## GtkTreeModelFilter GtkTreeModelFilter — A GtkTreeModel which hides parts of an underlying tree model |

## Synopsis

    #include <gtk/gtk.h>

    struct              GtkTreeModelFilter;
    gboolean            (*GtkTreeModelFilterVisibleFunc)    (GtkTreeModel *model,
                                                             GtkTreeIter *iter,
                                                             gpointer data);
    void                (*GtkTreeModelFilterModifyFunc)     (GtkTreeModel *model,
                                                             GtkTreeIter *iter,
                                                             GValue *value,
                                                             gint column,
                                                             gpointer data);
    GtkTreeModel *      gtk_tree_model_filter_new           (GtkTreeModel *child_model,
                                                             GtkTreePath *root);
    void                gtk_tree_model_filter_set_visible_func
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreeModelFilterVisibleFunc func,
                                                             gpointer data,
                                                             GDestroyNotify destroy);
    void                gtk_tree_model_filter_set_modify_func
                                                            (GtkTreeModelFilter *filter,
                                                             gint n_columns,
                                                             GType *types,
                                                             GtkTreeModelFilterModifyFunc func,
                                                             gpointer data,
                                                             GDestroyNotify destroy);
    void                gtk_tree_model_filter_set_visible_column
                                                            (GtkTreeModelFilter *filter,
                                                             gint column);
    GtkTreeModel *      gtk_tree_model_filter_get_model     (GtkTreeModelFilter *filter);
    gboolean            gtk_tree_model_filter_convert_child_iter_to_iter
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreeIter *filter_iter,
                                                             GtkTreeIter *child_iter);
    void                gtk_tree_model_filter_convert_iter_to_child_iter
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreeIter *child_iter,
                                                             GtkTreeIter *filter_iter);
    GtkTreePath *       gtk_tree_model_filter_convert_child_path_to_path
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreePath *child_path);
    GtkTreePath *       gtk_tree_model_filter_convert_path_to_child_path
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreePath *filter_path);
    void                gtk_tree_model_filter_refilter      (GtkTreeModelFilter *filter);
    void                gtk_tree_model_filter_clear_cache   (GtkTreeModelFilter *filter);

## Object Hierarchy

      GObject
       +----GtkTreeModelFilter

## Implemented Interfaces

GtkTreeModelFilter implements GtkTreeModel and GtkTreeDragSource.

## Properties

      "child-model"              GtkTreeModel*         : Read / Write / Construct Only
      "virtual-root"             GtkTreePath*          : Read / Write / Construct Only

## Description

A GtkTreeModelFilter is a tree model which wraps another tree model, and can do the following things:

- Filter specific rows, based on data from a "visible column", a column storing booleans indicating whether the row should be filtered or not, or based on the return value of a "visible function", which gets a model, iter and user_data and returns a boolean indicating whether the row should be filtered or not.

- Modify the "appearance" of the model, using a modify function. This is extremely powerful and allows for just changing some values and also for creating a completely different model based on the given child model.

- Set a different root node, also known as a "virtual root". You can pass in a GtkTreePath indicating the root node for the filter at construction time.

## Details

### struct GtkTreeModelFilter

    struct GtkTreeModelFilter;

The GtkTreeModelFilter struct contains only private fields.

### GtkTreeModelFilterVisibleFunc ()

    gboolean            (*GtkTreeModelFilterVisibleFunc)    (GtkTreeModel *model,
                                                             GtkTreeIter *iter,
                                                             gpointer data);

A function which decides whether the row indicated by `iter` is visible.

`model` : | the child model of the GtkTreeModelFilter
`iter` : | a GtkTreeIter pointing to the row in `model` whose visibility is determined
`data` : | user data given to `gtk_tree_model_filter_set_visible_func()`
Returns : | Whether the row indicated by `iter` is visible.

### GtkTreeModelFilterModifyFunc ()

    void                (*GtkTreeModelFilterModifyFunc)     (GtkTreeModel *model,
                                                             GtkTreeIter *iter,
                                                             GValue *value,
                                                             gint column,
                                                             gpointer data);

A function which calculates display values from raw values in the model. It must fill `value` with the display value for the column `column` in the row indicated by `iter`.

Since this function is called for each data access, it's not a particularly efficient operation.

`model` : | the GtkTreeModelFilter
`iter` : | a GtkTreeIter pointing to the row whose display values are determined
`value` : | A GValue which is already initialized for with the correct type for the column `column`.
`column` : | the column whose display value is determined
`data` : | user data given to `gtk_tree_model_filter_set_modify_func()`

### gtk_tree_model_filter_new ()

    GtkTreeModel *      gtk_tree_model_filter_new           (GtkTreeModel *child_model,
                                                             GtkTreePath *root);

Creates a new GtkTreeModel, with `child_model` as the child_model and `root` as the virtual root.

`child_model` : | A GtkTreeModel.
`root` : | A GtkTreePath or `NULL`. [allow-none]
Returns : | A new GtkTreeModel. [transfer full]

Since 2.4

### gtk_tree_model_filter_set_visible_func ()

    void                gtk_tree_model_filter_set_visible_func
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreeModelFilterVisibleFunc func,
                                                             gpointer data,
                                                             GDestroyNotify destroy);

Sets the visible function used when filtering the `filter` to be `func`. The function should return `TRUE` if the given row should be visible and `FALSE` otherwise.

If the condition calculated by the function changes over time (e.g. because it depends on some global parameters), you must call `gtk_tree_model_filter_refilter()` to keep the visibility information of the model uptodate.

Note that `func` is called whenever a row is inserted, when it may still be empty. The visible function should therefore take special care of empty rows, like in the example below.

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    static gboolean
    visible_func (GtkTreeModel *model,
                  GtkTreeIter  *iter,
                  gpointer      data)
    {
      /* Visible if row is non-empty and first column is "HI" */
      gchar *str;
      gboolean visible = FALSE;

      gtk_tree_model_get (model, iter, 0, &str, -1);
      if (str && strcmp (str, "HI") == 0)
        visible = TRUE;
      g_free (str);

      return visible;
    }

`filter` : | A GtkTreeModelFilter.
`func` : | A GtkTreeModelFilterVisibleFunc, the visible function.
`data` : | User data to pass to the visible function, or `NULL`. [allow-none]
`destroy` : | Destroy notifier of `data`, or `NULL`. [allow-none]

Since 2.4

### gtk_tree_model_filter_set_modify_func ()

    void                gtk_tree_model_filter_set_modify_func
                                                            (GtkTreeModelFilter *filter,
                                                             gint n_columns,
                                                             GType *types,
                                                             GtkTreeModelFilterModifyFunc func,
                                                             gpointer data,
                                                             GDestroyNotify destroy);

With the `n_columns` and `types` parameters, you give an array of column types for this model (which will be exposed to the parent model/view). The `func`, `data` and `destroy` parameters are for specifying the modify function. The modify function will get called for each data access, the goal of the modify function is to return the data which should be displayed at the location specified using the parameters of the modify function.

`filter` : | A GtkTreeModelFilter.
`n_columns` : | The number of columns in the filter model.
`types` : | The GTypes of the columns. [array length=n_columns]
`func` : | A GtkTreeModelFilterModifyFunc
`data` : | User data to pass to the modify function, or `NULL`. [allow-none]
`destroy` : | Destroy notifier of `data`, or `NULL`. [allow-none]

Since 2.4

### gtk_tree_model_filter_set_visible_column ()

    void                gtk_tree_model_filter_set_visible_column
                                                            (GtkTreeModelFilter *filter,
                                                             gint column);

Sets `column` of the child_model to be the column where `filter` should look for visibility information. `columns` should be a column of type `G_TYPE_BOOLEAN`, where `TRUE` means that a row is visible, and `FALSE` if not.

`filter` : | A GtkTreeModelFilter.
`column` : | A gint which is the column containing the visible information.

Since 2.4

### gtk_tree_model_filter_get_model ()

    GtkTreeModel *      gtk_tree_model_filter_get_model     (GtkTreeModelFilter *filter);

Returns a pointer to the child model of `filter`.

`filter` : | A GtkTreeModelFilter.
Returns : | A pointer to a GtkTreeModel. [transfer none]

Since 2.4

### gtk_tree_model_filter_convert_child_iter_to_iter ()

    gboolean            gtk_tree_model_filter_convert_child_iter_to_iter
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreeIter *filter_iter,
                                                             GtkTreeIter *child_iter);

Sets `filter_iter` to point to the row in `filter` that corresponds to the row pointed at by `child_iter`. If `filter_iter` was not set, `FALSE` is returned.

`filter` : | A GtkTreeModelFilter.
`filter_iter` : | An uninitialized GtkTreeIter. [out]
`child_iter` : | A valid GtkTreeIter pointing to a row on the child model.
Returns : | `TRUE`, if `filter_iter` was set, i.e. if `child_iter` is a valid iterator pointing to a visible row in child model.

Since 2.4

### gtk_tree_model_filter_convert_iter_to_child_iter ()

    void                gtk_tree_model_filter_convert_iter_to_child_iter
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreeIter *child_iter,
                                                             GtkTreeIter *filter_iter);

Sets `child_iter` to point to the row pointed to by `filter_iter`.

`filter` : | A GtkTreeModelFilter.
`child_iter` : | An uninitialized GtkTreeIter. [out]
`filter_iter` : | A valid GtkTreeIter pointing to a row on `filter`.

Since 2.4

### gtk_tree_model_filter_convert_child_path_to_path ()

    GtkTreePath *       gtk_tree_model_filter_convert_child_path_to_path
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreePath *child_path);

Converts `child_path` to a path relative to `filter`. That is, `child_path` points to a path in the child model. The rerturned path will point to the same row in the filtered model. If `child_path` isn't a valid path on the child model or points to a row which is not visible in `filter`, then `NULL` is returned.

`filter` : | A GtkTreeModelFilter.
`child_path` : | A GtkTreePath to convert.
Returns : | A newly allocated GtkTreePath, or `NULL`.

Since 2.4

### gtk_tree_model_filter_convert_path_to_child_path ()

    GtkTreePath *       gtk_tree_model_filter_convert_path_to_child_path
                                                            (GtkTreeModelFilter *filter,
                                                             GtkTreePath *filter_path);

Converts `filter_path` to a path on the child model of `filter`. That is, `filter_path` points to a location in `filter`. The returned path will point to the same location in the model not being filtered. If `filter_path` does not point to a location in the child model, `NULL` is returned.

`filter` : | A GtkTreeModelFilter.
`filter_path` : | A GtkTreePath to convert.
Returns : | A newly allocated GtkTreePath, or `NULL`.

Since 2.4

### gtk_tree_model_filter_refilter ()

    void                gtk_tree_model_filter_refilter      (GtkTreeModelFilter *filter);

Emits ::row_changed for each row in the child model, which causes the filter to re-evaluate whether a row is visible or not.

`filter` : | A GtkTreeModelFilter.

Since 2.4

### gtk_tree_model_filter_clear_cache ()

    void                gtk_tree_model_filter_clear_cache   (GtkTreeModelFilter *filter);

This function should almost never be called. It clears the `filter` of any cached iterators that haven't been reffed with `gtk_tree_model_ref_node()`. This might be useful if the child model being filtered is static (and doesn't change often) and there has been a lot of unreffed access to nodes. As a side effect of this function, all unreffed iters will be invalid.

`filter` : | A GtkTreeModelFilter.

Since 2.4

## Property Details

### The `"child-model"` property

      "child-model"              GtkTreeModel*         : Read / Write / Construct Only

The model for the filtermodel to filter.

### The `"virtual-root"` property

      "virtual-root"             GtkTreePath*          : Read / Write / Construct Only

The virtual root (relative to the child model) for this filtermodel.

## See Also

GtkTreeModelSort