修复 KDE Wayland 下 HMCL 不跟随缩放的问题 (#6736)

Co-authored-by: Glavo <zjx001202@gmail.com>

Author: olivezane

HMCL/src/main/java/org/jackhuang/hmcl/Launcher.java

@@ -57,8 +57,10 @@
 import javax.swing.*;
 import java.awt.*;
 import java.awt.datatransfer.StringSelection;
+import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
+import java.io.InputStreamReader;
 import java.lang.management.ManagementFactory;
 import java.lang.management.MemoryPoolMXBean;
 import java.net.CookieHandler;
@@ -68,16 +70,19 @@
 import java.nio.file.Paths;
 import java.text.DecimalFormat;
 import java.util.ArrayList;
+import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Stream;
 
 import static org.jackhuang.hmcl.setting.SettingsManager.settings;
 import static org.jackhuang.hmcl.ui.FXUtils.runInFX;
 import static org.jackhuang.hmcl.util.DataSizeUnit.MEGABYTES;
 import static org.jackhuang.hmcl.util.i18n.I18n.i18n;
 import static org.jackhuang.hmcl.util.logging.Logger.LOG;
 
+/// The main JavaFX application entry point.
 public final class Launcher extends Application {
     public static final CookieManager COOKIE_MANAGER = new CookieManager();
 
@@ -396,6 +401,8 @@ private static void setupWindowsAppUserModelID() {
         }
     }
 
+    /// Sets JavaFX VM options before the toolkit starts.
+    /// On Wayland, the UI scale is auto-detected when the user did not configure one explicitly.
     private static void setupJavaFXVMOptions() {
         if ("true".equalsIgnoreCase(System.getenv("HMCL_FORCE_GPU"))) {
             LOG.info("HMCL_FORCE_GPU: true");
@@ -451,47 +458,85 @@ private static void setupJavaFXVMOptions() {
             }
         }
 
+        float uiScaleLowerBound;
+        float uiScaleUpperBound;
+
+        if (OperatingSystem.CURRENT_OS == OperatingSystem.WINDOWS) {
+            // JavaFX behavior may be abnormal when the DPI scaling factor is too high
+            uiScaleLowerBound = 0.25f;
+            uiScaleUpperBound = 4f;
+        } else {
+            uiScaleLowerBound = 0.01f;
+            uiScaleUpperBound = 10f;
+        }
+
         String uiScale = System.getProperty("hmcl.uiScale", System.getenv("HMCL_UI_SCALE"));
-        if (uiScale != null) {
-            uiScale = uiScale.trim();
 
+        float scaleValue = Float.NaN;
+        if (uiScale != null && !(uiScale = uiScale.trim()).isEmpty()) {
             LOG.info("HMCL_UI_SCALE: " + uiScale);
 
             try {
-                float scaleValue;
                 if (uiScale.endsWith("%")) {
                     scaleValue = Integer.parseInt(uiScale.substring(0, uiScale.length() - 1)) / 100.0f;
                 } else if (uiScale.endsWith("dpi") || uiScale.endsWith("DPI")) {
                     scaleValue = Integer.parseInt(uiScale.substring(0, uiScale.length() - 3)) / 96.0f;
                 } else {
                     scaleValue = Float.parseFloat(uiScale);
                 }
+            } catch (Throwable e) {
+                LOG.warning("Invalid UI scale: " + uiScale);
+            }
+        } else if (OperatingSystem.CURRENT_OS.isLinuxOrBSD()) {
+            String xdgSessionType = Objects.requireNonNullElse(System.getenv("XDG_SESSION_TYPE"), "");
+            String xdgCurrentDesktop = Objects.requireNonNullElse(System.getenv("XDG_CURRENT_DESKTOP"), "");
 
-                float lowerBound;
-                float upperBound;
+            if ("wayland".equals(xdgSessionType)
+                    && StringUtils.startsWithIgnoreCase(xdgCurrentDesktop, "KDE")) {
+                try {
+                    @Nullable Path xrdb = SystemUtils.which("xrdb");
+                    @Nullable String xftDpi = xrdb != null ? SystemUtils.run(List.of(FileUtils.getAbsolutePath(xrdb), "-query"), inputStream -> {
+                        @Nullable String dpiLine;
+
+                        try (var reader = new InputStreamReader(inputStream, OperatingSystem.NATIVE_CHARSET);
+                             BufferedReader bufferedReader = new BufferedReader(reader);
+                             Stream<String> lines = bufferedReader.lines()) {
+                            dpiLine = lines.filter(line -> line.trim().startsWith("Xft.dpi:"))
+                                    .findFirst().orElse(null);
+                        }
 
-                if (OperatingSystem.CURRENT_OS == OperatingSystem.WINDOWS) {
-                    // JavaFX behavior may be abnormal when the DPI scaling factor is too high
-                    lowerBound = 0.25f;
-                    upperBound = 4f;
-                } else {
-                    lowerBound = 0.01f;
-                    upperBound = 10f;
-                }
+                        return dpiLine != null
+                                ? dpiLine.substring("Xft.dpi:".length()).trim()
+                                : null;
+                    }, java.time.Duration.ofSeconds(1)) : null;
+
+                    if (xftDpi != null) {
+                        float dpiValue = Float.parseFloat(xftDpi);
+                        float scale = dpiValue / 96f;
 
-                if (scaleValue >= lowerBound && scaleValue <= upperBound) {
-                    if (OperatingSystem.CURRENT_OS == OperatingSystem.WINDOWS) {
-                        System.getProperties().putIfAbsent("glass.win.uiScale", uiScale);
-                    } else if (OperatingSystem.CURRENT_OS == OperatingSystem.MACOS) {
-                        LOG.warning("macOS does not support setting UI scale, so it will be ignored");
-                    } else {
-                        System.getProperties().putIfAbsent("glass.gtk.uiScale", uiScale);
+                        if (scale > 1 && scale <= 10) {
+                            LOG.info("Detected Xft.dpi: %s (%.1fx)".formatted(dpiValue, scale));
+                            scaleValue = scale;
+                            uiScale = Float.toString(scale);
+                        }
                     }
+                } catch (Exception e) {
+                    LOG.warning("Failed to read Xft.dpi from xrdb", e);
+                }
+            }
+        }
+
+        if (Float.isFinite(scaleValue)) {
+            if (scaleValue >= uiScaleLowerBound && scaleValue <= uiScaleUpperBound) {
+                if (OperatingSystem.CURRENT_OS == OperatingSystem.WINDOWS) {
+                    System.getProperties().putIfAbsent("glass.win.uiScale", uiScale);
+                } else if (OperatingSystem.CURRENT_OS == OperatingSystem.MACOS) {
+                    LOG.warning("macOS does not support setting UI scale, so it will be ignored");
                 } else {
-                    LOG.warning("UI scale out of range: " + uiScale);
+                    System.getProperties().putIfAbsent("glass.gtk.uiScale", uiScale);
                 }
-            } catch (Throwable e) {
-                LOG.warning("Invalid UI scale: " + uiScale);
+            } else {
+                LOG.warning("UI scale out of range: " + uiScale);
             }
         }
     }

HMCLCore/src/main/java/org/jackhuang/hmcl/util/StringUtils.java

@@ -280,6 +280,10 @@ public static boolean endsWithAny(String str, Collection<String> suffixes) {
         return suffixes.stream().anyMatch(str::endsWith);
     }
 
+    public static boolean startsWithIgnoreCase(String str, String prefix) {
+        return str.regionMatches(true, 0, prefix, 0, prefix.length());
+    }
+
     public static Predicate<@Nullable String> compileQuery(String queryString) throws PatternSyntaxException {
         Predicate<@Nullable String> predicate;
         if (queryString.startsWith("regex:")) {