need help with pw_copy

[David England]

I don't think you can pw_copy into a canvas pixrect - isn't it just a
pointer with no memory allocated. Anyway, here's a program I gave to a
student who was having similar probelms. It draws a line, then copies the
canvas into a memory pirext and clears the canvas.  Finally it copies back
the saved pixrect.

Dave
de at comp.lancs.ac.uk

#include  <stdio.h>
#include  <suntool/sunview.h>
#include  <suntool/canvas.h>
#include  <suntool/panel.h>
#include  <pixrect/pixrect_hs.h

/* Compile with  cc -g test.c -lsuntool -lsunwindow -lpixrect */

Pixwin *pw;
static struct pixrect *pr;


drawline()
{
    pw_vector(pw, 0, 0, 50, 50, PIX_SRC, 1);
}

clear()
{

    pw_read(pr,0, 0, 100, 100, PIX_SRC, pw, 0, 0);
    pw_writebackground(pw, 0, 0, 100, 100, PIX_CLR );
}

redraw()
{
    pw_write(pw,0, 0 ,100, 100, PIX_SRC, pr, 0, 0);
}

main()
{

        Frame myframe;
    Panel mypan;
    Panel_item clearit, line, copyit;
        Canvas mycan;

    pr = mem_create(200,200,1);

        myframe = window_create(NULL, FRAME,
                                0);

    mypan = window_create(myframe,PANEL,
                WIN_ROWS, 2,
                WIN_COLUMNS, 20,
                0);

    line = panel_create_item(mypan, PANEL_BUTTON,
                                PANEL_LABEL_STRING, "line",
                                PANEL_NOTIFY_PROC, drawline,
                0);


    clearit = panel_create_item(mypan, PANEL_BUTTON,
                                PANEL_LABEL_STRING, "Clear",
                                PANEL_NOTIFY_PROC, clear,
                0);

    copyit = panel_create_item(mypan, PANEL_BUTTON,
                PANEL_LABEL_STRING, "Redraw",
                PANEL_NOTIFY_PROC, redraw,
                0);


        mycan = window_create(myframe, CANVAS,
                                WIN_HEIGHT, 100,
                                WIN_WIDTH ,100,
                CANVAS_RETAINED, TRUE,
                                0);


        pw = canvas_pixwin(mycan);


    window_fit_width(myframe);
    window_main_loop(myframe);

}