rewrite blur bitmap implementation

it uses RenderEffect for android 12+ and existing approach for older version.

Author: empratyush

app/src/main/java/app/grapheneos/camera/ui/activities/MainActivity.kt

@@ -68,7 +68,6 @@ import androidx.core.view.WindowInsetsControllerCompat
 import androidx.core.view.updateLayoutParams
 import androidx.core.view.updateMargins
 import app.grapheneos.camera.App
-import app.grapheneos.camera.BlurBitmap
 import app.grapheneos.camera.CamConfig
 import app.grapheneos.camera.CameraMode
 import app.grapheneos.camera.ITEM_TYPE_IMAGE
@@ -94,6 +93,7 @@ import app.grapheneos.camera.util.CameraControl
 import app.grapheneos.camera.util.ImageResizer
 import app.grapheneos.camera.util.executeIfAlive
 import app.grapheneos.camera.util.resolveActivity
+import app.grapheneos.camera.util.setBlurBitmapCompat
 import com.google.android.material.imageview.ShapeableImageView
 import com.google.android.material.snackbar.Snackbar
 import com.google.android.material.tabs.TabLayout
@@ -657,8 +657,9 @@ open class MainActivity : AppCompatActivity(),
                 }
             } else {
                 previewGrid.visibility = View.INVISIBLE
+                val lastFrame = lastFrame
                 if (lastFrame != null && this !is CaptureActivity) {
-                    mainOverlay.setImageBitmap(blurBitmap(lastFrame!!))
+                    setBlurBitmapCompat(mainOverlay, lastFrame)
                     settingsIcon.visibility = View.INVISIBLE
                     settingsIcon.isEnabled = false
                     mainOverlay.visibility = View.VISIBLE
@@ -1217,10 +1218,6 @@ open class MainActivity : AppCompatActivity(),
         }
     }
 
-    private fun blurBitmap(bitmap: Bitmap): Bitmap {
-        return BlurBitmap[bitmap]
-    }
-
 //    private val fTHandler : Handler = Handler(Looper.getMainLooper())
 //    private val fTRunnable : Runnable = Runnable {
 //        config.mPlayer.playFocusCompleteSound()

app/src/main/java/app/grapheneos/camera/util/BitmapUtils.kt

@@ -0,0 +1,25 @@
+package app.grapheneos.camera.util
+
+import android.graphics.Bitmap
+import android.graphics.RenderEffect
+import android.graphics.Shader
+import android.os.Build
+import android.widget.ImageView
+import androidx.annotation.RequiresApi
+
+fun setBlurBitmapCompat(view: ImageView, bitmap: Bitmap, radius: Float = 4f) {
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+        setBitmapWithBlurEffect(view, bitmap, radius)
+        return
+    }
+
+    //this will eventually be removed
+    view.setImageBitmap(app.grapheneos.camera.BlurBitmap[bitmap])
+}
+
+@RequiresApi(Build.VERSION_CODES.S)
+private fun setBitmapWithBlurEffect(view: ImageView, bitmap: Bitmap, radius: Float) {
+    val blurRenderEffect = RenderEffect.createBlurEffect(radius, radius, Shader.TileMode.CLAMP)
+    view.setImageBitmap(bitmap)
+    view.setRenderEffect(blurRenderEffect)
+}