Ncurses：刷新不重叠的窗口将刷新整个屏幕。 如何避免这种情况？

Question

I am hacking together a ncurses application which uses 5 windows:

• statusbar window - 1 X COLS right at the bottom of the screen.
• titlebar window - 1 X COLS right at the top of the screen.
• 3 content windows - LINES - 2 X COLS, inbetween the statusbar and titlebar.

Note that there are 3 content windows, which entirely overlap each other. I am manually deciding which is to be redrawn. The titlebar and statusbar windows do not overlap any other window.

One use case is for the user to choose a file to upload to a network daemon using a menu in one of the content windows. Upon selecting a file, the statusbar acts as a crude progressbar, drawing some hashes to indicate how far the file has been uploaded.

What this boils down to is using:

• wclear(status);
• mvwprintw(status, ...);
• wrefresh(status);

This works, but for some reason causes the entire screen to be redrawn, causing a horrible flickery mess. Having read the manual, I can not see why this should be the case; as long as the statusbar does not overlap any other windows, redrawing the statusbar should not cause a whole screen redraw?

Am I correct, or have I misunderstood? Is there a way to prevent this?

The code is here: https://github.com/vext01/hgd/blob/master/nchgdc.c#L812

Note, the code is vastly unfinished and lacks polish =)

My ncurses implementation is that of OpenBSD.

Answer 1

From the wclear man page:

The clear and wclear routines are like erase and werase, but they also call clearok, so that the screen is cleared completely on the next call to wrefresh for that window and repainted from scratch.