Add multi-line PROJ string export capability, and use it by default in projinfo (unless --single-line is specified) (fixes #1543)

docs/source/apps/projinfo.rst

@@ -260,8 +260,8 @@ The following control parameters can appear in any order:
 
 .. option:: --single-line
 
-    Output WKT or PROJJSON strings on a single line, instead of multiple intended lines by
-    default.
+    Output PROJ, WKT or PROJJSON strings on a single line, instead of multiple
+    indented lines by default.
 
 .. option:: --searchpaths
 

include/proj/io.hpp

@@ -387,6 +387,10 @@ class PROJ_GCC_DLL PROJStringFormatter {
     PROJ_DLL ~PROJStringFormatter();
     //! @endcond
 
+    PROJ_DLL PROJStringFormatter &setMultiLine(bool multiLine) noexcept;
+    PROJ_DLL PROJStringFormatter &setIndentationWidth(int width) noexcept;
+    PROJ_DLL PROJStringFormatter &setMaxLineLength(int maxLineLength) noexcept;
+
     PROJ_DLL void setUseApproxTMerc(bool flag);
 
     PROJ_DLL const std::string &toString() const;

scripts/reference_exported_symbols.txt

@@ -406,6 +406,9 @@ osgeo::proj::io::PROJStringFormatter::ingestPROJString(std::string const&)
 osgeo::proj::io::PROJStringFormatter::~PROJStringFormatter()
 osgeo::proj::io::PROJStringFormatter::setCRSExport(bool)
 osgeo::proj::io::PROJStringFormatter::setCurrentStepInverted(bool)
+osgeo::proj::io::PROJStringFormatter::setIndentationWidth(int)
+osgeo::proj::io::PROJStringFormatter::setMaxLineLength(int)
+osgeo::proj::io::PROJStringFormatter::setMultiLine(bool)
 osgeo::proj::io::PROJStringFormatter::setUseApproxTMerc(bool)
 osgeo::proj::io::PROJStringFormatter::startInversion()
 osgeo::proj::io::PROJStringFormatter::stopInversion()

src/apps/projinfo.cpp

@@ -350,11 +350,11 @@ static void outputObject(
                     objToExport = projStringExportable;
                 }
 
-                std::cout << objToExport->exportToPROJString(
-                                 PROJStringFormatter::create(
-                                     PROJStringFormatter::Convention::PROJ_5,
-                                     dbContext)
-                                     .get())
+                auto formatter = PROJStringFormatter::create(
+                    PROJStringFormatter::Convention::PROJ_5, dbContext);
+                formatter->setMultiLine(!outputOpt.singleLine &&
+                                        crs == nullptr);
+                std::cout << objToExport->exportToPROJString(formatter.get())
                           << std::endl;
             } catch (const std::exception &e) {
                 std::cerr << "Error when exporting to PROJ string: " << e.what()
@@ -376,9 +376,7 @@ static void outputObject(
                 }
                 auto formatter =
                     WKTFormatter::create(WKTFormatter::Convention::WKT2_2015);
-                if (outputOpt.singleLine) {
-                    formatter->setMultiLine(false);
-                }
+                formatter->setMultiLine(!outputOpt.singleLine);
                 formatter->setStrict(outputOpt.strict);
                 auto wkt = wktExportable->exportToWKT(formatter.get());
                 if (outputOpt.c_ify) {

src/iso19111/c_api.cpp

@@ -1504,9 +1504,16 @@ const char *proj_as_wkt(PJ_CONTEXT *ctx, const PJ *obj, PJ_WKT_TYPE type,
  * @param obj Object (must not be NULL)
  * @param type PROJ String version.
  * @param options NULL-terminated list of strings with "KEY=VALUE" format. or
- * NULL.
- * The currently recognized option is USE_APPROX_TMERC=YES to add the +approx
- * flag to +proj=tmerc or +proj=utm
+ * NULL. Currently supported options are:
+ * <ul>
+ * <li>USE_APPROX_TMERC=YES to add the +approx flag to +proj=tmerc or
+ * +proj=utm.</li>
+ * <li>MULTILINE=YES/NO. Defaults to NO</li>
+ * <li>INDENTATION_WIDTH=number. Defaults to 2 (when multiline output is
+ * on).</li>
+ * <li>MAX_LINE_LENGTH=number. Defaults to 80 (when multiline output is
+ * on).</li>
+ * </ul>
  * @return a string, or NULL in case of error.
  */
 const char *proj_as_proj_string(PJ_CONTEXT *ctx, const PJ *obj,
@@ -1542,9 +1549,21 @@ const char *proj_as_proj_string(PJ_CONTEXT *ctx, const PJ *obj,
     auto dbContext = getDBcontextNoException(ctx, __FUNCTION__);
     try {
         auto formatter = PROJStringFormatter::create(convention, dbContext);
-        if (options != nullptr && options[0] != nullptr) {
-            if (ci_equal(options[0], "USE_APPROX_TMERC=YES")) {
-                formatter->setUseApproxTMerc(true);
+        for (auto iter = options; iter && iter[0]; ++iter) {
+            const char *value;
+            if ((value = getOptionValue(*iter, "MULTILINE="))) {
+                formatter->setMultiLine(ci_equal(value, "YES"));
+            } else if ((value = getOptionValue(*iter, "INDENTATION_WIDTH="))) {
+                formatter->setIndentationWidth(std::atoi(value));
+            } else if ((value = getOptionValue(*iter, "MAX_LINE_LENGTH="))) {
+                formatter->setMaxLineLength(std::atoi(value));
+            } else if ((value = getOptionValue(*iter, "USE_APPROX_TMERC="))) {
+                formatter->setUseApproxTMerc(ci_equal(value, "YES"));
+            } else {
+                std::string msg("Unknown option :");
+                msg += *iter;
+                proj_log_error(ctx, __FUNCTION__, msg.c_str());
+                return nullptr;
             }
         }
         obj->lastPROJString = exportable->exportToPROJString(formatter.get());

src/iso19111/io.cpp

@@ -6722,6 +6722,10 @@ struct PROJStringFormatter::Private {
     bool coordOperationOptimizations_ = false;
     bool crsExport_ = false;
     bool legacyCRSToCRSContext_ = false;
+    bool multiLine_ = false;
+    int indentWidth_ = 2;
+    int indentLevel_ = 0;
+    int maxLineLength_ = 80;
 
     std::string result_{};
 
@@ -6780,6 +6784,36 @@ void PROJStringFormatter::setUseApproxTMerc(bool flag) {
 
 // ---------------------------------------------------------------------------
 
+/** \brief Whether to use multi line output or not. */
+PROJStringFormatter &
+PROJStringFormatter::setMultiLine(bool multiLine) noexcept {
+    d->multiLine_ = multiLine;
+    return *this;
+}
+
+// ---------------------------------------------------------------------------
+
+/** \brief Set number of spaces for each indentation level (defaults to 2).
+ */
+PROJStringFormatter &
+PROJStringFormatter::setIndentationWidth(int width) noexcept {
+    d->indentWidth_ = width;
+    return *this;
+}
+
+// ---------------------------------------------------------------------------
+
+/** \brief Set the maximum size of a line (when multiline output is enable).
+ * Can be set to 0 for unlimited length.
+ */
+PROJStringFormatter &
+PROJStringFormatter::setMaxLineLength(int maxLineLength) noexcept {
+    d->maxLineLength_ = maxLineLength;
+    return *this;
+}
+
+// ---------------------------------------------------------------------------
+
 /** \brief Returns the PROJ string. */
 const std::string &PROJStringFormatter::toString() const {
 
@@ -7308,28 +7342,56 @@ const std::string &PROJStringFormatter::toString() const {
                     pj_double_quote_string_param_if_needed(paramValue.value);
             }
         }
+
+        if (d->multiLine_) {
+            d->indentLevel_++;
+        }
     }
 
     for (const auto &step : d->steps_) {
+        std::string curLine;
         if (!d->result_.empty()) {
-            d->appendToResult("+step");
+            if (d->multiLine_) {
+                curLine = std::string(d->indentLevel_ * d->indentWidth_, ' ');
+                curLine += "+step";
+            } else {
+                curLine = " +step";
+            }
         }
         if (step.inverted) {
-            d->appendToResult("+inv");
+            curLine += " +inv";
         }
         if (!step.name.empty()) {
-            d->appendToResult(step.isInit ? "+init=" : "+proj=");
-            d->result_ += step.name;
+            if (!curLine.empty())
+                curLine += ' ';
+            curLine += step.isInit ? "+init=" : "+proj=";
+            curLine += step.name;
         }
         for (const auto &paramValue : step.paramValues) {
-            d->appendToResult("+");
-            d->result_ += paramValue.key;
+            std::string newKV = "+";
+            newKV += paramValue.key;
             if (!paramValue.value.empty()) {
-                d->result_ += '=';
-                d->result_ +=
+                newKV += '=';
+                newKV +=
                     pj_double_quote_string_param_if_needed(paramValue.value);
             }
+            if (d->maxLineLength_ > 0 && d->multiLine_ &&
+                curLine.size() + newKV.size() >
+                    static_cast<size_t>(d->maxLineLength_)) {
+                if (d->multiLine_ && !d->result_.empty())
+                    d->result_ += '\n';
+                d->result_ += curLine;
+                curLine = std::string(
+                    d->indentLevel_ * d->indentWidth_ + strlen("+step "), ' ');
+            } else {
+                if (!curLine.empty())
+                    curLine += ' ';
+            }
+            curLine += newKV;
         }
+        if (d->multiLine_ && !d->result_.empty())
+            d->result_ += '\n';
+        d->result_ += curLine;
     }
 
     if (d->result_.empty()) {

test/cli/testprojinfo

@@ -50,8 +50,8 @@ echo "Testing projinfo -o ALL EPSG:4326" >> ${OUT}
 $EXE -o ALL EPSG:4326 >>${OUT}
 echo "" >>${OUT}
 
-echo "Testing projinfo -s EPSG:4326 -t EPSG:32631" >> ${OUT}
-$EXE -s EPSG:4326 -t EPSG:32631 >>${OUT}
+echo "Testing projinfo -s EPSG:4326 -t EPSG:32631 --single-line" >> ${OUT}
+$EXE -s EPSG:4326 -t EPSG:32631 --single-line >>${OUT}
 echo "" >>${OUT}
 
 echo "Testing projinfo -s NAD27 -t NAD83" >> ${OUT}