Compile themes to BSS format

Every built-in theme is now available in both CSS and BSS formats.

base/pom.xml

@@ -58,6 +58,27 @@
                     </execution>
                 </executions>
             </plugin>
+            <!-- compile themes to BSS -->
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>1.6.0</version>
+                <executions>
+                    <execution>
+                        <id>compile-to-bss</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>java</goal>
+                        </goals>
+                        <configuration>
+                            <mainClass>atlantafx.base.theme.ThemeCompiler</mainClass>
+                            <arguments>
+                                <argument>${project.build.directory}/classes/atlantafx/base/theme</argument>
+                            </arguments>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 

base/src/main/java/atlantafx/base/theme/CupertinoDark.java

@@ -3,6 +3,7 @@
 package atlantafx.base.theme;
 
 import atlantafx.base.Preview;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * A theme based on <a href="https://developer.apple.com/design/">IOS</a> color palette.
@@ -30,6 +31,14 @@ public class CupertinoDark implements Theme {
         return "/atlantafx/base/theme/cupertino-dark.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/cupertino-dark.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/CupertinoLight.java

@@ -30,6 +30,14 @@ public class CupertinoLight implements Theme {
         return "/atlantafx/base/theme/cupertino-light.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/cupertino-light.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/Dracula.java

@@ -30,6 +30,14 @@ public class Dracula implements Theme {
         return "/atlantafx/base/theme/dracula.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/dracula.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/NordDark.java

@@ -27,6 +27,14 @@ public final class NordDark implements Theme {
         return "/atlantafx/base/theme/nord-dark.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/nord-dark.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/NordLight.java

@@ -27,6 +27,14 @@ public final class NordLight implements Theme {
         return "/atlantafx/base/theme/nord-light.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/nord-light.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/PrimerDark.java

@@ -27,6 +27,14 @@ public final class PrimerDark implements Theme {
         return "/atlantafx/base/theme/primer-dark.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/primer-dark.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/PrimerLight.java

@@ -27,6 +27,14 @@ public final class PrimerLight implements Theme {
         return "/atlantafx/base/theme/primer-light.css";
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String getUserAgentStylesheetBSS() {
+        return "/atlantafx/base/theme/primer-light.bss";
+    }
+
     /**
      * {@inheritDoc}
      */

base/src/main/java/atlantafx/base/theme/Theme.java

@@ -6,6 +6,7 @@ import static javafx.application.Application.STYLESHEET_CASPIAN;
 import static javafx.application.Application.STYLESHEET_MODENA;
 
 import javafx.application.Application;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Basic theme interface.
@@ -23,6 +24,14 @@ public interface Theme {
      */
     String getUserAgentStylesheet();
 
+    /**
+     * Returns the path to the theme user-agent stylesheet in binary
+     * (BSS) format. See {@link Application#setUserAgentStylesheet(String)} for more info.
+     * All built-in themes are available in BSS format, but custom themes may not,
+     * hence the method may return null value.
+     */
+    @Nullable String getUserAgentStylesheetBSS();
+
     /**
      * Signifies whether the theme uses a light font on a dark background
      * or vise versa.
@@ -52,6 +61,11 @@ public interface Theme {
                 return userAgentStylesheet;
             }
 
+            @Override
+            public @Nullable String getUserAgentStylesheetBSS() {
+                return null;
+            }
+
             @Override
             public boolean isDarkMode() {
                 return darkMode;

base/src/main/java/atlantafx/base/theme/ThemeCompiler.java

@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: MIT */
+
+package atlantafx.base.theme;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.stream.Stream;
+import javafx.css.Stylesheet;
+
+/**
+ * Lazy man CSS to BSS compiler wrapper.
+ */
+public class ThemeCompiler {
+
+    public static void main(String[] args) {
+        try {
+            if (args.length < 1) {
+                throw new IllegalArgumentException("You must provide the source directory path");
+            }
+
+            if (args.length > 1) {
+                throw new IllegalArgumentException(
+                    "Unexpected arguments were found: "
+                        + Arrays.toString(Arrays.copyOfRange(args, 1, args.length))
+                );
+            }
+
+            var dir = Paths.get(args[0]);
+            new ThemeCompiler().convertToBinary(dir);
+        } catch (IOException e) {
+            throw new RuntimeException(e.getMessage(), e);
+        }
+    }
+
+    /**
+     * Converts all CSS files in the specified directory to BSS.
+     *
+     * @param dir the source directory to scan for CSS files
+     * @throws IOException to punish you for using Java
+     */
+    public void convertToBinary(Path dir) throws IOException {
+        if (dir == null || !Files.exists(dir) || !Files.isDirectory(dir)) {
+            throw new IllegalArgumentException("Invalid directory: " + dir);
+        }
+
+        try (Stream<Path> stream = Files.list(dir)) {
+            stream.filter(f -> f.toString().endsWith(".css"))
+                .forEach(f -> {
+                    try {
+                        convertToBinary(f, f.resolveSibling(getFilename(f) + ".bss"));
+                    } catch (IOException e) {
+                        throw new RuntimeException(e);
+                    }
+                });
+        }
+    }
+
+    /**
+     * Converts the specified CSS file to BSS. If no output file is given,
+     * then the input file name is used with an extension of 'bss'.
+     *
+     * @param in  input file path
+     * @param out output file path
+     * @throws IOException to punish you for using Java
+     */
+    public void convertToBinary(Path in, Path out) throws IOException {
+        if (in == null || out == null) {
+            throw new IllegalArgumentException("Both input and output files must be specified.");
+        }
+
+        if (in.equals(out)) {
+            throw new IllegalArgumentException("Input file and output file cannot be the same.");
+        }
+
+        Stylesheet.convertToBinary(in.toFile(), out.toFile());
+    }
+
+    private String getFilename(Path f) {
+        String name = f.getFileName().toString();
+        return name.substring(0, name.lastIndexOf('.'));
+    }
+}

sampler/src/main/java/atlantafx/sampler/theme/SamplerTheme.java

@@ -30,6 +30,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import javafx.application.Application;
 import javafx.scene.Scene;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * The {@link Theme} decorator to work around some JavaFX CSS limitations.
@@ -87,6 +88,11 @@ public final class SamplerTheme implements Theme {
         return IS_DEV_MODE ? DUMMY_STYLESHEET : getResource().toURI().toString();
     }
 
+    @Override
+    public @Nullable String getUserAgentStylesheetBSS() {
+        return theme.getUserAgentStylesheetBSS();
+    }
+
     @Override
     public boolean isDarkMode() {
         return theme.isDarkMode();