GTK+ Reference Manual
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# GtkCurve

## Name

GtkCurve -- allows direct editing of a curve.

## Synopsis

    #include <gtk/gtk.h>

    struct      GtkCurve;
    GtkWidget*  gtk_curve_new                   (void);
    void        gtk_curve_reset                 (GtkCurve *curve);
    void        gtk_curve_set_gamma             (GtkCurve *curve,
                                                 gfloat gamma);
    void        gtk_curve_set_range             (GtkCurve *curve,
                                                 gfloat min_x,
                                                 gfloat max_x,
                                                 gfloat min_y,
                                                 gfloat max_y);
    void        gtk_curve_get_vector            (GtkCurve *curve,
                                                 int veclen,
                                                 gfloat vector[]);
    void        gtk_curve_set_vector            (GtkCurve *curve,
                                                 int veclen,
                                                 gfloat vector[]);
    void        gtk_curve_set_curve_type        (GtkCurve *curve,
                                                 GtkCurveType type);

## Object Hierarchy

      GObject
       +----GtkObject
             +----GtkWidget
                   +----GtkDrawingArea
                         +----GtkCurve

## Properties

      "curve-type"           GtkCurveType         : Read / Write
      "min-x"                gfloat               : Read / Write
      "max-x"                gfloat               : Read / Write
      "min-y"                gfloat               : Read / Write
      "max-y"                gfloat               : Read / Write

## Signal Prototypes

    "curve-type-changed"
                void        user_function      (GtkCurve *curve,
                                                gpointer user_data);

## Description

NOTE this widget is considered too specialized/little-used for GTK+, and will in the future be moved to some other package. If your application needs this widget, feel free to use it, as the widget does work and is useful in some applications; it's just not of general interest. However, we are not accepting new features for the widget, and it will eventually move out of the GTK+ distribution.

The GtkCurve widget allows the user to edit a curve covering a range of values. It is typically used to fine-tune color balances in graphics applications like the Gimp.

The GtkCurve widget has 3 modes of operation - spline, linear and free. In spline mode the user places points on the curve which are automatically connected together into a smooth curve. In linear mode the user places points on the curve which are connected by straight lines. In free mode the user can draw the points of the curve freely, and they are not connected at all.

## Details

### struct GtkCurve

    struct GtkCurve;

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

### gtk_curve_new ()

    GtkWidget*  gtk_curve_new                   (void);

Creates a new GtkCurve.

Returns : | a new GtkCurve.

### gtk_curve_reset ()

    void        gtk_curve_reset                 (GtkCurve *curve);

Resets the curve to a straight line from the minimum x and y values to the maximum x and y values (i.e. from the bottom-left to the top-right corners). The curve type is not changed.

`curve` : | a GtkCurve.

### gtk_curve_set_gamma ()

    void        gtk_curve_set_gamma             (GtkCurve *curve,
                                                 gfloat gamma);

Recomputes the entire curve using the given gamma value. A gamma value of 1 results in a straight line. Values greater than 1 result in a curve above the straight line. Values less than 1 result in a curve below the straight line. The curve type is changed to `GTK_CURVE_TYPE_FREE`. FIXME: Needs a more precise definition of gamma.

`curve` : | a GtkCurve.
`gamma` : | the gamma value.

### gtk_curve_set_range ()

    void        gtk_curve_set_range             (GtkCurve *curve,
                                                 gfloat min_x,
                                                 gfloat max_x,
                                                 gfloat min_y,
                                                 gfloat max_y);

Sets the minimum and maximum x and y values of the curve. The curve is also reset with a call to gtk_curve_reset().

`curve` : | a GtkCurve.
`min_x` : | the minimum x value.
`max_x` : | the maximum x value.
`min_y` : | the minimum y value.
`max_y` : | the maximum y value.

### gtk_curve_get_vector ()

    void        gtk_curve_get_vector            (GtkCurve *curve,
                                                 int veclen,
                                                 gfloat vector[]);

Returns a vector of points representing the curve.

`curve` : | a GtkCurve.
`veclen` : | the number of points to calculate.
`vector` : | returns the points.

### gtk_curve_set_vector ()

    void        gtk_curve_set_vector            (GtkCurve *curve,
                                                 int veclen,
                                                 gfloat vector[]);

Sets the vector of points on the curve. The curve type is set to `GTK_CURVE_TYPE_FREE`.

`curve` : | a GtkCurve.
`veclen` : | the number of points.
`vector` : | the points on the curve.

### gtk_curve_set_curve_type ()

    void        gtk_curve_set_curve_type        (GtkCurve *curve,
                                                 GtkCurveType type);

Sets the type of the curve. The curve will remain unchanged except when changing from a free curve to a linear or spline curve, in which case the curve will be changed as little as possible.

`curve` : | a GtkCurve.
`type` : | the type of the curve.

## Properties

"`curve-type`" (GtkCurveType : Read / Write)

  Is this curve linear, spline interpolated, or free-form

"`min-x`" (gfloat : Read / Write)

  Minimum possible value for X

"`max-x`" (gfloat : Read / Write)

  Maximum possible X value.

"`min-y`" (gfloat : Read / Write)

  Minimum possible value for Y

"`max-y`" (gfloat : Read / Write)

  Maximum possible value for Y

## Signals

### The "curve-type-changed" signal

    void        user_function                  (GtkCurve *curve,
                                                gpointer user_data);

Emitted when the curve type has been changed. The curve type can be changed explicitly with a call to gtk_curve_set_curve_type(). It is also changed as a side-effect of calling gtk_curve_reset() or gtk_curve_set_gamma().

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

## See Also

GtkGammaCurve

  a subclass for editing gamma curves.

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Special-purpose features | GtkGammaCurve