1 files changed, 114 insertions, 0 deletions
diff --git a/src/com/android/launcher3/graphics/ScrimView.java b/src/com/android/launcher3/graphics/ScrimView.java
new file mode 100644
index 000000000..feb3f030f
--- /dev/null
+++ b/src/com/android/launcher3/graphics/ScrimView.java
@@ -0,0 +1,114 @@
+/*
+ * 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.graphics;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.RectF;
+import android.support.v4.graphics.ColorUtils;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.animation.AccelerateInterpolator;
+import android.view.animation.Interpolator;
+
+import com.android.launcher3.R;
+import com.android.launcher3.Utilities;
+
+public class ScrimView extends View {
+
+    private static final boolean DEBUG = false;
+
+    private static final int MASK_HEIGHT_DP = 300;
+    private static final float MASK_START_LENGTH_FACTOR = 1f;
+    private static final float FINAL_ALPHA = 0.87f;
+    private static final int SCRIM_COLOR = ColorUtils.setAlphaComponent(
+            Color.WHITE, (int) (FINAL_ALPHA * 255));
+    private static final boolean APPLY_ALPHA = true;
+
+    private static Bitmap sFinalScrimMask;
+    private static Bitmap sAlphaScrimMask;
+
+    private final int mMaskHeight;
+    private int mVisibleHeight;
+    private final int mHeadStart;
+
+    private final RectF mAlphaMaskRect = new RectF();
+    private final RectF mFinalMaskRect = new RectF();
+    private final Paint mPaint = new Paint();
+    private float mProgress;
+    private final Interpolator mAccelerator = new AccelerateInterpolator();
+    private final Paint mDebugPaint = DEBUG ? new Paint() : null;
+
+    public ScrimView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        mMaskHeight = Utilities.pxFromDp(MASK_HEIGHT_DP, getResources().getDisplayMetrics());
+        mHeadStart = (int) (mMaskHeight * MASK_START_LENGTH_FACTOR);
+        mPaint.setColor(SCRIM_COLOR);
+
+        if (sFinalScrimMask == null) {
+            sFinalScrimMask = Utilities.convertToAlphaMask(
+                    Utilities.createOnePixBitmap(), FINAL_ALPHA);
+        }
+        if (sAlphaScrimMask == null) {
+            Bitmap alphaMaskFromResource = BitmapFactory.decodeResource(getResources(),
+                    R.drawable.all_apps_alpha_mask);
+            sAlphaScrimMask = Utilities.convertToAlphaMask(alphaMaskFromResource, FINAL_ALPHA);
+        }
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+        int width = MeasureSpec.getSize(widthMeasureSpec);
+        mVisibleHeight = MeasureSpec.getSize(heightMeasureSpec);
+        setMeasuredDimension(width, mVisibleHeight * 2);
+        setProgress(mProgress);
+    }
+
+    public void setProgress(float progress) {
+        mProgress = progress;
+        float initialY = mVisibleHeight - mHeadStart;
+        float fullTranslationY = mVisibleHeight;
+        float linTranslationY = initialY - progress * fullTranslationY;
+        setTranslationY(linTranslationY);
+
+        if (APPLY_ALPHA) {
+            int alpha = 55 + (int) (200f * mAccelerator.getInterpolation(progress));
+            mPaint.setAlpha(alpha);
+            invalidate();
+        }
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        mAlphaMaskRect.set(0, 0, getWidth(), mMaskHeight);
+        mFinalMaskRect.set(0, mMaskHeight, getWidth(), getHeight());
+        canvas.drawBitmap(sAlphaScrimMask, null, mAlphaMaskRect, mPaint);
+        canvas.drawBitmap(sFinalScrimMask, null, mFinalMaskRect, mPaint);
+
+        if (DEBUG) {
+            mDebugPaint.setColor(0xFF0000FF);
+            canvas.drawLine(0, mAlphaMaskRect.top, getWidth(), mAlphaMaskRect.top, mDebugPaint);
+            canvas.drawLine(0, mAlphaMaskRect.bottom, getWidth(), mAlphaMaskRect.bottom, mDebugPaint);
+        }
+    }
+
+}