Force load opencv before using OpenCV functions (#1808)

Force loads OpenCV before any OpenCV functions are used. `OpenCVLoader`
has all of its loading done in a static initializer field, so it's only
loaded once.

Also deprecates `OpenCVHelp.forceLoadOpenCV()`, since it's functionality
is the exact same.

Resolves #1803

Author: Gold872

photon-lib/src/main/java/org/photonvision/PhotonPoseEstimator.java

@@ -25,6 +25,7 @@
 package org.photonvision;
 
 import edu.wpi.first.apriltag.AprilTagFieldLayout;
+import edu.wpi.first.cscore.OpenCvLoader;
 import edu.wpi.first.hal.FRCNetComm.tResourceType;
 import edu.wpi.first.hal.HAL;
 import edu.wpi.first.math.Matrix;
@@ -159,6 +160,11 @@ public PhotonPoseEstimator(
         this.primaryStrategy = strategy;
         this.robotToCamera = robotToCamera;
 
+        if (strategy == PoseStrategy.MULTI_TAG_PNP_ON_RIO
+                || strategy == PoseStrategy.CONSTRAINED_SOLVEPNP) {
+            OpenCvLoader.forceStaticLoad();
+        }
+
         HAL.report(tResourceType.kResourceType_PhotonPoseEstimator, InstanceCount);
         InstanceCount++;
     }
@@ -231,6 +237,11 @@ public PoseStrategy getPrimaryStrategy() {
      */
     public void setPrimaryStrategy(PoseStrategy strategy) {
         checkUpdate(this.primaryStrategy, strategy);
+
+        if (strategy == PoseStrategy.MULTI_TAG_PNP_ON_RIO
+                || strategy == PoseStrategy.CONSTRAINED_SOLVEPNP) {
+            OpenCvLoader.forceStaticLoad();
+        }
         this.primaryStrategy = strategy;
     }
 

photon-lib/src/main/java/org/photonvision/simulation/PhotonCameraSim.java

@@ -28,6 +28,7 @@
 import edu.wpi.first.apriltag.AprilTagFields;
 import edu.wpi.first.cameraserver.CameraServer;
 import edu.wpi.first.cscore.CvSource;
+import edu.wpi.first.cscore.OpenCvLoader;
 import edu.wpi.first.cscore.VideoSource.ConnectionStrategy;
 import edu.wpi.first.math.MathUtil;
 import edu.wpi.first.math.Pair;
@@ -94,7 +95,7 @@ public class PhotonCameraSim implements AutoCloseable {
     private boolean videoSimProcEnabled = true;
 
     static {
-        OpenCVHelp.forceLoadOpenCV();
+        OpenCvLoader.forceStaticLoad();
     }
 
     @Override

photon-lib/src/main/java/org/photonvision/simulation/VideoSimUtil.java

@@ -26,6 +26,7 @@
 
 import edu.wpi.first.apriltag.AprilTag;
 import edu.wpi.first.cscore.CvSource;
+import edu.wpi.first.cscore.OpenCvLoader;
 import edu.wpi.first.math.geometry.Pose3d;
 import edu.wpi.first.math.geometry.Translation3d;
 import edu.wpi.first.math.util.Units;
@@ -62,7 +63,7 @@ public class VideoSimUtil {
     private static double fieldWidth = 8.0137;
 
     static {
-        OpenCVHelp.forceLoadOpenCV();
+        OpenCvLoader.forceStaticLoad();
 
         // create Mats of 10x10 apriltag images
         for (int i = 0; i < VideoSimUtil.kNumTags36h11; i++) {

photon-lib/src/test/java/org/photonvision/VisionSystemSimTest.java

@@ -33,6 +33,7 @@
 
 import edu.wpi.first.apriltag.AprilTag;
 import edu.wpi.first.apriltag.AprilTagFieldLayout;
+import edu.wpi.first.cscore.OpenCvLoader;
 import edu.wpi.first.hal.HAL;
 import edu.wpi.first.math.geometry.Pose2d;
 import edu.wpi.first.math.geometry.Pose3d;
@@ -57,7 +58,6 @@
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 import org.junit.jupiter.params.provider.ValueSource;
-import org.photonvision.estimation.OpenCVHelp;
 import org.photonvision.estimation.TargetModel;
 import org.photonvision.estimation.VisionEstimation;
 import org.photonvision.jni.PhotonTargetingJniLoader;
@@ -84,7 +84,7 @@ public static void setUp() {
             fail(e);
         }
 
-        OpenCVHelp.forceLoadOpenCV();
+        OpenCvLoader.forceStaticLoad();
 
         // See #1574 - test flakey, disabled until we address this
         assumeTrue(false);

photon-targeting/src/main/java/org/photonvision/estimation/OpenCVHelp.java

@@ -17,7 +17,7 @@
 
 package org.photonvision.estimation;
 
-import edu.wpi.first.cscore.CvSink;
+import edu.wpi.first.cscore.OpenCvLoader;
 import edu.wpi.first.math.MatBuilder;
 import edu.wpi.first.math.Matrix;
 import edu.wpi.first.math.Nat;
@@ -54,14 +54,12 @@ public final class OpenCVHelp {
     private static final Rotation3d NWU_TO_EDN;
     private static final Rotation3d EDN_TO_NWU;
 
-    // Creating a cscore object is sufficient to load opencv, per
-    // https://www.chiefdelphi.com/t/unsatisfied-link-error-when-simulating-java-robot-code-using-opencv/426731/4
-    private static CvSink dummySink = null;
-
+    /**
+     * @deprecated Replaced by {@link OpenCvLoader#forceStaticLoad()}
+     */
+    @Deprecated(since = "2025", forRemoval = true)
     public static void forceLoadOpenCV() {
-        if (dummySink != null) return;
-        dummySink = new CvSink("ignored");
-        dummySink.close();
+        OpenCvLoader.forceStaticLoad();
     }
 
     static {

photon-targeting/src/main/java/org/photonvision/estimation/VisionEstimation.java

@@ -19,6 +19,7 @@
 
 import edu.wpi.first.apriltag.AprilTag;
 import edu.wpi.first.apriltag.AprilTagFieldLayout;
+import edu.wpi.first.cscore.OpenCvLoader;
 import edu.wpi.first.math.MatBuilder;
 import edu.wpi.first.math.Matrix;
 import edu.wpi.first.math.Nat;
@@ -105,6 +106,8 @@ public static Optional<PnpResult> estimateCamPosePNP(
         if (knownTags.isEmpty() || corners.isEmpty() || corners.size() % 4 != 0) {
             return Optional.empty();
         }
+        OpenCvLoader.forceStaticLoad();
+
         Point[] points = OpenCVHelp.cornersToPoints(corners);
 
         // single-tag pnp
@@ -200,6 +203,8 @@ public static Optional<PnpResult> estimateRobotPoseConstrainedSolvepnp(
         if (knownTags.isEmpty() || corners.isEmpty() || corners.size() % 4 != 0) {
             return Optional.empty();
         }
+        OpenCvLoader.forceStaticLoad();
+
         Point[] points = OpenCVHelp.cornersToPoints(corners);
 
         // Undistort