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Decode polygons

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This commit is contained in:
Eric Fischer 2017-09-21 14:01:43 -07:00
parent 98f025fa35
commit a275a46bd8
1 changed files with 61 additions and 9 deletions
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70
shapefile.cpp
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@ -18,11 +18,6 @@ static unsigned int read16le(unsigned char *ba) {
((ba[1] & 0xFF) << 8);
}
static unsigned long long read64le(unsigned char *ba) {
return read32le(ba) |
(((long long) read32le(ba + 4)) << 32);
}
static unsigned int read32be(unsigned char *ba) {
return ((ba[0] & 0xFF) << 24) |
((ba[1] & 0xFF) << 16) |
@ -67,11 +62,11 @@ drawvec decode_geometry(unsigned char *data, size_t len, int *type) {
unsigned points = read32le(data + 40);
for (size_t i = 0; i < parts; i++) {
unsigned start = read32le(data + 44 * 4 * i);
unsigned start = read32le(data + 44 + 4 * i);
unsigned end;
if (i + 1 < parts) {
end = read32le(data + 44 * 4 * (i + 1));
end = read32le(data + 44 + 4 * (i + 1));
} else {
end = points;
}
@ -92,6 +87,63 @@ drawvec decode_geometry(unsigned char *data, size_t len, int *type) {
}
*type = VT_LINE;
} else if (t == 5) { // MultiPolygon
unsigned parts = read32le(data + 36);
unsigned points = read32le(data + 40);
std::vector<drawvec> inner;
std::vector<drawvec> outer;
for (size_t i = 0; i < parts; i++) {
unsigned start = read32le(data + 44 + 4 * i);
unsigned end;
if (i + 1 < parts) {
end = read32le(data + 44 + 4 * (i + 1));
} else {
end = points;
}
drawvec ring;
for (size_t j = start; j < end; j++) {
double lon = toDouble(data + 44 + 4 * parts + 16 * j);
double lat = toDouble(data + 44 + 4 * parts + 16 * j + 8);
long long x, y;
projection->project(lon, lat, 32, &x, &y);
if (j == start) {
ring.push_back(draw(VT_MOVETO, x, y));
} else {
ring.push_back(draw(VT_LINETO, x, y));
}
}
if (get_area(ring, 0, ring.size()) > 0) {
outer.push_back(ring);
} else {
inner.push_back(ring);
}
}
// Expectation from GeoJSON is that outer rings are the first
// or follow an end-polygon marker; inner rings follow anything else
for (size_t i = 0; i < outer.size(); i++) {
if (i != 0) {
dv.push_back(draw(VT_CLOSEPATH, 0, 0));
}
for (size_t j = 0; j < outer[i].size(); j++) {
dv.push_back(outer[i][j]);
}
}
for (size_t i = 0; i < inner.size(); i++) {
for (size_t j = 0; j < inner[i].size(); j++) {
dv.push_back(inner[i][j]);
}
}
*type = VT_POLYGON;
} else {
static bool warned = false;
if (!warned) {
@ -204,9 +256,9 @@ void parse_shapefile(struct serialization_state *sst, std::string fname, int lay
std::vector<std::string> full_keys;
std::vector<serial_val> full_values;
unsigned char *dbp = db + 1;
size_t dbp = 1;
for (size_t i = 0; i < columns.size(); i++) {
std::string s = std::string((char *) dbp, column_widths[i]);
std::string s = std::string((char *) (db + dbp), column_widths[i]);
dbp += column_widths[i];
while (s.size() > 0 && s[s.size() - 1] == ' ') {