fix(scanner): re-land the badge-dot prune and the dead adaptive thresholds

vendor/kik/scanner/src/androidTest/kotlin/com/kik/scan/KikCodeScanTest.kt

@@ -3,11 +3,11 @@ package com.kik.scan
 import android.graphics.Bitmap
 import android.graphics.Canvas
 import android.graphics.Color
-import android.graphics.drawable.ShapeDrawable
-import android.graphics.drawable.shapes.OvalShape
 import android.os.Debug
 import android.util.Log
+import androidx.core.content.ContextCompat
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
 import com.getcode.codes.kikcode.LuminancePlane
 import com.kik.kikx.kikcodes.ScanQuality
 import com.kik.kikx.kikcodes.implementation.KikCodeScannerImpl
@@ -36,9 +36,18 @@ class KikCodeScanTest {
     /**
      * The detector locates a code by its centre ellipse, so the badge well must be filled — in the
      * app that is the round logo drawable. An empty well is simply not scannable.
+     *
+     * Use the *real* artwork, not a plain white oval. The logo knocks its glyph out of the disc
+     * with the even-odd rule, and the glyph's round dot is itself an ellipse the detector can
+     * latch onto; a substituted oval has no dot and quietly hides that whole class of bug.
      */
     private val renderer = KikCodeContentRendererImpl().apply {
-        badge = ShapeDrawable(OvalShape()).apply { paint.color = Color.WHITE }
+        badge = requireNotNull(
+            ContextCompat.getDrawable(
+                InstrumentationRegistry.getInstrumentation().context,
+                com.kik.kikx.test.R.drawable.ic_logo_round_white,
+            )
+        )
     }
     private val scanner = KikCodeScannerImpl()
 

vendor/kik/scanner/src/androidTest/res/drawable/ic_logo_round_white.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="62dp"
+    android:height="62dp"
+    android:viewportWidth="62"
+    android:viewportHeight="62">
+  <path
+      android:pathData="M61.665,30.832C61.665,47.861 47.861,61.665 30.832,61.665C13.804,61.665 0,47.861 0,30.832C0,13.804 13.804,-0 30.832,-0C47.861,-0 61.665,13.804 61.665,30.832ZM24.843,15L24.811,15C22.154,15 20,17.154 20,19.811C20,22.469 22.154,24.623 24.811,24.623L24.811,24.623L34.434,24.623L34.434,24.623L37.642,24.623L39.245,24.623L39.246,24.623C41.903,24.623 44.057,22.469 44.057,19.812C44.057,17.154 41.903,15 39.246,15L39.245,15L37.642,15L34.434,15L34.434,15L24.843,15ZM34.434,27.188L36.038,27.188L36.038,27.188C38.695,27.188 40.849,29.342 40.849,32C40.849,34.657 38.695,36.811 36.038,36.811L36.038,36.811L34.434,36.811L24.858,36.811L24.811,36.811C22.154,36.811 20,34.657 20,32C20,29.343 22.154,27.188 24.811,27.188L24.811,27.188L24.811,27.188L34.434,27.188ZM29.623,44.189C29.623,41.531 27.469,39.377 24.811,39.377C22.154,39.377 20,41.531 20,44.189C20,46.846 22.154,49 24.811,49C27.469,49 29.623,46.846 29.623,44.189Z"
+      android:fillColor="#ffffff"
+      android:fillType="evenOdd"/>
+</vector>

vendor/kik/scanner/src/main/cpp/scan/scanner.cpp

@@ -417,23 +417,6 @@ bool detectKikCode(Mat &greyscale, Mat *out_progress, uint32_t device_quality, u
     Mat whitish;
     Mat blackish;
 
-    // --- START OF EDIT ---
-    // we switch to an inverted scheme (dark is high, light is low) if the
-    // center ellipse is dark, but we don't want to compute the extra threshold everytime
-    // so we only do this when needed.
-    //
-    // Using adaptive thresholding is more robust to lighting changes than a global threshold.
-    // It calculates a threshold for smaller regions, making it less susceptible to shadows or glare.
-    // A block size of 11 or higher is a good starting point and must be an odd number.
-    // The constant 'C' (here, 5) is subtracted from the mean, which helps in finding features.
-
-    // For finding dark features on a light background.
-    adaptiveThreshold(greyscale, blackish, 255, ADAPTIVE_THRESH_GAUSSIAN_C, THRESH_BINARY_INV, 21, 5);
-
-    // For finding light features on a dark background.
-    adaptiveThreshold(greyscale, whitish, 255, ADAPTIVE_THRESH_GAUSSIAN_C, THRESH_BINARY, 21, 5);
-    // --- END OF EDIT ---
-
     // we switch to an inverted scheme (dark is high, light is low) if the
     // center ellipse is dark, but we don't want to compute the extra threshold everytime
     // so we only do this when necessary
@@ -728,7 +711,15 @@ bool detectKikCode(Mat &greyscale, Mat *out_progress, uint32_t device_quality, u
             float dist = sqrt(pow(center1.x - center2.x, 2)
                        + pow(center1.y - center2.y, 2));
 
-            if (dist < 50 && 2 * potential_ellipses[i].size.area() > potential_ellipses[j].size.area()) {
+            float area1 = potential_ellipses[i].size.area();
+            float area2 = potential_ellipses[j].size.area();
+
+            // Only prune true near-duplicates -- the same physical circle fitted twice from the
+            // inner and outer edge of its stroke, which are comparable in area. A nearby ellipse
+            // that is much smaller is a *different* feature nested inside this one (e.g. the dot
+            // knocked out of the centre badge's glyph), and dropping the enclosing candidate in
+            // its favour loses the only ellipse that can yield finder points.
+            if (dist < 50 && 2 * area1 > area2 && 2 * area2 > area1) {
                 allowed = false;
                 break;
             }