上一篇文章《自定義viewgroup(2)》地址:http://blog.csdn.net/qq_18148011/article/details/53761551
代碼
package com.example.libingyuan.horizontallistview.ScrollViewGroup;
import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Scroller;
/**
* 自定義ViewGroup
* 在滾動的基礎上,增加了邊界限制
*/
public class ScrollViewGroup extends ViewGroup {
//滾動計算輔助類
private Scroller mScroller;
//手指落點的X座標
private float mLastMotionX = 0;
//屏幕寬度
private int screenWidth;
/**
* 使用new關鍵字創建對象的時候調用
* @param context 上下文
*/
public ScrollViewGroup(Context context) {
this(context, null);
}
/**
* 在XML文件中使用的時候調用
* @param context 上下文
* @param attrs 屬性:如 android:layout_width="wrap_content"
*/
public ScrollViewGroup(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
/**
* 在xml文件中調用,並且使用了自定義屬性的時候調用
* @param context 上下文
* @param attrs 屬性:如 android:layout_width="wrap_content"
* @param defStyleAttr 自定義屬性的id
*/
public ScrollViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
/**
* 初始化方法
* 初始化滾動輔助類Scroller以及計算出屏幕寬度
* @param context
*/
private void init(Context context) {
mScroller = new Scroller(context);
WindowManager manager = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
manager.getDefaultDisplay().getMetrics(outMetrics);
screenWidth = outMetrics.widthPixels;
}
/**
* 滾動時需要重寫的方法,用於控制滾動
*/
@Override
public void computeScroll() {
//判斷滾動時候停止
if (mScroller.computeScrollOffset()) {
//滾動到指定的位置
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
//這句話必須寫,否則不能實時刷新
postInvalidate();
}
}
/**
* 手指觸屏事件監聽
* @param event
* @return
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
int action = event.getAction();
float x = event.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
mLastMotionX = event.getX();
break;
case MotionEvent.ACTION_MOVE:
float delt = mLastMotionX - x;
mLastMotionX = x;
scrollBy((int) delt, 0);
break;
case MotionEvent.ACTION_UP:
View lastChild=getChildAt(getChildCount()-1);
int finalyChild= (int) (lastChild.getX()+lastChild.getWidth()-screenWidth);
if (getScrollX()<0){
scrollTo(0,0);
}
if (getScrollX()>=finalyChild)
scrollTo(finalyChild,0);
invalidate();
break;
default:
break;
}
return true;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//重新設置寬高
this.setMeasuredDimension(measureWidth(widthMeasureSpec, heightMeasureSpec), measureHeight(widthMeasureSpec, heightMeasureSpec));
}
/**
* 測量寬度
*/
private int measureWidth(int widthMeasureSpec, int heightMeasureSpec) {
// 寬度
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
//父控件的寬(wrap_content)
int width = 0;
int childCount = getChildCount();
//重新測量子view的寬度,以及最大高度
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
measureChild(child, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
width += childWidth;
}
return modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width;
}
/**
* 測量高度
*/
private int measureHeight(int widthMeasureSpec, int heightMeasureSpec) {
//高度
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
//父控件的高(wrap_content)
int height = 0;
int childCount = getChildCount();
//重新測量子view的寬度,以及最大高度
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
measureChild(child, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
height += childHeight;
}
height = height / childCount;
return modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height;
}
/**
* 給子佈局設定位置
*/
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childLeft = 0;//子View左邊的間距
int childWidth;//子View的寬度
int height = getHeight();//屏幕的寬度
int childCount = getChildCount();//子View的數量
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
child.layout(childLeft, 0, childLeft + childWidth, height);
childLeft += childWidth;
}
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}
}