diff --git a/src/com/android/launcher3/folder/PreviewBackground.java b/src/com/android/launcher3/folder/PreviewBackground.java
new file mode 100644
index 0000000..44ebbcd
--- /dev/null
+++ b/src/com/android/launcher3/folder/PreviewBackground.java
@@ -0,0 +1,430 @@
+/*
+ * Copyright (C) 2017 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.launcher3.folder;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.ObjectAnimator;
+import android.animation.ValueAnimator;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Matrix;
+import android.graphics.Paint;
+import android.graphics.Path;
+import android.graphics.PorterDuff;
+import android.graphics.PorterDuffXfermode;
+import android.graphics.RadialGradient;
+import android.graphics.Region;
+import android.graphics.Shader;
+import android.support.v4.graphics.ColorUtils;
+import android.util.Property;
+import android.view.View;
+
+import com.android.launcher3.CellLayout;
+import com.android.launcher3.DeviceProfile;
+import com.android.launcher3.Launcher;
+import com.android.launcher3.LauncherAnimUtils;
+import com.android.launcher3.util.Themes;
+
+/**
+ * This object represents a FolderIcon preview background. It stores drawing / measurement
+ * information, handles drawing, and animation (accept state <--> rest state).
+ */
+public class PreviewBackground {
+
+    private static final int CONSUMPTION_ANIMATION_DURATION = 100;
+
+    private final PorterDuffXfermode mClipPorterDuffXfermode
+            = new PorterDuffXfermode(PorterDuff.Mode.DST_IN);
+    // Create a RadialGradient such that it draws a black circle and then extends with
+    // transparent. To achieve this, we keep the gradient to black for the range [0, 1) and
+    // just at the edge quickly change it to transparent.
+    private final RadialGradient mClipShader = new RadialGradient(0, 0, 1,
+            new int[] {Color.BLACK, Color.BLACK, Color.TRANSPARENT },
+            new float[] {0, 0.999f, 1},
+            Shader.TileMode.CLAMP);
+
+    private final PorterDuffXfermode mShadowPorterDuffXfermode
+            = new PorterDuffXfermode(PorterDuff.Mode.DST_OUT);
+    private RadialGradient mShadowShader = null;
+
+    private final Matrix mShaderMatrix = new Matrix();
+    private final Path mPath = new Path();
+
+    private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+
+    float mScale = 1f;
+    private float mColorMultiplier = 1f;
+    private int mBgColor;
+    private float mStrokeWidth;
+    private int mStrokeAlpha = MAX_BG_OPACITY;
+    private int mShadowAlpha = 255;
+    private View mInvalidateDelegate;
+
+    int previewSize;
+    int basePreviewOffsetX;
+    int basePreviewOffsetY;
+
+    private CellLayout mDrawingDelegate;
+    public int delegateCellX;
+    public int delegateCellY;
+
+    // When the PreviewBackground is drawn under an icon (for creating a folder) the border
+    // should not occlude the icon
+    public boolean isClipping = true;
+
+    // Drawing / animation configurations
+    private static final float ACCEPT_SCALE_FACTOR = 1.25f;
+    private static final float ACCEPT_COLOR_MULTIPLIER = 1.5f;
+
+    // Expressed on a scale from 0 to 255.
+    private static final int BG_OPACITY = 160;
+    private static final int MAX_BG_OPACITY = 225;
+    private static final int SHADOW_OPACITY = 40;
+
+    private ValueAnimator mScaleAnimator;
+    private ObjectAnimator mStrokeAlphaAnimator;
+    private ObjectAnimator mShadowAnimator;
+
+    private static final Property<PreviewBackground, Integer> STROKE_ALPHA =
+            new Property<PreviewBackground, Integer>(Integer.class, "strokeAlpha") {
+                @Override
+                public Integer get(PreviewBackground previewBackground) {
+                    return previewBackground.mStrokeAlpha;
+                }
+
+                @Override
+                public void set(PreviewBackground previewBackground, Integer alpha) {
+                    previewBackground.mStrokeAlpha = alpha;
+                    previewBackground.invalidate();
+                }
+            };
+
+    private static final Property<PreviewBackground, Integer> SHADOW_ALPHA =
+            new Property<PreviewBackground, Integer>(Integer.class, "shadowAlpha") {
+                @Override
+                public Integer get(PreviewBackground previewBackground) {
+                    return previewBackground.mShadowAlpha;
+                }
+
+                @Override
+                public void set(PreviewBackground previewBackground, Integer alpha) {
+                    previewBackground.mShadowAlpha = alpha;
+                    previewBackground.invalidate();
+                }
+            };
+
+    public void setup(Launcher launcher, View invalidateDelegate,
+                      int availableSpace, int topPadding) {
+        mInvalidateDelegate = invalidateDelegate;
+        mBgColor = Themes.getAttrColor(launcher, android.R.attr.colorPrimary);
+
+        DeviceProfile grid = launcher.getDeviceProfile();
+        final int previewSize = grid.folderIconSizePx;
+        final int previewPadding = grid.folderIconPreviewPadding;
+
+        this.previewSize = (previewSize - 2 * previewPadding);
+
+        basePreviewOffsetX = (availableSpace - this.previewSize) / 2;
+        basePreviewOffsetY = previewPadding + grid.folderBackgroundOffset + topPadding;
+
+        // Stroke width is 1dp
+        mStrokeWidth = launcher.getResources().getDisplayMetrics().density;
+
+        float radius = getScaledRadius();
+        float shadowRadius = radius + mStrokeWidth;
+        int shadowColor = Color.argb(SHADOW_OPACITY, 0, 0, 0);
+        mShadowShader = new RadialGradient(0, 0, 1,
+                new int[] {shadowColor, Color.TRANSPARENT},
+                new float[] {radius / shadowRadius, 1},
+                Shader.TileMode.CLAMP);
+
+        invalidate();
+    }
+
+    int getRadius() {
+        return previewSize / 2;
+    }
+
+    int getScaledRadius() {
+        return (int) (mScale * getRadius());
+    }
+
+    int getOffsetX() {
+        return basePreviewOffsetX - (getScaledRadius() - getRadius());
+    }
+
+    int getOffsetY() {
+        return basePreviewOffsetY - (getScaledRadius() - getRadius());
+    }
+
+    /**
+     * Returns the progress of the scale animation, where 0 means the scale is at 1f
+     * and 1 means the scale is at ACCEPT_SCALE_FACTOR.
+     */
+    float getScaleProgress() {
+        return (mScale - 1f) / (ACCEPT_SCALE_FACTOR - 1f);
+    }
+
+    void invalidate() {
+        if (mInvalidateDelegate != null) {
+            mInvalidateDelegate.invalidate();
+        }
+
+        if (mDrawingDelegate != null) {
+            mDrawingDelegate.invalidate();
+        }
+    }
+
+    void setInvalidateDelegate(View invalidateDelegate) {
+        mInvalidateDelegate = invalidateDelegate;
+        invalidate();
+    }
+
+    public void drawBackground(Canvas canvas) {
+        mPaint.setStyle(Paint.Style.FILL);
+        int alpha = (int) Math.min(MAX_BG_OPACITY, BG_OPACITY * mColorMultiplier);
+        mPaint.setColor(ColorUtils.setAlphaComponent(mBgColor, alpha));
+
+        drawCircle(canvas, 0 /* deltaRadius */);
+
+        // Draw shadow.
+        if (mShadowShader == null) {
+            return;
+        }
+        float radius = getScaledRadius();
+        float shadowRadius = radius + mStrokeWidth;
+        mPaint.setColor(Color.BLACK);
+        int offsetX = getOffsetX();
+        int offsetY = getOffsetY();
+        final int saveCount;
+        if (canvas.isHardwareAccelerated()) {
+            saveCount = canvas.saveLayer(offsetX - mStrokeWidth, offsetY,
+                    offsetX + radius + shadowRadius, offsetY + shadowRadius + shadowRadius,
+                    null, Canvas.CLIP_TO_LAYER_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG);
+
+        } else {
+            saveCount = canvas.save(Canvas.CLIP_SAVE_FLAG);
+            clipCanvasSoftware(canvas, Region.Op.DIFFERENCE);
+        }
+
+        mShaderMatrix.setScale(shadowRadius, shadowRadius);
+        mShaderMatrix.postTranslate(radius + offsetX, shadowRadius + offsetY);
+        mShadowShader.setLocalMatrix(mShaderMatrix);
+        mPaint.setAlpha(mShadowAlpha);
+        mPaint.setShader(mShadowShader);
+        canvas.drawPaint(mPaint);
+        mPaint.setAlpha(255);
+        mPaint.setShader(null);
+        if (canvas.isHardwareAccelerated()) {
+            mPaint.setXfermode(mShadowPorterDuffXfermode);
+            canvas.drawCircle(radius + offsetX, radius + offsetY, radius, mPaint);
+            mPaint.setXfermode(null);
+        }
+
+        canvas.restoreToCount(saveCount);
+    }
+
+    public void fadeInBackgroundShadow() {
+        if (mShadowAnimator != null) {
+            mShadowAnimator.cancel();
+        }
+        mShadowAnimator = ObjectAnimator
+                .ofInt(this, SHADOW_ALPHA, 0, 255)
+                .setDuration(100);
+        mShadowAnimator.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                mShadowAnimator = null;
+            }
+        });
+        mShadowAnimator.start();
+    }
+
+    public void animateBackgroundStroke() {
+        if (mStrokeAlphaAnimator != null) {
+            mStrokeAlphaAnimator.cancel();
+        }
+        mStrokeAlphaAnimator = ObjectAnimator
+                .ofInt(this, STROKE_ALPHA, MAX_BG_OPACITY / 2, MAX_BG_OPACITY)
+                .setDuration(100);
+        mStrokeAlphaAnimator.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                mStrokeAlphaAnimator = null;
+            }
+        });
+        mStrokeAlphaAnimator.start();
+    }
+
+    public void drawBackgroundStroke(Canvas canvas) {
+        mPaint.setColor(ColorUtils.setAlphaComponent(mBgColor, mStrokeAlpha));
+        mPaint.setStyle(Paint.Style.STROKE);
+        mPaint.setStrokeWidth(mStrokeWidth);
+        drawCircle(canvas, 1 /* deltaRadius */);
+    }
+
+    public void drawLeaveBehind(Canvas canvas) {
+        float originalScale = mScale;
+        mScale = 0.5f;
+
+        mPaint.setStyle(Paint.Style.FILL);
+        mPaint.setColor(Color.argb(160, 245, 245, 245));
+        drawCircle(canvas, 0 /* deltaRadius */);
+
+        mScale = originalScale;
+    }
+
+    private void drawCircle(Canvas canvas,float deltaRadius) {
+        float radius = getScaledRadius();
+        canvas.drawCircle(radius + getOffsetX(), radius + getOffsetY(),
+                radius - deltaRadius, mPaint);
+    }
+
+    // It is the callers responsibility to save and restore the canvas layers.
+    void clipCanvasSoftware(Canvas canvas, Region.Op op) {
+        mPath.reset();
+        float r = getScaledRadius();
+        mPath.addCircle(r + getOffsetX(), r + getOffsetY(), r, Path.Direction.CW);
+        canvas.clipPath(mPath, op);
+    }
+
+    // It is the callers responsibility to save and restore the canvas layers.
+    void clipCanvasHardware(Canvas canvas) {
+        mPaint.setColor(Color.BLACK);
+        mPaint.setXfermode(mClipPorterDuffXfermode);
+
+        float radius = getScaledRadius();
+        mShaderMatrix.setScale(radius, radius);
+        mShaderMatrix.postTranslate(radius + getOffsetX(), radius + getOffsetY());
+        mClipShader.setLocalMatrix(mShaderMatrix);
+        mPaint.setShader(mClipShader);
+        canvas.drawPaint(mPaint);
+        mPaint.setXfermode(null);
+        mPaint.setShader(null);
+    }
+
+    private void delegateDrawing(CellLayout delegate, int cellX, int cellY) {
+        if (mDrawingDelegate != delegate) {
+            delegate.addFolderBackground(this);
+        }
+
+        mDrawingDelegate = delegate;
+        delegateCellX = cellX;
+        delegateCellY = cellY;
+
+        invalidate();
+    }
+
+    private void clearDrawingDelegate() {
+        if (mDrawingDelegate != null) {
+            mDrawingDelegate.removeFolderBackground(this);
+        }
+
+        mDrawingDelegate = null;
+        invalidate();
+    }
+
+    boolean drawingDelegated() {
+        return mDrawingDelegate != null;
+    }
+
+    private void animateScale(float finalScale, float finalMultiplier,
+                              final Runnable onStart, final Runnable onEnd) {
+        final float scale0 = mScale;
+        final float scale1 = finalScale;
+
+        final float bgMultiplier0 = mColorMultiplier;
+        final float bgMultiplier1 = finalMultiplier;
+
+        if (mScaleAnimator != null) {
+            mScaleAnimator.cancel();
+        }
+
+        mScaleAnimator = LauncherAnimUtils.ofFloat(0f, 1.0f);
+
+        mScaleAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
+            @Override
+            public void onAnimationUpdate(ValueAnimator animation) {
+                float prog = animation.getAnimatedFraction();
+                mScale = prog * scale1 + (1 - prog) * scale0;
+                mColorMultiplier = prog * bgMultiplier1 + (1 - prog) * bgMultiplier0;
+                invalidate();
+            }
+        });
+        mScaleAnimator.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationStart(Animator animation) {
+                if (onStart != null) {
+                    onStart.run();
+                }
+            }
+
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                if (onEnd != null) {
+                    onEnd.run();
+                }
+                mScaleAnimator = null;
+            }
+        });
+
+        mScaleAnimator.setDuration(CONSUMPTION_ANIMATION_DURATION);
+        mScaleAnimator.start();
+    }
+
+    public void animateToAccept(final CellLayout cl, final int cellX, final int cellY) {
+        Runnable onStart = new Runnable() {
+            @Override
+            public void run() {
+                delegateDrawing(cl, cellX, cellY);
+            }
+        };
+        animateScale(ACCEPT_SCALE_FACTOR, ACCEPT_COLOR_MULTIPLIER, onStart, null);
+    }
+
+    public void animateToRest() {
+        // This can be called multiple times -- we need to make sure the drawing delegate
+        // is saved and restored at the beginning of the animation, since cancelling the
+        // existing animation can clear the delgate.
+        final CellLayout cl = mDrawingDelegate;
+        final int cellX = delegateCellX;
+        final int cellY = delegateCellY;
+
+        Runnable onStart = new Runnable() {
+            @Override
+            public void run() {
+                delegateDrawing(cl, cellX, cellY);
+            }
+        };
+        Runnable onEnd = new Runnable() {
+            @Override
+            public void run() {
+                clearDrawingDelegate();
+            }
+        };
+        animateScale(1f, 1f, onStart, onEnd);
+    }
+
+    public int getBackgroundAlpha() {
+        return (int) Math.min(MAX_BG_OPACITY, BG_OPACITY * mColorMultiplier);
+    }
+
+    public float getStrokeWidth() {
+        return mStrokeWidth;
+    }
+}