Add a resize operation

core/src/main/java/edu/wpi/grip/core/operations/Operations.java

@@ -15,6 +15,7 @@ private Operations() { /* no op */}
 
     public static void addOperations(EventBus eventBus) {
         // Add the default built-in operations to the palette
+        eventBus.post(new OperationAddedEvent(new ResizeOperation()));
         eventBus.post(new OperationAddedEvent(new BlurOperation()));
         eventBus.post(new OperationAddedEvent(new DesaturateOperation()));
         eventBus.post(new OperationAddedEvent(new RGBThresholdOperation()));

core/src/main/java/edu/wpi/grip/core/operations/composite/ResizeOperation.java

@@ -0,0 +1,92 @@
+package edu.wpi.grip.core.operations.composite;
+
+import com.google.common.eventbus.EventBus;
+import edu.wpi.grip.core.InputSocket;
+import edu.wpi.grip.core.Operation;
+import edu.wpi.grip.core.OutputSocket;
+import edu.wpi.grip.core.SocketHints;
+
+import java.io.InputStream;
+import java.util.Optional;
+
+import static org.bytedeco.javacpp.opencv_core.Mat;
+import static org.bytedeco.javacpp.opencv_core.Size;
+import static org.bytedeco.javacpp.opencv_imgproc.*;
+import static org.bytedeco.javacpp.opencv_imgproc.resize;
+
+/**
+ * Scale an image to an exact width and height using one of several interpolation modes.  Scaling images down can
+ * be a useful optimization, and scaling them up might be necessary for combining multiple images that are different
+ * sizes.
+ */
+public class ResizeOperation implements Operation {
+
+    private enum Interpolation {
+        NEAREST("None", INTER_NEAREST),
+        LINEAR("Linear", INTER_LINEAR),
+        CUBIC("Cubic", INTER_CUBIC),
+        LANCZOS("Lanczos", INTER_LANCZOS4),
+        AREA("Area", INTER_AREA);
+
+        final String label;
+        final int value;
+
+        Interpolation(String label, int value) {
+            this.label = label;
+            this.value = value;
+        }
+
+        @Override
+        public String toString() {
+            return label;
+        }
+    }
+
+    @Override
+    public String getName() {
+        return "Resize Image";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Scale an image to an exact size";
+    }
+
+    @Override
+    public Optional<InputStream> getIcon() {
+        return Optional.of(getClass().getResourceAsStream("/edu/wpi/grip/ui/icons/resize.png"));
+    }
+
+    @Override
+    public InputSocket<?>[] createInputSockets(EventBus eventBus) {
+        return new InputSocket<?>[]{
+                new InputSocket<>(eventBus, SocketHints.Inputs.createMatSocketHint("Input", false)),
+                new InputSocket<>(eventBus, SocketHints.Inputs.createNumberSpinnerSocketHint("Width", 640)),
+                new InputSocket<>(eventBus, SocketHints.Inputs.createNumberSpinnerSocketHint("Height", 480)),
+                new InputSocket<>(eventBus, SocketHints.createEnumSocketHint("Interpolation", Interpolation.CUBIC)),
+        };
+    }
+
+    @Override
+    public OutputSocket<?>[] createOutputSockets(EventBus eventBus) {
+        return new OutputSocket<?>[]{
+                new OutputSocket<>(eventBus, SocketHints.Outputs.createMatSocketHint("Output")),
+        };
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public void perform(InputSocket<?>[] inputs, OutputSocket<?>[] outputs) {
+        final Mat input = ((InputSocket<Mat>) inputs[0]).getValue().get();
+        final Number width = ((InputSocket<Number>) inputs[1]).getValue().get();
+        final Number height = ((InputSocket<Number>) inputs[2]).getValue().get();
+        final Interpolation interpolation = ((InputSocket<Interpolation>) inputs[3]).getValue().get();
+
+        final OutputSocket<Mat> outputSocket = (OutputSocket<Mat>) outputs[0];
+        final Mat output = outputSocket.getValue().get();
+
+        resize(input, output, new Size(width.intValue(), height.intValue()), 0.0, 0.0, interpolation.value);
+
+        outputSocket.setValue(output);
+    }
+}