PinnedHeaderListView.java

/*
 * Copyright (C) 2010 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.
 */

// modified by @author Bhavya Mehta
package com.marshalchen.common.demoofui.listviewfilter.ui;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import com.marshalchen.common.uimodule.listviewfilter.IIndexBarFilter;
import com.marshalchen.common.uimodule.listviewfilter.IPinnedHeader;
import com.marshalchen.common.demoofui.listviewfilter.PinnedHeaderAdapter;


/*
 * A ListView that maintains a header pinned at the top of the list. The
 * pinned header can be pushed up and dissolved as needed.
 */
public class PinnedHeaderListView extends ListView implements IIndexBarFilter {

    // interface object that configure pinned header view position in list view
    IPinnedHeader mAdapter;
    
    // view objects
    View mHeaderView,mIndexBarView,mPreviewTextView;

    // flags that decide view visibility
    boolean mHeaderVisibility=false;
    boolean mPreviewVisibility=false;
    // initially show index bar view with it's content
    boolean mIndexBarVisibility=true;
    
    // context object
	Context mContext;
    
    // view height and width
	int mHeaderViewWidth,
    	mHeaderViewHeight,    	
    	mIndexBarViewWidth,
    	mIndexBarViewHeight,
    	mIndexBarViewMargin,    	
    	mPreviewTextViewWidth,
    	mPreviewTextViewHeight;
    
	// touched index bar Y axis position used to decide preview text view position
    float mIndexBarY;
    
	
    public PinnedHeaderListView(Context context) {
        super(context);
        this.mContext = context;
    }

    
    public PinnedHeaderListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.mContext = context;
    }

    
    public PinnedHeaderListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.mContext = context;
    }
    
    
    @Override
    public void setAdapter(ListAdapter adapter) {
        this.mAdapter = (PinnedHeaderAdapter)adapter;
        super.setAdapter(adapter);
    }

    
    public void setPinnedHeaderView(View headerView) {
         this.mHeaderView = headerView;
        // Disable vertical fading when the pinned header is present
        // TODO change ListView to allow separate measures for top and bottom fading edge;
        // in this particular case we would like to disable the top, but not the bottom edge.
        if (mHeaderView != null) {
            setFadingEdgeLength(0);
        }
    }
    
    
    public void setIndexBarView(View indexBarView) {
		mIndexBarViewMargin = 40;
		this.mIndexBarView = indexBarView;
	}
	

	public void setPreviewView(View previewTextView) {
		this.mPreviewTextView=previewTextView;
	}
	
    
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        if (mHeaderView != null) {           
        	measureChild(mHeaderView, widthMeasureSpec, heightMeasureSpec);
            mHeaderViewWidth = mHeaderView.getMeasuredWidth();
            mHeaderViewHeight = mHeaderView.getMeasuredHeight();
        }  
   
        if (mIndexBarView != null && mIndexBarVisibility) {           
        	measureChild(mIndexBarView, widthMeasureSpec, heightMeasureSpec);
        	mIndexBarViewWidth = mIndexBarView.getMeasuredWidth();
        	mIndexBarViewHeight = mIndexBarView.getMeasuredHeight();
        } 
       
        if (mPreviewTextView != null && mPreviewVisibility) {           
	       	measureChild(mPreviewTextView, widthMeasureSpec, heightMeasureSpec);
	       	mPreviewTextViewWidth = mPreviewTextView.getMeasuredWidth();
	       	mPreviewTextViewHeight = mPreviewTextView.getMeasuredHeight();
        } 
    }

    
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
    	super.onLayout(changed, left, top, right, bottom);

    	if (mHeaderView != null) {
            mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
            configureHeaderView(getFirstVisiblePosition());
        }
    	        
    	if (mIndexBarView != null && mIndexBarVisibility) {
    		mIndexBarView.layout(getMeasuredWidth()- mIndexBarViewMargin - mIndexBarViewWidth, mIndexBarViewMargin
    				, getMeasuredWidth()- mIndexBarViewMargin, getMeasuredHeight()- mIndexBarViewMargin);
        }
    	
    	if (mPreviewTextView != null && mPreviewVisibility) {
    		mPreviewTextView.layout(mIndexBarView.getLeft()-mPreviewTextViewWidth, (int)mIndexBarY-(mPreviewTextViewHeight/2)
   				, mIndexBarView.getLeft(), (int)(mIndexBarY-(mPreviewTextViewHeight/2))+mPreviewTextViewHeight);
        }
    }
    
    
    public void setIndexBarVisibility(Boolean isVisible) {
        if(isVisible) {
            mIndexBarVisibility=true;
        }
        else {
            mIndexBarVisibility=false;
        }
    }
    
    
    private void setPreviewTextVisibility(Boolean isVisible) {
    	if(isVisible) {
    	    mPreviewVisibility=true;
    	}
    	else {
    	    mPreviewVisibility=false;       
    	}
    }
    
   
	public void configureHeaderView(int position) {
        if (mHeaderView == null) {
            return;
        }

        int state = mAdapter.getPinnedHeaderState(position);
        
        switch (state) {
            
            case IPinnedHeader.PINNED_HEADER_GONE: 
                mHeaderVisibility = false;
                break;            
            case IPinnedHeader.PINNED_HEADER_VISIBLE: 
                if (mHeaderView.getTop() != 0) {
                    mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
                }
                mAdapter.configurePinnedHeader(mHeaderView, position);
                mHeaderVisibility = true;
                break;            
            case IPinnedHeader.PINNED_HEADER_PUSHED_UP: 
                View firstView = getChildAt(0);
                int bottom = firstView.getBottom();
                // int itemHeight = firstView.getHeight();
                int headerHeight = mHeaderView.getHeight();
                int y;
                if (bottom < headerHeight) {
                    y = (bottom - headerHeight);
                }
                else {
                    y = 0;
                }
               
                if (mHeaderView.getTop() != y) {
                    mHeaderView.layout(0, y, mHeaderViewWidth, mHeaderViewHeight + y);
                }
                mAdapter.configurePinnedHeader(mHeaderView, position); 
                mHeaderVisibility = true;
                break;
        }
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
    	super.dispatchDraw(canvas);// draw list view elements (zIndex == 1)
       
        if (mHeaderView != null && mHeaderVisibility) {
            drawChild(canvas, mHeaderView, getDrawingTime()); // draw pinned header view (zIndex == 2)
        }
    	if (mIndexBarView != null && mIndexBarVisibility) {  
    		drawChild(canvas, mIndexBarView, getDrawingTime()); // draw index bar view (zIndex == 3)
    	}
        if (mPreviewTextView != null && mPreviewVisibility) { 
        	drawChild(canvas, mPreviewTextView, getDrawingTime()); // draw preview text view (zIndex == 4)
        }
    }
	
    
	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		if (mIndexBarView != null && ((IndexBarView)mIndexBarView).onTouchEvent(ev)) {
		    setPreviewTextVisibility(true);
			return true;	
		}
		else {
		    setPreviewTextVisibility(false);
			return super.onTouchEvent(ev);
		}
	}

	
	@Override
	public void filterList(float indexBarY, int position,String previewText) {
		this.mIndexBarY=indexBarY;

		if(mPreviewTextView instanceof TextView)
			((TextView)mPreviewTextView).setText(previewText);
		
		setSelection(position);
	}
}