diff --git a/packages/SystemUI/res/drawable/brightness_progress_drawable.xml b/packages/SystemUI/res/drawable/brightness_progress_drawable.xml
index 88d8f78f..569ee76 100644
--- a/packages/SystemUI/res/drawable/brightness_progress_drawable.xml
+++ b/packages/SystemUI/res/drawable/brightness_progress_drawable.xml
@@ -30,7 +30,7 @@
     </item>
     <item android:id="@android:id/progress"
           android:gravity="center_vertical|fill_horizontal">
-            <com.android.systemui.util.RoundedCornerProgressDrawable
+            <com.android.systemui.util.BrightnessProgressDrawable
                 android:drawable="@drawable/brightness_progress_full_drawable"
             />
     </item>
diff --git a/packages/SystemUI/src/com/android/systemui/util/BrightnessProgressDrawable.kt b/packages/SystemUI/src/com/android/systemui/util/BrightnessProgressDrawable.kt
new file mode 100644
index 0000000..12a0c03
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/util/BrightnessProgressDrawable.kt
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.util
+
+import android.content.pm.ActivityInfo
+import android.content.res.Resources
+import android.graphics.Rect
+import android.graphics.drawable.Drawable
+import android.graphics.drawable.DrawableWrapper
+import android.graphics.drawable.InsetDrawable
+
+/**
+ * [DrawableWrapper] to use in the progress of brightness slider.
+ *
+ * This drawable is used to change the bounds of the enclosed drawable depending on the level to
+ * simulate a sliding progress, instead of using clipping or scaling. That way, the shape of the
+ * edges is maintained.
+ *
+ * Meant to be used with a rounded ends background, it will also prevent deformation when the slider
+ * is meant to be smaller than the rounded corner. The background should have rounded corners that
+ * are half of the height.
+ *
+ * This class also assumes that a "thumb" icon exists within the end's edge of the progress
+ * drawable, and the slider's width, when interacted on, if offset by half the size of the thumb
+ * icon which puts the icon directly underneath the user's finger.
+ */
+class BrightnessProgressDrawable @JvmOverloads constructor(drawable: Drawable? = null) :
+    InsetDrawable(drawable, 0) {
+
+    companion object {
+        private const val MAX_LEVEL = 10000 // Taken from Drawable
+    }
+
+    override fun onLayoutDirectionChanged(layoutDirection: Int): Boolean {
+        onLevelChange(level)
+        return super.onLayoutDirectionChanged(layoutDirection)
+    }
+
+    override fun onBoundsChange(bounds: Rect) {
+        super.onBoundsChange(bounds)
+        onLevelChange(level)
+    }
+
+    override fun onLevelChange(level: Int): Boolean {
+        val db = drawable?.bounds!!
+
+        // The thumb offset shifts the sun icon directly under the user's thumb
+        val thumbOffset = bounds.height() / 2
+        val width = bounds.width() * level / MAX_LEVEL + thumbOffset
+
+        // On 0, the width is bounds.height (a circle), and on MAX_LEVEL, the width is bounds.width
+        drawable?.setBounds(
+            bounds.left,
+            db.top,
+            width.coerceAtMost(bounds.width()).coerceAtLeast(bounds.height()),
+            db.bottom
+        )
+        return super.onLevelChange(level)
+    }
+
+    override fun getConstantState(): ConstantState {
+        // This should not be null as it was created with a state in the constructor.
+        return RoundedCornerState(super.getConstantState()!!)
+    }
+
+    override fun getChangingConfigurations(): Int {
+        return super.getChangingConfigurations() or ActivityInfo.CONFIG_DENSITY
+    }
+
+    override fun canApplyTheme(): Boolean {
+        return (drawable?.canApplyTheme() ?: false) || super.canApplyTheme()
+    }
+
+    private class RoundedCornerState(private val wrappedState: ConstantState) : ConstantState() {
+        override fun newDrawable(): Drawable {
+            return newDrawable(null, null)
+        }
+
+        override fun newDrawable(res: Resources?, theme: Resources.Theme?): Drawable {
+            val wrapper = wrappedState.newDrawable(res, theme) as DrawableWrapper
+            return BrightnessProgressDrawable(wrapper.drawable)
+        }
+
+        override fun getChangingConfigurations(): Int {
+            return wrappedState.changingConfigurations
+        }
+
+        override fun canApplyTheme(): Boolean {
+            return true
+        }
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/util/RoundedCornerProgressDrawable.kt b/packages/SystemUI/src/com/android/systemui/util/RoundedCornerProgressDrawable.kt
index 99eb03b..1059d6c 100644
--- a/packages/SystemUI/src/com/android/systemui/util/RoundedCornerProgressDrawable.kt
+++ b/packages/SystemUI/src/com/android/systemui/util/RoundedCornerProgressDrawable.kt
@@ -33,11 +33,6 @@
  * Meant to be used with a rounded ends background, it will also prevent deformation when the slider
  * is meant to be smaller than the rounded corner. The background should have rounded corners that
  * are half of the height.
- *
- * This class also assumes that a "thumb" icon exists within the end's edge of the progress
- * drawable, and the slider's width, when interacted on, if offset by half the size of the thumb
- * icon which puts the icon directly underneath the user's finger.
- *
  */
 class RoundedCornerProgressDrawable @JvmOverloads constructor(
     drawable: Drawable? = null
@@ -59,16 +54,9 @@
 
     override fun onLevelChange(level: Int): Boolean {
         val db = drawable?.bounds!!
-
-        // The thumb offset shifts the sun icon directly under the user's thumb
-        val thumbOffset = bounds.height() / 2
-        val width = bounds.width() * level / MAX_LEVEL + thumbOffset
-
         // On 0, the width is bounds.height (a circle), and on MAX_LEVEL, the width is bounds.width
-        drawable?.setBounds(
-            bounds.left, db.top,
-            width.coerceAtMost(bounds.width()).coerceAtLeast(bounds.height()), db.bottom
-        )
+        val width = bounds.height() + (bounds.width() - bounds.height()) * level / MAX_LEVEL
+        drawable?.setBounds(bounds.left, db.top, bounds.left + width, db.bottom)
         return super.onLevelChange(level)
     }
 
@@ -103,4 +91,4 @@
             return true
         }
     }
-}
+}
\ No newline at end of file