Add support for highlighting menu items

chrome/android/java/src/org/chromium/chrome/browser/appmenu/PulseDrawable.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.appmenu;
+
+import android.content.res.Resources;
+import android.graphics.Canvas;
+import android.graphics.ColorFilter;
+import android.graphics.Paint;
+import android.graphics.PixelFormat;
+import android.graphics.Rect;
+import android.graphics.drawable.Animatable;
+import android.graphics.drawable.Drawable;
+import android.os.SystemClock;
+import android.support.annotation.ColorInt;
+import android.support.annotation.ColorRes;
+import android.view.animation.Interpolator;
+
+import org.chromium.base.ApiCompatibilityUtils;
+
+/**
+ * A custom {@link Drawable} that will animate a pulse using the {@link PulseInterpolator}.  Meant
+ * to be created with a {@link PulseDrawable#Painter} that does the actual drawing work based on
+ * the pulse interpolation value.
+ */
+public class PulseDrawable extends Drawable implements Animatable {
+    private static final long PULSE_DURATION_MS = 2500;
+    private static final long FRAME_RATE = 60;
+
+    /**
+     * An interface that does the actual drawing work for this {@link Drawable}.  Not meant to be
+     * stateful, as this could be shared across multiple instances of this drawable if it gets
+     * copied or mutated.
+     */
+    public interface Painter {
+        /**
+         * Called when this drawable updates it's pulse interpolation.  Should mutate the drawable
+         * as necessary.  This is responsible for invalidating this {@link Drawable} if something
+         * needs to be redrawn.
+         *
+         * @param drawable      The {@link PulseDrawable} that is updated.
+         * @param interpolation The current progress of whatever is being pulsed.
+         */
+        void modifyDrawable(PulseDrawable drawable, float interpolation);
+
+        /**
+         * Called when this {@link PulseDrawable} needs to draw.  Should perform any draw operation
+         * for the specific type of pulse.
+         * @param drawable      The calling {@link PulseDrawable}.
+         * @param paint         A {@link Paint} object to use.  This will automatically have the
+         *                      color set.
+         * @param canvas        The {@link Canvas} to draw to.
+         * @param interpolation The current progress of whatever is being pulsed.
+         */
+        void draw(PulseDrawable drawable, Paint paint, Canvas canvas, float interpolation);
+    }
+
+    private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+    private final Rect mInset = new Rect();
+    private final Rect mOriginalBounds = new Rect();
+    private final Rect mInsetBounds = new Rect();
+
+    protected PulseState mState;

[Ted C, 2017/04/12 18:05:57]

why protected?

[David Trainor- moved to gerrit, 2017/04/12 18:59:37]

Ah I was planning on overriding this class for the sub-types... but found out I
couldn't easily do that because of the constant state.

+    private boolean mMutated;
+    private boolean mRunning;
+
+    /**
+     * Creates a new {@link PulseDrawable} instance.
+     * @param res          A {@link Resources} object used to load the {@link Drawable} parameters.
+     * @param color        A color resource.
+     * @param interpolator An {@link Interpolator} that defines how the pulse will fade in and out.
+     * @param painter      The {@link Painter} that will be responsible for drawing the pulse.
+     */
+    public PulseDrawable(
+            Resources res, @ColorRes int color, Interpolator interpolator, Painter painter) {
+        this(new PulseState(res, color, interpolator, painter));
+    }
+
+    private PulseDrawable(PulseState state) {
+        mState = state;
+    }
+
+    /** What color to set the pulse to. */
+    public void setColor(@ColorInt int color) {

[Ted C, 2017/04/12 18:05:57]

I'd rather this not be configurable right now.  I'd rather never get to a state
where we
use anything but one color

[David Trainor- moved to gerrit, 2017/04/12 18:59:37]

I can have it set light/dark if you'd like.  We only need two colors internally.

+        int alpha = getAlpha();
+        mState.color = mState.drawColor = color;
+        setAlpha(alpha);
+        invalidateSelf();
+    }
+
+    /** How much to inset the bounds of this {@link Drawable} by. */
+    public void setInset(int left, int top, int right, int bottom) {
+        mInset.set(left, top, right, bottom);
+        setBounds(mOriginalBounds);

[Ted C, 2017/04/12 18:05:57]

Should we only call this if !mOriginalBounds.isEmpty()?

[David Trainor- moved to gerrit, 2017/04/12 18:59:37]

Yes good point.

+    }
+
+    // Animatable implementation.
+    @Override
+    public void start() {
+        if (mRunning) {
+            unscheduleSelf(mNextFrame);
+            scheduleSelf(mNextFrame, SystemClock.uptimeMillis() + 1000 / FRAME_RATE);
+        } else {
+            mRunning = true;
+            if (mState.startTime == 0) mState.startTime = SystemClock.uptimeMillis();
+            mNextFrame.run();
+        }
+    }
+
+    @Override
+    public void stop() {
+        mRunning = false;
+        mState.startTime = 0;
+        unscheduleSelf(mNextFrame);
+    }
+
+    @Override
+    public boolean isRunning() {
+        return mRunning;
+    }
+
+    // Drawable implementation.
+    // Overriding only this method because {@link Drawable#setBounds(Rect)} calls into this.
+    @Override
+    public void setBounds(int left, int top, int right, int bottom) {
+        mOriginalBounds.set(left, top, right, bottom);
+        mInsetBounds.set(
+                left + mInset.left, top + mInset.top, right - mInset.right, bottom - mInset.bottom);
+        super.setBounds(
+                mInsetBounds.left, mInsetBounds.top, mInsetBounds.right, mInsetBounds.bottom);
+    }
+
+    @Override
+    public void draw(Canvas canvas) {
+        mPaint.setColor(mState.drawColor);
+        mState.painter.draw(this, mPaint, canvas, mState.progress);
+    }
+
+    @Override
+    public void setAlpha(int alpha) {
+        // Encode the alpha into the color.
+        alpha += alpha >> 7; // make it 0..256
+        final int baseAlpha = mState.color >>> 24;
+        final int useAlpha = baseAlpha * alpha >> 8;
+        final int useColor = (mState.color << 8 >>> 8) | (useAlpha << 24);
+        if (mState.drawColor != useColor) {
+            mState.drawColor = useColor;
+            invalidateSelf();
+        }
+    }
+
+    @Override
+    public int getAlpha() {
+        return mState.drawColor >>> 24;
+    }
+
+    @Override
+    public void setColorFilter(ColorFilter colorFilter) {
+        mPaint.setColorFilter(colorFilter);
+    }
+
+    @Override
+    public int getOpacity() {
+        return PixelFormat.TRANSLUCENT;
+    }
+
+    @Override
+    public boolean setVisible(boolean visible, boolean restart) {
+        final boolean changed = super.setVisible(visible, restart);
+        if (visible) {
+            if (changed || restart) start();
+        } else {
+            stop();
+        }
+        return changed;
+    }
+
+    @Override
+    public Drawable mutate() {
+        if (!mMutated && super.mutate() == this) {
+            mState = new PulseState(mState);
+            mMutated = true;
+        }
+        return this;
+    }
+
+    @Override
+    public ConstantState getConstantState() {
+        return mState;
+    }
+
+    private void stepPulse() {
+        long curTime = SystemClock.uptimeMillis();
+        long msIntoAnim = (curTime - mState.startTime) % PULSE_DURATION_MS;
+        float progress = ((float) msIntoAnim) / ((float) PULSE_DURATION_MS);
+        mState.progress = mState.interpolator.getInterpolation(progress);
+        mState.painter.modifyDrawable(PulseDrawable.this, mState.progress);
+    }
+
+    /**
+     * The {@link ConstantState} subclass for this {@link PulseDrawable}.
+     */
+    private static final class PulseState extends ConstantState {
+        // Current Paint State.
+        /** The current color, including alpha, to draw. */
+        public int drawColor;
+
+        /** The original color to draw (may not include any alpha updates. */

[Ted C, 2017/04/12 18:05:57]

may not, or does not?  also missing trailing )

I thought this always was the original color and never had the alpha modified.

[David Trainor- moved to gerrit, 2017/04/12 18:59:37]

It depends on whether or not the color passed in had alpha to begin with.

+        public int color;
+
+        // Current Animation State
+        /** The time from {@link SystemClock#updateMillis()} that this animation started at. */
+        public long startTime;
+
+        /** The current progress from 0 to 1 of the pulse. */
+        public float progress;
+
+        /** The {@link Interpolator} that makes the pulse and generates the progress. */
+        public Interpolator interpolator;
+
+        /**
+         * The {@link Painter} object that is responsible for modifying and drawing this
+         * {@link PulseDrawable}.
+         */
+        public Painter painter;
+
+        PulseState(Resources res, @ColorRes int color, Interpolator interpolator, Painter painter) {
+            this.color = this.drawColor = ApiCompatibilityUtils.getColor(res, color);
+
+            this.interpolator = new PulseInterpolator(interpolator);
+            this.painter = painter;
+        }
+
+        PulseState(PulseState other) {
+            drawColor = other.drawColor;
+            color = other.color;
+
+            startTime = other.startTime;
+
+            interpolator = other.interpolator;
+            painter = other.painter;
+        }
+
+        @Override
+        public Drawable newDrawable() {
+            return new PulseDrawable(this);
+        }
+
+        @Override
+        public int getChangingConfigurations() {
+            return 0;
+        }
+    }
+
+    private final Runnable mNextFrame = new Runnable() {

[Ted C, 2017/04/12 18:05:57]

I'd put this above the constructor as it is a local variable.

[David Trainor- moved to gerrit, 2017/04/12 18:59:37]

Done.

+        @Override
+        public void run() {
+            stepPulse();
+            if (mRunning) scheduleSelf(mNextFrame, SystemClock.uptimeMillis() + 1000 / FRAME_RATE);
+        }
+    };
+}