Android 滑动效果基础篇（四）—— Gallery + GridView

Android系统自带一个GridView和Gallery两个控件，GridView网格显示，Gallery单个浏览，两者结合起来可以真正实现Gallery浏览图片效果。

本示例通过GridView和Gallery两个控件，模仿实现一个完整的仿Gallery图像集的图片浏览效果。效果图如下：

1、GridView

首先，自定义一个GridImageAdapter图片适配器，用于填充GridView控件的图片

	public class GridImageAdapter extends BaseAdapter {
		private Context mContext;
		Drawable btnDrawable;

		public GridImageAdapter(Context context) {
			mContext = context;
			Resources resources = context.getResources();
			btnDrawable = resources.getDrawable(R.drawable.bg);
		}

		@Override
		public int getCount() {
			return ImageSource.mThumbIds.length;
		}

		@Override
		public Object getItem(int position) {
			return position;
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			ImageViewExt imageView;
			int space;

			if (convertView == null) {
				imageView = new ImageViewExt(mContext);
				if (imageCol == 5) {
					space = dm.heightPixels / imageCol - 6;
					imageView.setLayoutParams(new GridView.LayoutParams(space, space));
				} else {
					space = dm.widthPixels / imageCol - 6;
					imageView.setLayoutParams(new GridView.LayoutParams( space, space));
				}
				imageView.setAdjustViewBounds(true);
				imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);	// 缩放图片使其长和宽一样

				 imageView.setPadding(3, 3, 3, 3);
			} else {
				imageView = (ImageViewExt) convertView;
			}
			imageView.setImageResource(ImageSource.mThumbIds[position]);

			return imageView;
		}
	}

然后，用GridImageAdapter填充GridView

		gridView = (GridView) findViewById(R.id.myGrid);
		gridImageAdapter = new GridImageAdapter(this);
		gridView.setAdapter(gridImageAdapter);
		gridView.setOnItemClickListener(listener); // 设置点击监听事件

最后，设置GridView控件的点击监听事件

	AdapterView.OnItemClickListener listener = new AdapterView.OnItemClickListener() {
		@Override
		public void onItemClick(AdapterView<?> arg0, View arg1, int position, long id) {
			Intent intent = new Intent();
			intent.setClass(GridViewActivity.this, GalleryActivity.class);
			intent.putExtra("position", position);
			startActivity(intent);
		}
	};

2、Gallery

完成了GridView的图片显示、监听事件后，现在点击图片，会启动一个Activity来显示当前点击的图片，此时显示图片的控件便是Gallery

首先，同GridView一样，自定义一个ImageAdapter图片适配器，用来填充Gallery

	public class ImageAdapter extends BaseAdapter {
		private Context mContext; 
		private int mPos;

		public ImageAdapter(Context context) {
			mContext = context;
		}

		public void setOwnposition(int ownposition) {
			this.mPos = ownposition;
		}

		public int getOwnposition() {
			return mPos;
		}

		@Override
		public int getCount() {
			return ImageSource.mThumbIds.length;
		}

		@Override
		public Object getItem(int position) { 
			mPos=position;
			return position;
		}

		@Override
		public long getItemId(int position) {
			mPos=position; 
			return position;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			mPos=position;
			ImageView imageview = new ImageView(mContext);
			imageview.setBackgroundColor(0xFF000000);
			imageview.setScaleType(ImageView.ScaleType.FIT_CENTER);
			imageview.setLayoutParams(new myGallery.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
			imageview.setImageResource(ImageSource.mThumbIds[position]);
			
			return imageview;
		}
	}

然后，用ImageAdapter填充Gallery

		myGallery  galllery = (myGallery) findViewById(R.id.mygallery);
		Intent intent = getIntent();
		position = intent.getIntExtra("position", 0);	// 获取GridViewActivity传来的图片位置position 
		ImageAdapter imgAdapter=new ImageAdapter(this);		
		galllery.setAdapter(imgAdapter);		// 设置图片ImageAdapter
		galllery.setSelection(position); 		// 设置当前显示图片
	 	
	 	Animation an= AnimationUtils.loadAnimation(this,R.anim.scale );		// Gallery动画
	 	galllery.setAnimation(an); 

此时，如果细心可以注意到，我们的Gallery也是自己定义的myGallery，具体定义如下：

public class myGallery extends Gallery {
	boolean isFirst = false;
	boolean isLast = false;

	public myGallery(Context context) {
		super(context);
	}

	public myGallery(Context context, AttributeSet paramAttributeSet) {
		super(context, paramAttributeSet);
	}

	/** 是否向左滑动（true - 向左滑动； false - 向右滑动） */
	private boolean isScrollingLeft(MotionEvent e1, MotionEvent e2) {	
		return e2.getX() > e1.getX();
	}

	@Override
	public boolean onFling(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
		ImageAdapter ia = (ImageAdapter) this.getAdapter();
		int p = ia.getOwnposition();	// 获取当前图片的position
		int count = ia.getCount();		// 获取全部图片的总数count
		int kEvent;
		if (isScrollingLeft(e1, e2)) {
			if (p == 0 && isFirst) {
				Toast.makeText(this.getContext(), "已是第一页", Toast.LENGTH_SHORT).show();
			} else if (p == 0) {
				isFirst = true;
			} else {
				isLast = false;
			}

			kEvent = KeyEvent.KEYCODE_DPAD_LEFT;
		} else {
			if (p == count - 1 && isLast) {
				Toast.makeText(this.getContext(), "已到最后一页", Toast.LENGTH_SHORT).show();
			} else if (p == count - 1) {
				isLast = true;
			} else {
				isFirst = false;
			}

			kEvent = KeyEvent.KEYCODE_DPAD_RIGHT;
		}
		onKeyDown(kEvent, null);
		return true;
	}
}

GalleryActivity的布局文件gallery.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="horizontal"
    android:padding="10dip" >
    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#000000"
        android:padding="2dip" >
        <com.homer.gridgallery.myGallery
            android:id="@+id/mygallery"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:spacing="16dp" />
    </RelativeLayout>
</LinearLayout>

源码下载

参考推荐：

GridView

Grid View tutorial

Gallery

Gallery tutorial

ViewGroup