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/*
* Copyright (C) 2013 Google Inc.
* Licensed to 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.mail.ui;
import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.GradientDrawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Interpolator;
import com.android.mail.R;
/**
* Procedurally-drawn version of a horizontal indeterminate progress bar. Draws faster and more
* frequently (by making use of the animation timer), requires minimal memory overhead, and allows
* some configuration via attributes:
* <ul>
* <li>barColor (color attribute for the bar's solid color)
* <li>barHeight (dimension attribute for the height of the solid progress bar)
* <li>detentWidth (dimension attribute for the width of each transparent detent in the bar)
* </ul>
* <p>
* This progress bar has no intrinsic height, so you must declare it with one explicitly. (It will
* use the given height as the bar's shadow height.)
*/
public class ButteryProgressBar extends View {
private final GradientDrawable mShadow;
private final ValueAnimator mAnimator;
private final Paint mPaint = new Paint();
private final int mBarColor;
private final int mSolidBarHeight;
private final int mSolidBarDetentWidth;
private final float mDensity;
private int mSegmentCount;
/**
* The baseline width that the other constants below are optimized for.
*/
private static final int BASE_WIDTH_DP = 300;
/**
* A reasonable animation duration for the given width above. It will be weakly scaled up and
* down for wider and narrower widths, respectively-- the goal is to provide a relatively
* constant detent velocity.
*/
private static final int BASE_DURATION_MS = 500;
/**
* A reasonable number of detents for the given width above. It will be weakly scaled up and
* down for wider and narrower widths, respectively.
*/
private static final int BASE_SEGMENT_COUNT = 5;
private static final int DEFAULT_BAR_HEIGHT_DP = 4;
private static final int DEFAULT_DETENT_WIDTH_DP = 3;
public ButteryProgressBar(Context c) {
this(c, null);
}
public ButteryProgressBar(Context c, AttributeSet attrs) {
super(c, attrs);
mDensity = c.getResources().getDisplayMetrics().density;
final TypedArray ta = c.obtainStyledAttributes(attrs, R.styleable.ButteryProgressBar);
try {
mBarColor = ta.getColor(R.styleable.ButteryProgressBar_barColor,
c.getResources().getColor(android.R.color.holo_blue_light));
mSolidBarHeight = ta.getDimensionPixelSize(
R.styleable.ButteryProgressBar_barHeight,
Math.round(DEFAULT_BAR_HEIGHT_DP * mDensity));
mSolidBarDetentWidth = ta.getDimensionPixelSize(
R.styleable.ButteryProgressBar_detentWidth,
Math.round(DEFAULT_DETENT_WIDTH_DP * mDensity));
} finally {
ta.recycle();
}
mAnimator = new ValueAnimator();
mAnimator.setFloatValues(1.0f, 2.0f);
mAnimator.setRepeatCount(ValueAnimator.INFINITE);
mAnimator.setInterpolator(new ExponentialInterpolator());
mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
invalidate();
}
});
mPaint.setColor(mBarColor);
mShadow = new GradientDrawable(GradientDrawable.Orientation.TOP_BOTTOM,
new int[]{(mBarColor & 0x00ffffff) | 0x22000000, 0});
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
if (changed) {
final int w = getWidth();
mShadow.setBounds(0, mSolidBarHeight, w, getHeight() - mSolidBarHeight);
final float widthMultiplier = w / mDensity / BASE_WIDTH_DP;
// simple scaling by width is too aggressive, so dampen it first
final float durationMult = 0.3f * (widthMultiplier - 1) + 1;
final float segmentMult = 0.1f * (widthMultiplier - 1) + 1;
mAnimator.setDuration((int) (BASE_DURATION_MS * durationMult));
mSegmentCount = (int) (BASE_SEGMENT_COUNT * segmentMult);
}
}
@Override
protected void onDraw(Canvas canvas) {
if (!mAnimator.isStarted()) {
return;
}
mShadow.draw(canvas);
final float val = (Float) mAnimator.getAnimatedValue();
final int w = getWidth();
// Because the left-most segment doesn't start all the way on the left, and because it moves
// towards the right as it animates, we need to offset all drawing towards the left. This
// ensures that the left-most detent starts at the left origin, and that the left portion
// is never blank as the animation progresses towards the right.
final int offset = w >> mSegmentCount - 1;
// segments are spaced at half-width, quarter, eighth (powers-of-two). to maintain a smooth
// transition between segments, we used a power-of-two interpolator.
for (int i = 0; i < mSegmentCount; i++) {
final float l = val * (w >> (i + 1));
final float r = (i == 0) ? w + offset : l * 2;
canvas.drawRect(l + mSolidBarDetentWidth - offset, 0, r - offset, mSolidBarHeight,
mPaint);
}
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
start();
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
stop();
}
@Override
protected void onVisibilityChanged(View changedView, int visibility) {
super.onVisibilityChanged(changedView, visibility);
if (visibility == VISIBLE) {
start();
} else {
stop();
}
}
private void start() {
if (getVisibility() != VISIBLE) {
return;
}
mAnimator.start();
}
private void stop() {
mAnimator.cancel();
}
private static class ExponentialInterpolator implements Interpolator {
@Override
public float getInterpolation(float input) {
return (float) Math.pow(2.0, input) - 1;
}
}
}
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