GtkIImageTool

## GtkIImageTool GtkIImageTool — Interface for objects capable of being used as tools by GtkImageView |

## Synopsis

                        GtkIImageTool;
    gboolean            gtk_iimage_tool_button_press        (GtkIImageTool *tool,
                                                             GdkEventButton *ev);
    gboolean            gtk_iimage_tool_button_release      (GtkIImageTool *tool,
                                                             GdkEventButton *ev);
    gboolean            gtk_iimage_tool_motion_notify       (GtkIImageTool *tool,
                                                             GdkEventMotion *ev);
    void                gtk_iimage_tool_pixbuf_changed      (GtkIImageTool *tool,
                                                             gboolean reset_fit,
                                                             GdkRectangle *rect);
    void                gtk_iimage_tool_paint_image         (GtkIImageTool *tool,
                                                             GdkPixbufDrawOpts *opts,
                                                             GdkDrawable *drawable);
    GdkCursor *         gtk_iimage_tool_cursor_at_point     (GtkIImageTool *tool,
                                                             int x,
                                                             int y);

## Object Hierarchy

      GInterface
       +----GtkIImageTool

## Known Implementations

GtkIImageTool is implemented by GtkImageToolDragger, GtkImageToolPainter and GtkImageToolSelector.

## Description

GtkIImageTool is an interface that defines how GtkImageView interacts with objects that acts as tools. GtkImageView delegates many of its most important tasks (such as drawing) to its tool which carries out all the hard work. The GtkImageView package comes with two tools; GtkImageToolDragger and GtkImageToolSelector, but by implementing your own tool it is possible to extend GtkImageView to do stuff its author (thats me) didn't imagine.

GtkImageView uses GtkImageToolDragger by default, as that tool is he most generally useful one. However, it is trivial to make it use another tool.

          GtkImageView *view = GTK_IMAGE_VIEW (gtk_image_view_new ());
          GtkIImageTool *tool = gtk_image_tool_selector_new (view);
          gtk_image_view_set_tool (view, tool);

Using the above code makes the view use the selector tool instead of the default dragger tool.

## Details

### GtkIImageTool

    typedef struct _GtkIImageTool GtkIImageTool;

### gtk_iimage_tool_button_press ()

    gboolean            gtk_iimage_tool_button_press        (GtkIImageTool *tool,
                                                             GdkEventButton *ev);

`tool` : |
`ev` : |
Returns : |

### gtk_iimage_tool_button_release ()

    gboolean            gtk_iimage_tool_button_release      (GtkIImageTool *tool,
                                                             GdkEventButton *ev);

Handles a `GdkEventButton` event of a button release. The implementing function should return `TRUE` if it handled the event, for examply by releasing the grab, and `FALSE` otherwise.

`tool` : | the tool
`ev` : | a `GdkEventButton` event
Returns : | `TRUE` if the event was handled, `FALSE` otherwise

### gtk_iimage_tool_motion_notify ()

    gboolean            gtk_iimage_tool_motion_notify       (GtkIImageTool *tool,
                                                             GdkEventMotion *ev);

Handles a `GdkEventMotion` event. The implementing function should return `TRUE` if it handled the event and `FALSE` otherwise.

`tool` : | the tool
`ev` : | a `GdkEventMotion` event
Returns : | `TRUE` if the event was handled, `FALSE` otherwise

### gtk_iimage_tool_pixbuf_changed ()

    void                gtk_iimage_tool_pixbuf_changed      (GtkIImageTool *tool,
                                                             gboolean reset_fit,
                                                             GdkRectangle *rect);

Indiate to the tool that either a part of, or the whole pixbuf that the image view shows has changed. This method is called by the view whenever its pixbuf or its tool changes. That is, when any of the following methods are used:

- `gtk_image_view_set_pixbuf()`
- `gtk_image_view_set_tool()`
- `gtk_image_view_damage_pixels()`

If the `reset_fit` parameter is `TRUE`, it means that a new pixbuf has been loaded into the view. `rect` is a rectangle in image space coordinates that indicates which rectangular region of the pixbufs pixels that is modified. If `rect` is `NULL`, then all of the pixbuf has changed. See also GtkImageView::pixbuf-changed.

`tool` : | the tool
`reset_fit` : | whether the view is resetting its fit mode or not
`rect` : | rectangle containing the changed area or `NULL`

### gtk_iimage_tool_paint_image ()

    void                gtk_iimage_tool_paint_image         (GtkIImageTool *tool,
                                                             GdkPixbufDrawOpts *opts,
                                                             GdkDrawable *drawable);

Called whenever the image view decides that any part of the image it shows needs to be redrawn.

`tool` : | the tool
`opts` : | the GdkPixbufDrawOpts to use in this draw
`drawable` : | a GdkDrawable to draw on

### gtk_iimage_tool_cursor_at_point ()

    GdkCursor *         gtk_iimage_tool_cursor_at_point     (GtkIImageTool *tool,
                                                             int x,
                                                             int y);

Ask the tool what cursor it wants displayed. E.g. if the tool keeps track of image maps in the image, then this method can be implemented to return an appropriate cursor when the mouse pointer hovers at the specified point in the widget.

`tool` : |
`x` : | the mouse pointers X-coordinate
`y` : | the mouse pointers Y-coordinate
Returns : | The appropriate cursor or `NULL` if the widgets default cursor should be used.

## See Also

Non-instantiable classed types: Interfaces