qt: Introduce platform specific css sections

src/qt/guiutil.cpp

@@ -6,6 +6,7 @@
 #include <qt/guiutil.h>
 
 #include <qt/bitcoinaddressvalidator.h>
+#include <qt/bitcoingui.h>
 #include <qt/bitcoinunits.h>
 #include <qt/qvalidatedlineedit.h>
 #include <qt/walletmodel.h>
@@ -1057,14 +1058,49 @@ void loadStyleSheet(QWidget* widget, bool fDebugWidget)
                 return false;
             }
 
+            std::string platformName = gArgs.GetArg("-uiplatform", BitcoinGUI::DEFAULT_UIPLATFORM);
             stylesheet = std::make_unique<QString>();
 
             for (const auto& file : vecFiles) {
                 QFile qFile(file);
                 if (!qFile.open(QFile::ReadOnly)) {
                     throw std::runtime_error(strprintf("%s: Failed to open file: %s", __func__, file.toStdString()));
                 }
-                stylesheet->append(QLatin1String(qFile.readAll()));
+
+                QString strStyle = QLatin1String(qFile.readAll());
+                // Process all <os=...></os> groups in the stylesheet first
+                QRegularExpressionMatch osStyleMatch;
+                QRegularExpression osStyleExp(
+                        "^"
+                        "(<os=(?:'|\").+(?:'|\")>)" // group 1
+                        "((?:.|\n)+?)"              // group 2
+                        "(</os>?)"                  // group 3
+                        "$");
+                osStyleExp.setPatternOptions(QRegularExpression::MultilineOption);
+                QRegularExpressionMatchIterator it = osStyleExp.globalMatch(strStyle);
+
+                // For all <os=...></os> sections
+                while (it.hasNext() && (osStyleMatch = it.next()).isValid()) {
+                    QStringList listMatches = osStyleMatch.capturedTexts();
+
+                    // Full match + 3 group matches
+                    if (listMatches.size() % 4) {
+                        throw std::runtime_error(strprintf("%s: Invalid <os=...></os> section in file %s", __func__, file.toStdString()));
+                    }
+
+                    for (int i = 0; i < listMatches.size(); i += 4) {
+                        if (!listMatches[i + 1].contains(QString::fromStdString(platformName))) {
+                            // If os is not supported for this styles
+                            // just remove the full match
+                            strStyle.replace(listMatches[i], "");
+                        } else {
+                            // If its supported remove the <os=...></os> tags
+                            strStyle.replace(listMatches[i + 1], "");
+                            strStyle.replace(listMatches[i + 3], "");
+                        }
+                    }
+                }
+                stylesheet->append(strStyle);
             }
             return true;
         };

src/qt/res/css/dark.css

@@ -784,3 +784,38 @@ TransactionView
 ******************************************************/
 
 /***** No dark.css specific coloring here yet *****/
+
+
+/******************************************************
+*******************************************************
+STYLING OF OS SPECIFIC UI PARTS
+
+NOTE: GUIUtil::loadStyleSheet treats css code between <os="<os_list>"> and </os>
+different. It will only become added for operating systems provided in the list
+of the sections start tag.
+
+There may be multiple entries per section. Possible entries:
+
+- macosx
+- windows
+- other
+
+<os_list> must be a combination of the three options above separated by
+comma like in "windows,macosx".
+
+Its ok to have multiple <os="...">...</os> sections in a file with
+arbitrary OS combinations. They will all become added to the end of the
+file though. Means even putting an <os> section in the top of the file
+would become appended to the end of the file during loading which should
+be kept in mind when adding sections to avoid unexpected overwriting.
+*******************************************************
+******************************************************/
+
+<os="macosx, windows, other">
+
+/* Example section to add styles for all operating systems
+   Remove any to exclude it.
+*/
+
+</os>
+

src/qt/res/css/general.css

@@ -1849,3 +1849,39 @@ TransactionView QComboBox {
     min-height: 30px;
     margin-top: 15px;
 }
+
+
+/******************************************************
+*******************************************************
+STYLING OF OS SPECIFIC UI PARTS
+
+NOTE: GUIUtil::loadStyleSheet treats css code between <os="<os_list>"> and </os>
+different. It will only become added for operating systems provided in the list
+of the sections start tag.
+
+There may be multiple entries per section. Possible entries:
+
+- macosx
+- windows
+- other
+
+<os_list> must be a combination of the three options above separated by
+comma like in "windows,macosx".
+
+Its ok to have multiple <os="...">...</os> sections in a file with
+arbitrary OS combinations. They will all become added to the end of the
+file though. Means even putting an <os> section in the top of the file
+would become appended to the end of the file during loading which should
+be kept in mind when adding sections to avoid unexpected overwriting.
+*******************************************************
+******************************************************/
+
+
+<os="macosx, windows, other">
+
+/* Example section to add styles for all operating systems
+   Remove any to exclude it.
+*/
+
+</os>
+

src/qt/res/css/light.css

@@ -766,3 +766,39 @@ TransactionView
 ******************************************************/
 
 /***** No light.css specific coloring here yet *****/
+
+
+/******************************************************
+*******************************************************
+STYLING OF OS SPECIFIC UI PARTS
+
+NOTE: GUIUtil::loadStyleSheet treats css code between <os="<os_list>"> and </os>
+different. It will only become added for operating systems provided in the list
+of the sections start tag.
+
+There may be multiple entries per section. Possible entries:
+
+- macosx
+- windows
+- other
+
+<os_list> must be a combination of the three options above separated by
+comma like in "windows,macosx".
+
+Its ok to have multiple <os="...">...</os> sections in a file with
+arbitrary OS combinations. They will all become added to the end of the
+file though. Means even putting an <os> section in the top of the file
+would become appended to the end of the file during loading which should
+be kept in mind when adding sections to avoid unexpected overwriting.
+*******************************************************
+******************************************************/
+
+
+<os="macosx, windows, other">
+
+/* Example section to add styles for all operating systems
+   Remove any to exclude it.
+*/
+
+</os>
+