gridview作为android开发中常用的组件，其功能十分强大。但是，我们有时候有很多特殊的需求，需要在其基础上进行改造。有时候会有移动gridView中item位置的需求，这个网上已经有很多例子，博主就不在描述。今天博主讲的是移动gridView中item中的内容。博主没看过网上那些移动item位置的demo，不知道其原理是不是和博主想的一样。博主思考过，似乎博主的这种实现原理似乎也可以用作实现移动item位置。而之前博主百思不得其解的小米手机的桌面的自定义乱序排放，似乎也可以用这个原理去实现。好了，废话不多说，先上效果图
这里博主就以数字为内容来演示，不同的数字item的背景颜色不同来区分，长按住一个item后可以移动，每次移动，移动的item减1，移动到的item加1。效果还可以吧。好了，上代码，大家一起学习。了解其实现原理的同学完全可以自己修改代码开发可移动item的gridView
完整项目下载地址：http://download.csdn.net/detail/victorfreedom/8326829
（最近网络不给力，github上传有问题，等明天最后一篇自定义view专题讲解完了，再将所有项目一起上传吧，不介意那点分的同学可以先下载）
package com.freedom.gridview;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Bitmap;import android.graphics.PixelFormat;import android.util.AttributeSet;import android.view.Gravity;import android.view.MotionEvent;import android.view.View;import android.view.ViewConfiguration;import android.view.ViewGroup;import android.view.WindowManager;import android.view.animation.AnimationUtils;import android.widget.AdapterView;import android.widget.GridView;import android.widget.ImageView;import android.widget.Toast;import com.freedom.gridview.adapter.GridViewAdapter;import com.freedom.gridview.bean.Data;/** * @ClassName: FreedomGridView * @author victor_freedom ([email protected]) * @createddate 2015-1-4 下午10:25:52 * @Description: 可移动item内容的gridView */@SuppressLint("NewApi")public class FreedomGridView extends GridView { // 是否在移动中 private boolean isMove = false; // 是否是第一次移动 private boolean isFirst = true; // 是否是长按 private boolean isLongClick = false; // 图形 private Bitmap bitmap; // 移动的视图 private ImageView moveView = null; // 偏移量 private int offsetX, offsetY; // 在屏幕中触摸的位置 private int touchPositionInScreen; // 移动的目的位置 private int moveToPosition; // 在ITEM中触摸的坐标 private int touchPositionInItemX, touchPositionInItemY; // 移动速度 private int scaledTouchSlop; // 移动过程中，上下边距判定自动滑动距离 private int upScrollBounce; private int downScrollBounce; // 窗体管理者，用于添加视图 private WindowManager windowManager = null; private WindowManager.LayoutParams layoutParams = null; private GridViewAdapter adapter; public FreedomGridView(Context context) { super(context); scaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); } public FreedomGridView(Context context, AttributeSet attrs) { super(context, attrs); } public FreedomGridView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } /** * 长按判定 */ private Runnable longPressRun = new Runnable() { @Override public void run() { isLongClick = true; } }; /** * @Title: contains * @Description: 判断是否触摸坐标是否在视图里面 * @param v * @param xInView * @param yInView * @return * @throws */ private boolean contains(View v, int xInView, int yInView) { if (v instanceof ImageView) { return ((ImageView) v).getDrawable().getBounds() .contains(xInView, yInView); } return v.getBackground().getBounds().contains(xInView, yInView); } @Override public boolean onTouchEvent(MotionEvent ev) { // 拿到适配器 if (null == adapter || adapter.isEmpty()) { adapter = (GridViewAdapter) getAdapter(); } switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: // 拿到相对于触摸视图的坐标 int x = (int) ev.getX(); int y = (int) ev.getY(); // 拿到触摸位置 touchPositionInScreen = moveToPosition = this.pointToPosition(x, y); // 判断位置是否有效 if (moveToPosition == AdapterView.INVALID_POSITION) { break; } // 拿到当前触摸的可见item ViewGroup itemView = (ViewGroup) this.getChildAt(moveToPosition - this.getFirstVisiblePosition()); // 拿到点击位置相对于ITEM视图的偏移量 touchPositionInItemY = y - itemView.getTop(); touchPositionInItemX = x - itemView.getLeft(); // 拿到item视图里面的控件 View view = itemView.findViewById(R.id.desk_back); // 判断点击位置是否在视图里面 if (this.contains(view, touchPositionInItemX, touchPositionInItemX)) { try { int[] locationInScreen = new int[2]; view.getLocationOnScreen(locationInScreen); } catch (NullPointerException e) { break; } } // 移动视图时候的偏移量 this.offsetX = (int) (ev.getRawX() - x); this.offsetY = (int) (ev.getRawY() - y); // 获取触发当拖动视图到最顶端或者最底端自动滚动视图的边距 upScrollBounce = Math.min(y - scaledTouchSlop, getHeight() / 3); downScrollBounce = Math.max(y + scaledTouchSlop, getHeight() * 2 / 3); itemView.setDrawingCacheEnabled(true); // 拿item视图的bitmap bitmap = Bitmap.createBitmap(itemView.getDrawingCache()); itemView.destroyDrawingCache(); postDelayed(longPressRun, 1000); break; case MotionEvent.ACTION_MOVE: if (isLongClick) { int mx = (int) ev.getX(); int my = (int) ev.getY(); // 第一次移动，创建移动视图 if (isFirst) initWindowManager(bitmap, mx, my); onMove(mx, my); // 移除之前的runable removeCallbacks(longPressRun); return true; } break; case MotionEvent.ACTION_UP: int upY = (int) ev.getY(); int upX = (int) ev.getX(); if (isMove && isLongClick) { stopMove(); completeMove(upX, upY); isMove = false; isLongClick = false; break; } removeCallbacks(longPressRun); } return super.onTouchEvent(ev); } /** * @Title: initWindowManager * @Description: 创建移动视图 * @param bm * @param x * @param y * @throws */ public void initWindowManager(Bitmap bm, int x, int y) { stopMove(); isFirst = false; layoutParams = new WindowManager.LayoutParams(); layoutParams.gravity = Gravity.TOP | Gravity.LEFT; layoutParams.horizontalMargin = layoutParams.verticalMargin = 0; layoutParams.x = x - touchPositionInItemX + offsetX; layoutParams.y = y - touchPositionInItemY + offsetY; layoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT; layoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT; layoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS; layoutParams.format = PixelFormat.TRANSLUCENT; layoutParams.windowAnimations = 0; windowManager = (WindowManager) this.getContext().getSystemService( "window"); ImageView moveViewTemp = new ImageView(getContext()); moveViewTemp.setImageBitmap(bm); windowManager = (WindowManager) this.getContext().getSystemService( "window"); windowManager.addView(moveViewTemp, layoutParams); moveView = moveViewTemp; } /** * @Title: stopMove * @Description: 停止移动 * @throws */ public void stopMove() { if (moveView != null) { windowManager.removeView(moveView); moveView = null; } } /** * @Title: onMove * @Description: 视图移动的时候触发的方法 * @param x * @param y * @throws */ public void onMove(int x, int y) { isMove = true; // 避免拖动到无效区域 int tempPosition = this.pointToPosition(x, y); if (tempPosition != FreedomGridView.INVALID_POSITION) { this.moveToPosition = tempPosition; } // 移动的时候更新视图位置 if (moveView != null) { layoutParams.alpha = 0.8f; layoutParams.y = y - touchPositionInItemY + offsetY; layoutParams.x = x - touchPositionInItemX + offsetX; windowManager.updateViewLayout(moveView, layoutParams); } int scrollHeight = 0; if (y < upScrollBounce) { scrollHeight = 30; } else if (y > downScrollBounce) { scrollHeight = -30; } // 触发自动滚动 if (scrollHeight != 0) { smoothScrollToPositionFromTop(moveToPosition, getChildAt(moveToPosition - getFirstVisiblePosition()) .getTop() + scrollHeight, 1); } } /** * @Title: completeMove * @Description: 移动完成时 * @param x * @param y * @throws */ public void completeMove(int x, int y) { isFirst = true; // 拿到停止的位置 int tempPosition = this.pointToPosition(x, y); if (tempPosition != FreedomGridView.INVALID_POSITION) { this.moveToPosition = tempPosition; } if (y < getChildAt(0).getTop()) { return; } else if (y > getChildAt(getChildCount() - 1).getBottom()) { moveToPosition = getAdapter().getCount() - 1; return; } else { // 如果在有效位置 if (moveToPosition >= 0 && moveToPosition < getAdapter().getCount()) { ViewGroup itemView = (ViewGroup) this.getChildAt(moveToPosition - this.getFirstVisiblePosition()); if (itemView != null) { ImageView imaveView = (ImageView) itemView .findViewById(R.id.desk_back); // 判断是否移入了有效视图里面 boolean isIn = this.contains(imaveView, x - itemView.getLeft(), y - itemView.getTop()); // 如果已经移入了，并且不是触摸时的起始位置 if (isIn) { if (moveToPosition != touchPositionInScreen) { itemView.startAnimation(AnimationUtils .loadAnimation(getContext(), R.anim.desk_scale)); Data touchData = ((Data) adapter .getItem(touchPositionInScreen)); if (touchData.getNum() == 0) { Toast.makeText(getContext(), "数目为0不可变化", Toast.LENGTH_SHORT).show(); return; } Data toData = (Data) adapter .getItem(moveToPosition); if (toData.getNum() == 2) { Toast.makeText(getContext(), "数目为2不可变化", Toast.LENGTH_SHORT).show(); return; } touchData.setNum(touchData.getNum() - 1); toData.setNum(toData.getNum() + 1); adapter.notifyDataSetChanged(); } } } } } }}