Add possibility to read image to pre-created buffer, fixes #240

webcam-capture-drivers/driver-ffmpeg-cli/src/main/java/com/github/sarxos/webcam/ds/ffmpegcli/FFmpegCliDevice.java

@@ -138,6 +138,14 @@ public synchronized ByteBuffer getImageBytes() {
 		return ByteBuffer.wrap(readBytes());
 	}
 
+	@Override
+	public void getImageBytes(ByteBuffer buffer) {
+		if (!open.get()) {
+			return;
+		}
+		buffer.put(readBytes());
+	}
+
 	@Override
 	public BufferedImage getImage() {
 

webcam-capture/src/main/java/com/github/sarxos/webcam/Webcam.java

@@ -24,10 +24,10 @@
 import com.github.sarxos.webcam.ds.buildin.WebcamDefaultDriver;
 import com.github.sarxos.webcam.ds.cgt.WebcamCloseTask;
 import com.github.sarxos.webcam.ds.cgt.WebcamDisposeTask;
+import com.github.sarxos.webcam.ds.cgt.WebcamGetBufferTask;
+import com.github.sarxos.webcam.ds.cgt.WebcamGetImageTask;
 import com.github.sarxos.webcam.ds.cgt.WebcamOpenTask;
 import com.github.sarxos.webcam.ds.cgt.WebcamReadBufferTask;
-import com.github.sarxos.webcam.ds.cgt.WebcamReadImageTask;
-import com.github.sarxos.webcam.util.ImageUtils;
 
 
 /**
@@ -627,7 +627,7 @@ public BufferedImage getImage() {
 			// get image
 
 			t1 = System.currentTimeMillis();
-			BufferedImage image = transform(new WebcamReadImageTask(driver, device).getImage());
+			BufferedImage image = transform(new WebcamGetImageTask(driver, device).getImage());
 			t2 = System.currentTimeMillis();
 
 			if (image == null) {
@@ -694,14 +694,43 @@ public ByteBuffer getImageBytes() {
 		// buffers, just convert image to RGB byte array
 
 		if (device instanceof BufferAccess) {
-			return new WebcamReadBufferTask(driver, device).getBuffer();
+			return new WebcamGetBufferTask(driver, device).getBuffer();
 		} else {
-			BufferedImage image = getImage();
-			if (image != null) {
-				return ByteBuffer.wrap(ImageUtils.toRawByteArray(image));
-			} else {
-				return null;
-			}
+			throw new IllegalStateException(String.format("Driver %s does not support buffer access", driver.getClass().getName()));
+		}
+	}
+
+	/**
+	 * Get RAW image ByteBuffer. It will always return buffer with 3 x 1 bytes
+	 * per each pixel, where RGB components are on (0, 1, 2) and color space is
+	 * sRGB.<br>
+	 * <br>
+	 * 
+	 * <b>IMPORTANT!</b><br>
+	 * Some drivers can return direct ByteBuffer, so there is no guarantee that
+	 * underlying bytes will not be released in next read image operation.
+	 * Therefore, to avoid potential bugs you should convert this ByteBuffer to
+	 * bytes array before you fetch next image.
+	 * 
+	 * @return Byte buffer
+	 */
+	public void getImageBytes(ByteBuffer target) {
+
+		if (!isReady()) {
+			return;
+		}
+
+		assert driver != null;
+		assert device != null;
+
+		// some devices can support direct image buffers, and for those call
+		// processor task, and for those which does not support direct image
+		// buffers, just convert image to RGB byte array
+
+		if (device instanceof BufferAccess) {
+			new WebcamReadBufferTask(driver, device, target).readBuffer();
+		} else {
+			throw new IllegalStateException(String.format("Driver %s does not support buffer access", driver.getClass().getName()));
 		}
 	}
 

webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamDevice.java

@@ -22,13 +22,27 @@ public interface WebcamDevice {
 	public static interface BufferAccess {
 
 		/**
-		 * Get image in form of raw bytes. Do <b>not</b> use this buffer to set
-		 * bytes value, it should be used only for read purpose!
+		 * Read the underlying image memory buffer. This method will return new
+		 * reference to pre-allocated off-heap memory where image bytes are
+		 * stored. The size of this buffer is image width * height * 3 bytes.<br>
+		 * <br>
+		 * 
+		 * <b>NOTE!</b> Do <b>not</b> use this buffer to set bytes value. It
+		 * should be used only for read purpose!
 		 * 
 		 * @return Bytes buffer
 		 */
 		ByteBuffer getImageBytes();
 
+		/**
+		 * Copy the underlying image memory into the target buffer passed as the
+		 * argument.The remaining capacity of the target buffer needs to be at
+		 * least image width * height * 3 bytes.
+		 * 
+		 * @param target the buffer to which image data should be copied
+		 */
+		void getImageBytes(ByteBuffer target);
+
 	}
 
 	public static interface FPSSource {

webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamUpdater.java

@@ -13,7 +13,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.github.sarxos.webcam.ds.cgt.WebcamReadImageTask;
+import com.github.sarxos.webcam.ds.cgt.WebcamGetImageTask;
 
 
 /**
@@ -99,7 +99,7 @@ public void start() {
 
 		if (running.compareAndSet(false, true)) {
 
-			image.set(new WebcamReadImageTask(Webcam.getDriver(), webcam.getDevice()).getImage());
+			image.set(new WebcamGetImageTask(Webcam.getDriver(), webcam.getDevice()).getImage());
 
 			executor = Executors.newSingleThreadScheduledExecutor(THREAD_FACTORY);
 			executor.execute(this);
@@ -166,7 +166,7 @@ private void tick() {
 		BufferedImage img = null;
 
 		t1 = System.currentTimeMillis();
-		img = webcam.transform(new WebcamReadImageTask(driver, device).getImage());
+		img = webcam.transform(new WebcamGetImageTask(driver, device).getImage());
 		t2 = System.currentTimeMillis();
 
 		image.set(img);

webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/WebcamDefaultDevice.java

@@ -14,7 +14,6 @@
 import java.nio.ByteBuffer;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.concurrent.atomic.AtomicLong;
 
 import org.bridj.Pointer;
 import org.slf4j.Logger;
@@ -75,6 +74,7 @@ protected void handle() {
 
 			grabber.setTimeout(timeout);
 			result.set(grabber.nextFrame());
+			fresh.set(true);
 		}
 	}
 
@@ -119,9 +119,9 @@ protected void handle() {
 	private final AtomicBoolean open = new AtomicBoolean(false);
 
 	/**
-	 * When last frame was requested.
+	 * Is the last image fresh one.
 	 */
-	private final AtomicLong timestamp = new AtomicLong(-1);
+	private final AtomicBoolean fresh = new AtomicBoolean(false);
 
 	private Thread refresher = null;
 
@@ -132,6 +132,9 @@ protected void handle() {
 	private long t1 = -1;
 	private long t2 = -1;
 
+	/**
+	 * Current FPS.
+	 */
 	private volatile double fps = 0;
 
 	protected WebcamDefaultDevice(Device device) {
@@ -180,17 +183,24 @@ public ByteBuffer getImageBytes() {
 			LOG.debug("Webcam is disposed, image will be null");
 			return null;
 		}
-
 		if (!open.get()) {
 			LOG.debug("Webcam is closed, image will be null");
 			return null;
 		}
 
-		LOG.trace("Webcam device get image (next frame)");
+		// if image is not fresh, update it
+
+		if (fresh.compareAndSet(false, true)) {
+			updateFrameBuffer();
+		}
 
 		// get image buffer
 
+		LOG.trace("Webcam grabber get image pointer");
+
 		Pointer<Byte> image = grabber.getImage();
+		fresh.set(false);
+
 		if (image == null) {
 			LOG.warn("Null array pointer found instead of image");
 			return null;
@@ -203,6 +213,50 @@ public ByteBuffer getImageBytes() {
 		return image.getByteBuffer(length);
 	}
 
+	@Override
+	public void getImageBytes(ByteBuffer target) {
+
+		if (disposed.get()) {
+			LOG.debug("Webcam is disposed, image will be null");
+			return;
+		}
+		if (!open.get()) {
+			LOG.debug("Webcam is closed, image will be null");
+			return;
+		}
+
+		int minSize = size.width * size.height * 3;
+		int curSize = target.remaining();
+
+		if (minSize < curSize) {
+			throw new IllegalArgumentException(String.format("Not enough remaining space in target buffer (%d necessary vs %d remaining)", minSize, curSize));
+		}
+
+		// if image is not fresh, update it
+
+		if (fresh.compareAndSet(false, true)) {
+			updateFrameBuffer();
+		}
+
+		// get image buffer
+
+		LOG.trace("Webcam grabber get image pointer");
+
+		Pointer<Byte> image = grabber.getImage();
+		fresh.set(false);
+
+		if (image == null) {
+			LOG.warn("Null array pointer found instead of image");
+			return;
+		}
+
+		LOG.trace("Webcam device read buffer {} bytes", minSize);
+
+		image = image.validBytes(minSize);
+		image.getBytes(target);
+
+	}
+
 	@Override
 	public BufferedImage getImage() {
 
@@ -301,8 +355,6 @@ public void open() {
 
 		} while (++i < 3);
 
-		timestamp.set(System.currentTimeMillis());
-
 		LOG.debug("Webcam device {} is now open", this);
 
 		open.set(true);
@@ -370,11 +422,35 @@ public void setTimeout(int timeout) {
 		this.timeout = timeout;
 	}
 
+	/**
+	 * Update underlying memory buffer and fetch new frame.
+	 */
+	private void updateFrameBuffer() {
+
+		LOG.trace("Next frame");
+
+		if (t1 == -1 || t2 == -1) {
+			t1 = System.currentTimeMillis();
+			t2 = System.currentTimeMillis();
+		}
+
+		int result = new NextFrameTask(this).nextFrame();
+
+		t1 = t2;
+		t2 = System.currentTimeMillis();
+
+		fps = (4 * fps + 1000 / (t2 - t1 + 1)) / 5;
+
+		if (result == -1) {
+			LOG.error("Timeout when requesting image!");
+		} else if (result < -1) {
+			LOG.error("Error requesting new frame!");
+		}
+	}
+
 	@Override
 	public void run() {
 
-		int result = -1;
-
 		do {
 
 			if (Thread.interrupted()) {
@@ -387,27 +463,7 @@ public void run() {
 				return;
 			}
 
-			LOG.trace("Next frame");
-
-			if (t1 == -1 || t2 == -1) {
-				t1 = System.currentTimeMillis();
-				t2 = System.currentTimeMillis();
-			}
-
-			result = new NextFrameTask(this).nextFrame();
-
-			t1 = t2;
-			t2 = System.currentTimeMillis();
-
-			fps = (4 * fps + 1000 / (t2 - t1 + 1)) / 5;
-
-			if (result == -1) {
-				LOG.error("Timeout when requesting image!");
-			} else if (result < -1) {
-				LOG.error("Error requesting new frame!");
-			}
-
-			timestamp.set(System.currentTimeMillis());
+			updateFrameBuffer();
 
 		} while (open.get());
 	}

webcam-capture/src/main/java/com/github/sarxos/webcam/ds/cgt/WebcamGetBufferTask.java

@@ -0,0 +1,48 @@
+package com.github.sarxos.webcam.ds.cgt;
+
+import java.nio.ByteBuffer;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.github.sarxos.webcam.WebcamDevice;
+import com.github.sarxos.webcam.WebcamDevice.BufferAccess;
+import com.github.sarxos.webcam.WebcamDriver;
+import com.github.sarxos.webcam.WebcamTask;
+
+
+public class WebcamGetBufferTask extends WebcamTask {
+
+	private static final Logger LOG = LoggerFactory.getLogger(WebcamGetBufferTask.class);
+
+	private volatile ByteBuffer buffer = null;
+
+	public WebcamGetBufferTask(WebcamDriver driver, WebcamDevice device) {
+		super(driver, device);
+	}
+
+	public ByteBuffer getBuffer() {
+		try {
+			process();
+		} catch (InterruptedException e) {
+			LOG.debug("Image buffer request interrupted", e);
+			return null;
+		}
+		return buffer;
+	}
+
+	@Override
+	protected void handle() {
+
+		WebcamDevice device = getDevice();
+		if (!device.isOpen()) {
+			return;
+		}
+
+		if (!(device instanceof BufferAccess)) {
+			return;
+		}
+
+		buffer = ((BufferAccess) device).getImageBytes();
+	}
+}