From 9b72616c80a5195b7fd666c1a78c46478be3b346 Mon Sep 17 00:00:00 2001
From: asvitkine <alexei.svitkine@gmail.com>
Date: Sat, 30 Sep 2023 12:25:22 -0400
Subject: [PATCH] Mac: Add support for zooming map via touchpad pinch. (#12002)

* Mac: Add support for zooming map via touchpad pinch.

* Share some code.
---
 .idea/runConfigurations/HeadedGameRunner.xml  |  2 +-
 .../strategy/ui/ImageScrollerLargeView.java   | 21 ++++---
 game-app/game-headed/build.install4j          |  1 +
 .../org/triplea/swing/gestures/Gestures.java  | 58 +++++++++++++++++++
 .../swing/gestures/MagnificationListener.java | 12 ++++
 5 files changed, 86 insertions(+), 8 deletions(-)
 create mode 100644 lib/swing-lib/src/main/java/org/triplea/swing/gestures/Gestures.java
 create mode 100644 lib/swing-lib/src/main/java/org/triplea/swing/gestures/MagnificationListener.java

diff --git a/.idea/runConfigurations/HeadedGameRunner.xml b/.idea/runConfigurations/HeadedGameRunner.xml
index 485a11c4bce..bfd9b312698 100644
--- a/.idea/runConfigurations/HeadedGameRunner.xml
+++ b/.idea/runConfigurations/HeadedGameRunner.xml
@@ -2,7 +2,7 @@
   <configuration default="false" name="HeadedGameRunner" type="Application" factoryName="Application" singleton="false" nameIsGenerated="true">
     <option name="MAIN_CLASS_NAME" value="org.triplea.game.client.HeadedGameRunner" />
     <module name="triplea.game-app.game-headed.main" />
-    <option name="VM_PARAMETERS" value="-Xss1250K -Dsun.java2d.uiScale.enabled=false" />
+    <option name="VM_PARAMETERS" value="-Xss1250K -Dsun.java2d.uiScale.enabled=false --add-opens java.desktop/com.apple.eawt.event=ALL-UNNAMED" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/game-app/game-headed" />
     <extension name="coverage">
       <pattern>
diff --git a/game-app/game-core/src/main/java/games/strategy/ui/ImageScrollerLargeView.java b/game-app/game-core/src/main/java/games/strategy/ui/ImageScrollerLargeView.java
index dbefce66da0..7a5eae67b5f 100644
--- a/game-app/game-core/src/main/java/games/strategy/ui/ImageScrollerLargeView.java
+++ b/game-app/game-core/src/main/java/games/strategy/ui/ImageScrollerLargeView.java
@@ -22,6 +22,7 @@
 import javax.swing.JOptionPane;
 import javax.swing.SwingUtilities;
 import javax.swing.Timer;
+import org.triplea.swing.gestures.Gestures;
 
 /**
  * A large image that can be scrolled according to a ImageScrollModel. Generally used in conjunction
@@ -96,14 +97,8 @@ public ImageScrollerLargeView(final Dimension dimension, final ImageScrollModel
     final MouseWheelListener mouseWheelListener =
         e -> {
           if (e.isControlDown()) {
-            final int oldWidth = model.getBoxWidth();
-            final int oldHeight = model.getBoxHeight();
             final float zoomFactor = ClientSetting.mapZoomFactor.getValueOrThrow() / 100f;
-            setScale(scale - zoomFactor * e.getPreciseWheelRotation());
-            final Point mouse = getMousePosition();
-            final int dx = (int) (mouse.getX() / getWidth() * (oldWidth - model.getBoxWidth()));
-            final int dy = (int) (mouse.getY() / getHeight() * (oldHeight - model.getBoxHeight()));
-            model.set(model.getX() + dx, model.getY() + dy);
+            setScaleViaMouseZoom(scale - zoomFactor * e.getPreciseWheelRotation());
           } else {
             if (edge == NONE) {
               insideCount = 0;
@@ -223,6 +218,8 @@ public void componentResized(final ComponentEvent e) {
           repaint();
           notifyScollListeners();
         });
+    Gestures.registerMagnificationListener(
+        this, (double factor) -> setScaleViaMouseZoom(scale * factor));
   }
 
   public boolean wasLastActionDraggingAndReset() {
@@ -309,6 +306,16 @@ public void setScale(final double value) {
     refreshBoxSize();
   }
 
+  private void setScaleViaMouseZoom(double newScale) {
+    final int oldWidth = model.getBoxWidth();
+    final int oldHeight = model.getBoxHeight();
+    setScale(newScale);
+    final Point mouse = getMousePosition();
+    final int dx = (int) (mouse.getX() / getWidth() * (oldWidth - model.getBoxWidth()));
+    final int dy = (int) (mouse.getY() / getHeight() * (oldHeight - model.getBoxHeight()));
+    model.set(model.getX() + dx, model.getY() + dy);
+  }
+
   public double getMinScale() {
     final double minScale =
         scale
diff --git a/game-app/game-headed/build.install4j b/game-app/game-headed/build.install4j
index 2d4253c283e..82152eb4502 100644
--- a/game-app/game-headed/build.install4j
+++ b/game-app/game-headed/build.install4j
@@ -296,6 +296,7 @@ return Math.min(is32BitJavaRuntime ? 1024L : 2048L, halfMemoryMiB);</property>
                     <element index="0">-Xmx${installer:heapSizeMiB}M</element>
                     <element index="1">-Xms${installer:heapSizeMiB}M</element>
                     <element index="2">-Xss1250K</element>
+                    <element index="3">--add-opens java.desktop/com.apple.eawt.event=ALL-UNNAMED</element>
                   </property>
                 </serializedBean>
               </action>
diff --git a/lib/swing-lib/src/main/java/org/triplea/swing/gestures/Gestures.java b/lib/swing-lib/src/main/java/org/triplea/swing/gestures/Gestures.java
new file mode 100644
index 00000000000..90752d7ba36
--- /dev/null
+++ b/lib/swing-lib/src/main/java/org/triplea/swing/gestures/Gestures.java
@@ -0,0 +1,58 @@
+package org.triplea.swing.gestures;
+
+import games.strategy.engine.framework.system.SystemProperties;
+import java.lang.reflect.Proxy;
+import javax.swing.JComponent;
+
+/**
+ * Provides support for platform-specific gestures. Currently, supports only the magnification
+ * gestures on Mac (e.g. pinch to zoom using the trackpad).
+ *
+ * <p>Since there is no cross-platform API in Swing for this, it relies on Mac-specific
+ * com.apple.eawt classes for the support, which are loaded via reflection in order for the code to
+ * compile on all platforms.
+ *
+ * <p>This implementation is based on the following sources:
+ * https://stackoverflow.com/questions/69221217/multi-touch-gestures-in-java-swing-awt-and-java-17
+ * https://gist.github.com/alanwhite/42502f20390baf879d093691ebb72066
+ *
+ * <p>Note: This functionality requires passing the following args to java when running the app:
+ * --add-opens java.desktop/com.apple.eawt.event=ALL-UNNAMED
+ */
+public class Gestures {
+  @SuppressWarnings({"rawtypes"})
+  public static void registerMagnificationListener(JComponent c, MagnificationListener listener) {
+    // The current implementation only supports Mac.
+    if (!SystemProperties.isMac()) {
+      return;
+    }
+    // Wrapped in a try, as this may fail if the specific classes or their methods are not found.
+    try {
+      Class listenerClass = Class.forName("com.apple.eawt.event.MagnificationListener");
+      Object listenerProxy =
+          Proxy.newProxyInstance(
+              listenerClass.getClassLoader(),
+              new Class[] {listenerClass},
+              (proxy, method, args) -> {
+                if (method.getName().equals("magnify")) {
+                  try {
+                    Object mag = args[0].getClass().getMethod("getMagnification").invoke(args[0]);
+                    listener.magnify(1 + (double) mag);
+                  } catch (Exception e) {
+                    e.printStackTrace();
+                  }
+                }
+                return null;
+              });
+
+      Class.forName("com.apple.eawt.event.GestureUtilities")
+          .getMethod(
+              "addGestureListenerTo",
+              Class.forName("javax.swing.JComponent"),
+              Class.forName("com.apple.eawt.event.GestureListener"))
+          .invoke(null, c, listenerProxy);
+    } catch (Exception e) {
+      e.printStackTrace();
+    }
+  }
+}
diff --git a/lib/swing-lib/src/main/java/org/triplea/swing/gestures/MagnificationListener.java b/lib/swing-lib/src/main/java/org/triplea/swing/gestures/MagnificationListener.java
new file mode 100644
index 00000000000..8c76cdb2c89
--- /dev/null
+++ b/lib/swing-lib/src/main/java/org/triplea/swing/gestures/MagnificationListener.java
@@ -0,0 +1,12 @@
+package org.triplea.swing.gestures;
+
+/** Listener for magnification events (e.g. pinch gesture with a trackpad). */
+public interface MagnificationListener {
+  /**
+   * Called when a magnification event occurred.
+   *
+   * @param factor The magnification multiplier to apply over the current zoom level (e.g. 1 = no
+   *     change, 2 = double the zoom, etc).
+   */
+  void magnify(double factor);
+}