X11: keep colour game cursors by implementing the RENDER cursor subset

app/src/main/runtime/display/XServerDisplayActivity.java

@@ -2713,6 +2713,7 @@ this, shortcut, isCloudSyncEnabledForShortcut(),
                         extractGraphicsDriverFiles();
                         resolveAudioDriver();
                         changeWineAudioDriver();
+                        applyColorCursorRegistry();
 
                         try {
                             if (steamFuture != null) steamFuture.get();
@@ -8306,6 +8307,8 @@ private void setupXEnvironment() throws PackageManager.NameNotFoundException {
             overrideEnvVars.clear();
         }
 
+        applyColorCursors();
+
         environment = new XEnvironment(this, imageFs);
         environment.addComponent(
                 new SysVSharedMemoryComponent(
@@ -14118,6 +14121,24 @@ private void resolveAudioDriver() {
                 this, R.string.directaudio_unavailable, android.widget.Toast.LENGTH_LONG).show());
     }
 
+    private void applyColorCursors() {
+        if (waylandMode || gamescopeMode) return;
+        String toggle = envVars.get("BANNER_X11_RENDER");
+        if (toggle != null && (toggle.equals("0") || toggle.equalsIgnoreCase("false"))) return;
+        xServer.enableRenderCursors();
+    }
+
+    private void applyColorCursorRegistry() {
+        if (waylandMode) return;
+        File userRegFile = new File(imageFs.getRootDir(), ImageFs.WINEPREFIX + "/user.reg");
+        if (!userRegFile.exists()) return;
+        try (WineRegistryEditor registryEditor = new WineRegistryEditor(userRegFile)) {
+            registryEditor.setStringValue("Software\\Wine\\X11 Driver", "ClientSideWithRender", "N");
+        } catch (Exception e) {
+            Log.w(TAG, "Failed to disable client-side RENDER", e);
+        }
+    }
+
     private void changeWineAudioDriver() {
         if (!audioDriver.equals(container.getExtra("audioDriver"))) {
             File rootDir = imageFs.getRootDir();

app/src/main/runtime/display/xserver/CursorManager.java

@@ -1,6 +1,8 @@
 package com.winlator.cmod.runtime.display.xserver;
 
 import android.util.SparseArray;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 import java.nio.IntBuffer;
 
 public class CursorManager extends XResourceManager {
@@ -36,6 +38,107 @@ public Cursor createCursor(int id, short x, short y, Pixmap sourcePixmap, Pixmap
     return cursor;
   }
 
+  private static final String[] FALLBACK_ARROW = {
+    "X          ",
+    "XX         ",
+    "X.X        ",
+    "X..X       ",
+    "X...X      ",
+    "X....X     ",
+    "X.....X    ",
+    "X......X   ",
+    "X.......X  ",
+    "X........X ",
+    "X.....XXXXX",
+    "X..X..X    ",
+    "X.X X..X   ",
+    "XX  X..X   ",
+    "X    X..X  ",
+    "     X..X  ",
+    "      XX   "
+  };
+
+  public Cursor createFallbackArrowCursor(int id) {
+    if (cursors.indexOfKey(id) >= 0) return null;
+    short width = (short) FALLBACK_ARROW[0].length();
+    short height = (short) FALLBACK_ARROW.length;
+    ByteBuffer pixels =
+        ByteBuffer.allocateDirect(width * height * 4).order(ByteOrder.LITTLE_ENDIAN);
+    IntBuffer data = pixels.asIntBuffer();
+    for (int y = 0; y < height; y++) {
+      for (int x = 0; x < width; x++) {
+        char c = FALLBACK_ARROW[y].charAt(x);
+        data.put(y * width + x, c == 'X' ? 0xff000000 : c == '.' ? 0xffffffff : 0);
+      }
+    }
+    return addArgbCursor(id, 0, 0, width, height, pixels);
+  }
+
+  /**
+   * libXcursor hands over premultiplied ARGB32 pixels, while cursor drawables are blended with
+   * straight alpha, so the alpha is divided back out here.
+   */
+  public Cursor createArgbCursor(
+      int id, int hotX, int hotY, short width, short height, ByteBuffer argb) {
+    if (cursors.indexOfKey(id) >= 0) return null;
+    if (width <= 0 || height <= 0 || argb.capacity() < width * height * 4) return null;
+
+    ByteBuffer pixels =
+        ByteBuffer.allocateDirect(width * height * 4).order(ByteOrder.LITTLE_ENDIAN);
+    IntBuffer src = argb.duplicate().order(ByteOrder.LITTLE_ENDIAN).asIntBuffer();
+    IntBuffer dst = pixels.asIntBuffer();
+    boolean visible = false;
+    for (int i = 0; i < width * height; i++) {
+      int pixel = src.get(i);
+      int alpha = pixel >>> 24;
+      if (alpha == 0) {
+        dst.put(i, 0);
+        continue;
+      }
+      visible = true;
+      dst.put(i, alpha == 0xff ? pixel : (alpha << 24) | unpremultiply(pixel, alpha));
+    }
+    Cursor cursor = addArgbCursor(id, hotX, hotY, width, height, pixels);
+    // A fully transparent cursor is how games hide the pointer, so it must not become an arrow.
+    cursor.setVisible(visible);
+    return cursor;
+  }
+
+  private static int unpremultiply(int pixel, int alpha) {
+    int red = Math.min(0xff, (((pixel >> 16) & 0xff) * 0xff + alpha - 1) / alpha);
+    int green = Math.min(0xff, (((pixel >> 8) & 0xff) * 0xff + alpha - 1) / alpha);
+    int blue = Math.min(0xff, ((pixel & 0xff) * 0xff + alpha - 1) / alpha);
+    return (red << 16) | (green << 8) | blue;
+  }
+
+  private Cursor addArgbCursor(
+      int id, int hotX, int hotY, short width, short height, ByteBuffer pixels) {
+    Drawable drawable =
+        drawableManager.createDrawable(IDGenerator.generate(), width, height, (byte) 32);
+    drawable.drawImage(
+        (short) 0,
+        (short) 0,
+        (short) 0,
+        (short) 0,
+        width,
+        height,
+        (byte) 32,
+        pixels,
+        width,
+        height);
+    Cursor cursor =
+        new Cursor(
+            id,
+            Math.max(0, Math.min(hotX, width - 1)),
+            Math.max(0, Math.min(hotY, height - 1)),
+            drawable,
+            null,
+            null);
+    cursors.put(id, cursor);
+    triggerOnCreateResourceListener(cursor);
+    return cursor;
+  }
+
   public void freeCursor(int id) {
     triggerOnFreeResourceListener(cursors.get(id));
     cursors.remove(id);

app/src/main/runtime/display/xserver/XServer.java

@@ -11,6 +11,7 @@
 import com.winlator.cmod.runtime.display.xserver.extensions.Extension;
 import com.winlator.cmod.runtime.display.xserver.extensions.MITSHMExtension;
 import com.winlator.cmod.runtime.display.xserver.extensions.PresentExtension;
+import com.winlator.cmod.runtime.display.xserver.extensions.RenderExtension;
 import com.winlator.cmod.runtime.display.xserver.extensions.SyncExtension;
 import com.winlator.cmod.runtime.display.xserver.extensions.XInput2Extension;
 import com.winlator.cmod.shared.android.CursorLocker;
@@ -392,6 +393,14 @@ private void registerExtension(Extension ext, int[] nextEventId, int[] nextError
     extensions.put(ext.getMajorOpcode(), ext);
   }
 
+  public void enableRenderCursors() {
+    extensions.put(RenderExtension.MAJOR_OPCODE, new RenderExtension(this));
+  }
+
+  public boolean isRenderCursorsEnabled() {
+    return extensions.get(RenderExtension.MAJOR_OPCODE) != null;
+  }
+
   private void setupExtensions() {
     int[] nextEventId = {64};
     int[] nextErrorId = {128};