Android Open Source - PulltorefreshListView List Header View

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Back to project page PulltorefreshListView.

License

The source code is released under:

Apache License

Java Source Code

package yaochangwei.pulltorefreshlistview.widget;
/*from   w w w . j  a va2 s. c o  m*/
import yaochangwei.pulltorefreshlistview.widget.RefreshableListView.OnHeaderViewChangedListener;
import android.content.Context;
import android.os.CountDownTimer;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;

public class ListHeaderView extends ViewGroup {

  /** Set the height of the list header */
  private int mHeight;

  /** Interpolator */
  private static final Interpolator sInterpolator = new Interpolator() {

    public float getInterpolation(float t) {
      t -= 1.0f;
      return t * t * t + 1.0f;
    }

  };

  /** Max Duration */
  private static final int MAX_DURATION = 350;

  private int mDistance;
  private int mInitHeight;
  private boolean mImediateUpdate = false;

  // The height when user release can trigger update.
  private int mUpdateHeight;

  protected RefreshableListView mListView;

  private static final int INVALID_STATE = -1;

  /** The state shoudl be when close execute */
  private int mNextState = INVALID_STATE;

  OnHeaderViewChangedListener mOnHeaderViewChangedListener;

  /** The header upate status control the header view */
  int mUpdatingStatus = UPDATING_IDLE;

  private static final int UPDATING_IDLE = 0;
  private static final int UPDATING_READY = 1;
  private static final int UPDATING_ON_GOING = 2;
  private static final int UPDATING_FINISH = 3;

  /** Max pull height. */
  private int mMaxPullHeight;

  private static final int MAX_PULL_HEIGHT_DP = 200;

  public ListHeaderView(Context context, RefreshableListView list) {
    super(context);
    mListView = list;
    mMaxPullHeight = (int) (context.getResources().getDisplayMetrics().density
        * MAX_PULL_HEIGHT_DP + 0.5f);
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    final View childView = getChildView();
    if (childView == null) {
      return;
    }

    final int childViewWidth = childView.getMeasuredWidth();
    final int childViewHeight = childView.getMeasuredHeight();
    final int measuredHeight = getMeasuredHeight();
    childView.layout(0, measuredHeight - childViewHeight, childViewWidth,
        measuredHeight);
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int width = MeasureSpec.getSize(widthMeasureSpec);
    if (mHeight < 0) {
      mHeight = 0;
    }
    setMeasuredDimension(width, mHeight);

    final View childView = getChildView();
    if (childView != null) {
      childView.measure(widthMeasureSpec, heightMeasureSpec);
      mUpdateHeight = childView.getMeasuredHeight();
    }
  }

  public void startUpdate(Runnable runnable) {
    mUpdatingStatus = UPDATING_READY;
    mUpdateRunnable = runnable;
    mInitHeight = mHeight;
    mDistance = mInitHeight - mUpdateHeight;
    if (mDistance < 0) {
      mDistance = mInitHeight;
    }
    // getChildView().setVisibility(View.INVISIBLE);
    int duration = (int) (mDistance * 3);
    duration = duration > MAX_DURATION ? MAX_DURATION : duration;
    Log.d(VIEW_LOG_TAG, "duration:" + duration);
    final CloseTimer timer = new CloseTimer(duration);
    timer.startTimer();
  }

  private Runnable mUpdateRunnable;

  public int close(int nextState) {
    mUpdatingStatus = UPDATING_FINISH;
    if (mOnHeaderViewChangedListener != null) {
      mOnHeaderViewChangedListener.onViewUpdateFinish(this);
    }
    mDistance = mInitHeight = mHeight;
    int duration = (int) (mDistance * 4);
    duration = duration > MAX_DURATION ? MAX_DURATION : duration;
    mNextState = nextState;
    final CloseTimer timer = new CloseTimer(duration);
    timer.startTimer();
    return duration;
  }

  public boolean isUpdateNeeded() {
    if (mImediateUpdate) {
      mImediateUpdate = false;
      return true;
    }

    final int distance = mHeight - mUpdateHeight;
    boolean needUpdate = distance >= 0;
    return needUpdate;
  }

  public void moveToUpdateHeight() {
    setHeaderHeight(mUpdateHeight);
    mImediateUpdate = true;
  }

  private class CloseTimer extends CountDownTimer {

    private long mStart;
    private float mDurationReciprocal;

    private static final int COUNT_DOWN_INTERVAL = 15;

    public CloseTimer(long millisInFuture) {
      super(millisInFuture, COUNT_DOWN_INTERVAL);
      mDurationReciprocal = 1.0f / millisInFuture;
    }

    public void startTimer() {
      mStart = AnimationUtils.currentAnimationTimeMillis();
      start();
    }

    @Override
    public void onFinish() {
      float x = 1.0f;
      if (mNextState != INVALID_STATE) {
        mListView.setState(mNextState);
        mNextState = INVALID_STATE;
      }
      setHeaderHeight((int) (mInitHeight - mDistance * x));
      if (mUpdateRunnable != null) {
        final Runnable runnable = mUpdateRunnable;
        new Thread(runnable).start();
        mUpdateRunnable = null;
      }
    }

    @Override
    public void onTick(long millisUntilFinished) {
      final int interval = (int) (AnimationUtils
          .currentAnimationTimeMillis() - mStart);
      float x = interval * mDurationReciprocal;
      x = sInterpolator.getInterpolation(x);
      setHeaderHeight((int) (mInitHeight - mDistance * x));
    }

  }

  protected View getChildView() {
    final int childCount = getChildCount();
    if (childCount != 1) {
      return null;
    }
    return getChildAt(0);
  }

  @Override
  public void addView(View child) {
    final int childCount = getChildCount();
    if (childCount > 0) {
      throw new IllegalStateException(
          "ListHeaderView can only have one child view");
    }
    super.addView(child);
  }

  private boolean mCanUpdate;

  public void setHeaderHeight(int height) {
    if (mHeight == height && height == 0) {
      // ignore duplicate 0 height setting.
      return;
    }

    if (height > mMaxPullHeight) {
      return;
    }

    final int updateHeight = mUpdateHeight;
    mHeight = height;

    if (mUpdatingStatus != UPDATING_IDLE) {
      if (mUpdatingStatus == UPDATING_READY
          && mOnHeaderViewChangedListener != null) {
        mOnHeaderViewChangedListener.onViewUpdating(this);
        mUpdatingStatus = UPDATING_ON_GOING;
      }
    } else {
      if ((height < updateHeight) && mCanUpdate) {
        if (mOnHeaderViewChangedListener != null) {
          mOnHeaderViewChangedListener.onViewChanged(this, false);
        }
        mCanUpdate = false;
      } else if ((height >= updateHeight) && !mCanUpdate) {
        if (mOnHeaderViewChangedListener != null) {
          mOnHeaderViewChangedListener.onViewChanged(this, true);
        }
        mCanUpdate = true;
      }
    }
    requestLayout();

    if (height == 0) {
      mUpdatingStatus = UPDATING_IDLE;
      mCanUpdate = false;
    }
  }

}

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