MultiSlidingDrawer多方向抽屉导航

项目需求很复杂，各种要求。官方的drawerlayout和开源的slidingmenu已经不能满足我们的需求了，所以MultiSlidingDrawer就诞生了，支持左、右、上、下。甚至是在其它容器里面。
源码:

package com.lee.ademo.view;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SoundEffectConstants;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.animation.RotateAnimation;

import com.lee.ademo.activity.R;

public class MultiSlidingDrawer extends ViewGroup {

	public static final int ORIENTATION_RTL = 0;
	public static final int ORIENTATION_BTT = 1;
	public static final int ORIENTATION_LTR = 2;
	public static final int ORIENTATION_TTB = 3;

	private static final int TAP_THRESHOLD = 6;
	private static final float MAXIMUM_TAP_VELOCITY = 100.0f;
	private static final float MAXIMUM_MINOR_VELOCITY = 150.0f;
	private static final float MAXIMUM_MAJOR_VELOCITY = 200.0f;
	private static final float MAXIMUM_ACCELERATION = 2000.0f;
	private static final int VELOCITY_UNITS = 1000;
	private static final int MSG_ANIMATE = 1000;
	private static final int ANIMATION_FRAME_DURATION = 1000 / 60;

	private static final int EXPANDED_FULL_OPEN = -10001;
	private static final int COLLAPSED_FULL_CLOSED = -10002;

	private final int mHandleId;
	private final int mContentId;

	private View mHandle;
	private View mContent;

	private final Rect mFrame = new Rect();
	private final Rect mInvalidate = new Rect();
	private boolean mTracking;
	private boolean mLocked;

	private VelocityTracker mVelocityTracker;

	private boolean mInvert;
	private boolean mVertical;
	private boolean mExpanded;
	private int mBottomOffset;
	private int mTopOffset;
	private int mHandleHeight;
	private int mHandleWidth;

	private OnDrawerOpenListener mOnDrawerOpenListener;
	private OnDrawerCloseListener mOnDrawerCloseListener;
	private OnDrawerScrollListener mOnDrawerScrollListener;

	private final Handler mHandler = new SlidingHandler();
	private float mAnimatedAcceleration;
	private float mAnimatedVelocity;
	private float mAnimationPosition;
	private long mAnimationLastTime;
	private long mCurrentAnimationTime;
	private int mTouchDelta;
	private boolean mAnimating;
	private boolean mAllowSingleTap;
	private boolean mAnimateOnClick;

	private final int mTapThreshold;
	private final int mMaximumTapVelocity;
	private int mMaximumMinorVelocity;
	private int mMaximumMajorVelocity;
	private int mMaximumAcceleration;
	private final int mVelocityUnits;

	public static interface OnDrawerOpenListener {
		public void onDrawerOpened();
	}

	public static interface OnDrawerCloseListener {
		public void onDrawerClosed();
	}

	public static interface OnDrawerScrollListener {
		public void onScrollStarted();

		public void onScrollEnded();
	}

	protected RotateAnimation openRotateAnimation;
	protected RotateAnimation closeRotateAnimation;

	public MultiSlidingDrawer(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public MultiSlidingDrawer(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		TypedArray a = context.obtainStyledAttributes(attrs,
				R.styleable.MultiSlidingDrawer, defStyle, 0);

		int orientation = a.getInt(R.styleable.MultiSlidingDrawer_direction,
				ORIENTATION_BTT);
		mVertical = (orientation == ORIENTATION_BTT || orientation == ORIENTATION_TTB);
		mBottomOffset = (int) a.getDimension(
				R.styleable.MultiSlidingDrawer_bottomOffset, 0.0f);
		mTopOffset = (int) a.getDimension(
				R.styleable.MultiSlidingDrawer_topOffset, 0.0f);
		mAllowSingleTap = a.getBoolean(
				R.styleable.MultiSlidingDrawer_allowSingleTap, true);
		mAnimateOnClick = a.getBoolean(
				R.styleable.MultiSlidingDrawer_animateOnClick, true);
		mInvert = (orientation == ORIENTATION_TTB || orientation == ORIENTATION_LTR);

		int handleId = a
				.getResourceId(R.styleable.MultiSlidingDrawer_handle, 0);
		if (handleId == 0) {
			throw new IllegalArgumentException(
					"The handle attribute is required and must refer "
							+ "to a valid child.");
		}

		int contentId = a.getResourceId(R.styleable.MultiSlidingDrawer_content,
				0);
		if (contentId == 0) {
			throw new IllegalArgumentException(
					"The content attribute is required and must refer "
							+ "to a valid child.");
		}

		if (handleId == contentId) {
			throw new IllegalArgumentException(
					"The content and handle attributes must refer "
							+ "to different children.");
		}
		mHandleId = handleId;
		mContentId = contentId;

		final float density = getResources().getDisplayMetrics().density;
		mTapThreshold = (int) (TAP_THRESHOLD * density + 0.5f);
		mMaximumTapVelocity = (int) (MAXIMUM_TAP_VELOCITY * density + 0.5f);
		mMaximumMinorVelocity = (int) (MAXIMUM_MINOR_VELOCITY * density + 0.5f);
		mMaximumMajorVelocity = (int) (MAXIMUM_MAJOR_VELOCITY * density + 0.5f);
		mMaximumAcceleration = (int) (MAXIMUM_ACCELERATION * density + 0.5f);
		mVelocityUnits = (int) (VELOCITY_UNITS * density + 0.5f);
		if (mInvert) {
			mMaximumAcceleration = -mMaximumAcceleration;
			mMaximumMajorVelocity = -mMaximumMajorVelocity;
			mMaximumMinorVelocity = -mMaximumMinorVelocity;
		}
		a.recycle();
		setAlwaysDrawnWithCacheEnabled(false);
		if (openRotateAnimation == null) {
			openRotateAnimation = new RotateAnimation(0, -180,
					RotateAnimation.RELATIVE_TO_SELF, 0.5f,
					RotateAnimation.RELATIVE_TO_SELF, 0.5f);
			openRotateAnimation.setFillAfter(true);
		}
		if (closeRotateAnimation == null) {
			closeRotateAnimation = new RotateAnimation(0, 0,
					RotateAnimation.RELATIVE_TO_SELF, 0.5f,
					RotateAnimation.RELATIVE_TO_SELF, 0.5f);
			closeRotateAnimation.setFillAfter(true);
		}
	}

	@Override
	protected void onFinishInflate() {
		mHandle = findViewById(mHandleId);
		if (mHandle == null) {
			throw new IllegalArgumentException(
					"The handle attribute is must refer to an"
							+ " existing child.");
		}
		mHandle.setOnClickListener(new DrawerToggler());

		mContent = findViewById(mContentId);
		if (mContent == null) {
			throw new IllegalArgumentException(
					"The content attribute is must refer to an"
							+ " existing child.");
		}
		mContent.setVisibility(View.GONE);
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
		int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);

		int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
		int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);

		if (widthSpecMode == MeasureSpec.UNSPECIFIED
				|| heightSpecMode == MeasureSpec.UNSPECIFIED) {
			throw new RuntimeException(
					"SlidingDrawer cannot have UNSPECIFIED dimensions");
		}

		final View handle = mHandle;
		measureChild(handle, widthMeasureSpec, heightMeasureSpec);

		if (mVertical) {
			int height = heightSpecSize - handle.getMeasuredHeight()
					- mTopOffset;
			mContent.measure(MeasureSpec.makeMeasureSpec(widthSpecSize,
					MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(height,
					MeasureSpec.EXACTLY));
		} else {
			int width = widthSpecSize - handle.getMeasuredWidth() - mTopOffset;
			mContent.measure(MeasureSpec.makeMeasureSpec(width,
					MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
					heightSpecSize, MeasureSpec.EXACTLY));
		}

		setMeasuredDimension(widthSpecSize, heightSpecSize);
	}

	@Override
	protected void dispatchDraw(Canvas canvas) {
		final long drawingTime = getDrawingTime();
		final View handle = mHandle;
		final boolean isVertical = mVertical;

		drawChild(canvas, handle, drawingTime);

		if (mTracking || mAnimating) {
			final Bitmap cache = mContent.getDrawingCache();
			if (cache != null) {
				if (isVertical) {
					if (mInvert) {
						canvas.drawBitmap(cache, 0, handle.getTop()
								- (getBottom() - getTop()) + mHandleHeight,
								null);
					} else {
						canvas.drawBitmap(cache, 0, handle.getBottom(), null);
					}
				} else {
					canvas.drawBitmap(cache,
							mInvert ? handle.getLeft() - cache.getWidth()
									: handle.getRight(), 0, null);
				}
			} else {
				canvas.save();
				if (mInvert) {
					canvas.translate(isVertical ? 0 : handle.getLeft()
							- mTopOffset - mContent.getMeasuredWidth(),
							isVertical ? handle.getTop() - mTopOffset
									- mContent.getMeasuredHeight() : 0);
				} else {
					canvas.translate(isVertical ? 0 : handle.getLeft()
							- mTopOffset, isVertical ? handle.getTop()
							- mTopOffset : 0);
				}
				drawChild(canvas, mContent, drawingTime);
				canvas.restore();
			}
			invalidate();
		} else if (mExpanded) {
			drawChild(canvas, mContent, drawingTime);
		}
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		if (mTracking) {
			return;
		}

		final int width = r - l;
		final int height = b - t;

		final View handle = mHandle;

		int handleWidth = handle.getMeasuredWidth();
		int handleHeight = handle.getMeasuredHeight();

		int handleLeft;
		int handleTop;

		final View content = mContent;

		if (mVertical) {
			handleLeft = (width - handleWidth) / 2;
			if (mInvert) {
				handleTop = mExpanded ? height - mBottomOffset - handleHeight
						: mTopOffset;
				content.layout(0, mTopOffset, content.getMeasuredWidth(),
						mTopOffset + content.getMeasuredHeight());
			} else {
				handleTop = mExpanded ? mTopOffset : height - handleHeight
						+ mBottomOffset;
				content.layout(0, mTopOffset + handleHeight,
						content.getMeasuredWidth(), mTopOffset + handleHeight
								+ content.getMeasuredHeight());
			}
		} else {
			handleTop = (height - handleHeight) / 2;
			if (mInvert) {
				handleLeft = mExpanded ? width - mBottomOffset - handleWidth
						: mTopOffset;
				content.layout(mTopOffset, 0,
						mTopOffset + content.getMeasuredWidth(),
						content.getMeasuredHeight());
			} else {
				handleLeft = mExpanded ? mTopOffset : width - handleWidth
						+ mBottomOffset;
				content.layout(mTopOffset + handleWidth, 0, mTopOffset
						+ handleWidth + content.getMeasuredWidth(),
						content.getMeasuredHeight());
			}
		}

		handle.layout(handleLeft, handleTop, handleLeft + handleWidth,
				handleTop + handleHeight);
		mHandleHeight = handle.getHeight();
		mHandleWidth = handle.getWidth();
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent event) {
		if (mLocked) {
			return false;
		}

		final int action = event.getAction();

		float x = event.getX();
		float y = event.getY();

		final Rect frame = mFrame;
		final View handle = mHandle;

		handle.getHitRect(frame);
		if (!mTracking && !frame.contains((int) x, (int) y)) {
			return false;
		}

		if (action == MotionEvent.ACTION_DOWN) {
			// 设置无背景
			mTracking = true;
			handle.setPressed(true);
			// Must be called before prepareTracking()
			prepareContent();

			// Must be called after prepareContent()
			if (mOnDrawerScrollListener != null) {
				mOnDrawerScrollListener.onScrollStarted();
			}

			if (mVertical) {
				final int top = mHandle.getTop();
				mTouchDelta = (int) y - top;
				prepareTracking(top);
			} else {
				final int left = mHandle.getLeft();
				mTouchDelta = (int) x - left;
				prepareTracking(left);
			}
			mVelocityTracker.addMovement(event);
		}

		return true;
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		if (mLocked) {
			return true;
		}

		if (mTracking) {
			mVelocityTracker.addMovement(event);
			final int action = event.getAction();
			switch (action) {
			case MotionEvent.ACTION_DOWN:
				break;
			case MotionEvent.ACTION_MOVE:
				moveHandle((int) (mVertical ? event.getY() : event.getX())
						- mTouchDelta);
				break;
			case MotionEvent.ACTION_UP:
			case MotionEvent.ACTION_CANCEL: {
				final VelocityTracker velocityTracker = mVelocityTracker;
				velocityTracker.computeCurrentVelocity(mVelocityUnits);

				float yVelocity = velocityTracker.getYVelocity();
				float xVelocity = velocityTracker.getXVelocity();
				boolean negative;

				final boolean vertical = mVertical;
				if (vertical) {
					negative = yVelocity < 0;
					if (xVelocity < 0) {
						xVelocity = -xVelocity;
					}
					// fix by Maciej Ciemięga.
					if ((!mInvert && xVelocity > mMaximumMinorVelocity)
							|| (mInvert && xVelocity < mMaximumMinorVelocity)) {
						xVelocity = mMaximumMinorVelocity;
					}
				} else {
					negative = xVelocity < 0;
					if (yVelocity < 0) {
						yVelocity = -yVelocity;
					}
					// fix by Maciej Ciemięga.
					if ((!mInvert && yVelocity > mMaximumMinorVelocity)
							|| (mInvert && yVelocity < mMaximumMinorVelocity)) {
						yVelocity = mMaximumMinorVelocity;
					}
				}

				float velocity = (float) Math.hypot(xVelocity, yVelocity);
				if (negative) {
					velocity = -velocity;
				}

				final int handleTop = mHandle.getTop();
				final int handleLeft = mHandle.getLeft();
				final int handleBottom = mHandle.getBottom();
				final int handleRight = mHandle.getRight();

				if (Math.abs(velocity) < mMaximumTapVelocity) {
					boolean c1;
					boolean c2;
					boolean c3;
					boolean c4;

					if (mInvert) {
						c1 = (mExpanded && (getBottom() - handleBottom) < mTapThreshold
								+ mBottomOffset);
						c2 = (!mExpanded && handleTop < mTopOffset
								+ mHandleHeight - mTapThreshold);
						c3 = (mExpanded && (getRight() - handleRight) < mTapThreshold
								+ mBottomOffset);
						c4 = (!mExpanded && handleLeft > mTopOffset
								+ mHandleWidth + mTapThreshold);
					} else {
						c1 = (mExpanded && handleTop < mTapThreshold
								+ mTopOffset);
						c2 = (!mExpanded && handleTop > mBottomOffset
								+ getBottom() - getTop() - mHandleHeight
								- mTapThreshold);
						c3 = (mExpanded && handleLeft < mTapThreshold
								+ mTopOffset);
						c4 = (!mExpanded && handleLeft > mBottomOffset
								+ getRight() - getLeft() - mHandleWidth
								- mTapThreshold);
					}

					if (vertical ? c1 || c2 : c3 || c4) {

						if (mAllowSingleTap) {
							playSoundEffect(SoundEffectConstants.CLICK);

							if (mExpanded) {
								animateClose(vertical ? handleTop : handleLeft);
							} else {
								animateOpen(vertical ? handleTop : handleLeft);
							}
						} else {
							performFling(vertical ? handleTop : handleLeft,
									velocity, false);
						}
					} else {
						performFling(vertical ? handleTop : handleLeft,
								velocity, false);
					}
				} else {
					performFling(vertical ? handleTop : handleLeft, velocity,
							false);
				}
			}
				break;
			}
		}
		return mTracking || mAnimating || super.onTouchEvent(event);
	}

	private void animateClose(int position) {
		prepareTracking(position);
		performFling(position, mMaximumAcceleration, true);
	}

	private void animateOpen(int position) {
		prepareTracking(position);
		performFling(position, -mMaximumAcceleration, true);
	}

	private void performFling(int position, float velocity, boolean always) {
		mAnimationPosition = position;
		mAnimatedVelocity = velocity;

		boolean c1;
		boolean c2;
		boolean c3;

		if (mExpanded) {
			int bottom = mVertical ? getBottom() : getRight();
			int handleHeight = mVertical ? mHandleHeight : mHandleWidth;

			c1 = mInvert ? velocity < mMaximumMajorVelocity
					: velocity > mMaximumMajorVelocity;
			c2 = mInvert ? (bottom - (position + handleHeight)) + mBottomOffset > handleHeight
					: position > mTopOffset
							+ (mVertical ? mHandleHeight : mHandleWidth);
			c3 = mInvert ? velocity < -mMaximumMajorVelocity
					: velocity > -mMaximumMajorVelocity;
			if (always || (c1 || (c2 && c3))) {
				// We are expanded, So animate to CLOSE!
				mAnimatedAcceleration = mMaximumAcceleration;
				if (mInvert) {
					if (velocity > 0) {
						mAnimatedVelocity = 0;
					}
				} else {
					if (velocity < 0) {
						mAnimatedVelocity = 0;
					}
				}
			} else {
				// We are expanded, but they didn't move sufficiently to cause
				// us to retract. Animate back to the expanded position. so
				// animate BACK to expanded!
				mAnimatedAcceleration = -mMaximumAcceleration;

				if (mInvert) {
					if (velocity < 0) {
						mAnimatedVelocity = 0;
					}
				} else {
					if (velocity > 0) {
						mAnimatedVelocity = 0;
					}
				}
			}
		} else {

			// WE'RE COLLAPSED

			c1 = mInvert ? velocity < mMaximumMajorVelocity
					: velocity > mMaximumMajorVelocity;
			c2 = mInvert ? (position < (mVertical ? getHeight() : getWidth()) / 2)
					: (position > (mVertical ? getHeight() : getWidth()) / 2);
			c3 = mInvert ? velocity < -mMaximumMajorVelocity
					: velocity > -mMaximumMajorVelocity;

			if (!always && (c1 || (c2 && c3))) {
				mAnimatedAcceleration = mMaximumAcceleration;

				if (mInvert) {
					if (velocity > 0) {
						mAnimatedVelocity = 0;
					}
				} else {
					if (velocity < 0) {
						mAnimatedVelocity = 0;
					}
				}
			} else {
				mAnimatedAcceleration = -mMaximumAcceleration;

				if (mInvert) {
					if (velocity < 0) {
						mAnimatedVelocity = 0;
					}
				} else {
					if (velocity > 0) {
						mAnimatedVelocity = 0;
					}
				}
			}
		}

		long now = SystemClock.uptimeMillis();
		mAnimationLastTime = now;
		mCurrentAnimationTime = now + ANIMATION_FRAME_DURATION;
		mAnimating = true;
		mHandler.removeMessages(MSG_ANIMATE);
		mHandler.sendMessageAtTime(mHandler.obtainMessage(MSG_ANIMATE),
				mCurrentAnimationTime);
		stopTracking();
	}

	private void prepareTracking(int position) {
		mTracking = true;
		mVelocityTracker = VelocityTracker.obtain();
		boolean opening = !mExpanded;

		if (opening) {
			mAnimatedAcceleration = mMaximumAcceleration;
			mAnimatedVelocity = mMaximumMajorVelocity;
			if (mInvert)
				mAnimationPosition = mTopOffset;
			else
				mAnimationPosition = mBottomOffset
						+ (mVertical ? getHeight() - mHandleHeight : getWidth()
								- mHandleWidth);
			moveHandle((int) mAnimationPosition);
			mAnimating = true;
			mHandler.removeMessages(MSG_ANIMATE);
			long now = SystemClock.uptimeMillis();
			mAnimationLastTime = now;
			mCurrentAnimationTime = now + ANIMATION_FRAME_DURATION;
			mAnimating = true;
		} else {
			if (mAnimating) {
				mAnimating = false;
				mHandler.removeMessages(MSG_ANIMATE);
			}
			moveHandle(position);
		}
	}

	private void moveHandle(int position) {
		final View handle = mHandle;

		if (mVertical) {
			if (position == EXPANDED_FULL_OPEN) {
				if (mInvert)
					handle.offsetTopAndBottom(mBottomOffset + getBottom()
							- getTop() - mHandleHeight);
				else
					handle.offsetTopAndBottom(mTopOffset - handle.getTop());
				invalidate();
			} else if (position == COLLAPSED_FULL_CLOSED) {
				if (mInvert) {
					handle.offsetTopAndBottom(mTopOffset - handle.getTop());
				} else {
					handle.offsetTopAndBottom(mBottomOffset + getBottom()
							- getTop() - mHandleHeight - handle.getTop());
				}
				invalidate();
			} else {
				final int top = handle.getTop();
				int deltaY = position - top;
				if (position < mTopOffset) {
					deltaY = mTopOffset - top;
				} else if (deltaY > mBottomOffset + getBottom() - getTop()
						- mHandleHeight - top) {
					deltaY = mBottomOffset + getBottom() - getTop()
							- mHandleHeight - top;
				}

				handle.offsetTopAndBottom(deltaY);

				final Rect frame = mFrame;
				final Rect region = mInvalidate;

				handle.getHitRect(frame);
				region.set(frame);

				region.union(frame.left, frame.top - deltaY, frame.right,
						frame.bottom - deltaY);
				region.union(0, frame.bottom - deltaY, getWidth(), frame.bottom
						- deltaY + mContent.getHeight());

				invalidate(region);
			}
		} else {
			if (position == EXPANDED_FULL_OPEN) {
				if (mInvert)
					handle.offsetLeftAndRight(mBottomOffset + getRight()
							- getLeft() - mHandleWidth);
				else
					handle.offsetLeftAndRight(mTopOffset - handle.getLeft());
				invalidate();
			} else if (position == COLLAPSED_FULL_CLOSED) {
				if (mInvert)
					handle.offsetLeftAndRight(mTopOffset - handle.getLeft());
				else
					handle.offsetLeftAndRight(mBottomOffset + getRight()
							- getLeft() - mHandleWidth - handle.getLeft());
				invalidate();
			} else {
				final int left = handle.getLeft();
				int deltaX = position - left;
				if (position < mTopOffset) {
					deltaX = mTopOffset - left;
				} else if (deltaX > mBottomOffset + getRight() - getLeft()
						- mHandleWidth - left) {
					deltaX = mBottomOffset + getRight() - getLeft()
							- mHandleWidth - left;
				}
				handle.offsetLeftAndRight(deltaX);

				final Rect frame = mFrame;
				final Rect region = mInvalidate;

				handle.getHitRect(frame);
				region.set(frame);

				region.union(frame.left - deltaX, frame.top, frame.right
						- deltaX, frame.bottom);
				region.union(frame.right - deltaX, 0, frame.right - deltaX
						+ mContent.getWidth(), getHeight());

				invalidate(region);
			}
		}
	}

	private void prepareContent() {
		if (mAnimating) {
			return;
		}

		// Something changed in the content, we need to honor the layout request
		// before creating the cached bitmap
		final View content = mContent;
		if (content.isLayoutRequested()) {

			if (mVertical) {
				final int handleHeight = mHandleHeight;
				int height = getBottom() - getTop() - handleHeight - mTopOffset;
				content.measure(MeasureSpec.makeMeasureSpec(getRight()
						- getLeft(), MeasureSpec.EXACTLY), MeasureSpec
						.makeMeasureSpec(height, MeasureSpec.EXACTLY));

				if (mInvert)
					content.layout(0, mTopOffset, content.getMeasuredWidth(),
							mTopOffset + content.getMeasuredHeight());
				else
					content.layout(
							0,
							mTopOffset + handleHeight,
							content.getMeasuredWidth(),
							mTopOffset + handleHeight
									+ content.getMeasuredHeight());

			} else {

				final int handleWidth = mHandle.getWidth();
				int width = getRight() - getLeft() - handleWidth - mTopOffset;
				content.measure(MeasureSpec.makeMeasureSpec(width,
						MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
						getBottom() - getTop(), MeasureSpec.EXACTLY));

				if (mInvert)
					content.layout(mTopOffset, 0,
							mTopOffset + content.getMeasuredWidth(),
							content.getMeasuredHeight());
				else
					content.layout(handleWidth + mTopOffset, 0, mTopOffset
							+ handleWidth + content.getMeasuredWidth(),
							content.getMeasuredHeight());
			}
		}
		// Try only once... we should really loop but it's not a big deal
		// if the draw was cancelled, it will only be temporary anyway
		content.getViewTreeObserver().dispatchOnPreDraw();
		content.buildDrawingCache();

		content.setVisibility(View.GONE);
	}

	private void stopTracking() {
		mHandle.setPressed(false);
		mTracking = false;

		if (mOnDrawerScrollListener != null) {
			mOnDrawerScrollListener.onScrollEnded();
		}

		if (mVelocityTracker != null) {
			mVelocityTracker.recycle();
			mVelocityTracker = null;
		}
	}

	private void doAnimation() {
		if (mAnimating) {
			incrementAnimation();

			if (mInvert) {
				if (mAnimationPosition < mTopOffset) {
					mAnimating = false;
					closeDrawer();
				} else if (mAnimationPosition >= mTopOffset
						+ (mVertical ? getHeight() : getWidth()) - 1) {
					mAnimating = false;
					openDrawer();
				} else {
					moveHandle((int) mAnimationPosition);
					mCurrentAnimationTime += ANIMATION_FRAME_DURATION;
					mHandler.sendMessageAtTime(
							mHandler.obtainMessage(MSG_ANIMATE),
							mCurrentAnimationTime);
				}
			} else {
				if (mAnimationPosition >= mBottomOffset
						+ (mVertical ? getHeight() : getWidth()) - 1) {
					mAnimating = false;
					closeDrawer();
				} else if (mAnimationPosition < mTopOffset) {
					mAnimating = false;
					openDrawer();
				} else {
					moveHandle((int) mAnimationPosition);
					mCurrentAnimationTime += ANIMATION_FRAME_DURATION;
					mHandler.sendMessageAtTime(
							mHandler.obtainMessage(MSG_ANIMATE),
							mCurrentAnimationTime);
				}
			}
		}
	}

	private void incrementAnimation() {
		long now = SystemClock.uptimeMillis();
		float t = (now - mAnimationLastTime) / 1000.0f; // ms -> s
		final float position = mAnimationPosition;
		final float v = mAnimatedVelocity; // px/s
		final float a = mInvert ? mAnimatedAcceleration : mAnimatedAcceleration; // px/s/s
		mAnimationPosition = position + (v * t) + (0.5f * a * t * t); // px
		mAnimatedVelocity = v + (a * t); // px/s
		mAnimationLastTime = now; // ms
	}

	public void toggle() {
		if (!mExpanded) {
			openDrawer();
		} else {
			closeDrawer();
		}
		invalidate();
		requestLayout();
	}

	public void animateToggle() {
		if (!mExpanded) {
			animateOpen();
		} else {
			animateClose();
		}
	}

	public void open() {
		openDrawer();
		invalidate();
		requestLayout();

		sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);
	}

	public void close() {
		closeDrawer();
		invalidate();
		requestLayout();
	}

	public void animateClose() {
		prepareContent();
		final OnDrawerScrollListener scrollListener = mOnDrawerScrollListener;
		if (scrollListener != null) {
			scrollListener.onScrollStarted();
		}
		animateClose(mVertical ? mHandle.getTop() : mHandle.getLeft());

		if (scrollListener != null) {
			scrollListener.onScrollEnded();
		}
	}

	public void animateOpen() {
		prepareContent();
		final OnDrawerScrollListener scrollListener = mOnDrawerScrollListener;
		if (scrollListener != null) {
			scrollListener.onScrollStarted();
		}
		animateOpen(mVertical ? mHandle.getTop() : mHandle.getLeft());

		sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);

		if (scrollListener != null) {
			scrollListener.onScrollEnded();
		}
	}

	private void closeDrawer() {
		moveHandle(COLLAPSED_FULL_CLOSED);
		mContent.setVisibility(View.GONE);
		mContent.destroyDrawingCache();

		if (!mExpanded) {
			return;
		}

		mExpanded = false;
		if (mOnDrawerCloseListener != null) {
			mOnDrawerCloseListener.onDrawerClosed();
		}
		mHandle.startAnimation(closeRotateAnimation);
	}

	private void openDrawer() {
		moveHandle(EXPANDED_FULL_OPEN);
		mContent.setVisibility(View.VISIBLE);

		if (mExpanded) {
			return;
		}

		mExpanded = true;

		if (mOnDrawerOpenListener != null) {
			mOnDrawerOpenListener.onDrawerOpened();
		}
		mHandle.startAnimation(openRotateAnimation);
	}

	public void setOnDrawerOpenListener(
			OnDrawerOpenListener onDrawerOpenListener) {
		mOnDrawerOpenListener = onDrawerOpenListener;
	}

	public void setOnDrawerCloseListener(
			OnDrawerCloseListener onDrawerCloseListener) {
		mOnDrawerCloseListener = onDrawerCloseListener;
	}

	public void setOnDrawerScrollListener(
			OnDrawerScrollListener onDrawerScrollListener) {
		mOnDrawerScrollListener = onDrawerScrollListener;
	}

	public View getHandle() {
		return mHandle;
	}

	public View getContent() {
		return mContent;
	}

	public void unlock() {
		mLocked = false;
	}

	public void lock() {
		mLocked = true;
	}

	public boolean isOpened() {
		return mExpanded;
	}

	public boolean isMoving() {
		return mTracking || mAnimating;
	}

	private class DrawerToggler implements OnClickListener {

		public void onClick(View v) {
			if (mLocked) {
				return;
			}
			// mAllowSingleTap isn't relevant here; you're *always*
			// allowed to open/close the drawer by clicking with the
			// trackball.
			if (mAnimateOnClick) {
				animateToggle();
			} else {
				toggle();
			}
		}
	}

	@SuppressLint("HandlerLeak")
	private class SlidingHandler extends Handler {

		public void handleMessage(Message m) {
			switch (m.what) {
			case MSG_ANIMATE:
				doAnimation();
				break;
			}
		}
	}
}

 

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