Fix app to folder icon animation.

- Needed to account for the preview bounds (similar to BubbleTextView icon
  bounds)
- Also needed to update the bitmap shift amount so that it is re-centered
- Moved ShiftedBitmapDrawable to its own class in graphics package

Bug: 123900446
Change-Id: Ifa9e3f688e55d017cf86a0285f5cdb1b014f01e6

src/com/android/launcher3/graphics/ShiftedBitmapDrawable.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2019 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.graphics;
+
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.ColorFilter;
+import android.graphics.Paint;
+import android.graphics.PixelFormat;
+import android.graphics.drawable.Drawable;
+
+/**
+ * A simple drawable which draws a bitmap at a fixed position irrespective of the bounds
+ */
+public class ShiftedBitmapDrawable extends Drawable {
+
+    private final Paint mPaint = new Paint(Paint.FILTER_BITMAP_FLAG);
+    private final Bitmap mBitmap;
+    private float mShiftX;
+    private float mShiftY;
+
+    public ShiftedBitmapDrawable(Bitmap bitmap, float shiftX, float shiftY) {
+        mBitmap = bitmap;
+        mShiftX = shiftX;
+        mShiftY = shiftY;
+    }
+
+    public float getShiftX() {
+        return mShiftX;
+    }
+
+    public float getShiftY() {
+        return mShiftY;
+    }
+
+    public void setShiftX(float shiftX) {
+        mShiftX = shiftX;
+    }
+
+    public void setShiftY(float shiftY) {
+        mShiftY = shiftY;
+    }
+
+    @Override
+    public void draw(Canvas canvas) {
+        canvas.drawBitmap(mBitmap, mShiftX, mShiftY, mPaint);
+    }
+
+    @Override
+    public void setAlpha(int i) { }
+
+    @Override
+    public void setColorFilter(ColorFilter colorFilter) {
+        mPaint.setColorFilter(colorFilter);
+    }
+
+    @Override
+    public int getOpacity() {
+        return PixelFormat.TRANSLUCENT;
+    }
+}