/*Demonstrates symmetry.
Right-click and draw line of symmetry.
If the line of symmetry is a point, symmetry is turned-off.
*/

U0 SymmetryDemo()
{
        I64  message_code, x1, y1, x2, y2, arg1, arg2;
        CDC *dc = DCAlias;

        SettingsPush; //See SettingsPush
        Fs->win_inhibit = WIG_TASK_DEFAULT - WIF_SELF_FOCUS - WIF_SELF_BORDER;

        WinBorder;
        WinMax;
        DocClear;
        DCFill;
        dc->flags |= DCF_SYMMETRY;
        DCSymmetrySet(dc, Fs->pix_width / 2, 0, Fs->pix_width / 2, 1);
        do
        {
                message_code = MessageGet(&arg1, &arg2, 1 << MESSAGE_KEY_DOWN + 1 << MESSAGE_MS_L_DOWN + 1 << MESSAGE_MS_R_DOWN);
                switch (message_code)
                {
                        case MESSAGE_MS_R_DOWN:
                                dc->flags &= ~DCF_SYMMETRY;
                                dc->color = ROP_XOR + RED ^ TRANSPARENT;
                                x1 = arg1;
                                y1 = arg2;
                                x2 = arg1;
                                y2 = arg2;
                                while (message_code != MESSAGE_MS_R_UP)
                                {
                                        GrLine3(dc, x1, y1, 0, x2, y2, 0);
                                        message_code = MessageGet(&arg1, &arg2, 1 << MESSAGE_MS_R_UP + 1<< MESSAGE_MS_MOVE);
                                        GrLine3(dc, x1, y1, 0, x2, y2, 0);
                                        x2 = arg1;
                                        y2 = arg2;
                                }
                                GrLine3(dc, x1, y1, 0, x2, y2, 0);
                                if (DCSymmetry3Set(dc, x1, y1, 0, x2, y2, 0, x2, y2, 1))
                                        dc->flags |= DCF_SYMMETRY;
                                break;

                        case MESSAGE_MS_L_DOWN:
                                dc->color = ROP_XOR + BLACK ^ TRANSPARENT;
                                x1 = arg1;
                                y1 = arg2;
                                x2 = arg1;
                                y2 = arg2;
                                while (message_code != MESSAGE_MS_L_UP)
                                {
                                        GrLine3(dc, x1, y1, 0, x2, y2, 0);
                                        message_code = MessageGet(&arg1, &arg2, 1 << MESSAGE_MS_L_UP + 1 << MESSAGE_MS_MOVE);
                                        GrLine3(dc, x1, y1, 0, x2, y2, 0);
                                        x2 = arg1;
                                        y2 = arg2;
                                }
                                GrLine3(dc, x1, y1, 0, x2, y2, 0);
                                break;
                }
        }
        while (message_code != MESSAGE_KEY_DOWN || (arg1 != CH_ESC && arg1 != CH_SHIFT_ESC));

        MessageGet(,, 1 << MESSAGE_KEY_UP);
        DCFill;
        DCDel(dc);
        SettingsPop;
}

SymmetryDemo;  //Execute when #included