High level drawing api

GtkFortran High Level Graphics API

The graphics specific modules provide a high level interface to the GtkDrawingArea widget which is compatible with the plplot library and at least in simple cases relieves the user of the hassle of managing redraws. There is also a high level interface to the gdk-pixbuf library that allows the easy mapping of 2 and 3 dimensional Fortran arrays to GdkPixbuf objects.

gtk_draw_hl

This module provides a high-level drawing interface which automatically handles redrawing on exposure, and bundles the most likely events to be needed.

Note:

This module has undergone a major rewrite which has considerably streamlined the code. To the ordinary user, the most noticable difference is that the backing image is now a cairo image surface rather than a GDK pixbuf. When using PLplot, the "memcairo" device is not readily usable any more, however cumulative plotting (e.g. PLplot's strip charts) now works correctly.

Routine List

• hl_gtk_drawing_area_new; Create the drawing area.
• hl_gtk_drawing_area_get_surface; Get the backing cairo surface
• hl_gtk_drawing_area_expose_cb; Default callback for expose events.
• hl_gtk_drawing_area_destroy_cb; Default callback for destroy signal
• hl_gtk_drawing_area_resize_cb; Default callback for size-allocate signal
• hl_gtk_drawing_area_cairo_new; Create a cairo context attached to the backing surface.
• hl_gtk_drawing_area_resize: Resize the drawing area and the backing surface
• hl_gtk_drawing_area_cairo_destroy; Destroy the context.

hl_gtk_drawing_area_new

  function hl_gtk_drawing_area_new(scroll, size, ssize, expose_event, &
       & data_expose, button_press_event, data_button_press, &
       & button_release_event, data_button_release, scroll_event, &
       & data_scroll, motion_event, data_motion, realize, data_realize, &
       & configure_event, data_configure, key_press_event, data_key_press, &
       & key_release_event, data_key_release, enter_event, data_enter, &
       & leave_event, data_leave, destroy, data_destroy, event_mask, &
       & event_exclude, auto_add_mask, &
       & tooltip, has_alpha, size_allocate, data_size_allocate) result(plota)

    type(c_ptr) :: plota
    type(c_ptr), intent(out), optional :: scroll
    integer(kind=c_int), intent(in), optional, dimension(2) :: size, ssize
    type(c_funptr), optional :: expose_event, button_press_event, &
         & button_release_event, scroll_event, key_press_event, &
         & key_release_event, motion_event, realize, configure_event,&
         & enter_event, leave_event, destroy, size_allocate
    type(c_ptr), intent(in), optional :: data_expose, data_button_press, &
         & data_button_release, data_scroll, data_motion, data_realize, &
         & data_configure, data_key_press, data_key_release, data_enter, &
         & data_leave, data_destroy, data_size_allocate
    integer(kind=c_int), intent(in), optional :: event_mask, event_exclude
    integer(kind=c_int), intent(in), optional :: auto_add_mask
    character(kind=c_char), dimension(*), optional, intent(in) :: tooltip
    integer(kind=c_int), intent(in), optional :: has_alpha

A high-level drawing area

Argument	Type	Required?	Description
SCROLL	c_ptr	optional	If present, then the drawing area will be placed in a scrollable window, whose pointer will be returned here. If it is present, then it rather than the drawable should be used for packing.
SIZE	c_int()	optional	The requested size for the area. If no size is given then a default size of 256x256 is used.
SSIZE	c_int() :	optional	The requested size for a scrolling window
EXPOSE_EVENT	c_funptr	optional	Callback for expose-event signal N.B. In GTK3 the signal is called "draw". If this is not given then a default handler is provided which copies the image surface to the drawing area.
DATA_EXPOSE	c_ptr	optional	Data for expose_event callback
BUTTON_PRESS_EVENT	c_funptr	optional	Callback for button-press-event signal
DATA_BUTTON_PRESS	c_ptr	optional	Data for button_press_event callback
BUTTON_RELEASE_EVENT	c_funptr	optional	Callback for button-release-event signal
DATA_BUTTON_RELEASE	c_ptr	optional	Data for button_release_event callback
SCROLL_EVENT	c_funptr	optional	Callback for scroll-event signal
DATA_SCROLL	c_ptr	optional	Data for scroll_event callback
REALIZE	c_funptr	optional	Callback for realize signal
DATA_REALIZE	c_ptr	optional	Data for realize callback
CONFIGURE_EVENT	c_funptr	optional	Callback for configure-event signal
DATA_CONFIGURE	c_ptr	optional	Data for configure_event callback
KEY_PRESS_EVENT	c_funptr	optional	Callback for key-press-event signal
DATA_KEY_PRESS	c_ptr	optional	Data for key_press_event callback
KEY_RELEASE_EVENT	c_funptr	optional	Callback for key-release-event signal
DATA_KEY_RELEASE	c_ptr	optional	Data for key_release_event callback
MOTION_EVENT	c_funptr	optional	Callback for the motion-notify-event signal
DATA_MOTION	c_ptr	optional	Data for motion_event
ENTER_EVENT	c_funptr	optional	Callback for the enter-notify-event signal
DATA_ENTER	c_ptr	optional	Data for enter_event
LEAVE_EVENT	c_funptr	optional	Callback for the leave-notify-event signal
DATA_LEAVE	c_ptr	optional	Data for leave_event
DESTROY	c_funptr	optional	Callback when the widget is destroyed.
DATA_DESTROY	c_ptr	optional	Data to pass to the destroy callback.
EVENT_MASK	c_int	optional	Mask for which events to pass.
EVENT_EXCLUDE	c_int	optional	Mask for events not to pass (this might be used to prevent auto-enabling an event that should only be enabled by user actions)
AUTO_ADD_MASK	boolean	optional	Set to FALSE to disable automatically adding events to the event mask if a handler is provided.
TOOLTIP	string	optional	Tooltip for the drawing area.
HAS_ALPHA	boolean	optional	If a pixbuf is used, should it have an alpha (transparency) channel (default=FALSE)
SIZE_ALLOCATE	c_funptr	optional	Callback for the 'size-allocate' signal
DATA_SIZE_ALLOCATE	c_ptr	optional	Data for size_allocate.

Odd notes on mask interactions and other things.

• Scroll (wheel) events, are enabled by GDK_SCROLL_MASK or GDK_BUTTON_PRESS_MASK, thus (as far as I can see) there is no way to mask wheel events while allowing button presses to be processed.
• It does not appear to be possible to remove events by unsetting bits in the event mask.
• Adding a tooltip looks to implicitly enable some events.
• An example where an explict EVENT_MASK and EVENT_EXCLUDE might be useful would be to enable motion events only if a button is down.
• If an explicit size is given then the drawing area cannot be made smaller than that by resizing the containing window

hl_gtk_drawing_area_get_surface

  function hl_gtk_drawing_area_get_surface(area) result(isurface)
    type(c_ptr) :: isurface
    type(c_ptr), intent(in) :: area

Convenience routine to get the backing surface of a drawing area.

Argument	Type	Required?	Description
AREA	c_ptr	required	The drawing area whose surface is required.

hl_gtk_drawing_area_expose_cb

  function hl_gtk_drawing_area_expose_cb(area, event, data) bind(c) &
       & result(rv)
    integer(kind=c_int) :: rv
    type(c_ptr), value :: area, event, data

Default callback for exposing a drawing area. For this to be connected no explicit expose callback should be specified.

Argument	Type	Required?	Description
AREA	c_ptr	required	The drawing area
EVENT	c_ptr	required	GTK2 = event structure, GTK3 = a cairo context Since this differs between versions, we won't use it.
DATA	c_ptr	required	A pointer to user data (not used).

hl_gtk_drawing_area_destroy_cb

  subroutine hl_gtk_drawing_area_destroy_cb(area, data) bind(c)
    type(c_ptr), value :: area, data

Default callback for the destroy signal on the drawing area. Just destroys the backing surface.

Argument	Type	Required?	Description
AREA	c_ptr	required	The drawing area being destroyed.
DATA	c_ptr	required	User data for the callback (not used)

hl_gtk_drawing_area_resize_cb

  subroutine hl_gtk_drawing_area_resize_cb(area, data) bind(c)
    type(c_ptr), value :: area, data

Default call back for resizing the drawing area, just copies the old backing store to the new one

Argument	Type	Required?	Description
AREA	c_ptr	required	The drawing area being destroyed.
DATA	c_ptr	required	User data for the callback (not used)

hl_gtk_drawing_area_cairo_new

  function hl_gtk_drawing_area_cairo_new(area) result(cr)
    type(c_ptr) :: cr
    type(c_ptr), intent(in) :: area

Create a cairo context which will draw into the backing surface

Argument	Type	Required?	Description
AREA	c_ptr	required	The drawing area to which we will draw. After the drawing operations, you should call gtk_widget_queue_draw to update the plot on the screen and hl_gtk_pixbuf_cairo_destroy to destroy the cairo context.

hl_gtk_drawing_area_cairo_destroy

  subroutine hl_gtk_drawing_area_cairo_destroy(cr, destroy_surface)

    type(c_ptr), intent(inout) :: cr
    integer(kind=c_int), intent(in), optional :: destroy_surface

Update the backing surface and destroy the cairo context

Argument	Type	Required?	Description
CR	c_ptr	required	The cairo context to put in the pixbuf
DESTROY_SURFACE	boolean	optional	Set to TRUE to destroy the cairo_surface as well as the context. Normally the cairo surface is destroyed by the destroy callback of the drawing area, so does not need to be explicitly destroyed.

This is called following drawing operations to the context created by hl_gtk_drawing_area_cairo_new. N.B. This does not update the window, use gtk_widget_queue_draw to do that.

hl_gtk_drawing_area_resize

  subroutine hl_gtk_drawing_area_resize(area, size, copy)
    type(c_ptr), intent(in) :: area
    integer(kind=c_int), intent(in), optional, dimension(2) :: size
    logical, optional, intent(in) :: copy

Resize a drawing area and its backing store.

Argument	Type	Required?	Description
AREA	c_ptr	required	The area to resize.
SIZE	int(2)	optional	The new size, if omitted, then the backing store is resized to match the drawing area (e.g. after resizing the containing window).

GDK_PIXBUF_HL

Some routines to facilitate the use of GDK pixbufs from Fortran. Allows the use of short-int images to avoid the issues that may result from Fortran's 8-bit integers being signed while GdkPixbuf pixels are unsigned.

hl_gdk_pixbuf_new_empty

  function hl_gdk_pixbuf_new_empty(width, height, alpha, bits) &
       & result(pixbuf)
    type(c_ptr) :: pixbuf
    integer(kind=c_int), intent(in) :: width, height
    integer(kind=c_int), intent(in), optional :: alpha, bits

Create a new empty pixbuf of the given size

Argument	Type	Required?	Description
WIDTH	int	required	The width in pixels of the pixbuf
HEIGHT	int	required	The height in pixels of the pixbuf
ALPHA	boolean	optional	Whether to include an alpha channel (default=FALSE)
BITS	int	optional	The nuber of bits per sample (default=8).

This routine will usually be called via the generic interface hl_gdk_pixbuf_new.

hl_gdk_pixbuf_new_file

  function hl_gdk_pixbuf_new_file(file, width, height, aspect, &
       & error) result(pixbuf)
    type(c_ptr) :: pixbuf
    character(len=*), intent(in) :: file
    integer(kind=c_int), optional, intent(in) :: width, height, aspect
    character(len=*), optional, intent(out) :: error

Read an image file into a new pixbuf

Argument	Type	Required?	Description
FILE	string	required	The file to read
WIDTH	int	optional	The desired width for the pixbuf
HEIGHT	int	optional	The desired height for the pixbuf
ASPECT	boolean	optional	If sizing is given then set to TRUE to preserve the aspect ratio, or FALSE not to. If both dimensions are given, then the default is FALSE, if one is given, the default is TRUE.
ERROR	gerror	optional	The error code & message.

This routine will usually be called via the generic interface hl_gdk_pixbuf_new.

hl_gdk_pixbuf_new_data8

  function hl_gdk_pixbuf_new_data8(data) result(pixbuf)
    type(c_ptr) :: pixbuf
    integer(kind=c_int8_t), dimension(:,:,:), intent(in) :: data

Create a pixbuf from an RGB(A) array of values.

Argument	Type	Required?	Description
DATA	int8	required	The data values as a 1..4 x n x m array.

This routine will usually be called via the generic interface hl_gdk_pixbuf_new.

hl_gdk_pixbuf_new_data8g

  function hl_gdk_pixbuf_new_data8g(data) result(pixbuf)
    type(c_ptr) :: pixbuf
    integer(kind=c_int8_t), dimension(:,:), intent(in) :: data

Create a pixbuf from a greyscale array of values.

Argument	Type	Required?	Description
DATA	int8	required	The data values as a n x m array.

This routine will usually be called via the generic interface hl_gdk_pixbuf_new.

hl_gdk_pixbuf_new_data16

  function hl_gdk_pixbuf_new_data16(data) result(pixbuf)
    type(c_ptr) :: pixbuf
    integer(kind=c_short), dimension(:,:,:), intent(in) :: data

Create a pixbuf from an RGB(A) array of values. This version uses 2-byte integers to avoid the signing issues of the c_int8_t type.

Argument	Type	Required?	Description
DATA	short	required	The data values as a 1..4 x n x m array.

This routine will usually be called via the generic interface hl_gdk_pixbuf_new.

hl_gdk_pixbuf_new_data16g

  function hl_gdk_pixbuf_new_data16g(data) result(pixbuf)
    type(c_ptr) :: pixbuf
    integer(kind=c_short), dimension(:,:), intent(in) :: data

Create a pixbuf from a greyscale array of values. This version uses 2-byte integers to avoid the signing issues of the c_int8_t type.

Argument	Type	Required?	Description
DATA	short	required	The data values as a n x m array.

This routine will usually be called via the generic interface hl_gdk_pixbuf_new.

hl_gdk_pixbuf_get_pixels8

  subroutine hl_gdk_pixbuf_get_pixels8(pixbuf, pixels)
    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_int8_t), dimension(:,:,:), allocatable, intent(out) :: pixels

Get the pixels of a pixbuf and return them as a Fortran 3xnxm or 4xnxm array

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to read
PIXELS	int8	required	Will contain the image.

This is normally called via the generic hl_gdk_pixbuf_get_pixels interface. Implemented as a subroutine to allow this.

hl_gdk_pixbuf_get_pixels16

  subroutine hl_gdk_pixbuf_get_pixels16(pixbuf, pixels)
    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_short), dimension(:,:,:), allocatable, intent(out) :: pixels

Get the pixels of a pixbuf and return them as a Fortran 3xnxm or 4xnxm array. This version returns as a short array to evade the signing issues of 8-bit integers in Fortran

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to read
PIXELS	short	required	Will contain the image.

This is normally called via the generic hl_gdk_pixbuf_get_pixels interface. Implemented as a subroutine to allow this.

hl_gdk_pixbuf_set_pixels8

  subroutine hl_gdk_pixbuf_set_pixels8(pixbuf, pixels, xoff, yoff)
    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_int8_t), dimension(:,:,:), intent(in) :: pixels
    integer, intent(in), optional :: xoff, yoff

Set the pixels of a pixbuf from a Fortran array.

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to update
PIXELS	int8	required	Contains the image to insert.
XOFF	int	optional	The X-offset at which to write the image.
YOFF	int	optional	The Y-offset at which to write the image.

This is normally called via the generic hl_gdk_pixbuf_set_pixels interface. N.B. To leave a gap at the "high" sides of the pixbuf, just use a smaller input array or array slice than the pixbuf size.

hl_gdk_pixbuf_set_pixels8g

  subroutine hl_gdk_pixbuf_set_pixels8g(pixbuf, pixels, xoff, yoff)
    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_int8_t), dimension(:,:), intent(in) :: pixels
    integer, intent(in), optional :: xoff, yoff

Set the pixels of a pixbuf from a Fortran array (greyscale).

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to update
PIXELS	int8	required	Contains the image to insert.
XOFF	int	optional	The X-offset at which to write the image.
YOFF	int	optional	The Y-offset at which to write the image.

This is normally called via the generic hl_gdk_pixbuf_set_pixels interface. N.B. To leave a gap at the "high" sides of the pixbuf, just use a smaller input array or array slice than the pixbuf size.

hl_gdk_pixbuf_set_pixels16

  subroutine hl_gdk_pixbuf_set_pixels16(pixbuf, pixels, xoff, yoff)
    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_short), dimension(:,:,:), intent(in) :: pixels
    integer, intent(in), optional :: xoff, yoff

Set the pixels of a pixbuf from a Fortran array (16-bit).

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to update
PIXELS	short	required	Contains the image to insert.
XOFF	int	optional	The X-offset at which to write the image.
YOFF	int	optional	The Y-offset at which to write the image.

This is normally called via the generic hl_gdk_pixbuf_set_pixels interface. N.B. To leave a gap at the "high" sides of the pixbuf, just use a smaller input array or array slice than the pixbuf size.

hl_gdk_pixbuf_set_pixels16g

  subroutine hl_gdk_pixbuf_set_pixels16g(pixbuf, pixels, xoff, yoff)
    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_short), dimension(:,:), intent(in) :: pixels
    integer, intent(in), optional :: xoff, yoff

Set the pixels of a pixbuf from a Fortran array (16-bit, greyscale).

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to update
PIXELS	short	required	Contains the image to insert.
XOFF	int	optional	The X-offset at which to write the image.
YOFF	int	optional	The Y-offset at which to write the image.

This is normally called via the generic hl_gdk_pixbuf_set_pixels interface. N.B. To leave a gap at the "high" sides of the pixbuf, just use a smaller input array or array slice than the pixbuf size.

hl_gdk_pixbuf_info

  subroutine hl_gdk_pixbuf_info(pixbuf, nchannels, bits, alpha, &
       & height, width, rowstride)

    type(c_ptr), intent(in) :: pixbuf
    integer(kind=c_int), optional, intent(out) :: nchannels, bits, alpha, &
         & height, width, rowstride

Return information about an existing pixbuf.

Argument	Type	Required?	Description
PIXBUF	c_ptr	required	The pixbuf to be queried.
NCHANNELS	int	optional	How many channels does the pixbuf have?
BITS	int	optional	How many bits per pixel?
ALPHA	boolean	optional	Does the pixbuf have an alpha channel?
HEIGHT	int	optional	How many rows in the image.
WIDTH	int	optional	How many columns in the image.
ROWSTRIDE	int	optional	How many bytes between the start of successive rows.

hl_gdk_pixbuf_get_formats

  subroutine hl_gdk_pixbuf_get_formats(names, writable, description, &
       & scalable, license)

    character(len=*), intent(out), dimension(:), allocatable :: names
    logical, intent(out), dimension(:), allocatable, optional :: writable, &
         & scalable
    character(len=*), intent(out), dimension(:), allocatable, &
         & optional :: license
    character(len=*), intent(out), dimension(:), allocatable, &
         & optional :: description

Get information about the available file formats for reading/writing pixbufs.

Argument	Type	Required?	Description
NAMES	f_string()	required	The names found
WRITABLE	logical()	optional	Whether the formats are writable.
DESCRIPTION	f_string()	optional	Descriptions of the formats.
SCALABLE	logical()	optional	Whether the formats are scalable.
LICENSE	f_string()	optional	The licence of the format module.

hl_gdk_pixbuf_format_info

  function hl_gdk_pixbuf_format_info(name, mime_types, extensions, &
       & writable, scalable, description, license) result(found)

    logical :: found
    character(len=*), intent(in) :: name
    character(len=*), intent(out), optional, allocatable, &
         & dimension(:) :: mime_types, extensions
    logical, intent(out), optional :: writable, scalable
    character(len=*), intent(out), optional :: description, license

Get information about a specific file type.

Argument	Type	Required?	Description
NAME	string	required	The file type to query.
MIME_TYPE	fstring()	optional	Will contain a list of mime-types associated with this file type.
EXTENSIONS	fstring()	optional	Will contain a list of file extensions normally used for this type.
WRITABLE	logical	optional	Whether the type is writable.
SCALABLE	logical	optional	Whether the type is scalable.
DESCRIPTION	f_string	optional	A description of the file type.
LICENSE	f_string	optional	The license of the module for the file type.

Returns .true. if the type is found, .false. if it is not.

hl_gdk_pixbuf_format_find

  function hl_gdk_pixbuf_format_find(mime_type, extension) result(name)
    character(len=hl_gdk_pixbuf_type_len) :: name
    character(len=*), intent(in), optional :: mime_type, extension

Find the format type appropriate to a mime_type or a filename extension.

Argument	Type	Required?	Description
MIME_TYPE	f_string	optional	The mime-type to match.
EXTENSION	f_string	optional	The file extension to match.

If no match is found then an empty string is returned. Mime_type has precedence over extension.