Unifying focus indicator handling for workspace and all-apps

Adding an abstract FocusIndicatorHelper based on FocusIndicatorView
which draws the background instead of using a dummy view.

Change-Id: Id560195323d2ddad8fcd77ba675cf3f4fd4a94ab

3 files changed, 379 insertions, 0 deletions

diff --git a/src/com/android/launcher3/keyboard/FocusIndicatorHelper.java b/src/com/android/launcher3/keyboard/FocusIndicatorHelper.java
new file mode 100644
index 000000000..7672f5a79
--- /dev/null
+++ b/src/com/android/launcher3/keyboard/FocusIndicatorHelper.java
@@ -0,0 +1,242 @@
+/*
+ * Copyright (C) 2016 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.keyboard;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.ObjectAnimator;
+import android.animation.PropertyValuesHolder;
+import android.animation.RectEvaluator;
+import android.animation.ValueAnimator;
+import android.animation.ValueAnimator.AnimatorUpdateListener;
+import android.annotation.TargetApi;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.Rect;
+import android.os.Build.VERSION_CODES;
+import android.util.Property;
+import android.view.View;
+import android.view.View.OnFocusChangeListener;
+
+import com.android.launcher3.R;
+
+/**
+ * A helper class to draw background of a focused view.
+ */
+@TargetApi(VERSION_CODES.LOLLIPOP)
+public abstract class FocusIndicatorHelper implements
+        OnFocusChangeListener, AnimatorUpdateListener {
+
+    private static final float MIN_VISIBLE_ALPHA = 0.2f;
+    private static final long ANIM_DURATION = 150;
+
+    public static final Property<FocusIndicatorHelper, Float> ALPHA =
+            new Property<FocusIndicatorHelper, Float>(Float.TYPE, "alpha") {
+                @Override
+                public void set(FocusIndicatorHelper object, Float value) {
+                    object.setAlpha(value);
+                }
+
+                @Override
+                public Float get(FocusIndicatorHelper object) {
+                    return object.mAlpha;
+                }
+            };
+
+    public static final Property<FocusIndicatorHelper, Float> SHIFT =
+            new Property<FocusIndicatorHelper, Float>(
+                    Float.TYPE, "shift") {
+
+                @Override
+                public void set(FocusIndicatorHelper object, Float value) {
+                    object.mShift = value;
+                }
+
+                @Override
+                public Float get(FocusIndicatorHelper object) {
+                    return object.mShift;
+                }
+            };
+
+    private static final RectEvaluator RECT_EVALUATOR = new RectEvaluator(new Rect());
+    private static final Rect sTempRect1 = new Rect();
+    private static final Rect sTempRect2 = new Rect();
+
+    private final View mContainer;
+    private final Paint mPaint;
+    private final int mMaxAlpha;
+
+    private final Rect mDirtyRect = new Rect();
+    private boolean mIsDirty = false;
+
+    private View mLastFocusedView;
+
+    private View mCurrentView;
+    private View mTargetView;
+    /**
+     * The fraction indicating the position of the focusRect between {@link #mCurrentView}
+     * & {@link #mTargetView}
+     */
+    private float mShift;
+
+    private ObjectAnimator mCurrentAnimation;
+    private float mAlpha;
+
+    public FocusIndicatorHelper(View container) {
+        mContainer = container;
+
+        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+        int color = container.getResources().getColor(R.color.focused_background);
+        mMaxAlpha = Color.alpha(color);
+        mPaint.setColor(0xFF000000 | color);
+
+        setAlpha(0);
+        mShift = 0;
+    }
+
+    protected void setAlpha(float alpha) {
+        mAlpha = alpha;
+        mPaint.setAlpha((int) (mAlpha * mMaxAlpha));
+    }
+
+    @Override
+    public void onAnimationUpdate(ValueAnimator animation) {
+        invalidateDirty();
+    }
+
+    protected void invalidateDirty() {
+        if (mIsDirty) {
+            mContainer.invalidate(mDirtyRect);
+            mIsDirty = false;
+        }
+
+        Rect newRect = getDrawRect();
+        if (newRect != null) {
+            mContainer.invalidate(newRect);
+        }
+    }
+
+    public void draw(Canvas c) {
+        if (mAlpha > 0) {
+            Rect newRect = getDrawRect();
+            if (newRect != null) {
+                mDirtyRect.set(newRect);
+                c.drawRect(mDirtyRect, mPaint);
+                mIsDirty = true;
+            }
+        }
+    }
+
+    private Rect getDrawRect() {
+        if (mCurrentView != null) {
+            viewToRect(mCurrentView, sTempRect1);
+
+            if (mShift > 0 && mTargetView != null) {
+                viewToRect(mTargetView, sTempRect2);
+                return RECT_EVALUATOR.evaluate(mShift, sTempRect1, sTempRect2);
+            } else {
+                return sTempRect1;
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public void onFocusChange(View v, boolean hasFocus) {
+        if (hasFocus) {
+            endCurrentAnimation();
+
+            if (mAlpha > MIN_VISIBLE_ALPHA) {
+                mTargetView = v;
+
+                mCurrentAnimation = ObjectAnimator.ofPropertyValuesHolder(this,
+                        PropertyValuesHolder.ofFloat(ALPHA, 1),
+                        PropertyValuesHolder.ofFloat(SHIFT, 1));
+                mCurrentAnimation.addListener(new ViewSetListener(v, true));
+            } else {
+                setCurrentView(v);
+
+                mCurrentAnimation = ObjectAnimator.ofPropertyValuesHolder(this,
+                        PropertyValuesHolder.ofFloat(ALPHA, 1));
+            }
+
+            mLastFocusedView = v;
+        } else {
+            if (mLastFocusedView == v) {
+                mLastFocusedView = null;
+                endCurrentAnimation();
+                mCurrentAnimation = ObjectAnimator.ofPropertyValuesHolder(this,
+                        PropertyValuesHolder.ofFloat(ALPHA, 0));
+                mCurrentAnimation.addListener(new ViewSetListener(null, false));
+            }
+        }
+
+        // invalidate once
+        invalidateDirty();
+
+        mLastFocusedView = hasFocus ? v : null;
+        if (mCurrentAnimation != null) {
+            mCurrentAnimation.addUpdateListener(this);
+            mCurrentAnimation.setDuration(ANIM_DURATION).start();
+        }
+    }
+
+    protected void endCurrentAnimation() {
+        if (mCurrentAnimation != null) {
+            mCurrentAnimation.cancel();
+            mCurrentAnimation = null;
+        }
+    }
+
+    protected void setCurrentView(View v) {
+        mCurrentView = v;
+        mShift = 0;
+        mTargetView = null;
+    }
+
+    /**
+     * Gets the position of {@param v} relative to {@link #mContainer}.
+     */
+    public abstract void viewToRect(View v, Rect outRect);
+
+    private class ViewSetListener extends AnimatorListenerAdapter {
+        private final View mViewToSet;
+        private final boolean mCallOnCancel;
+        private boolean mCalled = false;
+
+        public ViewSetListener(View v, boolean callOnCancel) {
+            mViewToSet = v;
+            mCallOnCancel = callOnCancel;
+        }
+
+        @Override
+        public void onAnimationCancel(Animator animation) {
+            if (!mCallOnCancel) {
+                mCalled = true;
+            }
+        }
+
+        @Override
+        public void onAnimationEnd(Animator animation) {
+            if (!mCalled) {
+                setCurrentView(mViewToSet);
+                mCalled = true;
+            }
+        }
+    }
+}
diff --git a/src/com/android/launcher3/keyboard/FocusedItemDecorator.java b/src/com/android/launcher3/keyboard/FocusedItemDecorator.java
new file mode 100644
index 000000000..9c80b0f08
--- /dev/null
+++ b/src/com/android/launcher3/keyboard/FocusedItemDecorator.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2016 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.keyboard;
+
+import android.graphics.Canvas;
+import android.graphics.Rect;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.ItemDecoration;
+import android.support.v7.widget.RecyclerView.State;
+import android.view.View;
+import android.view.View.OnFocusChangeListener;
+
+/**
+ * {@link ItemDecoration} for drawing and animating focused view background.
+ */
+public class FocusedItemDecorator extends ItemDecoration {
+
+    private FocusIndicatorHelper mHelper;
+
+    public FocusedItemDecorator(View container) {
+        mHelper = new FocusIndicatorHelper(container) {
+
+            @Override
+            public void viewToRect(View v, Rect outRect) {
+                outRect.set(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
+            }
+        };
+    }
+
+    public OnFocusChangeListener getFocusListener() {
+        return mHelper;
+    }
+
+    @Override
+    public void onDraw(Canvas c, RecyclerView parent, State state) {
+        mHelper.draw(c);
+    }
+}
diff --git a/src/com/android/launcher3/keyboard/ViewGroupFocusHelper.java b/src/com/android/launcher3/keyboard/ViewGroupFocusHelper.java
new file mode 100644
index 000000000..bd5c06e5b
--- /dev/null
+++ b/src/com/android/launcher3/keyboard/ViewGroupFocusHelper.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2016 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.keyboard;
+
+import android.graphics.Rect;
+import android.view.View;
+import android.view.View.OnFocusChangeListener;
+
+import com.android.launcher3.PagedView;
+
+/**
+ * {@link FocusIndicatorHelper} for a generic view group.
+ */
+public class ViewGroupFocusHelper extends FocusIndicatorHelper {
+
+    private final View mContainer;
+
+    public ViewGroupFocusHelper(View container) {
+        super(container);
+        mContainer = container;
+    }
+
+    @Override
+    public void viewToRect(View v, Rect outRect) {
+        outRect.left = 0;
+        outRect.top = 0;
+
+        computeLocationRelativeToContainer(v, outRect);
+
+        // If a view is scaled, its position will also shift accordingly. For optimization, only
+        // consider this for the last node.
+        outRect.left += (1 - v.getScaleX()) * v.getWidth() / 2;
+        outRect.top += (1 - v.getScaleY()) * v.getHeight() / 2;
+
+        outRect.right = outRect.left + (int) (v.getScaleX() * v.getWidth());
+        outRect.bottom = outRect.top + (int) (v.getScaleY() * v.getHeight());
+    }
+
+    private void computeLocationRelativeToContainer(View child, Rect outRect) {
+        View parent = (View) child.getParent();
+        outRect.left += child.getLeft();
+        outRect.top += child.getTop();
+
+        if (parent != mContainer) {
+            if (parent instanceof PagedView) {
+                PagedView page = (PagedView) parent;
+                outRect.left -= page.getScrollForPage(page.indexOfChild(child));
+            }
+
+            computeLocationRelativeToContainer(parent, outRect);
+        }
+    }
+
+    /**
+     * Sets the alpha of this FocusIndicatorHelper to 0 when a view with this listener
+     * receives focus.
+     */
+    public View.OnFocusChangeListener getHideIndicatorOnFocusListener() {
+        return new OnFocusChangeListener() {
+            @Override
+            public void onFocusChange(View v, boolean hasFocus) {
+                if (hasFocus) {
+                    endCurrentAnimation();
+                    setCurrentView(null);
+                    setAlpha(0);
+                    invalidateDirty();
+                }
+            }
+        };
+    }
+}