Interactive drawing of an ellipse.

draw_ellipse returns the parameter for any orientated ellipse, which has been created interactively by the user in the window.

The created ellipse is described by its center, its two half axes and the angle between the first half axis and the horizontal coordinate axis.

To create an ellipse you have to determine the center of the ellipse with the left mouse button. Keeping the button pressed determines the length (Radius1) and the orientation (Phi) of the first half axis. In doing so a temporary default length for the second half axis is assumed, which may be modified afterwards on demand. After another mouse click in the center of the created ellipse you can move it. A mouse click close to a vertex ``grips'' it to modify the length of the appropriate half axis. You may modify the orientation only, if a vertex of the first half axis is gripped.

Pressing the right mouse button terminates the procedure. After terminating the procedure the ellipse is not visible in the window any longer.

read_image(Image,'affe') 
draw_ellipse(WindowHandle,Row,Column,Phi,Radius1,Radius2) 
gen_ellipse(Ellipse,Row,Column,Phi,Radius1,Radius2) 
reduce_domain(Image,Ellipse,GrayEllipse) 
sobel_amp(GrayEllipse,Sobel,'sum_abs',3) 
disp_image(Sobel,WindowHandle).

draw_ellipse returns 2 (H_MSG_TRUE), if the window is valid and the needed drawing mode (see set_insert) is available. If necessary, an exception handling is raised.

draw_ellipse is reentrant, local, and processed without parallelization.

open_window

reduce_domain, disp_region, set_colored, set_line_width, set_draw, set_insert

draw_ellipse_mod, draw_circle, draw_region

gen_ellipse, draw_rectangle1, draw_rectangle2, draw_polygon, set_insert

System