* Add LibgdxFrameConverter to convert Frame to Libgdx Pixmap (pull #2315)

Author: shan-luan

CHANGELOG.md

@@ -1,4 +1,5 @@
 
+ * Add `LibgdxFrameConverter` to convert `Frame` to Libgdx `Pixmap` ([pull #2315](https://github.com/bytedeco/javacv/pull/2315))
  * Fix `FFmpegFrameRecorder` dropped frame issues with audio samples ([pull #2307](https://github.com/bytedeco/javacv/pull/2307))
  * Add `FrameFilter.videoFilterArgs/audioFilterArgs` properties to support multiple different inputs ([pull #2304](https://github.com/bytedeco/javacv/pull/2304))
  * Ensure `FFmpegFrameGrabber.start()` skips over streams with no codecs ([issue #2299](https://github.com/bytedeco/javacv/issues/2299))

pom.xml

@@ -169,6 +169,13 @@
       <version>2.3.2</version>
       <optional>true</optional>
     </dependency>
+
+    <dependency>
+      <groupId>com.badlogicgames.gdx</groupId>
+      <artifactId>gdx</artifactId>
+      <version>1.13.1</version>
+      <optional>true</optional>
+    </dependency>
   </dependencies>
 
   <repositories>

src/main/java/org/bytedeco/javacv/LibgdxFrameConverter.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2025 shan-luan
+ *
+ * Licensed either under the Apache License, Version 2.0, or (at your option)
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (subject to the "Classpath" exception),
+ * either version 2, or any later version (collectively, the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *     http://www.gnu.org/licenses/
+ *     http://www.gnu.org/software/classpath/license.html
+ *
+ * or as provided in the LICENSE.txt file that accompanied this code.
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.bytedeco.javacv;
+
+import com.badlogic.gdx.graphics.Pixmap;
+
+import java.nio.ByteBuffer;
+
+/**
+ * A utility class for converting between {@link Pixmap} and {@link Frame}.
+ * The alpha channel is not converted and memory cannot be shared.
+ *
+ * @author shan-luan
+ */
+public class LibgdxFrameConverter extends FrameConverter<Pixmap> {
+    /**
+     * Converts a {@link Pixmap} to a {@link Frame}.
+     *
+     * @param pixmap the Pixmap to convert,RGBA8888 format
+     * @return the converted Frame
+     */
+    @Override
+    public Frame convert(Pixmap pixmap) {
+        if (pixmap == null) return null;
+
+        Frame frame = new Frame(pixmap.getWidth(), pixmap.getHeight(), Frame.DEPTH_UBYTE, 3, pixmap.getWidth() * 3);
+
+        ByteBuffer pixmapBuffer = pixmap.getPixels().duplicate();
+        ByteBuffer frameBuffer = (ByteBuffer) frame.image[0];
+
+        int numPixels = pixmap.getWidth() * pixmap.getHeight();
+        for (int i = 0; i < numPixels; i++) {
+            byte r = pixmapBuffer.get();
+            byte g = pixmapBuffer.get();
+            byte b = pixmapBuffer.get();
+            pixmapBuffer.position(pixmapBuffer.position() + 1);
+
+            frameBuffer.put(b);
+            frameBuffer.put(g);
+            frameBuffer.put(r);
+        }
+
+        frameBuffer.flip();
+        return frame;
+    }
+
+    /**
+     * Converts a {@link Frame} to a {@link Pixmap}.
+     *
+     * @param frame the Frame to convert
+     * @return the converted Pixmap, RGBA8888 format
+     */
+    @Override
+    public Pixmap convert(Frame frame) {
+        if (frame == null || frame.image[0] == null) return null;
+        Pixmap pixmap = new Pixmap(frame.imageWidth, frame.imageHeight, Pixmap.Format.RGBA8888);
+        ByteBuffer frameBuffer = ((ByteBuffer) frame.image[0]).duplicate();
+        ByteBuffer pixmapBuffer = pixmap.getPixels();
+        pixmapBuffer.position(0);
+        frameBuffer.rewind();
+
+        int numPixels = frame.imageWidth * frame.imageHeight;
+        for (int i = 0; i < numPixels; i++) {
+            byte b = frameBuffer.get();
+            byte g = frameBuffer.get();
+            byte r = frameBuffer.get();
+
+            pixmapBuffer.put(r);
+            pixmapBuffer.put(g);
+            pixmapBuffer.put(b);
+            pixmapBuffer.put((byte) -1);// alpha always set to 255
+        }
+
+        pixmapBuffer.flip();
+        return pixmap;
+    }
+
+    /**
+     * Converts a {@link Frame} to a {@link Pixmap}.
+     * Available only when the format of the Frame is {@link org.bytedeco.ffmpeg.global.avutil
+     * #AV_PIX_FMT_RGBA}.
+     * Faster than {@link #convert(Frame)}
+     *
+     * @param frame the Frame to convert
+     * @return the converted Pixmap, RGBA8888 format
+     */
+    public Pixmap fastConvert(Frame frame) {
+        if (frame == null || frame.image[0] == null) return null;
+
+        Pixmap pixmap = new Pixmap(frame.imageWidth, frame.imageHeight, Pixmap.Format.RGBA8888);
+        ByteBuffer frameBuffer = ((ByteBuffer) frame.image[0]).duplicate();
+        ByteBuffer pixmapBuffer = pixmap.getPixels();
+        pixmapBuffer.position(0);
+        frameBuffer.rewind();
+        pixmapBuffer.put(frameBuffer);
+        pixmapBuffer.flip();
+        return pixmap;
+    }
+}