Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/widget/SlowedProgressBar.java

+// Copyright 2015 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.widget;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.util.AttributeSet;
+import android.widget.ProgressBar;
+
+import org.chromium.base.annotations.SuppressFBWarnings;
+
+/**
+ * A throttled version of {@link ProgressBar}.  This steals calls to
+ * {@link android.view.View#postInvalidateOnAnimation} and delays them if necessary to reach a
+ * specific FPS.
+ */
+public class SlowedProgressBar extends ProgressBar {
+    private long mLastDrawTimeMs = 0;
+    private boolean mPendingInvalidation = false;
+    private static final int MIN_MS_PER_FRAME = 66;
+    private int mTargetProgress;
+
+    private final Runnable mInvalidationRunnable = new Runnable() {
+        @Override
+        public void run() {
+            mPendingInvalidation = false;
+            invalidate();
+        }
+    };
+
+    private final Runnable mUpdateProgressRunnable = new Runnable() {
+        @Override
+        public void run() {
+            setProgressInternal(mTargetProgress);
+        }
+    };
+
+    /**
+     * Create a new progress bar with range 0...100 and initial progress of 0.
+     * @param context the application environment.
+     */
+    public SlowedProgressBar(Context context) {
+        super(context, null);
+    }
+
+    /**
+     * Create a new progress bar with range 0...100 and initial progress of 0.
+     * @param context the application environment.
+     * @param attrs the xml attributes that should be used to initialize this view.
+     */
+    public SlowedProgressBar(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    /**
+     * Create a new progress bar with range 0...100 and initial progress of 0.
+     * @param context the application environment.
+     * @param attrs the xml attributes that should be used to initialize this view.
+     * @param defStyle the default style to apply to this view.
+     */
+    public SlowedProgressBar(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    /**
+     * Keep track of the last time we drew.
+     */
+    @Override
+    public void onDraw(Canvas canvas) {
+        mLastDrawTimeMs = System.currentTimeMillis();
+        super.onDraw(canvas);
+    }
+
+    /**
+     * Delay invalidations to be no more than 1 per MIN_MS_PER_FRAME;
+     * never allow more than one invalidation outstanding.
+     */
+    @Override
+    public void postInvalidateOnAnimation() {
+        if (mPendingInvalidation) return;
+        long nextDrawTime = mLastDrawTimeMs + MIN_MS_PER_FRAME;
+        long delay = Math.max(0, nextDrawTime - System.currentTimeMillis());
+        mPendingInvalidation = true;
+        postOnAnimationDelayed(mInvalidationRunnable, delay);
+    }
+
+    /**
+     * Ensure invalidations always occurs in the scope of animation.
+     * @param progress The progress value to set the visuals to.
+     */
+    @SuppressFBWarnings("CHROMIUM_SYNCHRONIZED_METHOD")
+    @Override
+    public synchronized void setProgress(int progress) {
+        if (mTargetProgress == progress) return;
+        mTargetProgress = progress;
+        removeCallbacks(mUpdateProgressRunnable);
+        postOnAnimation(mUpdateProgressRunnable);
+    }
+
+    /**
+     * Called to update the progress visuals.
+     * @param progress The progress value to set the visuals to.
+     */
+    protected void setProgressInternal(int progress) {
+        super.setProgress(progress);
+    }
+}