Operator Reference
dev_open_window (Operator)
dev_open_window — Open a new graphics window.
Signature
dev_open_window( : : Row, Column, Width, Height, Background : WindowHandle)
Description
dev_open_window opens a new graphics window, which can
be used to display iconic objects like images, regions, and lines
as well as to perform textual output. This window automatically
becomes active, which means that all output (dev_display
and automatic display of operator results) is redirected to this
window. This is shown by the lucent lamp on the Active
button.
Each graphics window is identified by its WindowHandle.
This logical number is displayed in the title bar of the graphics
window and is required as input parameter for some operators
like disp_image, disp_region,
draw_circle, get_mbutton, write_string,
and set_rgb.
The graphics window is closed by pressing the Close
button of the window frame, via the Visualization menu,
or by calling dev_close_window.
Graphics Window Position
By default, the graphics window opens within the canvas
window. If this is not desired,
select Restore Default Layout use ->
Docked Graphics Window from the Window menu
in HDevelop. See also “Canvas Window” in the
“HDevelop User's Guide”.
The parameters Row and Column are used to
pass the position of the window. Its reference point (0, 0)
on the canvas is visualized by a cross.
For floating windows, the reference point is by default the
upper left corner of the HDevelop main window. You can change
this reference point, so that, for example, the graphics
window position aligns with the upper left corner of the
screen. To do so, open the HDevelop preferences and choose
the desired Origin of coordinates under
General options.
Moreover, you can adapt the window position via the setting
Window open offset. These offset values are added to
the row and the column index, respectively. See also “Menu
Window open offset” in the “HDevelop User's
Guide”.
Graphics Window Visualization
The background of the created graphics window is set to the color
specified in Background. This parameter is not
available for the operator open_window. There, the same
behavior can be achieved by calling
set_window_attr(::'background_color',Background:) in
advance.
As a default, the visible image part in the graphics window
(viewport) is set in a way that images are displayed without
clipping and fitted completely into the window. The image part
is adapted to the window's size according to this rule for the
first image that is displayed after a program reset or the
loading of a new program or if the current image has a different
image size than the image that was displayed before. The size of
the window is not adapted automatically, hence, if the aspect
ratio of the image differs from that of the window, the image is
distorted to fit into the window. This can be changed via the
Window Size menu.
The visible image part can be changed interactively by spinning
the mouse wheel, using the Move or Zoom mode,
via the Image Size menu, with the help of the
Zoom tab card on the Visualization Parameters
dialog, or with the operator dev_set_part.
The display parameters of the graphics window can be specified
via its context menu, the Visualization menu, the
Visualization Parameters dialog, or the appropriate
HDevelop operators like dev_set_color,
dev_set_line_width, dev_set_draw. Depending on
the Apply Immediately preference, the parameter changes
are applied to the lastly displayed object or apply from now on
for all following objects. In contrast to the standard HALCON
window operators, the new settings are also used for all new
graphics windows.
Graphics Window History
Each graphics window manages a history that contains the
-
objects and
-
display parameters
that have been displayed or changed since the most recent
clear action or display of a full image. This history is used if
a redraw of the window is triggered, e.g., after a change of the
window's size, in order to reconstruct the complete window
contents. Other iconic output that was displayed using HALCON
operators like disp_image or disp_region, text
(write_string), or geometric objects (disp_line,
disp_circle, etc.) are not part of the history,
and can therefore not be redrawn. Only the object
classes image, region, and XLD that are displayed with the
HDevelop operator dev_display or by HDevelop actions
like double clicking on an icon are part of the history.
Pressing the Clear button clears the graphics
window contents and the history of the window. This can also be
achieved by using the operator dev_clear_window.
This will not affect the current display parameters.
Further Information
Additional information about the underlying HALCON window can
be found at open_window. For more information about the
graphics window, please have a look at the
“HDevelop User's Guide”.
Attention
Using the code export feature of HDevelop, the code that is
generated for this operator may have a different behavior than
the related HALCON operator. For a detailed description of the
code export of HDevelop graphics operators into the different
programming languages, in the “HDevelop User's Guide”,
see the chapter Code Export ->
General Aspects of Code Generation
-> Graphics Windows.
Parameters
Row (input_control) rectangle.origin.y → (integer)
Row index of upper left corner.
Default: 0
Value range:
0
≤
Row
Minimum increment: 1
Recommended increment: 1
Column (input_control) rectangle.origin.x → (integer)
Column index of upper left corner.
Default: 0
Value range:
0
≤
Column
Minimum increment: 1
Recommended increment: 1
Width (input_control) rectangle.extent.x → (integer)
Width of the window.
Default: 512
Minimum increment: 1
Recommended increment: 1
Restriction:
Width > 0 || Width == -1
Height (input_control) rectangle.extent.y → (integer)
Height of the window.
Default: 512
Minimum increment: 1
Recommended increment: 1
Restriction:
Height > 0 || Height == -1
Background (input_control) integer → (integer / string)
Color of the background of the new window.
Default: 'black'
WindowHandle (output_control) window → (handle)
Window handle.
Example (HDevelop)
dev_close_window ()
read_image (For5, 'for5')
get_image_size (For5, Width, Height)
dev_open_window (0, 0, Width, Height, 'black', WindowHandle)
dev_display (For5)
dev_set_lut ('rainbow')
dev_display (For5)
stop ()
dev_set_lut ('default')
dev_display (For5)
stop ()
dev_set_part (100, 100, 300, 300)
dev_display (For5)
Result
If the values of the specified parameters are correct,
dev_open_window returns 2 (
H_MSG_TRUE)
. Otherwise, an
exception is raised and an error code returned.
Possible Successors
dev_display,
dev_set_lut,
dev_set_color,
dev_set_draw,
dev_set_part
Alternatives
See also
Module
Foundation