used in newly-written code.

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: `destination_value * pow (source_value/255, 1/gamma)`. 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.

#### Parameters

gamma_ | the new gamma value. |

### gtk_preview_set_color_cube ()

    void
    gtk_preview_set_color_cube (guint nred_shades,
                                guint ngreen_shades,
                                guint nblue_shades,
                                guint ngray_shades);

`gtk_preview_set_color_cube` is deprecated and should not be used in newly-written code.

This function is deprecated and does nothing. GdkRGB automatically picks an optimium color cube for the display.

#### Parameters

nred_shades | ignored |
ngreen_shades | ignored |
nblue_shades | ignored |
ngray_shades | ignored |

### gtk_preview_set_install_cmap ()

    void
    gtk_preview_set_install_cmap (gint install_cmap);

`gtk_preview_set_install_cmap` is deprecated and should not be used in newly-written code.

This function is deprecated and does nothing. GdkRGB will automatically pick a private colormap if it cannot allocate sufficient colors.

#### Parameters

install_cmap | ignored. |

### gtk_preview_set_reserved ()

    void
    gtk_preview_set_reserved (gint nreserved);

`gtk_preview_set_reserved` is deprecated and should not be used in newly-written code.

This function is deprecated and does nothing.

#### Parameters

nreserved | ignored. |

### gtk_preview_set_dither ()

    void
    gtk_preview_set_dither (GtkPreview *preview,
                            GdkRgbDither dither);

`gtk_preview_set_dither` is deprecated and should not be used in newly-written code.

Set the dithering mode for the display.

#### Parameters

preview | a GtkPreview. |
dither | the dithering mode. |

### gtk_preview_get_visual ()

    GdkVisual *
    gtk_preview_get_visual (void);

`gtk_preview_get_visual` is deprecated and should not be used in newly-written code.

Returns the visual used by preview widgets. This function is deprecated, and you should use `gdk_rgb_get_visual()` instead.

#### Returns

the visual for previews.

### gtk_preview_get_cmap ()

    GdkColormap *
    gtk_preview_get_cmap (void);

`gtk_preview_get_cmap` is deprecated and should not be used in newly-written code.

Returns the colormap used by preview widgets. This function is deprecated, and you should use `gdk_rgb_get_cmap()` instead.

#### Returns

the colormap for previews.

### gtk_preview_get_info ()

    GtkPreviewInfo *
    gtk_preview_get_info (void);

`gtk_preview_get_info` is deprecated and should not be used in newly-written code.

Return a GtkPreviewInfo structure containing global information about preview widgets.

#### Returns

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

### gtk_preview_reset ()

    void
    gtk_preview_reset (void);

`gtk_preview_reset` is deprecated and should not be used in newly-written code.

This function is deprecated and does nothing. It was once used for changing the colormap and visual on the fly.

## Types and Values

### struct GtkPreview

    struct GtkPreview;

`GtkPreview` is deprecated and should not be used in newly-written code.

The GtkPreview struct contains private data only, and should be accessed using the functions below.

### struct GtkPreviewInfo

    struct GtkPreviewInfo {
      guchar *lookup;

      gdouble gamma;
    };

`GtkPreviewInfo` is deprecated and should not be used in newly-written code.

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.)

GdkVisual *visual; | the visual used by all previews.
GdkColormap *cmap; | the colormap used by all previews.
gdouble gamma; | the gamma correction value used by all previews (See `gtk_preview_set_gamma()`).

### union GtkDitherInfo

`GtkDitherInfo` is deprecated and should not be used in newly-written code.

This union not used in GTK+.

## Property Details

### The `“expand”` property

      “expand”                   gboolean

Whether the preview widget should take up the entire space it is allocated.

Flags: Read / Write

Default value: FALSE

## See Also

GdkRGB | the backend used by GtkPreview.