Add AdvancedFilterCountoursOperation

Fixes issue #441

Author: drbobbob

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

@@ -27,6 +27,7 @@ public static void addOperations(EventBus eventBus) {
         eventBus.post(new OperationAddedEvent(new HSLThresholdOperation()));
         eventBus.post(new OperationAddedEvent(new FindContoursOperation()));
         eventBus.post(new OperationAddedEvent(new FilterContoursOperation()));
+        eventBus.post(new OperationAddedEvent(new AdvancedFilterContoursOperation()));
         eventBus.post(new OperationAddedEvent(new ConvexHullsOperation()));
         eventBus.post(new OperationAddedEvent(new FindBlobsOperation()));
         eventBus.post(new OperationAddedEvent(new FindLinesOperation()));

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

@@ -0,0 +1,115 @@
+package edu.wpi.grip.core.operations.composite;
+
+import com.google.common.eventbus.EventBus;
+import edu.wpi.grip.core.*;
+
+import java.io.InputStream;
+import java.util.List;
+import java.util.Optional;
+
+import static org.bytedeco.javacpp.opencv_core.*;
+import static org.bytedeco.javacpp.opencv_imgproc.*;
+
+/**
+ * An {@link Operation} that takes in a list of contours and outputs a list of any contours in the input that match
+ * all of several criteria.  Right now, the user can specify a minimum area, minimum perimeter, and ranges for width
+ * and height.
+ * <p>
+ * This is useful because running a Find Contours on a real-life image typically leads to many small undesirable
+ * contours from noise and small objects, as well as contours that do not meet the expected characteristics of the
+ * feature we're actually looking for.  So, this operation can help narrow them down.
+ */
+public class AdvancedFilterContoursOperation implements Operation {
+
+    private final SocketHint<ContoursReport> contoursHint = new SocketHint.Builder<>(ContoursReport.class)
+            .identifier("Contours").initialValueSupplier(ContoursReport::new).build();
+
+    private final SocketHint<Number> minVertexHint =
+            SocketHints.Inputs.createNumberSpinnerSocketHint("Min Vertex Count", 0, 0, Integer.MAX_VALUE);
+
+    private final SocketHint<Number> maxVertexHint =
+            SocketHints.Inputs.createNumberSpinnerSocketHint("Max Vertex Count", 0, 1000, Integer.MAX_VALUE);
+
+    private final SocketHint<Boolean> forceConvexHint =
+            SocketHints.createBooleanSocketHint("Force Convex", false);
+
+    private final SocketHint<Number> minRatioHint =
+            SocketHints.Inputs.createNumberSpinnerSocketHint("Min Ratio", 0, 0, Integer.MAX_VALUE);
+
+    private final SocketHint<Number> maxRatioHint =
+            SocketHints.Inputs.createNumberSpinnerSocketHint("Max Ratio", 1000, 0, Integer.MAX_VALUE);
+
+    @Override
+    public String getName() {
+        return "Advanced Filter Contours";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Find contours matching certain advanced criteria.";
+    }
+
+    @Override
+    public Category getCategory() {
+        return Category.FEATURE_DETECTION;
+    }
+
+    @Override
+    public Optional<InputStream> getIcon() {
+        return Optional.of(getClass().getResourceAsStream("/edu/wpi/grip/ui/icons/find-contours.png"));
+    }
+
+    @Override
+    public InputSocket<?>[] createInputSockets(EventBus eventBus) {
+        return new InputSocket<?>[]{
+                new InputSocket<>(eventBus, contoursHint),
+                new InputSocket<>(eventBus, minVertexHint),
+                new InputSocket<>(eventBus, maxVertexHint),
+                new InputSocket<>(eventBus, forceConvexHint),
+                new InputSocket<>(eventBus, minRatioHint),
+                new InputSocket<>(eventBus, maxRatioHint),
+        };
+    }
+
+    @Override
+    public OutputSocket<?>[] createOutputSockets(EventBus eventBus) {
+        return new OutputSocket<?>[]{new OutputSocket<>(eventBus, contoursHint)};
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public void perform(InputSocket<?>[] inputs, OutputSocket<?>[] outputs) {
+        final InputSocket<ContoursReport> inputSocket = (InputSocket<ContoursReport>) inputs[0];
+        final double minVertexCount = ((Number) inputs[1].getValue().get()).doubleValue();
+        final double maxVertexCount = ((Number) inputs[2].getValue().get()).doubleValue();
+        final boolean forceConvex = ((Boolean) inputs[3].getValue().get()).booleanValue();
+        final double minRatio = ((Number) inputs[4].getValue().get()).doubleValue();
+        final double maxRatio = ((Number) inputs[5].getValue().get()).doubleValue();
+
+        final MatVector inputContours = inputSocket.getValue().get().getContours();
+        final MatVector outputContours = new MatVector(inputContours.size());
+
+        // Add contours from the input vector to the output vector only if they pass all of the criteria (minimum
+        // area, minimum perimeter, width, and height, etc...)
+        int filteredContourCount = 0;
+        for (int i = 0; i < inputContours.size(); i++) {
+            final Mat contour = inputContours.get(i);
+
+            if(contour.rows() < minVertexCount || contour.rows() > maxVertexCount) continue;
+
+            if(forceConvex && !isContourConvex(contour)) continue;
+
+            final Rect bb = boundingRect(contour);
+            final double ratio = bb.width() / bb.height();
+            if (ratio < minRatio || ratio > maxRatio) continue;
+
+            outputContours.put(filteredContourCount++, contour);
+        }
+
+        outputContours.resize(filteredContourCount);
+
+        final OutputSocket<ContoursReport> outputSocket = (OutputSocket<ContoursReport>) outputs[0];
+        outputSocket.setValue(new ContoursReport(outputContours,
+                inputSocket.getValue().get().getRows(), inputSocket.getValue().get().getCols()));
+    }
+}