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# Package Gtk.Curve

The Gtk_Curve 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 Gtk_Curve 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.

- Gtk.Curve Widget Hierarchy
- Gtk.Curve Signals
- Gtk.Curve Types
- Gtk.Curve Subprograms

## Widget Hierarchy

    Gtk_Object                    (see section Package Gtk.Object)
       \___ Gtk_Widget            (see section Package Gtk.Widget)
          \___ Gtk_Drawing_Area   (see section Package Gtk.Drawing_Area)
             \___ Gtk_Curve       (see section Package Gtk.Curve)

## Signals

- "curve-type-changed" procedure Handler (Curve : access Gtk_Curve_Record'Class);
  Emitted when the curve type has been changed. The curve type can be changed explicitly with a call to Set_Curve_Type. It is also changed as a side-effect of calling Reset or Set_Gamma.

## Types

    type Gtk_Curve_Type is
        (Curve_Type_Linear,
         Curve_Type_Spline,
         Curve_Type_Free);

## Subprograms

    procedure Gtk_New
      (Curve              : out    Gtk_Curve);
| Create a new Curve.
    function Get_Type              return Gtk.Gtk_Type;
| Return the internal value associated with a Gtk_Curve.
    procedure Reset
      (Curve              : access Gtk_Curve_Record);
| Reset the curve. Reset to a straight line from the minimum x & y values to the maximum x & y values (i.e. from the bottom-left to the top-right corners). The curve type is not changed.
    procedure Set_Gamma
      (Curve              : access Gtk_Curve_Record;
       Gamma              : in     Gfloat);
| Recompute the entire curve using the given gamma value. A gamma value of 1.0 results in a straight line. Values greater than 1.0 result in a curve above the straight line. Values less than 1.0 result in a curve below the straight line. The curve type is changed to Curve_Type_Free.
    procedure Set_Range
      (Curve              : access Gtk_Curve_Record;
       Min_X              : in     Gfloat;
       Max_X              : in     Gfloat;
       Min_Y              : in     Gfloat;
       Max_Y              : in     Gfloat);
| Set the minimum and maximum x & y values of the curve. The curve is also reset with a call to Reset.
    procedure Set_Vector
      (Curve              : access Gtk_Curve_Record;
       Vector             : in     Gfloat_Array);
| Set the vector of points on the curve. The curve type is set to Curve_Type_Free.
    procedure Get_Vector
      (Curve              : access Gtk_Curve_Record;
       Vector             : in out Gfloat_Array);
| Return a vector of points representing the curve.
    procedure Set_Curve_Type
      (Curve              : access Gtk_Curve_Record;
       Curve_Type         : in     Gtk_Curve_Type);
| Set 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.

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