Utility functions that mimic Gtk.Style drawing methods, but using Cairo instead of Gdk. This allow smooth transition to Gtk3 that will get rid of those Gdk drawing methods and only use Cairo.
<group>Configuration and Themes</group>
type Arrow_Head is (None, Open, Solid, Diamond, Circle);
The various styles of arrow heads (filled with Fill style). When displaying a circle, the Length of the arrow style is the radius of the circle.
type Arrow_Style is record
Head : Arrow_Head;
Length : Glib.Gdouble := 8.0;
Angle : Glib.Gdouble := 0.4;
Stroke : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Black_RGBA;
Fill : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Null_RGBA;
Line_Width : Glib.Gdouble := 1.0;
end record;
subtype Cairo_Color is Gdk.RGBA.Gdk_RGBA;
subtype Cairo_Color_Val is Glib.Gdouble range 0.0 .. 1.0;
In cairo, the color components are expressed as percents.
function Complementary
(Color : Gdk.RGBA.Gdk_RGBA) return Gdk.RGBA.Gdk_RGBA
Return the complementary color
function Copy (Source : Font_Style) return Font_Style
Return a copy of the given font style.
function Create_Rgba_Pattern
(Color : Cairo_Color) return Cairo.Cairo_Pattern
Default_Font : constant Font_Style := (others => <>);
Some of the attributes like Halign are only taken into account when using Gtkada.Canvas_View.Text_Item.
procedure Delete_Overlay
(Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class;
Overlay : in out Cairo.Cairo_Surface)
Delete the overlay created by Draw_Overlay, and force a refresh of the toplevel window.
procedure Draw_Arrows_And_Symbols
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Points : Point_Array;
Relative : Boolean := False)
Draw arrow heads and symbols to both ends of the line, based on Self. This is similar to Polyline, but does not draw the line itself. Relative should be True if each point are defined relative to the previous point.
procedure Draw_Ellipse
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Topleft : Point;
Width, Height : Glib.Gdouble)
Draw an ellipse inscribed in the specified rectangle
procedure Draw_Layout
(Cr : Cairo.Cairo_Context;
Color : Gdk.Color.Gdk_Color;
X, Y : Glib.Gint;
Layout : Pango.Layout.Pango_Layout)
Draws the Pango layout at position (X, Y) using Color.
procedure Draw_Layout
(Cr : Cairo.Cairo_Context;
Color : Cairo_Color;
X, Y : Glib.Gint;
Layout : Pango.Layout.Pango_Layout)
Draws the Pango layout at position (X, Y) using Color.
procedure Draw_Line
(Cr : Cairo.Cairo_Context;
Color : Gdk.Color.Gdk_Color;
X1, Y1, X2, Y2 : Glib.Gint)
Draws a line between (X1, Y1) and (X2, Y2) using the specified color.
Additional drawing styles can be specified by using Cairo.Set_Line_XXXX on the Cairo_Context before calling this procedure.
procedure Draw_Line
(Cr : Cairo.Cairo_Context;
Color : Cairo_Color;
X1, Y1, X2, Y2 : Glib.Gint)
Draws a line between (X1, Y1) and (X2, Y2) using the specified color.
Additional drawing styles can be specified by using Cairo.Set_Line_XXXX on the Cairo_Context before calling this procedure.
procedure Draw_Overlay
(Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class;
Overlay : in out Cairo.Cairo_Surface;
Do_Draw : not null access procedure
(Context : Cairo.Cairo_Context;
Draw : Boolean))
Create an overlay on top of widget on which you can draw. This overlay is created if it doesn't exist (so Overlay must be initialied to Null_Surface initially). It is displayed on top of the toplevel window that contains Widget, and will be fully visible until some of the children of that toplevel window get a "draw" event. At that point, the children will partially override the overlay. This is not a problem in practice if the overlay is displayed while performing operations like a drag-and-drop. Do_Draw is the callback used to do the actual drawing or erasing of the overlay (depending on whether Draw is True or False). The context passed in argument has been properly translated and clipped so that (0, 0) are the coordinates of the top-left corner of widget.
When Draw is False, the procedure should display a filled rectangle. The context has already been set up so that filling will in fact redraw what was previously hidden. This is more efficient that having Draw_Overlay systematically fill the whole area.
procedure Draw_Pixbuf
(Cr : Cairo.Cairo_Context;
Pixbuf : Gdk.Pixbuf.Gdk_Pixbuf;
X, Y : Glib.Gint)
Draws a pixbuf at coordinate X, Y
Note that Gdk_Pixmap or Gdk_Bitmap are not supported, as those are server-side images, so depend on a surface attached to a screen. As a result, those would not be drawn on a non-screen surface (such as an internal Image_Surface).
procedure Draw_Pixbuf_With_Scale
(Cr : Cairo.Cairo_Context;
Pixbuf : Gdk.Pixbuf.Gdk_Pixbuf;
X, Y : Glib.Gdouble;
Widget : access Gtk.Widget.Gtk_Widget_Record'Class := null)
Draw the pixbuf at the specified coordinates. This takes into account the scale factor on the screen, so that the image is properly sized on hi-dpi (retina) displays. The pixbuf must have been created with the proper scale factor as well, using for instance Gtk.Icon_Theme.Load_Icon_For_Scale. It is often more convenient to pass the name of the icon, as found in the icon theme, and let gtk+ create the pixbuf automatically. The widget is used to compute the appropriate scale factor.
procedure Draw_Pixbuf_With_Scale
(Cr : Cairo.Cairo_Context;
Icon_Name : String;
X, Y : Glib.Gdouble;
Size : Glib.Gint;
Widget : access Gtk.Widget.Gtk_Widget_Record'Class := null)
Draw the pixbuf at the specified coordinates. This takes into account the scale factor on the screen, so that the image is properly sized on hi-dpi (retina) displays. The pixbuf must have been created with the proper scale factor as well, using for instance Gtk.Icon_Theme.Load_Icon_For_Scale. It is often more convenient to pass the name of the icon, as found in the icon theme, and let gtk+ create the pixbuf automatically. The widget is used to compute the appropriate scale factor.
procedure Draw_Polycurve
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Points : Point_Array;
Show_Arrows : Boolean := True;
Relative : Boolean := False)
Same as Drawpolyline, but draws bezier curves. Points is an array of both points and control points, as in: pt1, ctrl1, ctrl2, pt2, ctrl3, ctrl4, pt3, ...
procedure Draw_Polyline
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Points : Point_Array;
Close : Boolean := False;
Show_Arrows : Boolean := True;
Relative : Boolean := False)
Draw a line joining all the points. If Close is true, the last point is also linked to the first. If Self defines arrows or symbols on either ends, they are also displayed if Show_Arrows is True. Relative should be set to True if the points are relative: the first point has item coordinates, and all remaining points are relative to the previous point.
procedure Draw_Rect
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Topleft : Point;
Width, Height : Glib.Gdouble;
Radius : Glib.Gdouble := 0.0)
Draw a rectangle with the given style. If Radius is not null, this is a rounded rectangle. Draw_Rect will automatically call Finish path to display te path, but Path_Rect will only prepare it (it returns False if no path was prepared)
procedure Draw_Rectangle
(Cr : Cairo.Cairo_Context;
Color : Gdk.Color.Gdk_Color;
Filled : Boolean;
X, Y, Width, Height : Glib.Gint;
Corner_Radius : Glib.Gdouble := 0.0)
Draws a rectangle of size Width x Height at position (X, Y) and (X2, Y2) using the specified color. Corner_Radius allows you to draw a rounded rectangle if set to a value > 0.0
Additional drawing styles can be specified by using Cairo.Set_Line_XXXX on the Cairo_Context before calling this procedure.
procedure Draw_Rectangle
(Cr : Cairo.Cairo_Context;
Color : Cairo_Color;
Filled : Boolean;
X, Y, Width, Height : Glib.Gint;
Corner_Radius : Glib.Gdouble := 0.0)
Draws a rectangle of size Width x Height at position (X, Y) and (X2, Y2) using the specified color. Corner_Radius allows you to draw a rounded rectangle if set to a value > 0.0
Additional drawing styles can be specified by using Cairo.Set_Line_XXXX on the Cairo_Context before calling this procedure.
procedure Draw_Shadow
(Cr : Cairo.Cairo_Context;
Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class;
Shadow_Type : Gtk.Enums.Gtk_Shadow_Type;
X, Y, Width, Height : Glib.Gint;
Corner_Radius : Glib.Gdouble := 0.0)
Draws a Frame of size Width x Height at position (X, Y) and (X2, Y2) using the specified color. Corner_Radius allows you to draw a rounded frame if set to a value > 0.
Additional drawing styles can be specified by using Cairo.Set_Line_XXXX on the Cairo_Context before calling this procedure.
procedure Draw_Text
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Layout : not null access Pango.Layout.Pango_Layout_Record'Class;
Topleft : Point;
Text : String;
Max_Width : Glib.Gdouble := Glib.Gdouble'First;
Max_Height : Glib.Gdouble := Glib.Gdouble'First)
Draw text at specific coordinates. Topleft is the position of the top-left corner for the text, or the middle line if the text's vertical_align is set to middle. Max_Width is optional, but is used to resolve alignment.
type Drawing_Style is tagged private;
This type provides a set of high-level subprograms to draw on a cairo context (and thus they can be used when drawing Canvas_Item).
This type is reference-counted: it will be automatically freed when no longer used in your application. If you store the same instance of Drawing_Style in two contexts, modifying one will also modify the other.
procedure Finish_Path
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Clear_Path : Boolean := True)
This is for use when you are creating your own paths via standard cairo calls. This will call Stroke and Fill with the appropriate parameters found in Self.
type Font_Style is record
Name : Pango.Font.Pango_Font_Description := null;
Underline : Pango.Enums.Underline := Pango.Enums.Pango_Underline_None;
Strikethrough : Boolean := False;
Color : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Black_RGBA;
Line_Spacing : Glib.Gint := 1;
Halign : Pango.Enums.Alignment := Pango.Enums.Pango_Align_Left;
end record;
Some of the attributes like Halign are only taken into account when using Gtkada.Canvas_View.Text_Item.
Space between two lines
function Get_Arrow_From (Self : Drawing_Style) return Arrow_Style
Access the various properties of the style
function Get_Arrow_To (Self : Drawing_Style) return Arrow_Style
Access the various properties of the style
function Get_Fill (Self : Drawing_Style) return Cairo.Cairo_Pattern
Access the various properties of the style
function Get_First_Device
(Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class;
Source : Gdk.Types.Gdk_Input_Source) return Gdk.Device.Gdk_Device
Return the first device that matches the given source. This can be used to simulate keyboard events (using Source_Keyboard) or mouse events (Source_Mouse) for instance. The returned value (if not null) must be Ref-ed before being assigned to an event for instance.
function Get_Font (Self : Drawing_Style) return Font_Style
Access the various properties of the style
function Get_Line_Width (Self : Drawing_Style) return Glib.Gdouble
Access the various properties of the style
procedure Get_Offset
(Window : not null access Gtk.Widget.Gtk_Widget_Record'Class;
Parent : not null access Gtk.Widget.Gtk_Widget_Record'Class;
X, Y : out Glib.Gint)
Get the position of Window within parent's window (not that this is not necessarily the same as the position within Parent if the latter does not have a window).
function Get_Shadow (Self : Drawing_Style) return Shadow_Style
Access the various properties of the style
function Get_Stroke (Self : Drawing_Style) return Gdk.RGBA.Gdk_RGBA
Access the various properties of the style
function Gtk_New
(Stroke : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Black_RGBA;
Fill : Cairo.Cairo_Pattern := Cairo.Null_Pattern;
Font : Font_Style := Default_Font;
Line_Width : Glib.Gdouble := 1.0;
Dashes : Cairo.Dash_Array := Cairo.No_Dashes;
Arrow_From : Arrow_Style := No_Arrow_Style;
Arrow_To : Arrow_Style := No_Arrow_Style;
Symbol_From : Symbol_Style := No_Symbol;
Symbol_To : Symbol_Style := No_Symbol;
Shadow : Shadow_Style := No_Shadow;
Sloppy : Boolean := False)
return Drawing_Style
Creates a new instance of drawing style.
The style will free the Font.Name object, so you will need to pass the result of either Pango.Font.Copy or Pango.Font.From_String.
this is generated created through the functions in Cairo.Pattern. The pattern is adopted by the style, which will unreferenced it when not needed. As such, if the pattern is shared between multiple styles you need to Ref it. When the style is used with a Gtkada.Canvas_View.Container_Item or one of its children, and pattern is a gradient, it should be defined in the 0.0 .. 1.0 pattern space, and will be resized automatically based on the computed size of the item.
if true, a sort of approximate drawing is done for lines and text, so that it looks like the drawing was done by hand.
type HSLA_Color is record
Hue : Glib.Gdouble;
Saturation : Glib.Gdouble;
Lightness : Glib.Gdouble;
Alpha : Glib.Gdouble;
end record;
The Hue is the colour's position on the colour wheel, expressed in degrees from 0° to 359°, representing the 360° of the wheel; 0° being red, 180° being red's opposite colour cyan, and so on. The mapping is: 0.0 => 0° 1.0 => 360°
Saturation is the intensity of the colour, how dull or bright it is. The lower the saturation, the duller (greyer) the colour looks. This is expressed as a percentage, 100% being full saturation, the brightest, and 0% being no saturation, grey.
Lightness is how light the colour is. Slightly different to saturation. The more white in the colour the higher its Lightness value, the more black, the lower its Lightness. So 100% Lightness turns the colour white, 0% Lightness turns the colour black, and the "pure" colour would be 50% Lightness.
type HSV_Color is record
H, S, V, A : Glib.Gdouble;
end record;
Used when manipulating Cairo color. The HSV color space is useful when wanting to shade a color (change it's value), (de)saturate it, or modify its hue.
function Lighten
(Color : Gdk.RGBA.Gdk_RGBA;
Amount : Percent) return Gdk.RGBA.Gdk_RGBA
Return a lighter version of the color
Amount is a modifier: 0.0 means the color is unchanged, 0.1 means the color is modified by 10%, and so on.
procedure Load_Css_File
(Path : String;
Error : access procedure (Str : String) := null;
Priority : Gtk.Style_Provider.Priority)
Load CSS file and register it as a default CSS provider for the whole application. In case of error, the procedure Error is called if defined.
procedure Load_Css_String
(Data : String;
Error : access procedure (Str : String) := null;
Priority : Gtk.Style_Provider.Priority)
Load CSS file and register it as a default CSS provider for the whole application. In case of error, the procedure Error is called if defined.
procedure Measure_Text
(Self : Drawing_Style;
Layout : not null access Pango.Layout.Pango_Layout_Record'Class;
Text : String;
Width : out Glib.Gdouble;
Height : out Glib.Gdouble)
Measure the size the text would take on the screen
No_Arrow_Style : constant Arrow_Style :=
(None, 0.0, 0.0, Gdk.RGBA.Black_RGBA, Gdk.RGBA.Null_RGBA, 1.0);
No_Drawing_Style : constant Drawing_Style;
No_Shadow : constant Shadow_Style := (Gdk.RGBA.Null_RGBA, 5.0, 5.0);
No_Symbol : constant Symbol_Style := (None, Gdk.RGBA.Black_RGBA, 16.0, 1.0);
Distance is the distance from the end of the line to the symbol. It should in general be greater than the length of the arrow (see Arrow_Style above)
function Path_Ellipse
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Topleft : Point;
Width, Height : Glib.Gdouble) return Boolean
Draw an ellipse inscribed in the specified rectangle
function Path_Polycurve
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Points : Point_Array;
Relative : Boolean := False) return Boolean
Same as Drawpolyline, but draws bezier curves. Points is an array of both points and control points, as in: pt1, ctrl1, ctrl2, pt2, ctrl3, ctrl4, pt3, ...
function Path_Polyline
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Points : Point_Array;
Close : Boolean := False;
Relative : Boolean := False) return Boolean
Draw a line joining all the points. If Close is true, the last point is also linked to the first. If Self defines arrows or symbols on either ends, they are also displayed if Show_Arrows is True. Relative should be set to True if the points are relative: the first point has item coordinates, and all remaining points are relative to the previous point.
function Path_Rect
(Self : Drawing_Style;
Cr : Cairo.Cairo_Context;
Topleft : Point;
Width, Height : Glib.Gdouble;
Radius : Glib.Gdouble := 0.0) return Boolean
Draw a rectangle with the given style. If Radius is not null, this is a rounded rectangle. Draw_Rect will automatically call Finish path to display te path, but Path_Rect will only prepare it (it returns False if no path was prepared)
subtype Percent is Glib.Gdouble range 0.0 .. 1.0;
type Point is record
X, Y : Glib.Gdouble;
end record;
type Point_Array is array (Natural range <>) of Point;
type Point_Array_Access is access all Point_Array;
procedure Rounded_Rectangle
(Cr : Cairo.Cairo_Context;
X, Y, W, H : Glib.Gdouble;
Radius : Glib.Gdouble)
Draws a rounded rectangle at coordinate X, Y with W and H size. If Radius > 0, then the corner will be rounded.
procedure Set_Fill
(Self : Drawing_Style;
Fill : Cairo.Cairo_Pattern := Cairo.Null_Pattern)
Overriding specific attributes of the style
procedure Set_Source_Color
(Cr : Cairo.Cairo_Context; Color : Cairo_Color)
procedure Set_Stroke
(Self : Drawing_Style;
Stroke : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Black_RGBA)
Overriding specific attributes of the style
function Shade
(Color : Gdk.Color.Gdk_Color;
Value : Percent) return Cairo_Color
Modifies the lightning of the color by the specified value.
Value is a modifier: 0.0 means the color is unchanged, 0.1 means the color is modified by 10%, and so on.
function Shade
(Color : Cairo_Color;
Value : Percent) return Cairo_Color
Modifies the lightning of the color by the specified value.
Value is a modifier: 0.0 means the color is unchanged, 0.1 means the color is modified by 10%, and so on.
function Shade_Or_Lighten
(Color : Gdk.RGBA.Gdk_RGBA;
Amount : Percent := 0.4) return Gdk.RGBA.Gdk_RGBA
Return a lighter or darker version of Color, depending on whether color is rather dark or rather light.
Amount is a modifier: 0.0 means the color is unchanged, 0.1 means the color is modified by 10%, and so on.
type Shadow_Style is record
Color : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Null_RGBA;
X_Offset : Glib.Gdouble := 2.0;
Y_Offset : Glib.Gdouble := 2.0;
end record;
function Snapshot
(Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class)
return Cairo.Cairo_Surface
Create a snapshot of the widget. This allocates a new surface and draws the widget on it. The surface needs to be destroyed when you are done with it using Surface_Destroy. The snapshot can be drawn on another surface using Set_Source_Surface (Cr, the_snapshot, 0.0, 0.0); Set_Operator (Cr, Cairo_Operator_Source); Rectangle (Cr, ....); Cairo.Fill (Cr); The 0.0 values might need to be adjusted if your widget does not have its own window. In this case, you should use: Get_Allocation (Widget, Alloc); -- and replace 0.0 with Gdouble (Alloc.X)
type Symbol_Name is (None, Cross, Strike, Double_Strike);
Distance is the distance from the end of the line to the symbol. It should in general be greater than the length of the arrow (see Arrow_Style above)
type Symbol_Style is record
Name : Symbol_Name;
Stroke : Gdk.RGBA.Gdk_RGBA := Gdk.RGBA.Black_RGBA;
Distance : Glib.Gdouble := 16.0;
Line_Width : Glib.Gdouble := 1.0;
end record;
Distance is the distance from the end of the line to the symbol. It should in general be greater than the length of the arrow (see Arrow_Style above)
function To_Cairo (Color : Gdk.Color.Gdk_Color) return Cairo_Color
Translations between one color definition to another
function To_Cairo (Color : Cairo_Color) return Gdk.RGBA.Gdk_RGBA
Translations between one color definition to another
function To_Cairo (HSV : HSV_Color) return Cairo_Color
Translations between one color definition to another
function To_Hex (Color : Gdk.RGBA.Gdk_RGBA) return String
Return a hexadecimal approximate representation of the color, of the form "#rrggbb". This loses the alpha chanel. The output is suitable for use in a markup (see Gtk.Label.Set_Markup for instance)
function To_HSLA (Color : Gdk.RGBA.Gdk_RGBA) return HSLA_Color
Translations between one color definition to another
function To_HSV (Color : Cairo_Color) return HSV_Color
Translations between one color definition to another
function To_RGBA (Color : HSLA_Color) return Gdk.RGBA.Gdk_RGBA
Translations between one color definition to another