JNA: EXCEPTION_ACCESS_VIOLATION

Question

I JNA verwenden diese Funktion in libpotrace.dll zu nennen, ist diese Funktion:

potrace_state_t *potrace_trace(const potrace_param_t *param, 
const potrace_bitmap_t *bm); 

Die Parameter in der Bibliothek sind:

typedef unsigned long potrace_word; 

struct potrace_bitmap_s { 
    int w, h;    /* width and height, in pixels */ 
    int dy;    /* words per scanline (not bytes) */ 
    potrace_word *map;  /* raw data, dy*h words */ 
}; 
typedef struct potrace_bitmap_s potrace_bitmap_t; 

struct potrace_param_s { 
    int turdsize;  /* area of largest path to be ignored */ 
    int turnpolicy;  /* resolves ambiguous turns in path decomposition */ 
    double alphamax;  /* corner threshold */ 
    int opticurve;  /* use curve optimization? */ 
    double opttolerance; /* curve optimization tolerance */ 
    potrace_progress_t progress; /* progress callback function */ 
}; 
typedef struct potrace_param_s potrace_param_t; 

in meinem Java-Code ich habe:

public class Potrace_bitmap_t extends Structure{ 
    public int w=36; 
    public int h=2; /* width and height, in pixels */ 
    public int dy=2; /* words per scanline (not bytes) */ 
    public long [] map =new long[dy*h]; 
} 

public class potrace_param_t extends Structure{  
    //public static class ByValue extends Nat implements Structure.ByValue { } 

    public int turdsize=0; 
    public int turnpolicy=0; 
    public double alphamax=0; 
    public int opticurve=0; 
    public double opttolerance=0; 

} 

potrace_param_t na=lib.potrace_param_default();/*This function returns a fresh set of tracing parameters, initialized to defaults. 
Potrace_bitmap_t bm=new Potrace_bitmap_t(); 
bm.map[0]=1113215L; 
bm.map[1]=4026531840L; 
bm.map[2]=3276415L; 
bm.map[3]=4026531840L; 
Potrace_state_t pt=lib.potrace_trace(na, bm); 

Wenn ich potrace_trace execute() dieser Fehler auftritt:

An unexpected error has been detected by Java Runtime Environment: 

EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x6504fbee, pid=2728, tid=2436 

Java VM: Java HotSpot(TM) Client VM (1.6.0_03-b05 mixed mode, sharing) 
Problematic frame: 
C [libpotrace.dll+0xfbee] 

An error report file with more information is saved as hs_err_pid2728.log 

If you would like to submit a bug report, please visit: 
    http://java.sun.com/webapps/bugreport/crash.jsp 

Ich verstehe nicht warum. danke.

Answer 1

Ihr viertes Feld von Potrace_bitmap_t sollte ein Zeiger sein, kein Array von 64-Bit-Werten. Du verpasst das letzte Feld von potrace_param_t.

Answer 2

aber in der doc der Bibliothek, fand ich diese

w = 36; 
h = 12; 
dy = 2; 
map[22] = 0xfff0fc02; map[23] = 0x00000000; 
map[20] = 0x7ff1fe02; map[21] = 0x00000000; 
map[18] = 0x3ff3ff07; map[19] = 0x00000000; 
map[16] = 0x1ff7ff87; map[17] = 0x00000000; 
map[14] = 0x0ff7cf8f; map[15] = 0x80000000; 
map[12] = 0x07f7878f; map[13] = 0x80000000; 
map[10] = 0x03f7879f; map[11] = 0xc0000000; 
map[8] = 0x01f7cf9f; map[9] = 0xc0000000; 
map[6] = 0x00f7ffbf; map[7] = 0xe0000000; 
map[4] = 0x0073ff3f; map[5] = 0xe0000000; 
map[2] = 0x0031fe7f; map[3] = 0xf0000000; 
map[0] = 0x0010fc7f; map[1] = 0xf0000000;