android非常好用的抽屉控件

【实例截图】

【核心代码】

package com.zz;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
import android.view.animation.TranslateAnimation;
import android.widget.FrameLayout;
import android.widget.LinearLayout;

public class Panel extends LinearLayout {

    private static final String TAG = "Panel";

	/**
     * Callback invoked when the panel is opened/closed.
     */
    public static interface OnPanelListener {
        /**
         * Invoked when the panel becomes fully closed.
         */
        public void onPanelClosed(Panel panel);
        /**
         * Invoked when the panel becomes fully opened.
         */
        public void onPanelOpened(Panel panel);
    }
    
    private boolean mIsShrinking;
	private int mPosition;
	private int mDuration;
	private boolean mLinearFlying;
	private int mHandleId;
	private int mContentId;
	private View mHandle;
	private View mContent;
	private Drawable mOpenedHandle;
	private Drawable mClosedHandle;
	private float mTrackX;
	private float mTrackY;
	private float mVelocity;
	
	private OnPanelListener panelListener;

	public static final int TOP = 0;
	public static final int BOTTOM = 1;
	public static final int LEFT = 2;
	public static final int RIGHT = 3;
	
	private enum State {
		ABOUT_TO_ANIMATE,
		ANIMATING,
		READY,
		TRACKING,
		FLYING,
	};
	private State mState;
	private Interpolator mInterpolator;
	private GestureDetector mGestureDetector;
	private int mContentHeight;
	private int mContentWidth;
	private int mOrientation;
	private float mWeight;
	private PanelOnGestureListener mGestureListener;
	private boolean mBringToFront;
	
	public Panel(Context context, AttributeSet attrs) {
		super(context, attrs);
		TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.Panel);
		mDuration = a.getInteger(R.styleable.Panel_animationDuration, 750);		// duration defaults to 750 ms
		mPosition = a.getInteger(R.styleable.Panel_position, BOTTOM);			// position defaults to BOTTOM
		mLinearFlying = a.getBoolean(R.styleable.Panel_linearFlying, false);	// linearFlying defaults to false
		mWeight = a.getFraction(R.styleable.Panel_weight, 0, 1, 0.0f);			// weight defaults to 0.0
		if (mWeight < 0 || mWeight > 1) {
			mWeight = 0.0f;
			Log.w(TAG, a.getPositionDescription()   ": weight must be > 0 and <= 1");
		}
		mOpenedHandle = a.getDrawable(R.styleable.Panel_openedHandle);
		mClosedHandle = a.getDrawable(R.styleable.Panel_closedHandle);

		RuntimeException e = null;
		mHandleId = a.getResourceId(R.styleable.Panel_handle, 0);
		if (mHandleId == 0) {
			e = new IllegalArgumentException(a.getPositionDescription()   
					": The handle attribute is required and must refer to a valid child.");
		}
		mContentId = a.getResourceId(R.styleable.Panel_content, 0);
		if (mContentId == 0) {
			e = new IllegalArgumentException(a.getPositionDescription()   
					": The content attribute is required and must refer to a valid child.");
		}
		a.recycle();
		
		if (e != null) {
			throw e;
		}
		mOrientation = (mPosition == TOP || mPosition == BOTTOM)? VERTICAL : HORIZONTAL;
		setOrientation(mOrientation);
		mState = State.READY;
		mGestureListener = new PanelOnGestureListener();
		mGestureDetector = new GestureDetector(mGestureListener);
		mGestureDetector.setIsLongpressEnabled(false);
		
		// i DON'T really know why i need this...
		setBaselineAligned(false);
	}

    /**
     * Sets the listener that receives a notification when the panel becomes open/close.
     *
     * @param onPanelListener The listener to be notified when the panel is opened/closed.
     */
    public void setOnPanelListener(OnPanelListener onPanelListener) {
        panelListener = onPanelListener;
    }
    
    /**
     * Gets Panel's mHandle
     * 
     * @return Panel's mHandle
     */
    public View getHandle() {
		return mHandle;
	}
    
    /**
     * Gets Panel's mContent
     * 
     * @return Panel's mContent 
     */
    public View getContent() {
		return mContent;
	}

    
    /**
     * Sets the acceleration curve for panel's animation.
     * 
     * @param i The interpolator which defines the acceleration curve 
     */
    public void setInterpolator(Interpolator i) {
    	mInterpolator = i; 
    }
    
	/**
	 * Set the opened state of Panel.
     * 
     * @param open True if Panel is to be opened, false if Panel is to be closed.
	 * @param animate True if use animation, false otherwise.
	 *
	 * @return True if operation was performed, false otherwise.
	 * 
	 */
	public boolean setOpen(boolean open, boolean animate) {
		if (mState == State.READY && isOpen() ^ open) {
			mIsShrinking = !open;
			if (animate) {
				mState = State.ABOUT_TO_ANIMATE;
				if (!mIsShrinking) {
					// this could make flicker so we test mState in dispatchDraw()
					// to see if is equal to ABOUT_TO_ANIMATE
					mContent.setVisibility(VISIBLE);
				}
				post(startAnimation);
			} else {
				mContent.setVisibility(open? VISIBLE : GONE);
				postProcess();
			}
			return true;
		}
		return false;
	}

    /**
     * Returns the opened status for Panel.
     * 
     * @return True if Panel is opened, false otherwise.
     */
	public boolean isOpen() {
		return mContent.getVisibility() == VISIBLE;
	}

	@Override
	protected void onFinishInflate() {
		super.onFinishInflate();
		mHandle = findViewById(mHandleId);
		if (mHandle == null) {
			String name = getResources().getResourceEntryName(mHandleId);
            throw new RuntimeException("Your Panel must have a child View whose id attribute is 'R.id."   name   "'");
		}
		mHandle.setOnTouchListener(touchListener);
		mHandle.setOnClickListener(clickListener);
		
		mContent = findViewById(mContentId);
		if (mContent == null) {
			String name = getResources().getResourceEntryName(mHandleId);
            throw new RuntimeException("Your Panel must have a child View whose id attribute is 'R.id."   name   "'");
		}

		// reposition children
		removeView(mHandle);
		removeView(mContent);
		if (mPosition == TOP || mPosition == LEFT) {
			addView(mContent);
			addView(mHandle);
		} else {
			addView(mHandle);
			addView(mContent);
		}

		if (mClosedHandle != null) {
			mHandle.setBackgroundDrawable(mClosedHandle);
		}
		mContent.setClickable(true);
		mContent.setVisibility(GONE);
		if (mWeight > 0) {
			ViewGroup.LayoutParams params = mContent.getLayoutParams();
			if (mOrientation == VERTICAL) {
				params.height = ViewGroup.LayoutParams.FILL_PARENT;
			} else {
				params.width = ViewGroup.LayoutParams.FILL_PARENT;
			}
			mContent.setLayoutParams(params);
		}
	}

	@Override
	protected void onAttachedToWindow() {
		super.onAttachedToWindow();
		ViewParent parent = getParent();
		if (parent != null && parent instanceof FrameLayout) {
			mBringToFront = true;
		}
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		if (mWeight > 0 && mContent.getVisibility() == VISIBLE) {
			View parent = (View) getParent();
			if (parent != null) {
				if (mOrientation == VERTICAL) {
					heightMeasureSpec = MeasureSpec.makeMeasureSpec((int) (parent.getHeight() * mWeight), MeasureSpec.EXACTLY);
				} else {
					widthMeasureSpec = MeasureSpec.makeMeasureSpec((int) (parent.getWidth() * mWeight), MeasureSpec.EXACTLY);
				}
			}
		}
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
	}
	
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		super.onLayout(changed, l, t, r, b);
		mContentWidth = mContent.getWidth();
		mContentHeight = mContent.getHeight();
	}

	@Override
	protected void dispatchDraw(Canvas canvas) {
//		String name = getResources().getResourceEntryName(getId());
//		Log.d(TAG, name   " ispatchDraw "   mState);
		// this is why 'mState' was added:
		// avoid flicker before animation start
		if (mState == State.ABOUT_TO_ANIMATE && !mIsShrinking) {
			int delta = mOrientation == VERTICAL? mContentHeight : mContentWidth;
			if (mPosition == LEFT || mPosition == TOP) {
				delta = -delta;
			}
			if (mOrientation == VERTICAL) {
				canvas.translate(0, delta);
			} else {
				canvas.translate(delta, 0);
			}
		}
		if (mState == State.TRACKING || mState == State.FLYING) {
			canvas.translate(mTrackX, mTrackY);
		}
		super.dispatchDraw(canvas);
	}
	
	private float ensureRange(float v, int min, int max) {
		v = Math.max(v, min);
		v = Math.min(v, max);
		return v;
	}

	OnTouchListener touchListener = new OnTouchListener() {
		int initX;
		int initY;
		boolean setInitialPosition;
		public boolean onTouch(View v, MotionEvent event) {
			if (mState == State.ANIMATING) {
				// we are animating
				return false;
			}
//			Log.d(TAG, "state: "   mState   " x: "   event.getX()   " y: "   event.getY());
			int action = event.getAction();
			if (action == MotionEvent.ACTION_DOWN) {
				if (mBringToFront) {
					bringToFront();
				}
				initX = 0;
				initY = 0;
				if (mContent.getVisibility() == GONE) {
					// since we may not know content dimensions we use factors here
					if (mOrientation == VERTICAL) {
						initY = mPosition == TOP? -1 : 1;
					} else {
						initX = mPosition == LEFT? -1 : 1;
					}
				}
				setInitialPosition = true;
			} else {
				if (setInitialPosition) {
					// now we know content dimensions, so we multiply factors...
					initX *= mContentWidth;
					initY *= mContentHeight;
					// ... and set initial panel's position
					mGestureListener.setScroll(initX, initY);
					setInitialPosition = false;
					// for offsetLocation we have to invert values
					initX = -initX;
					initY = -initY;
				}
				// offset every ACTION_MOVE & ACTION_UP event 
				event.offsetLocation(initX, initY);
			}
			if (!mGestureDetector.onTouchEvent(event)) {
				if (action == MotionEvent.ACTION_UP) {
					// tup up after scrolling
					post(startAnimation);
				}
			}
			return false;
		}
	};
	
	OnClickListener clickListener = new OnClickListener() {
		public void onClick(View v) {
			if (mBringToFront) {
				bringToFront();
			}
			if (initChange()) {
				post(startAnimation);
			}
		}
	};

	public boolean initChange() {
		if (mState != State.READY) {
			// we are animating or just about to animate
			return false;
		}
		mState = State.ABOUT_TO_ANIMATE;
		mIsShrinking = mContent.getVisibility() == VISIBLE;
		if (!mIsShrinking) {
			// this could make flicker so we test mState in dispatchDraw()
			// to see if is equal to ABOUT_TO_ANIMATE
			mContent.setVisibility(VISIBLE);
		}
		return true;
	}

	Runnable startAnimation = new Runnable() {
		public void run() {
			// this is why we post this Runnable couple of lines above:
			// now its save to use mContent.getHeight() && mContent.getWidth()
			TranslateAnimation animation;
			int fromXDelta = 0, toXDelta = 0, fromYDelta = 0, toYDelta = 0;
			if (mState == State.FLYING) {
				mIsShrinking = (mPosition == TOP || mPosition == LEFT) ^ (mVelocity > 0);
			}
			int calculatedDuration;
			if (mOrientation == VERTICAL) {
				int height = mContentHeight;
				if (!mIsShrinking) {
					fromYDelta = mPosition == TOP? -height : height;
				} else {
					toYDelta = mPosition == TOP? -height : height;
				}
				if (mState == State.TRACKING) {
					if (Math.abs(mTrackY - fromYDelta) < Math.abs(mTrackY - toYDelta)) {
						mIsShrinking = !mIsShrinking;
						toYDelta = fromYDelta;
					}
					fromYDelta = (int) mTrackY;
				} else
				if (mState == State.FLYING) {
					fromYDelta = (int) mTrackY;
				}
				// for FLYING events we calculate animation duration based on flying velocity
				// also for very high velocity make sure duration >= 20 ms
				if (mState == State.FLYING && mLinearFlying) {
					calculatedDuration = (int) (1000 * Math.abs((toYDelta - fromYDelta) / mVelocity));
					calculatedDuration = Math.max(calculatedDuration, 20);
				} else {
					calculatedDuration = mDuration * Math.abs(toYDelta - fromYDelta) / mContentHeight;
				}
			} else {
				int width = mContentWidth;
				if (!mIsShrinking) {
					fromXDelta = mPosition == LEFT? -width : width;
				} else {
					toXDelta = mPosition == LEFT? -width : width;
				}
				if (mState == State.TRACKING) {
					if (Math.abs(mTrackX - fromXDelta) < Math.abs(mTrackX - toXDelta)) {
						mIsShrinking = !mIsShrinking;
						toXDelta = fromXDelta;
					}
					fromXDelta = (int) mTrackX;
				} else
				if (mState == State.FLYING) {
					fromXDelta = (int) mTrackX;
				}
				// for FLYING events we calculate animation duration based on flying velocity
				// also for very high velocity make sure duration >= 20 ms
				if (mState == State.FLYING && mLinearFlying) {
					calculatedDuration = (int) (1000 * Math.abs((toXDelta - fromXDelta) / mVelocity));
					calculatedDuration = Math.max(calculatedDuration, 20);
				} else {
					calculatedDuration = mDuration * Math.abs(toXDelta - fromXDelta) / mContentWidth;
				}
			}
			
			mTrackX = mTrackY = 0;
			if (calculatedDuration == 0) {
				mState = State.READY;
				if (mIsShrinking) {
					mContent.setVisibility(GONE);
				}
				postProcess();
				return;
			}
			
			animation = new TranslateAnimation(fromXDelta, toXDelta, fromYDelta, toYDelta);
			animation.setDuration(calculatedDuration);
			animation.setAnimationListener(animationListener);
			if (mState == State.FLYING && mLinearFlying) {
				animation.setInterpolator(new LinearInterpolator());
			} else
			if (mInterpolator != null) {
				animation.setInterpolator(mInterpolator);
			}
			startAnimation(animation);
		}
	};

	private AnimationListener animationListener = new AnimationListener() {
		public void onAnimationEnd(Animation animation) {
			mState = State.READY;
			if (mIsShrinking) {
				mContent.setVisibility(GONE);
			}
			postProcess();
		}
		public void onAnimationRepeat(Animation animation) {
		}
		public void onAnimationStart(Animation animation) {
			mState = State.ANIMATING;
		}
	};

	private void postProcess() {
		if (mIsShrinking && mClosedHandle != null) {
			mHandle.setBackgroundDrawable(mClosedHandle);
		} else
		if (!mIsShrinking && mOpenedHandle != null) {
			mHandle.setBackgroundDrawable(mOpenedHandle);
		}
		// invoke listener if any
		if (panelListener != null) {
			if (mIsShrinking) {
				panelListener.onPanelClosed(Panel.this);
			} else {
				panelListener.onPanelOpened(Panel.this);
			}
		}
	}
	
	class PanelOnGestureListener implements OnGestureListener {
		float scrollY;
		float scrollX;
		public void setScroll(int initScrollX, int initScrollY) {
			scrollX = initScrollX;
			scrollY = initScrollY;
		}
		public boolean onDown(MotionEvent e) {
			scrollX = scrollY = 0;
			initChange();
			return true;
		}
		public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
			mState = State.FLYING;
			mVelocity = mOrientation == VERTICAL? velocityY : velocityX;
			post(startAnimation);
			return true;
		}
		public void onLongPress(MotionEvent e) {
			// not used
		}
		public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
			mState = State.TRACKING;
			float tmpY = 0, tmpX = 0;
			if (mOrientation == VERTICAL) {
				scrollY -= distanceY;
				if (mPosition == TOP) {
					tmpY = ensureRange(scrollY, -mContentHeight, 0);
				} else  {
					tmpY = ensureRange(scrollY, 0, mContentHeight);
				}
			} else {
				scrollX -= distanceX;
				if (mPosition == LEFT) {
					tmpX = ensureRange(scrollX, -mContentWidth, 0);
				} else {
					tmpX = ensureRange(scrollX, 0, mContentWidth);
				}
			}
			if (tmpX != mTrackX || tmpY != mTrackY) {
				mTrackX = tmpX;
				mTrackY = tmpY;
				invalidate();
			}
			return true;
		}
		public void onShowPress(MotionEvent e) {
			// not used
		}
		public boolean onSingleTapUp(MotionEvent e) {
			// not used
			return false;
		}
	}
}