Expose display mode bit depth in DisplayInfo (#2871)

jme3-core/src/main/java/com/jme3/system/DisplayInfo.java

@@ -34,8 +34,7 @@
 import java.util.Objects;
 
 /**
- * This class holds information about the display that was returned by glfwGetMonitors() calls in
- * the context class
+ * Information about a display and its current display mode.
  *
  * @author Kevin Bales
  * @author wil
@@ -54,6 +53,9 @@ public final class DisplayInfo {
     /** rate - refresh rate that was return from Lwjgl3. */
     private int rate;
 
+    /** Pixel format depth of the current display mode, in bits per pixel. */
+    private int bitDepth;
+
     /** primary - indicates if the display is the primary monitor. */
     private boolean primary;
 
@@ -63,7 +65,7 @@ public final class DisplayInfo {
     private String name;
 
     /**
-     * Create a new display mode object with the default values
+     * Create a new display info object with the default values
      */
     DisplayInfo() {
         this(0L /*NULL*/, 1080, 1920, 60, false, "Generic Monitor");
@@ -127,6 +129,15 @@ void setRate(int rate) {
         this.rate = rate;
     }
 
+    /**
+     * Sets the pixel format depth of the current display mode, in bits per pixel.
+     *
+     * @param bitDepth the number of bits per pixel, or 0 if unavailable
+     */
+    void setBitDepth(int bitDepth) {
+        this.bitDepth = bitDepth;
+    }
+
     /**
      * Set this display as primary or not.
      * @param primary {@code true} if the display is primary, {@code false} otherwise.
@@ -179,6 +190,17 @@ public int getRate() {
         return rate;
     }
 
+    /**
+     * Returns the current display mode's pixel format size in bits per pixel.
+     * This does not describe depth or stencil buffers. A value of 0 means that the
+     * backend could not report a single bit depth.
+     *
+     * @return the number of bits per pixel, or 0 if unavailable
+     */
+    public int getBitDepth() {
+        return bitDepth;
+    }
+
     /**
      * Determines if this display belongs to the main monitor.
      * @return {@code true} if the display is primary, {@code false} otherwise.
@@ -205,6 +227,7 @@ public int hashCode() {
         hash = 97 * hash + this.width;
         hash = 97 * hash + this.height;
         hash = 97 * hash + this.rate;
+        hash = 97 * hash + this.bitDepth;
         hash = 97 * hash + (this.primary ? 1 : 0);
         hash = 97 * hash + Objects.hashCode(this.name);
         return hash;
@@ -237,6 +260,9 @@ public boolean equals(Object obj) {
         if (this.rate != other.rate) {
             return false;
         }
+        if (this.bitDepth != other.bitDepth) {
+            return false;
+        }
         if (this.primary != other.primary) {
             return false;
         }

jme3-core/src/main/java/com/jme3/system/Displays.java

@@ -28,8 +28,7 @@
 import java.util.ArrayList;
 
 /**
- * This class holds all information about all displays that where return from the glfwGetMonitors()
- * call. It stores them into an ArrayList
+ * Holds information about the displays detected by the active desktop context.
  *
  * @author Kevin Bales
  */
@@ -74,6 +73,7 @@ public DisplayInfo get(int pos) {
 
     /**
      * Set information about this display stored in displayPos display in the array list.
+     * The bit depth is set to 0 (unavailable) when using this overload.
      *
      * @param displayPos ArrayList position of display to update
      * @param name name of the display
@@ -82,12 +82,28 @@ public DisplayInfo get(int pos) {
      * @param rate the current refresh rate the display is set to
      */
     public void setInfo(int displayPos, String name, int width, int height, int rate) {
+        setInfo(displayPos, name, width, height, rate, 0);
+    }
+
+    /**
+     * Set information about this display stored in displayPos display in the array list.
+     *
+     * @param displayPos ArrayList position of display to update
+     * @param name name of the display
+     * @param width the current width the display is displaying
+     * @param height the current height the display is displaying
+     * @param rate the current refresh rate the display is set to
+     * @param bitDepth the current display mode's pixel format size in bits per pixel,
+     * or 0 if unavailable
+     */
+    public void setInfo(int displayPos, String name, int width, int height, int rate, int bitDepth) {
         if (displayPos < displays.size()) {
             DisplayInfo info = displays.get(displayPos);
             if (info != null) {
                 info.setWidth(width);
                 info.setHeight(height);
                 info.setRate(rate);
+                info.setBitDepth(bitDepth);
                 info.setName(name);
             }
         }

jme3-core/src/test/java/com/jme3/system/DisplayInfoTest.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2026 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without
+ *   specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.jme3.system;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+class DisplayInfoTest {
+
+    @Test
+    void reportsCurrentDisplayModeBitDepth() {
+        Displays displays = new Displays();
+        int displayIndex = displays.addNewMonitor(1L);
+
+        displays.setInfo(displayIndex, "Test display", 1920, 1080, 60, 32);
+
+        assertEquals(32, displays.get(displayIndex).getBitDepth());
+    }
+
+    @Test
+    void legacySetInfoLeavesBitDepthUnavailable() {
+        Displays displays = new Displays();
+        int displayIndex = displays.addNewMonitor(1L);
+
+        displays.setInfo(displayIndex, "Test display", 1920, 1080, 60);
+
+        assertEquals(0, displays.get(displayIndex).getBitDepth());
+    }
+
+    @Test
+    void bitDepthIsPartOfDisplayInfoEquality() {
+        Displays first = new Displays();
+        int firstIndex = first.addNewMonitor(1L);
+        first.setInfo(firstIndex, "Test display", 1920, 1080, 60, 24);
+
+        Displays second = new Displays();
+        int secondIndex = second.addNewMonitor(1L);
+        second.setInfo(secondIndex, "Test display", 1920, 1080, 60, 32);
+
+        assertNotEquals(first.get(firstIndex), second.get(secondIndex));
+    }
+}

jme3-lwjgl3/src/main/java/com/jme3/system/lwjgl/LwjglCanvas.java

@@ -1027,9 +1027,10 @@ public Displays getDisplays() {
             int width  = mode.getWidth();
             int height = mode.getHeight();
             int rate   = mode.getRefreshRate();
+            int bitDepth = Math.max(0, mode.getBitDepth());
 
             displays.addNewMonitor(i + 1);
-            displays.setInfo(i, gd.getIDstring(), width, height, rate);
+            displays.setInfo(i, gd.getIDstring(), width, height, rate, bitDepth);
 
             if (defaultgd.equals(gd)) {
                 displays.setPrimaryDisplay(i);

jme3-lwjgl3/src/main/java/com/jme3/system/lwjgl/LwjglWindow.java

@@ -1436,7 +1436,8 @@ public Displays getDisplays() {
                 int width = mode != null ? mode.w() : 0;
                 int height = mode != null ? mode.h() : 0;
                 int rate = mode != null ? Math.round(mode.refresh_rate()) : 0;
-                displayList.setInfo(monPos, name, width, height, rate);
+                int bitDepth = mode != null ? SDL_BITSPERPIXEL(mode.format()) : 0;
+                displayList.setInfo(monPos, name, width, height, rate, bitDepth);
 
                 LOGGER.log(Level.INFO, "Display id: {0} Resolution: {1} x {2} @ {3}",
                         new Object[]{displayId, width, height, rate});