Top level screen for App Fuel Gauge.

Shows sorted list of power usage (with some debug information) by the top 10
apps and subsystems. Doesn't yet take into account certain subsystems such
as data network usage, audio/video DSP usage, Bluetooth and lights other than
screen backlight.

Screen, Idle, Wifi and Voice usage and CPU time are accounted for.

Also need to add detail screens for each item and suggested actions.

src/com/android/settings/fuelgauge/PowerGaugePreference.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2009 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.settings.fuelgauge;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.ColorFilter;
+import android.graphics.PixelFormat;
+import android.graphics.drawable.Drawable;
+import android.preference.Preference;
+import android.view.View;
+import android.widget.ImageView;
+
+import com.android.settings.R;
+
+/**
+ * Custom preference for displaying power consumption as a bar and an icon on the left for the
+ * subsystem/app type.
+ *
+ */
+public class PowerGaugePreference extends Preference {
+
+    private Drawable mIcon;
+    private GaugeDrawable mGauge;
+    private double mValue;
+
+    public PowerGaugePreference(Context context, Drawable icon) {
+        super(context);
+        setLayoutResource(R.layout.preference_powergauge);
+        mIcon = icon;
+        mGauge = new GaugeDrawable();
+        mGauge.bar = context.getResources().getDrawable(R.drawable.app_gauge);
+    }
+
+    /**
+     * Sets the width of the gauge in percentage (0 - 100)
+     * @param percent
+     */
+    void setGaugeValue(double percent) {
+        mValue = percent;
+        mGauge.percent = mValue;
+    }
+
+    @Override
+    protected void onBindView(View view) {
+        super.onBindView(view);
+
+        ImageView appIcon = (ImageView) view.findViewById(R.id.appIcon);
+        if (mIcon == null) {
+            mIcon = getContext().getResources().getDrawable(android.R.drawable.sym_def_app_icon);
+        }
+        appIcon.setImageDrawable(mIcon);
+
+        ImageView appGauge = (ImageView) view.findViewById(R.id.appGauge);
+        appGauge.setImageDrawable(mGauge);
+    }
+
+    static class GaugeDrawable extends Drawable {
+        Drawable bar;
+        double percent;
+        int lastWidth = -1;
+
+        @Override
+        public void draw(Canvas canvas) {
+            if (lastWidth == -1) {
+                lastWidth = getBarWidth();
+                bar.setBounds(0, 0, lastWidth, bar.getIntrinsicHeight());
+            }
+            bar.draw(canvas);
+        }
+
+        @Override
+        public int getOpacity() {
+            return PixelFormat.TRANSLUCENT;
+        }
+
+        @Override
+        public void setAlpha(int alpha) {
+            // Ignore
+        }
+
+        @Override
+        public void setColorFilter(ColorFilter cf) {
+            // Ignore
+        }
+
+        private int getBarWidth() {
+            int width = (int) ((this.getBounds().width() * percent) / 100);
+            int intrinsicWidth = bar.getIntrinsicWidth();
+            return Math.max(width, intrinsicWidth);
+        }
+
+        @Override
+        public int getIntrinsicHeight() {
+            return bar.getIntrinsicHeight();
+        }
+    }
+}