Geografic-Information-System/display/d.zoom/pan.c

/* possible TODO: add support for magnify (zoom=) */

#include <grass/gis.h>
#include <grass/display.h>
#include "local_proto.h"
#include <grass/glocale.h>


int do_pan(struct Cell_head *window)
{
    int screen_x, screen_y, button;
    int end = 0, printmenu = 1;

    while (!end) {
	if (printmenu) {
	    fprintf(stderr, _("\n\nButtons:\n"));
	    fprintf(stderr, _("Left:   Pan\n"));
	    fprintf(stderr, _("Right:  Quit\n"));
	    printmenu = 0;
	}

	R_get_location_with_pointer(&screen_x, &screen_y, &button);


	if (button == 1) {
	    /* pan */
	    pan_window(window, screen_x, screen_y);
	    printmenu = 1;
	}
	else if (button == 2) {
	    /* noop */
	    printmenu = 1;
	}
	else if (button == 3) {
	    end = 1;
	}
    }

    return (0);
}



int pan_window(struct Cell_head *window, int screen_x, int screen_y)
{
    double px, py, uxc, uyc, ux1, uy1, ux2, uy2;
    double north, south, east, west, ns, ew;
    int t;

    px = D_d_to_u_col((double)screen_x);
    py = D_d_to_u_row((double)screen_y);
    fprintf(stderr, "\n");
    print_coor(window, py, px);
    fprintf(stderr, "\n");

    uxc = D_d_to_u_col((double)screen_x);
    uyc = D_d_to_u_row((double)screen_y);
    t = uxc / window->ew_res;
    uxc = t * window->ew_res;
    t = uyc / window->ns_res;
    uyc = t * window->ns_res;

    ew = window->east - window->west;
    ns = window->north - window->south;

    ux1 = uxc - ew / 2;
    ux2 = uxc + ew / 2;
    uy1 = uyc - ns / 2;
    uy2 = uyc + ns / 2;

    north = uy1 > uy2 ? uy1 : uy2;
    south = uy1 < uy2 ? uy1 : uy2;
    west = ux1 < ux2 ? ux1 : ux2;
    east = ux1 > ux2 ? ux1 : ux2;

    if (window->proj == PROJECTION_LL) {
	if (north > 90) {
	    north = 90;
	    south = 90 - ns;
	}
	else if (south < -90) {
	    south = -90;
	    north = -90 + ns;
	}
    }

    set_win(window, east, north, west, south, 0);

    return (0);
}