自然息屏流程

USER_ACTIVITY_SCREEN_BRIGHT（亮屏） → USER_ACTIVITY_SCREEN_DIM（DIM） → USER_ACTIVITY_SCREEN_DREAM（灭屏）变化，最终进入ASLEEP后。在息屏时会执行一个变暗的动画

frameworks\base\services\core\java\com\android\server\display\DisplayPowerController.java

变暗的动画，执行动画代码中 会获取屏幕亮度，并且把亮度值进行转换：

private void animateScreenBrightness(float target, float sdrTarget, float rate) {
if (DEBUG) {
Slog.d(TAG, “Animating brightness: target=” + target + “, sdrTarget=” + sdrTarget
+ “, rate=” + rate);
}
if (mScreenBrightnessRampAnimator.animateTo(target, sdrTarget, rate)) {
Trace.traceCounter(Trace.TRACE_TAG_POWER, “TargetScreenBrightness”, (int) target);
// TODO(b/153319140) remove when we can get this from the above trace invocation
SystemProperties.set(“debug.tracing.screen_brightness”, String.valueOf(target));
noteScreenBrightness(target);
}
}

其中mScreenBrightnessRampAnimator.animateTo(target, sdrTarget, rate）在

frameworks\base\services\core\java\com\android\server\display\RampAnimator.java

public boolean animateTo(float targetLinear, float rate) {
// Convert the target from the linear into the HLG space.
final float target = BrightnessUtils.convertLinearToGamma(targetLinear);

    // Immediately jump to the target the first time.
    if (mFirstTime || rate <= 0) {
        if (mFirstTime || target != mCurrentValue) {
            mFirstTime = false;
            mRate = 0;
            mTargetValue = target;
            mCurrentValue = target;
            setPropertyValue(target);
            if (mAnimating) {
                mAnimating = false;
                cancelAnimationCallback();
            }
            if (mListener != null) {
                mListener.onAnimationEnd();
            }
            return true;
        }
        return false;
    }

    // Adjust the rate based on the closest target.
    // If a faster rate is specified, then use the new rate so that we converge
    // more rapidly based on the new request.
    // If a slower rate is specified, then use the new rate only if the current
    // value is somewhere in between the new and the old target meaning that
    // we will be ramping in a different direction to get there.
    // Otherwise, continue at the previous rate.
    if (!mAnimating
            || rate > mRate
            || (target <= mCurrentValue && mCurrentValue <= mTargetValue)
            || (mTargetValue <= mCurrentValue && mCurrentValue <= target)) {
        mRate = rate;
    }

    final boolean changed = (mTargetValue != target);
    mTargetValue = target;

    // Start animating.
    if (!mAnimating && target != mCurrentValue) {
        mAnimating = true;
        mAnimatedValue = mCurrentValue;
        mLastFrameTimeNanos = System.nanoTime();
        postAnimationCallback();
    }

    return changed;
}

其中setPropertyValue是设置亮度值

private void setPropertyValue(float val) {
final float linearVal = BrightnessUtils.convertGammaToLinear(val);
mProperty.setValue(mObject, linearVal);
}

再看2.中的

postAnimationCallback();
private void postAnimationCallback() {
mChoreographer.postCallback(Choreographer.CALLBACK_ANIMATION, mAnimationCallback, null);
}

private final Runnable mAnimationCallback = new Runnable() {
@Override // Choreographer callback
public void run() {
final long frameTimeNanos = mChoreographer.getFrameTimeNanos();
final float timeDelta = (frameTimeNanos - mLastFrameTimeNanos)
* 0.000000001f;
mLastFrameTimeNanos = frameTimeNanos;

        // Advance the animated value towards the target at the specified rate
        // and clamp to the target. This gives us the new current value but
        // we keep the animated value around to allow for fractional increments
        // towards the target.
        final float scale = ValueAnimator.getDurationScale();
        if (scale == 0) {
            // Animation off.
            mAnimatedValue = mTargetValue;
        } else {
            final float amount = timeDelta * mRate / scale;
            if (mTargetValue > mCurrentValue) {
                mAnimatedValue = Math.min(mAnimatedValue + amount, mTargetValue);
            } else {
                mAnimatedValue = Math.max(mAnimatedValue - amount, mTargetValue);
            }
        }
        final float oldCurrentValue = mCurrentValue;
        mCurrentValue = mAnimatedValue;
        if (!BrightnessSynchronizer.floatEquals(oldCurrentValue, mCurrentValue)) {
            setPropertyValue(mCurrentValue);
        }
        if (!BrightnessSynchronizer.floatEquals(mTargetValue, mCurrentValue)) {
            postAnimationCallback();
        } else {
            mAnimating = false;
            if (mListener != null) {
                mListener.onAnimationEnd();
            }
        }
    }
};

其中修改亮度调用的却是

if (!BrightnessSynchronizer.floatEquals(oldCurrentValue, mCurrentValue)) {
mProperty.setValue(mObject, mCurrentValue);
}
将此处改变亮度的api改成3.的设置亮度

if (!BrightnessSynchronizer.floatEquals(oldCurrentValue, mCurrentValue)) {
setPropertyValue(mCurrentValue);
}
其他项目此处是有谷歌提交记录 这个项目没完全改掉