GtkImageView

## GtkImageView GtkImageView — General purpose image viewer for Gtk+ Screenshot of the `./tests/interactive` demo application |

## Synopsis

    enum                GtkImageTransp;
                        GtkImageView;
    GtkWidget *         gtk_image_view_new                  (void);
    gboolean            gtk_image_view_get_viewport         (GtkImageView *view,
                                                             GdkRectangle *rect);
    gboolean            gtk_image_view_get_draw_rect        (GtkImageView *view,
                                                             GdkRectangle *rect);
    void                gtk_image_view_get_check_colors     (GtkImageView *view,
                                                             int *check_color1,
                                                             int *check_color2);
    gboolean            gtk_image_view_image_to_widget_rect (GtkImageView *view,
                                                             GdkRectangle *rect_in,
                                                             GdkRectangle *rect_out);
    void                gtk_image_view_set_offset           (GtkImageView *view,
                                                             gdouble x,
                                                             gdouble y,
                                                             gboolean invalidate);
    void                gtk_image_view_set_transp           (GtkImageView *view,
                                                             GtkImageTransp transp,
                                                             int transp_color);
    gboolean            gtk_image_view_get_fitting          (GtkImageView *view);
    void                gtk_image_view_set_fitting          (GtkImageView *view,
                                                             gboolean fitting);
    GdkPixbuf *         gtk_image_view_get_pixbuf           (GtkImageView *view);
    void                gtk_image_view_set_pixbuf           (GtkImageView *view,
                                                             GdkPixbuf *pixbuf,
                                                             gboolean reset_fit);
    gdouble             gtk_image_view_get_zoom             (GtkImageView *view);
    void                gtk_image_view_set_zoom             (GtkImageView *view,
                                                             gdouble zoom);
    void                gtk_image_view_set_black_bg         (GtkImageView *view,
                                                             gboolean black_bg);
    gboolean            gtk_image_view_get_black_bg         (GtkImageView *view);
    void                gtk_image_view_set_show_frame       (GtkImageView *view,
                                                             gboolean show_frame);
    gboolean            gtk_image_view_get_show_frame       (GtkImageView *view);
    void                gtk_image_view_set_interpolation    (GtkImageView *view,
                                                             GdkInterpType interp);
    GdkInterpType       gtk_image_view_get_interpolation    (GtkImageView *view);
    void                gtk_image_view_set_show_cursor      (GtkImageView *view,
                                                             gboolean show_cursor);
    gboolean            gtk_image_view_get_show_cursor      (GtkImageView *view);
    void                gtk_image_view_set_tool             (GtkImageView *view,
                                                             GtkIImageTool *tool);
    GtkIImageTool *     gtk_image_view_get_tool             (GtkImageView *view);
    void                gtk_image_view_zoom_in              (GtkImageView *view);
    void                gtk_image_view_zoom_out             (GtkImageView *view);
    void                gtk_image_view_damage_pixels        (GtkImageView *view,
                                                             GdkRectangle *rect);
    const char *        gtk_image_view_library_version      (void);

## Object Hierarchy

      GObject
       +----GInitiallyUnowned
             +----GtkObject
                   +----GtkWidget
                         +----GtkImageView
                               +----GtkAnimView

## Implemented Interfaces

GtkImageView implements AtkImplementorIface and GtkBuildable.

## Signals

      "mouse-wheel-scroll"                             : Run Last
      "pixbuf-changed"                                 : Run Last
      "scroll"                                         : Run Last / Action
      "set-fitting"                                    : Run Last / Action
      "set-scroll-adjustments"                         : Run Last
      "set-zoom"                                       : Run Last / Action
      "zoom-changed"                                   : Run Last
      "zoom-in"                                        : Run Last / Action
      "zoom-out"                                       : Run Last / Action

## Description

GtkImageView is a full-featured general purpose image viewer widget for GTK. It provides a scrollable, zoomable pane in which a pixbuf can be displayed.

### Keybindings

When focused, GtkImageView responds to the following keybindings:

Keys | Corresponding function | Description
--- | --- | ---
`GDK_KP_Add`, `GDK_equal`, `GDK_plus` | `gtk_image_view_zoom_in()` | Causes the widget to zoom in one step.
`GDK_KP_Subtract`, `GDK_minus` | `gtk_image_view_zoom_out()` | Causes the widget to zoom out one step.
`GDK_1` | `gtk_image_view_set_zoom()` | Sets zoom to 100%.
`GDK_2` | `gtk_image_view_set_zoom()` | Sets zoom to 200%.
`GDK_3` | `gtk_image_view_set_zoom()` | Sets zoom to 300%.
`GDK_x` | `gtk_image_view_set_fitting()` | Sets fitting to `TRUE` so that the whole pixbuf becomes visible.
`GDK_Page_Up`, `GDK_Up` + `GDK_SHIFT_MASK` |  | Scroll the view half a page upwards.
`GDK_Page_Down`, `GDK_Down` + `GDK_SHIFT_MASK` |  | Scroll the view half a page downwards.
`GDK_Left` + `GDK_SHIFT_MASK` |  | Scroll the view half a page leftwards.
`GDK_Right` + `GDK_SHIFT_MASK` |  | Scroll the view half a page rightwards.

### Mouse actions

When focused, GtkImageView responds to the following mouse actions:

Mouse gesture | Description
--- | ---
Mouse wheel scroll + `GDK_CONTROL_MASK` | Increase or decrease the zoom of the view depending on the direction of the scroll.

### Coordinate systems

Operations on GtkImageView are executed in three different 2D coordinate systems:

- Image coordinates: each coordinate represents a pixel in the image. The range of valid coordinates goes from (0,0)-(p.w,p.h), where p.w and p.h is the width and height of the image.
- Widget coordinates: each coordinate represents a pixel in the image view widgets coordinate system. The range of valid coordinates goes from (0,0)-(a.w,a.h) where a.w and a.h is the allocated width and height of the widget. Naturally, these coordinates are only valid for as long as the widget is realized.
- Zoom coordinates: this coordinate system is the most frequently used coordinate system in GtkImageView. The range of valid coordinates goes from (0,0)-z(p.w,p.h) where p.w and p.h is the width and height of the image and z is the current zoom of the view. In other words, this coordinate system is simply the image coordinate system scaled.

### Settings

GtkImageView has a few settings that can be configured by users of the library. For example, when showing transparent images it may in certain cases be better to draw alpha transparent parts using the widgets background color instead of the default checkerboard:

            gtk_image_view_set_transp (GTK_IMAGE_VIEW (view),
                                       GTK_IMAGE_TRANSP_COLOR,
                                       0x00000000);

When the window that is showing the widget is fullscreened, other settings has to be tweaked to make the view look as good as possible:

            gtk_image_view_set_show_cursor (GTK_IMAGE_VIEW (view), FALSE);
            gtk_image_view_set_show_frame (GTK_IMAGE_VIEW (view), FALSE);
            gtk_image_view_set_black_bg (GTK_IMAGE_VIEW (view), TRUE);

Naturally, you should reset these settings again when the view leaves fullscreen mode.

GtkImageView aggresively caches the scaled image data. This behaviour is most often beneficial and makes the widget very fast. For example, try opening a very large image (4000x2000 pixels or so) in GtkImageView. The widget will spend some time bilinearly scaling the image at the start. Then try minimizing and unminimizing the window. The image will reappear immedately because the view has cached it.

However, this feature means that a client application must signal to the view when it changes the pixels on the pixbuf the view shows. The right way to do that is to use the `gtk_image_view_damage_pixels()` function. Code that merely tries to update the view by requesting that it should be redrawn will not work.

          // Do some operation on the pixbuf data here
          gtk_widget_queue_draw_area (10, 10, 50, 50) // Incorrect!

## Example

This is the minimal code needed for using GtkImageView.

    #include <gtkimageview/gtkimageview.h>
    int
    main (int argc, char *argv[])
    {
        gtk_init (&argc, &argv);
        GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
        GtkWidget *view = gtk_image_view_new ();
        GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file ("tests/gnome_logo.jpg", NULL);

        gtk_image_view_set_pixbuf (GTK_IMAGE_VIEW (view), pixbuf, TRUE);
        gtk_container_add (GTK_CONTAINER (window), view);
        gtk_widget_show_all (window);
        gtk_main ();
    }

Compile and run with:

    $ gcc -o minimal minimal.c `pkg-config --cflags --libs gtkimageview`
    $ ./minimal

The result should look something like the following:

Note that because the example doesn't use GtkImageScrollWin many nice features aren't available.

## Details

### enum GtkImageTransp

    typedef enum
    {
        GTK_IMAGE_TRANSP_COLOR = 0,
        GTK_IMAGE_TRANSP_BACKGROUND,
        GTK_IMAGE_TRANSP_GRID
    } GtkImageTransp;

This enum defines the valid transparency settings for how the image view should draw transparent parts of alpha images. Their primary use is as a value for the first parameter to the `gtk_image_view_set_transp()` method.

Their interpretation is as follows:

- GTK_IMAGE_TRANSP_COLOR : Use a single color.
- GTK_IMAGE_TRANSP_BACKGROUND : Use the background color of the widget
- GTK_IMAGE_TRANSP_GRID : Use light and dark gray checkerboard pattern.

### GtkImageView

    typedef struct _GtkImageView GtkImageView;

GtkImageView is the main class in the library. All of its fields are private, they are only shown here for completeness. Use `gtk_image_view_new()` to instantiate GtkImageView objects.

### gtk_image_view_new ()

    GtkWidget *         gtk_image_view_new                  (void);

Creates a new image view with default values. The default values are:

- black bg : `FALSE`
- fitting : `TRUE`
- image tool : a GtkImageToolDragger instance
- interpolation mode : `GDK_INTERP_BILINEAR`
- offset : (0, 0)
- pixbuf : `NULL`
- show cursor: `TRUE`
- show frame : `TRUE`
- transp : GTK_IMAGE_TRANSP_GRID
- zoom : 1.0

Returns : | a new GtkImageView.

### gtk_image_view_get_viewport ()

    gboolean            gtk_image_view_get_viewport         (GtkImageView *view,
                                                             GdkRectangle *rect);

Fills in the rectangle with the current viewport. If pixbuf is `NULL`, there is no viewport, `rect` is left untouched and `FALSE` is returned. If the view is not allocated, the rectangles coordinates are set to the views offset and its width and height to zero.

The current viewport is defined as the rectangle, in zoomspace coordinates as the area of the loaded pixbuf the GtkImageView is currently showing.

`view` : | a GtkImageView
`rect` : | a GdkRectangle to fill in with the current viewport or `NULL`.
Returns : | `TRUE` if a GdkPixbuf is shown, `FALSE` otherwise.

### gtk_image_view_get_draw_rect ()

    gboolean            gtk_image_view_get_draw_rect        (GtkImageView *view,
                                                             GdkRectangle *rect);

Get the rectangle in the widget where the pixbuf is painted.

For example, if the widgets allocated size is 100, 100 and the pixbufs size is 50, 50 and the zoom factor is 1.0, then the pixbuf will be drawn centered on the widget. `rect` will then be (25,25)-[50,50].

If the view is not allocated, then the rectangle will be set to (0,0)-[0,0] and `TRUE` is returned.

This method is useful when converting from widget to image or zoom space coordinates.

`view` : | a GtkImageView
`rect` : | a GdkRectangle to fill in with the area of the widget in which the pixbuf is drawn.
Returns : | `TRUE` if the view has a pixbuf, `FALSE` otherwise.

### gtk_image_view_get_check_colors ()

    void                gtk_image_view_get_check_colors     (GtkImageView *view,
                                                             int *check_color1,
                                                             int *check_color2);

Reads the two colors used to draw transparent parts of images with an alpha channel. Note that if the `transp` setting of the view is `GTK_IMAGE_TRANSP_BACKGROUND` or `GTK_IMAGE_TRANSP_COLOR`, then both colors will be equal.

`view` : | A GtkImageView.
`check_color1` : | A pointer to an integer where the first check color should be stored.
`check_color2` : | A pointer to an integer wherer the second check color should be stored.

### gtk_image_view_image_to_widget_rect ()

    gboolean            gtk_image_view_image_to_widget_rect (GtkImageView *view,
                                                             GdkRectangle *rect_in,
                                                             GdkRectangle *rect_out);

Convert a rectangle in image space coordinates to widget space coordinates. If the view is not realized, or if it contains no pixbuf, then the conversion was unsuccessful, `FALSE` is returned and `rect_out` is left unmodified.

The size of `rect_out` is rounded up. For example, if the zoom factor is 0.25 and the width of the input rectangle is 2, then its with in widget space coordinates is 0.5 which is rounded up to 1.

Note that this function may return a rectangle that is not visible on the widget.

`view` : | a GtkImageView
`rect_in` : | a GdkRectangle in image space coordinates to convert
`rect_out` : | a GdkRectangle to fill in with the widget space coordinates
Returns : | `TRUE` if the conversion was successful, `FALSE` otherwise

### gtk_image_view_set_offset ()

    void                gtk_image_view_set_offset           (GtkImageView *view,
                                                             gdouble x,
                                                             gdouble y,
                                                             gboolean invalidate);

Sets the offset of where in the image the GtkImageView should begin displaying image data.

The offset is clamped so that it will never cause the GtkImageView to display pixels outside the pixbuf. Setting this attribute causes the widget to repaint itself if it is realized.

If `invalidate` is `TRUE`, the views entire area will be invalidated instead of redrawn immediately. The view is then queued for redraw, which means that additional operations can be performed on it before it is redrawn.

The difference can sometimes be important like when you are overlaying data and get flicker or artifacts when setting the offset. If that happens, setting `invalidate` to `TRUE` could fix the problem. See the source code to GtkImageToolSelector for an example.

Normally, `invalidate` should always be `FALSE` because it is much faster to repaint immedately than invalidating.

`view` : | A GtkImageView.
`x` : | X-component of the offset in zoom space coordinates.
`y` : | Y-component of the offset in zoom space coordinates.
`invalidate` : | whether to invalidate the view or redraw immediately.

### gtk_image_view_set_transp ()

    void                gtk_image_view_set_transp           (GtkImageView *view,
                                                             GtkImageTransp transp,
                                                             int transp_color);

Sets how the view should draw transparent parts of images with an alpha channel. If `transp` is `GTK_IMAGE_TRANSP_COLOR`, the specified color will be used. Otherwise the `transp_color` argument is ignored. If it is `GTK_IMAGE_TRANSP_BACKGROUND`, the background color of the widget will be used. If it is `GTK_IMAGE_TRANSP_GRID`, then a grid with light and dark gray boxes will be drawn on the transparent parts.

Calling this method causes the widget to immediately repaint. It also causes the ::pixbuf-changed signal to be emitted. This is done so that other widgets (such as GtkImageNav) will have a chance to render a view of the pixbuf with the new transparency settings.

The default values are:

- transp : `GTK_IMAGE_TRANSP_GRID`
- transp_color : `0x000000`

`view` : | A GtkImageView.
`transp` : | The transparency type to use when drawing transparent images.
`transp_color` : | Color to use when drawing transparent images.

### gtk_image_view_get_fitting ()

    gboolean            gtk_image_view_get_fitting          (GtkImageView *view);

Returns the fitting setting of the view.

`view` : | a GtkImageView
Returns : | `TRUE` if the view is fitting the image, `FALSE` otherwise.

### gtk_image_view_set_fitting ()

    void                gtk_image_view_set_fitting          (GtkImageView *view,
                                                             gboolean fitting);

Sets whether to fit or not. If `TRUE`, then the view will adapt the zoom so that the whole pixbuf is visible.

Setting the fitting causes the widget to immediately repaint itself.

Fitting is by default `TRUE`.

`view` : | a GtkImageView.
`fitting` : | whether to fit the image or not

### gtk_image_view_get_pixbuf ()

    GdkPixbuf *         gtk_image_view_get_pixbuf           (GtkImageView *view);

Returns the pixbuf this view shows.

`view` : | A GtkImageView.
Returns : | The pixbuf this view shows.

### gtk_image_view_set_pixbuf ()

    void                gtk_image_view_set_pixbuf           (GtkImageView *view,
                                                             GdkPixbuf *pixbuf,
                                                             gboolean reset_fit);

Sets the `pixbuf` to display, or `NULL` to not display any pixbuf. Normally, `reset_fit` should be `TRUE` which enables fitting. Which means that, initially, the whole pixbuf will be shown.

Sometimes, the fit mode should not be reset. For example, if GtkImageView is showing an animation, it would be bad to reset the fit mode for each new frame. The parameter should then be `FALSE` which leaves the fit mode of the view untouched.

This method should not be used if merely the contents of the pixbuf has changed. See `gtk_image_view_damage_pixels()` for that.

If `reset_fit` is `TRUE`, the ::zoom-changed signal is emitted, otherwise not. The ::pixbuf-changed signal is also emitted.

The default pixbuf is `NULL`.

`view` : | A GtkImageView.
`pixbuf` : | The pixbuf to display.
`reset_fit` : | Whether to reset fitting or not.

### gtk_image_view_get_zoom ()

    gdouble             gtk_image_view_get_zoom             (GtkImageView *view);

Get the current zoom factor of the view.

`view` : | a GtkImageView
Returns : | the current zoom factor

### gtk_image_view_set_zoom ()

    void                gtk_image_view_set_zoom             (GtkImageView *view,
                                                             gdouble zoom);

Sets the zoom of the view.

Fitting is always disabled after this method has run. The ::zoom-changed signal is unconditionally emitted.

The default value is 1.0.

`view` : | a GtkImageView
`zoom` : | the new zoom factor

### gtk_image_view_set_black_bg ()

    void                gtk_image_view_set_black_bg         (GtkImageView *view,
                                                             gboolean black_bg);

If `TRUE`, the view uses a black background. If `FALSE`, the view uses the default (normally gray) background.

The default value is `FALSE`.

`view` : | A GtkImageView.
`black_bg` : | Whether to use a black background or not.

### gtk_image_view_get_black_bg ()

    gboolean            gtk_image_view_get_black_bg         (GtkImageView *view);

Returns whether the view renders the widget on a black background or not.

`view` : | A GtkImageView.
Returns : | `TRUE` if a black background is used, otherwise `FALSE`.

### gtk_image_view_set_show_frame ()

    void                gtk_image_view_set_show_frame       (GtkImageView *view,
                                                             gboolean show_frame);

Sets whether to draw a frame around the image or not. When `TRUE`, a one pixel wide frame is shown around the image. Setting this attribute causes the widget to immediately repaint itself.

The default value is `TRUE`.

`view` : | a GtkImageView
`show_frame` : | whether to show a frame around the pixbuf or not

### gtk_image_view_get_show_frame ()

    gboolean            gtk_image_view_get_show_frame       (GtkImageView *view);

Returns whether a one pixel frame is drawn around the pixbuf or not.

`view` : | A GtkImageView.
Returns : | `TRUE` if a frame is drawn around the pixbuf, otherwise `FALSE`.

### gtk_image_view_set_interpolation ()

    void                gtk_image_view_set_interpolation    (GtkImageView *view,
                                                             GdkInterpType interp);

Sets the interpolation mode of how the view. `GDK_INTERP_HYPER` is the slowest, but produces the best results. `GDK_INTERP_NEAREST` is the fastest, but provides bad rendering quality. `GDK_INTERP_BILINEAR` is a good compromise.

Setting the interpolation mode causes the widget to immediately repaint itself.

The default interpolation mode is `GDK_INTERP_BILINEAR`.

`view` : | A GtkImageView.
`interp` : | The interpolation to use. One of `GDK_INTERP_NEAREST`, `GDK_INTERP_BILINEAR` and `GDK_INTERP_HYPER`.

### gtk_image_view_get_interpolation ()

    GdkInterpType       gtk_image_view_get_interpolation    (GtkImageView *view);

Returns the current interpolation mode of the view.

`view` : | a GtkImageView
Returns : | the interpolation

### gtk_image_view_set_show_cursor ()

    void                gtk_image_view_set_show_cursor      (GtkImageView *view,
                                                             gboolean show_cursor);

Sets whether to show the mouse cursor when the mouse is over the widget or not. Hiding the cursor is useful when the widget is fullscreened.

The default value is `TRUE`.

`view` : | A GtkImageView.
`show_cursor` : | whether to show the cursor or not

### gtk_image_view_get_show_cursor ()

    gboolean            gtk_image_view_get_show_cursor      (GtkImageView *view);

Returns whether to show the mouse cursor when the mouse is over the widget or not.

`view` : | A GtkImageView.
Returns : | `TRUE` if the cursor is shown, otherwise `FALSE`.

### gtk_image_view_set_tool ()

    void                gtk_image_view_set_tool             (GtkImageView *view,
                                                             GtkIImageTool *tool);

Set the image tool to use. If the new tool is the same as the current tool, then nothing will be done. Otherwise `gtk_iimage_tool_pixbuf_changed()` is called so that the tool has a chance to generate initial data for the pixbuf.

Setting the tool causes the widget to immediately repaint itself.

The default image tool is a GtkImageToolDragger instance. See also GtkIImageTool.

`view` : | A GtkImageView.
`tool` : | The image tool to use (must not be `NULL`)

### gtk_image_view_get_tool ()

    GtkIImageTool *     gtk_image_view_get_tool             (GtkImageView *view);

Gets the image tool GtkImageView uses for rendering and handling input events.

`view` : | A GtkImageView
Returns : | The currently bound image tool

### gtk_image_view_zoom_in ()

    void                gtk_image_view_zoom_in              (GtkImageView *view);

Zoom in the view one step. Calling this method causes the widget to immediately repaint itself.

`view` : | a GtkImageView

### gtk_image_view_zoom_out ()

    void                gtk_image_view_zoom_out             (GtkImageView *view);

Zoom out the view one step. Calling this method causes the widget to immediately repaint itself.

`view` : | a GtkImageView

### gtk_image_view_damage_pixels ()

    void                gtk_image_view_damage_pixels        (GtkImageView *view,
                                                             GdkRectangle *rect);

Mark the pixels in the rectangle as damaged. That the pixels are damaged, means that they have been modified and that the view must redraw them to ensure that the visible part of the image corresponds to the pixels in that image. Calling this method emits the ::pixbuf-changed signal.

This method must be used when modifying the image data:

        // Drawing something cool in the area 20,20 - 60,60 here...
        ...
        // And force an update
        gtk_image_view_damage_pixels (view, &(GdkRectangle){20, 20, 60, 60});

If the whole pixbuf has been modified then `rect` should be `NULL` to indicate that a total update is needed.

See also `gtk_image_view_set_pixbuf()`.

`view` : | a GtkImageView
`rect` : | rectangle in image space coordinates to mark as damaged or `NULL`, to mark the whole pixbuf as damaged.

### gtk_image_view_library_version ()

    const char *        gtk_image_view_library_version      (void);

Returns a string with the format "major.minor.micro" which denotes the runtime version of GtkImageView being used.

Returns : | a string describing the version of GtkImageView.The returned string is owned by GtkImageView and should not be modified or freed.

## Signal Details

### The `"mouse-wheel-scroll"` signal

    void                user_function                      (GtkImageView      *view,
                                                            GdkScrollDirection direction,
                                                            gpointer           user_data)      : Run Last

The ::mouse-wheel-scroll signal is emitted when the mouse wheel is scrolled on the view and `GTK_CONTROL_MASK` is not held down.

`view` : | The GtkImageView that emitted the signal.
`direction` : | The direction of the scroll; `GDK_SCROLL_UP`, `GDK_SCROLL_DOWN`, `GDK_SCROLL_LEFT` or `GDK_SCROLL_RIGHT`.
`user_data` : | user data set when the signal handler was connected.

### The `"pixbuf-changed"` signal

    void                user_function                      (GtkImageView *view,
                                                            gpointer      user_data)      : Run Last

The ::pixbuf-changed signal is emitted when the pixbuf the image view shows is changed and when its image data is changed. Listening to this signal is useful if you, for example, have a label that displays the width and height of the pixbuf in the view.

        // Handler that will be called when the pixbuf changes.
        static void
        pixbuf_cb (GtkImageView *view,
                   GtkLabel     *label)
        {
            GdkPixbuf *new_pb = gtk_image_view_get_pixbuf (view);
            if (!new_pb)
            {
                // Empty label if no pixbuf.
                gtk_label_set_text (label, "");
                return;
            }
            int width = gdk_pixbuf_get_width (new_pb);
            int height = gdk_pixbuf_get_height (new_pb);
            char *text = g_strdup_printf ("%d, %d", width, height);
            gtk_label_set_text (label, text);
            g_free (text);
        }
        ...
        GtkWidget *label = gtk_label_new ("");
        g_signal_connect (G_OBJECT (view), "pixbuf-changed",
                          G_CALLBACK (pixbuf_cb), label);

`view` : | The view that emitted the signal.
`user_data` : | user data set when the signal handler was connected.

### The `"scroll"` signal

    void                user_function                      (GtkImageView *view,
                                                            GtkScrollType xscroll,
                                                            GtkScrollType yscroll,
                                                            gpointer      user_data)      : Run Last / Action

The ::scroll signal is a keybinding signal emitted when a key is used to scroll the view. The signal should not be used by clients of this library.

`view` : | The GtkImageView that received the signal.
`xscroll` : | Horizontal scroll constant.
`yscroll` : | Vertical scroll constant.
`user_data` : | user data set when the signal handler was connected.

### The `"set-fitting"` signal

    void                user_function                      (GtkImageView *imageview,
                                                            gint          arg1,
                                                            gpointer      user_data)      : Run Last / Action

`imageview` : | the object which received the signal.
`arg1` : |
`user_data` : | user data set when the signal handler was connected.

### The `"set-scroll-adjustments"` signal

    void                user_function                      (GtkImageView  *arg0,
                                                            GtkAdjustment *arg1,
                                                            GtkAdjustment *arg2,
                                                            gpointer       user_data)      : Run Last

Do we really need this signal? It should be intrinsic to the GtkWidget class, shouldn't it?

`user_data` : | user data set when the signal handler was connected.

### The `"set-zoom"` signal

    void                user_function                      (GtkImageView *view,
                                                            gdouble       zoom,
                                                            gpointer      user_data)      : Run Last / Action

The ::set-zoom signal is a keybinding signal emitted when `GDK_1`, `GDK_2` or `GDK_3` is pressed on the widget which causes the zoom to be set to 100%, 200% or 300%. The signal should not be used by clients of this library.

`view` : | The GtkImageView that received the signal.
`zoom` : | The new zoom factor.
`user_data` : | user data set when the signal handler was connected.

### The `"zoom-changed"` signal

    void                user_function                      (GtkImageView *view,
                                                            gpointer      user_data)      : Run Last

The ::zoom-changed signal is emitted when the zoom factor of the view changes. Listening to this signal is useful if, for example, you have a label that displays the zoom factor of the view. Use `gtk_image_view_get_zoom()` to retrieve the value. For example:

        // Handler that will be called when the zoom changes.
        static void
        zoom_cb (GtkImageView *view,
                 GtkLabel     *label)
        {
            gdouble zoom = gtk_image_view_get_zoom (view);
            char *text = g_strdup_printf ("%d%%", (int)(zoom * 100.0));
            gtk_label_set_text (label, text);
            g_free (text);
        }
        ...
        // Connect the callback to the signal.
        GtkWidget *label = gtk_label_new ("100%");
        g_signal_connect (G_OBJECT (view), "zoom-changed",
                          G_CALLBACK (zoom_cb), label);

`view` : | The GtkImageView that emitted the signal.
`user_data` : | user data set when the signal handler was connected.

### The `"zoom-in"` signal

    void                user_function                      (GtkImageView *imageview,
                                                            gpointer      user_data)      : Run Last / Action

`imageview` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.

### The `"zoom-out"` signal

    void                user_function                      (GtkImageView *view,
                                                            gpointer      user_data)      : Run Last / Action

The ::zoom-out signal is a keybinding signal emitted when `GDK_minus` or `GDK_KP_Subtract` is pressed on the widget. The signal should not be used by clients of this library.

`view` : | The GtkImageView that received the signal.
`user_data` : | user data set when the signal handler was connected.

## See Also

GtkAnimView