Why does this crash? - Printable Version

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struct img_struct {

    void *lock_offset;

    int64 lock_id;

    uint8 valid;  // 0,1 0=invalid

    uint8 text;    // if set, surface is a text surface

    uint8 console; // dummy surface to absorb unimplemented console functionality

    uint16 width, height;

    uint8 bytes_per_pixel;  // 1,2,4

    uint8 bits_per_pixel;  // 1,2,4,8,16(text),32

    uint32 mask;            // 1,3,0xF,0xFF,0xFFFF,0xFFFFFFFF

    uint16 compatible_mode; // 0,1,2,7,8,9,10,11,12,13,32,256

    uint32 color, background_color, draw_color;

    uint32 font;              // 8,14,16,?

    int16 top_row, bottom_row; // VIEW PRINT settings, unique (as in QB) to each "page"

    int16 cursor_x, cursor_y;  // unique (as in QB) to each "page"

    uint8 cursor_show, cursor_firstvalue, cursor_lastvalue;

    union {

        uint8 *offset;

        uint32 *offset32;

    };

    uint32 flags;

    uint32 *pal;

    int32 transparent_color; //-1 means no color is transparent

    uint8 alpha_disabled;

    uint8 holding_cursor;

    uint8 print_mode;

    // BEGIN apm ('active page migration')

    // everything between apm points is migrated during active page changes

    // note: apm data is only relevent to graphics modes

    uint8 apm_p1;

    int32 view_x1, view_y1, view_x2, view_y2;

    int32 view_offset_x, view_offset_y;

    float x, y;

    uint8 clipping_or_scaling;

    float scaling_x, scaling_y, scaling_offset_x, scaling_offset_y;

    float window_x1, window_y1, window_x2, window_y2;

    double draw_ta;

    double draw_scale;

    uint8 apm_p2;

    // END apm

};

// img_struct flags

#    define IMG_FREEPAL 1 // free palette data before freeing image

#    define IMG_SCREEN 2  // img is linked to other screen pages

#    define IMG_FREEMEM 4 // if set, it means memory must be freed

_SOURCE Picture _Display ' Turn off auto display FOR y = 0 TO 719 FOR x = 0 TO 1279 Pixel(x, y).soft = _NEWIMAGE(1, 1, 32) _DEST Pixel(x, y).soft PSET (0, 0), POINT(x, y) Pixel(x, y).hard = _COPYIMAGE(Pixel(x, y).soft, 33) Pixel(x, y).ox = x Pixel(x, y).oy = y _DEST 0 ' temporarily print values to figure PRINT x, y, Pixel(x, y).soft, Pixel(x, y).hard ' out why this crashes NEXT x _Display ' Obviously you can leave this out if you don't want to see anything during the loop NEXT y _AutoDisplay ' turn it back on