Implement anti-ghosting inpainting for original background blur during photo capture as described in 25_FIX_CAMERA.md

android-project/app/src/main/java/com/photobooth/app/MainActivity.kt

@@ -1829,7 +1829,20 @@ class MainActivity : AppCompatActivity() {
                             solidBg
                         }
                     } else {
-                        capturedImage
+                        // Triệt tiêu Ghost Shadow (Bóng ma rế viền) bằng giãn cơ thể ẩn (Inpainting Dilate)
+                        val cleanBg = android.graphics.Bitmap.createBitmap(w, h, android.graphics.Bitmap.Config.ARGB_8888)
+                        for (y in 0 until h) {
+                            for (x in 0 until w) {
+                                val idx = y * w + x
+                                val alpha = alphaMask[idx]
+                                if (alpha > 0.01f) {
+                                    cleanBg.setPixel(x, y, getNearestBackgroundPixel(capturedImage, alphaMask, x, y, w, h))
+                                } else {
+                                    cleanBg.setPixel(x, y, capturedImage.getPixel(x, y))
+                                }
+                            }
+                        }
+                        cleanBg
                     }
                     
                     val bgPixels = IntArray(w * h)
@@ -1896,6 +1909,37 @@ class MainActivity : AppCompatActivity() {
         return capturedImage
     }
 
+    private fun getNearestBackgroundPixel(
+        src: android.graphics.Bitmap,
+        alphaMask: FloatArray,
+        startX: Int,
+        startY: Int,
+        w: Int,
+        h: Int
+    ): Int {
+        val maxDist = 30
+        for (r in 1..maxDist) {
+            // Check 4 directions: left, right, up, down
+            var px = startX - r
+            if (px >= 0) {
+                if (alphaMask[startY * w + px] <= 0.01f) return src.getPixel(px, startY)
+            }
+            px = startX + r
+            if (px < w) {
+                if (alphaMask[startY * w + px] <= 0.01f) return src.getPixel(px, startY)
+            }
+            var py = startY - r
+            if (py >= 0) {
+                if (alphaMask[py * w + startX] <= 0.01f) return src.getPixel(startX, py)
+            }
+            py = startY + r
+            if (py < h) {
+                if (alphaMask[py * w + startX] <= 0.01f) return src.getPixel(startX, py)
+            }
+        }
+        return src.getPixel(0, 0)
+    }
+
     private fun blurAlphaMaskBox(arr: FloatArray, w: Int, h: Int, radius: Int) {
         if (radius <= 0) return
         val temp = FloatArray(w * h)