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POJNA : Exception_Access_Violation
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copied!<p>I use JNA to call this function in libpotrace.dll, this function is: </p> <pre><code>potrace_state_t *potrace_trace(const potrace_param_t *param, const potrace_bitmap_t *bm); </code></pre> <p>The parameters in library are:</p> <pre><code>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; </code></pre> <p>in my java code I have:</p> <pre><code>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); </code></pre> <p>When I execute potrace_trace() this error occurs :</p> <pre><code>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 </code></pre> <p>I do not understand why. thanks.</p>

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