Merge RFC4 (#1865)

This commit is the result of the squashing of rfc4_dev branch in a single
commit. It implements mostly RFC 4 related work.

* Grid handling:
  - remove obsolete and presumably unfinished implementation of grid catalog functionality
  - all grid functionality is in grids.cpp/.hpp
  - vertical and horizontal grid shift: rework to no longer load whole grid into memory
  - remove hgrids and vgrids member from PJ structure, and store them in hgridshift/vgridshift/deformation structures
  - build systems: add optional libtiff dependency. Must be explicitly disabled if not desired
  - add support for horizontal and vertical grids in GeoTIFF, if libtiff is available
  - add GenericShiftGridSet and GenericShiftGrid classes, relying on TIFF grids, that can be used for generic purpose grid-based adjustment
  - add a +proj=xyzgridshift method to perform geocentric translation by grid. Used for French NTF to RGF93 transformation using gr3df97a.tif grid
  - deformation: add support for +grids= for GeoTIFF grids
  - horizontal grid shift: fix failures on points slightly outside a subgrid (fixes #209)

* File management:
  - add a filemanager.cpp/.hpp to deal with file related work
  - test for legacy proj_api.h fileapi
  - proj.h: add proj_context_set_fileapi() and proj_context_set_sqlite3_vfs_name() (fixes #866)
  - add capability to read resource files from the user writable directory

* Network access:
  - build systems: add optional curl dependency
  - add a curl-based default implementation for network related functionality
  - proj.h: add C API to control network functionality, and optionaly provide network callbacks
  - add data/proj.ini with default settings
  - add a SQLite3 local cache of downloaded chunks
  - add proj_is_download_needed() and proj_download_file()

* Use Win32 Unicode APIs and expect all strings to be UTF-8 (fixes #1765)
  For backward compatibility, if PROJ_LIB content is found to be not UTF-8 or
  pointing to a non existing directory, then an attempt at interpretating it
  in the ANSI page encoding is done.
  proj_context_set_search_paths() now assumes strings to be in UTF-8, and
  functions returning paths will also return values in UTF-8.

1 files changed, 89 insertions, 0 deletions

diff --git a/test/unit/pj_transform_test.cpp b/test/unit/pj_transform_test.cpp
index 1f4473c1..ddb054f0 100644
--- a/test/unit/pj_transform_test.cpp
+++ b/test/unit/pj_transform_test.cpp
@@ -616,6 +616,22 @@ TEST(proj_api_h, pj_set_finder) {
 
 // ---------------------------------------------------------------------------
 
+TEST(proj_api_h, default_fileapi) {
+    auto ctx = pj_ctx_alloc();
+    auto fid = pj_open_lib(ctx, "proj.db", "rb");
+    ASSERT_NE(fid, nullptr);
+    char header[6];
+    ASSERT_EQ(pj_ctx_fread(ctx, header, 1, 6, fid), 6U);
+    ASSERT_TRUE(memcmp(header, "SQLite", 6) == 0);
+    ASSERT_EQ(pj_ctx_ftell(ctx, fid), 6);
+    ASSERT_EQ(pj_ctx_fseek(ctx, fid, 0, SEEK_SET), 0);
+    ASSERT_EQ(pj_ctx_ftell(ctx, fid), 0);
+    pj_ctx_fclose(ctx, fid);
+    pj_ctx_free(ctx);
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(pj_transform_test, ob_tran_to_meter_as_dest) {
     auto src = pj_init_plus(
         "+ellps=WGS84 +a=57.29577951308232 +proj=eqc +lon_0=0.0 +no_defs");
@@ -633,6 +649,79 @@ TEST(pj_transform_test, ob_tran_to_meter_as_dest) {
 
 // ---------------------------------------------------------------------------
 
+struct Spy {
+    bool gotInMyFOpen = false;
+    bool gotInMyFRead = false;
+    bool gotInMyFSeek = false;
+    bool gotInMyFTell = false;
+    bool gotInMyFClose = false;
+};
+
+struct MyFile {
+    FILE *fp;
+    Spy *spy;
+};
+
+static PAFile myFOpen(projCtx ctx, const char *filename, const char *access) {
+    FILE *fp = fopen(filename, access);
+    if (!fp)
+        return nullptr;
+    MyFile *myF = new MyFile;
+    myF->spy = (Spy *)pj_ctx_get_app_data(ctx);
+    myF->spy->gotInMyFOpen = true;
+    myF->fp = fp;
+    return reinterpret_cast<PAFile>(myF);
+}
+
+static size_t myFRead(void *buffer, size_t size, size_t nmemb, PAFile file) {
+    MyFile *myF = reinterpret_cast<MyFile *>(file);
+    myF->spy->gotInMyFRead = true;
+    return fread(buffer, size, nmemb, myF->fp);
+}
+
+static int myFSeek(PAFile file, long offset, int whence) {
+    MyFile *myF = reinterpret_cast<MyFile *>(file);
+    myF->spy->gotInMyFSeek = true;
+    return fseek(myF->fp, offset, whence);
+}
+
+static long myFTell(PAFile file) {
+    MyFile *myF = reinterpret_cast<MyFile *>(file);
+    myF->spy->gotInMyFTell = true;
+    return ftell(myF->fp);
+}
+
+static void myFClose(PAFile file) {
+    MyFile *myF = reinterpret_cast<MyFile *>(file);
+    myF->spy->gotInMyFClose = true;
+    fclose(myF->fp);
+    delete myF;
+}
+
+TEST(proj_api_h, custom_fileapi) {
+    auto ctx = pj_ctx_alloc();
+    Spy spy;
+    pj_ctx_set_app_data(ctx, &spy);
+    projFileAPI myAPI = {myFOpen, myFRead, myFSeek, myFTell, myFClose};
+    pj_ctx_set_fileapi(ctx, &myAPI);
+    EXPECT_EQ(pj_ctx_get_fileapi(ctx), &myAPI);
+    auto fid = pj_open_lib(ctx, "proj.db", "rb");
+    ASSERT_NE(fid, nullptr);
+    char header[6];
+    ASSERT_EQ(pj_ctx_fread(ctx, header, 1, 6, fid), 6U);
+    ASSERT_TRUE(memcmp(header, "SQLite", 6) == 0);
+    ASSERT_EQ(pj_ctx_ftell(ctx, fid), 6);
+    ASSERT_EQ(pj_ctx_fseek(ctx, fid, 0, SEEK_SET), 0);
+    ASSERT_EQ(pj_ctx_ftell(ctx, fid), 0);
+    pj_ctx_fclose(ctx, fid);
+    pj_ctx_free(ctx);
+    EXPECT_TRUE(spy.gotInMyFOpen);
+    EXPECT_TRUE(spy.gotInMyFRead);
+    EXPECT_TRUE(spy.gotInMyFSeek);
+    EXPECT_TRUE(spy.gotInMyFTell);
+    EXPECT_TRUE(spy.gotInMyFClose);
+}
+
 TEST(pj_transform_test, ob_tran_to_meter_as_srouce) {
     auto src = pj_init_plus("+ellps=WGS84 +proj=ob_tran +o_proj=latlon "
                             "+o_lon_p=0.0 +o_lat_p=90.0 +lon_0=360.0 "