1//--------------------------------------------------------------------------
2// Parsing of GPS info from exif header.
3//
4// Matthias Wandel,  Dec 1999 - Dec 2002
5//--------------------------------------------------------------------------
6#include "jhead.h"
7
8#include <string.h>
9#include <utils/Log.h>
10
11
12#define TAG_GPS_LAT_REF    1
13#define TAG_GPS_LAT        2
14#define TAG_GPS_LONG_REF   3
15#define TAG_GPS_LONG       4
16#define TAG_GPS_ALT_REF    5
17#define TAG_GPS_ALT        6
18#define TAG_GPS_TIMESTAMP  7
19#define TAG_GPS_PROCESSING_METHOD 27
20#define TAG_GPS_DATESTAMP  29
21
22static TagTable_t GpsTags[]= {
23    { 0x00, "GPSVersionID", FMT_BYTE, 4},
24    { 0x01, "GPSLatitudeRef", FMT_STRING, 2},
25    { 0x02, "GPSLatitude", FMT_URATIONAL, 3},
26    { 0x03, "GPSLongitudeRef", FMT_STRING, 2},
27    { 0x04, "GPSLongitude", FMT_URATIONAL, 3},
28    { 0x05, "GPSAltitudeRef", FMT_BYTE, 1},
29    { 0x06, "GPSAltitude", FMT_URATIONAL, 1},
30    { 0x07, "GPSTimeStamp", FMT_SRATIONAL, 3},
31    { 0x08, "GPSSatellites", FMT_STRING, -1},
32    { 0x09, "GPSStatus", FMT_STRING, 2},
33    { 0x0A, "GPSMeasureMode", FMT_STRING, 2},
34    { 0x0B, "GPSDOP", FMT_SRATIONAL, 1},
35    { 0x0C, "GPSSpeedRef", FMT_STRING, 2},
36    { 0x0D, "GPSSpeed", FMT_SRATIONAL, 1},
37    { 0x0E, "GPSTrackRef", FMT_STRING, 2},
38    { 0x0F, "GPSTrack", FMT_SRATIONAL, 1},
39    { 0x10, "GPSImgDirectionRef", FMT_STRING, -1},
40    { 0x11, "GPSImgDirection", FMT_SRATIONAL, 1},
41    { 0x12, "GPSMapDatum", FMT_STRING, -1},
42    { 0x13, "GPSDestLatitudeRef", FMT_STRING, 2},
43    { 0x14, "GPSDestLatitude", FMT_SRATIONAL, 3},
44    { 0x15, "GPSDestLongitudeRef", FMT_STRING, 2},
45    { 0x16, "GPSDestLongitude", FMT_SRATIONAL, 3},
46    { 0x17, "GPSDestBearingRef", FMT_STRING, 1},
47    { 0x18, "GPSDestBearing", FMT_SRATIONAL, 1},
48    { 0x19, "GPSDestDistanceRef", FMT_STRING, 2},
49    { 0x1A, "GPSDestDistance", FMT_SRATIONAL, 1},
50    { 0x1B, "GPSProcessingMethod", FMT_UNDEFINED, -1},
51    { 0x1C, "GPSAreaInformation", FMT_STRING, -1},
52    { 0x1D, "GPSDateStamp", FMT_STRING, 11},
53    { 0x1E, "GPSDifferential", FMT_SSHORT, 1},
54};
55
56#define MAX_GPS_TAG  (sizeof(GpsTags) / sizeof(TagTable_t))
57#define EXIF_ASCII_PREFIX_LEN (sizeof(ExifAsciiPrefix))
58
59// Define the line below to turn on poor man's debugging output
60#undef SUPERDEBUG
61
62#ifdef SUPERDEBUG
63#define printf ALOGE
64#endif
65
66
67int IsGpsTag(const char* tag) {
68    return strstr(tag, "GPS") == tag;
69}
70
71TagTable_t* GpsTagToTagTableEntry(unsigned short tag)
72{
73    unsigned int i;
74    for (i = 0; i < MAX_GPS_TAG; i++) {
75        if (GpsTags[i].Tag == tag) {
76            printf("found tag %d", tag);
77            int format = GpsTags[i].Format;
78            if (format == 0) {
79                printf("tag %s format not defined", GpsTags[i].Desc);
80                return NULL;
81            }
82            return &GpsTags[i];
83        }
84    }
85    printf("tag %d NOT FOUND", tag);
86    return NULL;
87}
88
89int GpsTagToFormatType(unsigned short tag)
90{
91    unsigned int i;
92    for (i = 0; i < MAX_GPS_TAG; i++) {
93        if (GpsTags[i].Tag == tag) {
94            printf("found tag %d", tag);
95            int format = GpsTags[i].Format;
96            if (format == 0) {
97                printf("tag %s format not defined", GpsTags[i].Desc);
98                return -1;
99            }
100            return format;
101        }
102    }
103    printf("tag %d NOT FOUND", tag);
104    return -1;
105}
106
107int GpsTagNameToValue(const char* tagName)
108{
109    unsigned int i;
110    for (i = 0; i < MAX_GPS_TAG; i++) {
111        if (strcmp(GpsTags[i].Desc, tagName) == 0) {
112            printf("found GPS tag %s val %d", GpsTags[i].Desc, GpsTags[i].Tag);
113            return GpsTags[i].Tag;
114        }
115    }
116    printf("GPS tag %s NOT FOUND", tagName);
117    return -1;
118}
119
120
121//--------------------------------------------------------------------------
122// Process GPS info directory
123//--------------------------------------------------------------------------
124void ProcessGpsInfo(unsigned char * DirStart, int ByteCountUnused, unsigned char * OffsetBase, unsigned ExifLength)
125{
126    int de;
127    unsigned a;
128    int NumDirEntries;
129
130    NumDirEntries = Get16u(DirStart);
131    #define DIR_ENTRY_ADDR(Start, Entry) (Start+2+12*(Entry))
132
133    if (ShowTags){
134        printf("(dir has %d entries)\n",NumDirEntries);
135    }
136
137    ImageInfo.GpsInfoPresent = TRUE;
138    strcpy(ImageInfo.GpsLat, "? ?");
139    strcpy(ImageInfo.GpsLong, "? ?");
140    ImageInfo.GpsAlt[0] = 0;
141
142    for (de=0;de<NumDirEntries;de++){
143        unsigned Tag, Format, Components;
144        unsigned char * ValuePtr;
145        int ComponentSize;
146        unsigned ByteCount;
147        unsigned char * DirEntry;
148        DirEntry = DIR_ENTRY_ADDR(DirStart, de);
149
150        if (DirEntry+12 > OffsetBase+ExifLength){
151            ErrNonfatal("GPS info directory goes past end of exif",0,0);
152            return;
153        }
154
155        Tag = Get16u(DirEntry);
156        Format = Get16u(DirEntry+2);
157        Components = Get32u(DirEntry+4);
158
159        if ((Format-1) >= NUM_FORMATS) {
160            // (-1) catches illegal zero case as unsigned underflows to positive large.
161            ErrNonfatal("Illegal number format %d for tag %04x", Format, Tag);
162            continue;
163        }
164
165        ComponentSize = BytesPerFormat[Format];
166        ByteCount = Components * ComponentSize;
167
168#ifdef SUPERDEBUG
169    printf("GPS tag %x format %s #components %d componentsize %d bytecount %d", Tag, formatStr(Format), Components, ComponentSize,
170            ByteCount);
171#endif
172
173        if (ByteCount > 4){
174            unsigned OffsetVal;
175            OffsetVal = Get32u(DirEntry+8);
176            // If its bigger than 4 bytes, the dir entry contains an offset.
177            if (OffsetVal+ByteCount > ExifLength){
178                // Bogus pointer offset and / or bytecount value
179                ErrNonfatal("Illegal value pointer for tag %04x", Tag,0);
180                continue;
181            }
182            ValuePtr = OffsetBase+OffsetVal;
183        }else{
184            // 4 bytes or less and value is in the dir entry itself
185            ValuePtr = DirEntry+8;
186        }
187
188        switch(Tag){
189            char FmtString[21];
190            char TempString[MAX_BUF_SIZE];
191            double Values[3];
192
193            case TAG_GPS_LAT_REF:
194                ImageInfo.GpsLat[0] = ValuePtr[0];
195                ImageInfo.GpsLatRef[0] = ValuePtr[0];
196                ImageInfo.GpsLatRef[1] = '\0';
197                break;
198
199            case TAG_GPS_LONG_REF:
200                ImageInfo.GpsLong[0] = ValuePtr[0];
201                ImageInfo.GpsLongRef[0] = ValuePtr[0];
202                ImageInfo.GpsLongRef[1] = '\0';
203                break;
204
205            case TAG_GPS_LAT:
206            case TAG_GPS_LONG:
207                if (Format != FMT_URATIONAL){
208                    ErrNonfatal("Inappropriate format (%d) for GPS coordinates!", Format, 0);
209                }
210                strcpy(FmtString, "%0.0fd %0.0fm %0.0fs");
211                for (a=0;a<3;a++){
212                    int den, digits;
213
214                    den = Get32s(ValuePtr+4+a*ComponentSize);
215                    digits = 0;
216                    while (den > 1 && digits <= 6){
217                        den = den / 10;
218                        digits += 1;
219                    }
220                    if (digits > 6) digits = 6;
221                    FmtString[1+a*7] = (char)('2'+digits+(digits ? 1 : 0));
222                    FmtString[3+a*7] = (char)('0'+digits);
223
224                    Values[a] = ConvertAnyFormat(ValuePtr+a*ComponentSize, Format);
225                }
226
227                sprintf(TempString, FmtString, Values[0], Values[1], Values[2]);
228
229                if (Tag == TAG_GPS_LAT){
230                    strncpy(ImageInfo.GpsLat+2, TempString, 29);
231                }else{
232                    strncpy(ImageInfo.GpsLong+2, TempString, 29);
233                }
234
235                sprintf(TempString, "%d/%d,%d/%d,%d/%d",
236                    Get32s(ValuePtr), Get32s(4+(char*)ValuePtr),
237                    Get32s(8+(char*)ValuePtr), Get32s(12+(char*)ValuePtr),
238                    Get32s(16+(char*)ValuePtr), Get32s(20+(char*)ValuePtr));
239                if (Tag == TAG_GPS_LAT){
240                    strncpy(ImageInfo.GpsLatRaw, TempString, MAX_BUF_SIZE);
241                }else{
242                    strncpy(ImageInfo.GpsLongRaw, TempString, MAX_BUF_SIZE);
243                }
244                break;
245
246            case TAG_GPS_ALT_REF:
247                ImageInfo.GpsAlt[0] = (char)(ValuePtr[0] ? '-' : ' ');
248                ImageInfo.GpsAltRef = (char)ValuePtr[0];
249                break;
250
251            case TAG_GPS_ALT:
252                sprintf(ImageInfo.GpsAlt + 1, "%.2fm",
253                    ConvertAnyFormat(ValuePtr, Format));
254                ImageInfo.GpsAltRaw.num = Get32u(ValuePtr);
255                ImageInfo.GpsAltRaw.denom = Get32u(4+(char *)ValuePtr);
256                break;
257
258            case TAG_GPS_TIMESTAMP:
259                snprintf(ImageInfo.GpsTimeStamp,
260                    sizeof(ImageInfo.GpsTimeStamp), "%d:%d:%d",
261                    (int) ConvertAnyFormat(ValuePtr, Format),
262                    (int) ConvertAnyFormat(ValuePtr + 8, Format),
263                    (int) ConvertAnyFormat(ValuePtr + 16, Format)
264                );
265                break;
266
267            case TAG_GPS_DATESTAMP:
268                strncpy(ImageInfo.GpsDateStamp, (char*)ValuePtr, sizeof(ImageInfo.GpsDateStamp));
269                break;
270
271            case TAG_GPS_PROCESSING_METHOD:
272                if (ByteCount > EXIF_ASCII_PREFIX_LEN &&
273                    memcmp(ValuePtr, ExifAsciiPrefix, EXIF_ASCII_PREFIX_LEN) == 0) {
274                    int length =
275                        ByteCount < GPS_PROCESSING_METHOD_LEN + EXIF_ASCII_PREFIX_LEN ?
276                        ByteCount - EXIF_ASCII_PREFIX_LEN : GPS_PROCESSING_METHOD_LEN;
277                    memcpy(ImageInfo.GpsProcessingMethod,
278                        (char*)(ValuePtr + EXIF_ASCII_PREFIX_LEN), length);
279                    ImageInfo.GpsProcessingMethod[length] = 0;
280                } else {
281                    ALOGW("Unsupported encoding for GPSProcessingMethod");
282                }
283                break;
284        }
285
286        if (ShowTags){
287            // Show tag value.
288            if (Tag < MAX_GPS_TAG){
289                printf("        %s =", GpsTags[Tag].Desc);
290            }else{
291                // Show unknown tag
292                printf("        Illegal GPS tag %04x=", Tag);
293            }
294
295            switch(Format){
296                case FMT_UNDEFINED:
297                    // Undefined is typically an ascii string.
298
299                case FMT_STRING:
300                    // String arrays printed without function call (different from int arrays)
301                    {
302                        printf("\"");
303                        for (a=0;a<ByteCount;a++){
304                            int ZeroSkipped = 0;
305                            if (ValuePtr[a] >= 32){
306                                if (ZeroSkipped){
307                                    printf("?");
308                                    ZeroSkipped = 0;
309                                }
310                                putchar(ValuePtr[a]);
311                            }else{
312                                if (ValuePtr[a] == 0){
313                                    ZeroSkipped = 1;
314                                }
315                            }
316                        }
317                        printf("\"\n");
318                    }
319                    break;
320
321                default:
322                    // Handle arrays of numbers later (will there ever be?)
323                    for (a=0;;){
324                        PrintFormatNumber(ValuePtr+a*ComponentSize, Format, ByteCount);
325                        if (++a >= Components) break;
326                        printf(", ");
327                    }
328                    printf("\n");
329            }
330        }
331    }
332}
333
334
335