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# Package Gtk.Extra.Plot`_`Canvas

A Gtk_Plot_Canvas is a special kind of drawing area used with Gtk_Plot widgets. It provides drag-and-drop capabilities for the texts, legends, points... available in a Gtk_Plot. Note that this widget is specifically designed for Gtk_Plot widgets, and won't provide any other capability for other kinds of widgets.

Like any child of Gtk_Layout, this widget can have an almost unlimited size for its children, and provides scrolling.

- Gtk.Extra.Plot_Canvas Widget Hierarchy
- Gtk.Extra.Plot_Canvas Signals
- Gtk.Extra.Plot_Canvas Types
- Gtk.Extra.Plot_Canvas Subprograms

## Widget Hierarchy

    Gtk_Object                    (see section Package Gtk.Object)
       \___ Gtk_Widget            (see section Package Gtk.Widget)
          \___ Gtk_Container      (see section Package Gtk.Container)
             \___ Gtk_Fixed       (see section Package Gtk.Fixed)
                \___ Gtk_Plot_Canvas (see section Package Gtk.Extra.Plot_Canvas)

## Signals

- "changed" procedure Handler (Canvas : access Gtk_Plot_Canvas_Record'Class);
  Called when the contents of the canvas has changed (an item was moved interactively by the user). A region of the canvas was selected by the user.
- "delete_item" procedure Handler (Canvas : access Gtk_Plot_Canvas_Record'Class;
  Item : Gtk_Plot_Canvas_Child);
  Called when an item is being removed from the canvas
- "move_item" function Handler (Canvas : access Gtk_Plot_Canvas_Record'Class;
  Item : Gtk_Plot_Canvas_Child;
  New_X : Gdouble;
  New_Y : Gdouble)
  return Boolean;
  An item was moved on the canvas. Its coordinates have not changed yet, but if the handler returns True they will become (New_X, New_Y). If the handler returns False, nothing happens.
- "resize_item" function Handler (Canvas : access Gtk_Plot_Canvas_Record'Class;
  Item : Gtk_Plot_Canvas_Child;
  New_Width : Gdouble;
  New_Height : Gdouble)
  return Boolean;
  An item is being resized. Its size has not changed yet, but if the handler returns True it will become (New_Width, New_Height). If the handler returns False, nothing happens.
- "select_item" function Handler (Canvas : access Gtk_Plot_Canvas_Record'Class;
  Event : Gdk_Button_Event;
  Item : Gtk_Plot_Canvas_Child)
  return Boolean;
  Called when an item was selected. An item can be anything, from a text to a plot When this signal is called, the item was simply selected, but not dragged. The handler should return False if the item can not be selected.
- "select_region" procedure Handler (Canvas : access Gtk_Plot_Canvas_Record'Class;
  X_Min : Gdouble;
  Y_Min : Gdouble;
  X_Max : Gdouble;
  Y_Max : Gdouble);

## Types

    type Child_Draw_Func is access procedure
        (Canvas : System.Address;
         Child  : Gtk_Plot_Canvas_Child);
| Generic format of functions used to draw a child of the canvas. Canvas is a System.Address since these functions are called directly from C and GtkAda can't insert its hooks. However, you can use the Convert function below to convert to a Gtk_Plot_Canvas.
    type Gtk_Plot_Canvas_Child is new Gdk.C_Proxy;
    type Plot_Canvas_Action is
        (Action_Inactive,
         Action_Selection,
         Action_Drag,
         Action_Resize);
| The action being performed on the canvas.
    type Plot_Canvas_Arrow is new Gint;
    type Plot_Canvas_Flag is new Gint;
    type Plot_Canvas_Pos is
        (Canvas_Out,
         Canvas_In,
         Canvas_Left,
         Canvas_Right,
         Canvas_Top,
         Canvas_Bottom,
         Canvas_Top_Left,
         Canvas_Top_Right,
         Canvas_Bottom_Left,
         Canvas_Bottom_Right);
| The position of the items in the canvas.
    type Plot_Canvas_Type is
        (None,
         Plot,
         Axis,
         Legends,
         Title,
         Text,
         Data,
         Line,
         Rectangle,
         Ellipse,
         Custom);
| The type of data that can be put in a canvas. Plot is only for a Gtk.Extra.Plot.Gtk_Plot widget.

## Subprograms

### Creating and manipulating the canvas
    procedure Gtk_New
      (Widget             : out    Gtk_Plot_Canvas;
       Width              : in     Gint;
       Height             : in     Gint;
       Magnification      : in     Gdouble := 1.0);
| Create a new Gtk_Plot_Canvas, with a specific screen size. Since the widget can have an unlimited internal size, it does not try to set its size to accommodate all of its children.
    function Get_Type              return Gtk.Gtk_Type;
| Return the internal value associated with a Gtk_Plot_Canvas.
    function Child_Get_Type        return Gtk.Gtk_Type;
| Return the internal value associated with a Gtk_Plot_Canvas_Child.
    procedure Refresh
      (Canvas             : access Gtk_Plot_Canvas_Record);
| Force a refresh of the canvas on the screen. The screen is updated from the contents of the double-buffer.
    procedure Paint
      (Canvas             : access Gtk_Plot_Canvas_Record);
| Redraw each of the items included in the canvas. The painting is done in the double-buffer, and must be drawn on the screen with Refresh.
    function Get_Pixmap
      (Canvas             : access Gtk_Plot_Canvas_Record)
       return Gdk.Pixmap.Gdk_Pixmap;
| Return the pixmap associated with the Canvas. If you add your own items on the canvas (see Child_New below), you can draw them on this pixmap to make them visible on the canvas. You need to call Refresh to send this pixmap to the screen.
    procedure Grid_Set_Visible
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Visible            : in     Boolean);
| Indicate whether the grid should be visible or not.
    procedure Grid_Set_Step
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Step               : in     Gint);
| Set the space between two lines of the grid.
    procedure Grid_Set_Attributes
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Style              : in     Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              : in     Gint;
       Color              : in     Gdk.Color.Gdk_Color);
| Set the attributes of the grid.
    procedure Add_Plot
      (Plot_Canvas        : access Gtk_Plot_Canvas_Record;
       Plot               : access Gtk.Extra.Plot.Gtk_Plot_Record'Class;
       X                  : in     Gdouble;
       Y                  : in     Gdouble);
| Add a new plot to the list handled by the canvas. The canvas will then provide drag-and-drop functionalities for that plot. The plot is displayed at the relative screen coordinates (X, Y). Plot becomes the new active plot, and its associated pixmap becomes the Plot_Canvas itself.
    procedure Set_Active_Plot
      (Plot_Canvas        : access Gtk_Plot_Canvas_Record;
       Plot               : access Gtk.Extra.Plot.Gtk_Plot_Record'Class);
| Modify the active plot in the canvas. The active plot is generally the one that received the last click event (drag-and-drop, etc.). This should be set before emitting any of the signals in this class.
    procedure Cancel_Action
      (Plot_Canvas        : access Gtk_Plot_Canvas_Record);
| Cancel the current action. This can be called in the user callbacks to ignore temporarily some of the signals below.
    function Get_Active_Plot
      (Canvas             : access Gtk_Plot_Canvas_Record)
       return Gtk.Extra.Plot.Gtk_Plot;
| Return the active plot. In the callbacks for the signals below, this is the widget that got the signal.
    function Get_Active_Data
      (Canvas             : access Gtk_Plot_Canvas_Record)
       return Gtk.Extra.Plot_Data.Gtk_Plot_Data;
| Return the active dataset (which of course belongs to the active plot). This is the dataset that was last clicked on.
    procedure Get_Active_Point
      (Canvas             : access Gtk_Plot_Canvas_Record;
       X                  : out    Gdouble;
       Y                  : out    Gdouble;
       Index              : out    Gint);
| Return the relative coordinates of the active point in the active dataset. Index will contain the index of the active point in the list of the canvas'children, or -1 if there is no active point. This is the index in the coordinates arrays of Get_Active_Data. This is the one that was last clicked on.
    procedure Set_Size
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Width              : in     Gint;
       Height             : in     Gint);
| Modify the size allocated for the canvas, and the size of the pixmap the plots are displayed on.
    procedure Unselect
      (Canvas             : access Gtk_Plot_Canvas_Record);
| Unselect the currently selected item.
    procedure Set_Magnification
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Magnification      :        Gdouble := 1.0);
| Changes the magnification for the canvas. 1.0 is the default value. Higher values will zoom in, while lower values will zoom out.
    procedure Set_Background
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Background         :        Gdk.Color.Gdk_Color);
| Set the background color for the canvas.
    procedure Get_Pixel
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Px                 : in     Gdouble;
       Py                 : in     Gdouble;
       X                  : out    Gint;
       Y                  : out    Gint);
| Convert from relative coordinates to absolute ones.
    procedure Get_Position
      (Canvas             : access Gtk_Plot_Canvas_Record;
       X                  : in     Gint;
       Y                  : in     Gint;
       Px                 : out    Gdouble;
       Py                 : out    Gdouble);
| Convert from absolute coordinates to relative ones.
### Canvas items
There are several different types of items that can be put on the canvas, and then manipulated interactively by the user.
    function Convert
      (Canvas             :        System.Address)
       return Gtk_Plot_Canvas;
| Convert from a System.Address returned by C to a real Gtk_Plot_Canvas structure.
    procedure Set_Draw_Func
      (Child              :        Gtk_Plot_Canvas_Child;
       Draw               :        Child_Draw_Func);
| Set the function used to draw the item. This should be used only for items whose type is Custom, since other items have their own drawing functions.
    function Get_Active_Item
      (Canvas             : access Gtk_Plot_Canvas_Record)
       return Gtk_Plot_Canvas_Child;
| Return the currently selected item.
    function Put_Text
      (Canvas             : access Gtk_Plot_Canvas_Record;
       X                  : in     Gdouble;
       Y                  : in     Gdouble;
       Ps_Font            : in     String;
       Height             : in     Gint;
       Angle              : in     Gint;
       Fg                 : in     Gdk.Color.Gdk_Color;
       Bg                 : in     Gdk.Color.Gdk_Color;
       Transparent        : in     Boolean;
       Justification      : in     Gtk.Enums.Gtk_Justification;
       Text               : in     String)
       return Gtk_Plot_Canvas_Child;
| Put an arbitrary text in the layout. Ps_Font should be the name of a postscript font. (X, Y) are the relative coordinates to which the text should be drawn. The only legal values for Angle are 0, 90, 180 and 270 degrees. Text can contain some special characters, that change is renderering. They all begin with a '\' (backslash) character, followed by one of: '0' .. '9' : Change the font (take the nth font in the family 'g' : Select the "Symbol" font 'B' : Activate bold characters. 'i' : Activate italic characters. 'S' or '^' : Activate superscripts. 's' or '_' : Activate subscripts. '+' : Increment the fontsize by 3 pixels. '-' : Decrement the fontsize by 3 pixels. 'N' : Restore the default characteristics of the font. 'b' : Move back one character.
    function Put_Line
      (Canvas             : access Gtk_Plot_Canvas_Record;
       X1                 :        Gdouble;
       Y1                 :        Gdouble;
       X2                 :        Gdouble;
       Y2                 :        Gdouble;
       Style              :        Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              :        Gfloat;
       Color              :        Gdk.Color.Gdk_Color;
       Arrow_Mask         :        Plot_Canvas_Arrow)
       return Gtk_Plot_Canvas_Child;
| Draw a line in the background of the canvas.
    function Put_Rectangle
      (Canvas             : access Gtk_Plot_Canvas_Record;
       X1                 :        Gdouble;
       Y1                 :        Gdouble;
       X2                 :        Gdouble;
       Y2                 :        Gdouble;
       Style              :        Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              :        Gfloat;
       Fg                 :        Gdk.Color.Gdk_Color;
       Bg                 :        Gdk.Color.Gdk_Color;
       Border             :        Gtk.Extra.Plot.Plot_Border_Style;
       Fill               :        Boolean := False)
       return Gtk_Plot_Canvas_Child;
| Draw a rectangle in the canvas.
    function Put_Ellipse
      (Canvas             : access Gtk_Plot_Canvas_Record;
       X1                 :        Gdouble;
       Y1                 :        Gdouble;
       X2                 :        Gdouble;
       Y2                 :        Gdouble;
       Style              :        Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              :        Gfloat;
       Fg                 :        Gdk.Color.Gdk_Color;
       Bg                 :        Gdk.Color.Gdk_Color;
       Fill               :        Boolean := False)
       return Gtk_Plot_Canvas_Child;
| Draw an ellipse in the canvas.
    procedure Line_Set_Attributes
      (Child              :        Gtk_Plot_Canvas_Child;
       Style              :        Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              :        Gfloat;
       Color              :        Gdk.Color.Gdk_Color;
       Mask               :        Plot_Canvas_Arrow);
| Change the attributes of a line.
    procedure Rectangle_Set_Attributes
      (Child              :        Gtk_Plot_Canvas_Child;
       Style              :        Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              :        Gfloat;
       Fg                 :        Gdk.Color.Gdk_Color;
       Bg                 :        Gdk.Color.Gdk_Color;
       Border             :        Gtk.Extra.Plot.Plot_Border_Style;
       Fill               :        Boolean := False);
| Change the attributes of a rectangle.
    procedure Ellipse_Set_Attributes
      (Child              :        Gtk_Plot_Canvas_Child;
       Style              :        Gtk.Extra.Plot_Data.Plot_Line_Style;
       Width              :        Gfloat;
       Fg                 :        Gdk.Color.Gdk_Color;
       Bg                 :        Gdk.Color.Gdk_Color;
       Fill               :        Boolean := False);
| Change the attributes for an ellipse.
### Custom children
You can insert your own items in a canvas. While the canvas will take care of moving the item, it is your responsability to provide a visual rendering for it.
    function Child_New
      (Child_Type         :        Plot_Canvas_Type := Custom)
       return Gtk_Plot_Canvas_Child;
| Create a new child.
    procedure Put_Child
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Child              :        Gtk_Plot_Canvas_Child;
       X1                 :        Gdouble;
       Y1                 :        Gdouble;
       X2                 :        Gdouble;
       Y2                 :        Gdouble);
| Insert a new item in the canvas. It will occupy the area defined by the four coordinates.
    procedure Child_Move
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Child              :        Gtk_Plot_Canvas_Child;
       X1                 :        Gdouble;
       Y1                 :        Gdouble);
| Move an item, but does not change its size.
    procedure Child_Move_Resize
      (Canvas             : access Gtk_Plot_Canvas_Record;
       Child              :        Gtk_Plot_Canvas_Child;
       X1                 :        Gdouble;
       Y1                 :        Gdouble;
       X2                 :        Gdouble;
       Y2                 :        Gdouble);
| Move an resize an item in the canvas.
    function Get_Item_Type
      (Item               :        Gtk_Plot_Canvas_Child)
       return Plot_Canvas_Type;
| Return the type of the item.
    function Get_Allocation_Width
      (Child              :        Gtk_Plot_Canvas_Child)
       return Guint;
| Return the current width of the child.
    function Get_Allocation_Height
      (Child              :        Gtk_Plot_Canvas_Child)
       return Guint;
| Return the current height of the child.
    function Get_Allocation_X
      (Child              :        Gtk_Plot_Canvas_Child)
       return Gint;
| Return the current position of the child, relative to its canvas.
    function Get_Allocation_Y
      (Child              :        Gtk_Plot_Canvas_Child)
       return Gint;
| Return the current position of the child, relative to its canvas.
    function Get_Flags
      (Child              :        Gtk_Plot_Canvas_Child)
       return Plot_Canvas_Flag;
| Return the list of actions currently possible on the child.
    procedure Set_Flags
      (Child              :        Gtk_Plot_Canvas_Child;
       Flags              :        Plot_Canvas_Flag);
| Modify the list of actions possible for a child.
### Flags
Some flags are defined for this widget. You can not access them through the usual interface in Gtk.Object.Flag_Is_Set since this widget is not part of the standard gtk+ packages. Instead, use the functions below. "can_select" True if it is possible to select a region of the canvas "can_select_item" True if it is possible to select any of the item on the canvas. "can_select_point" True if the individual points in the plots can be selected and interactively moved by the user. "can_dnd" True if it is possible to drag an item on the canvas. "can_dnd_point" True if the points of the plots can be moved interactively.
    function Plot_Canvas_Flag_Is_Set
      (Plot_Canvas        : access Gtk_Plot_Canvas_Record;
       Flag               : in     Guint16)
       return Boolean;
| Test whether one of the flags for a Gtk_Plot_Canvas widget or its children is set.
    procedure Plot_Canvas_Set_Flags
      (Plot_Canvas        : access Gtk_Plot_Canvas_Record;
       Flags              : in     Guint16);
| Set the flags for a Gtk_Plot_Canvas widget or its children. Note that the flags currently set are not touched by this function. This can only be used for the flags defined in the Gtk.Extra.Gtk_Plot_Canvas package.
    procedure Plot_Canvas_Unset_Flags
      (Plot_Canvas        : access Gtk_Plot_Canvas_Record;
       Flags              : in     Guint16);
| Unset the flags for a Gtk_Plot_Canvas.

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