如何在自定义ListView中加载动态图像我按照本教程在水平http://www.dev-smart.com/archives/34中显示ListView，但问题是此示例使用了相同的示例图标，但是我想使用从资源或Web解析中获取的动态图像
HorizontalListViewDemo.java：
public class HorizontalListViewDemo extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listviewdemo);
HorizontialListView listview = (HorizontialListView) findViewById(R.id.listview);
listview.setAdapter(mAdapter);
}
private static String[] dataObjects = new String[]{ "Text #1",
"Text #2",
"Text #3" };
private BaseAdapter mAdapter = new BaseAdapter() {
@Override
public int getCount() {
return dataObjects.length;
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View retval =
LayoutInflater.from(parent.getContext()).inflate(R.layout.viewitem, null);
TextView title = (TextView) retval.findViewById(R.id.title);
title.setText(dataObjects[position]);
return retval;
}
};
}
布局文件：
<linearlayout xmlns:android="http://schemas.android.com/apk/res
/android" android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#fff">
<com.devsmart.android.ui.horizontiallistview android:id="@+id/listview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ddd">
</com.devsmart.android.ui.horizontiallistview>
</linearlayout>
<linearlayout xmlns:android="http://schemas.android.com
/apk/res/android" android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:background="#fff">
<imageview android:id="@+id/image"
android:layout_width="150dip"
android:layout_height="150dip"
android:scaletype="centerCrop"
android:src="@drawable/icon">
<textview android:id="@+id/title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textcolor="#000"
android:gravity="center_horizontal">
</textview></imageview></linearlayout>
HorizontalListView.java
public class HorizontalListView extends
AdapterView<ListAdapter> {
public boolean mAlwaysOverrideTouch = true;
protected ListAdapter mAdapter;
private int mLeftViewIndex = -1;
private int mRightViewIndex = 0;
protected int mCurrentX;
protected int mNextX;
private int mMaxX = Integer.MAX_VALUE;
private int mDisplayOffset = 0;
protected Scroller mScroller;
private GestureDetector mGesture;
private Queue<View> mRemovedViewQueue = new LinkedList<View>();
private OnItemSelectedListener mOnItemSelected;
private OnItemClickListener mOnItemClicked;
private OnItemLongClickListener mOnItemLongClicked;
private boolean mDataChanged = false;
public HorizontalListView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
private synchronized void initView() {
mLeftViewIndex = -1;
mRightViewIndex = 0;
mDisplayOffset = 0;
mCurrentX = 0;
mNextX = 0;
mMaxX = Integer.MAX_VALUE;
mScroller = new Scroller(getContext());
mGesture = new GestureDetector(getContext(), mOnGesture);
}
@Override
public void setOnItemSelectedListener(AdapterView.OnItemSelectedListener
listener) {
mOnItemSelected = listener;
}
@Override
public void setOnItemClickListener(AdapterView.OnItemClickListener listener){
mOnItemClicked = listener;
}
@Override
public void setOnItemLongClickListener(AdapterView.OnItemLongClickListener
listener) {
mOnItemLongClicked = listener;
}
private DataSetObserver mDataObserver = new DataSetObserver() {
@Override
public void onChanged() {
synchronized(HorizontalListView.this){
mDataChanged = true;
}
invalidate();
requestLayout();
}
@Override
public void onInvalidated() {
reset();
invalidate();
requestLayout();
}
};
@Override
public ListAdapter getAdapter() {
return mAdapter;
}
@Override
public View getSelectedView() {
//TODO: implement
return null;
}
@Override
public void setAdapter(ListAdapter adapter) {
if(mAdapter != null) {
mAdapter.unregisterDataSetObserver(mDataObserver);
}
mAdapter = adapter;
mAdapter.registerDataSetObserver(mDataObserver);
reset();
}
private synchronized void reset(){
initView();
removeAllViewsInLayout();
requestLayout();
}
@Override
public void setSelection(int position) {
//TODO: implement
}
private void addAndMeasureChild(final View child, int viewPos) {
LayoutParams params = child.getLayoutParams();
if(params == null) {
params = new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT);
}
addViewInLayout(child, viewPos, params, true);
child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
MeasureSpec.makeMeasureSpec(getHeight(),
MeasureSpec.AT_MOST));
}
@Override
protected synchronized void onLayout(boolean changed, int left, int top, int
right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if(mAdapter == null){
return;
}
if(mDataChanged){
int oldCurrentX = mCurrentX;
initView();
removeAllViewsInLayout();
mNextX = oldCurrentX;
mDataChanged = false;
}
if(mScroller.computeScrollOffset()){
int scrollx = mScroller.getCurrX();
mNextX = scrollx;
}
if(mNextX <= 0){
mNextX = 0;
mScroller.forceFinished(true);
}
if(mNextX >= mMaxX) {
mNextX = mMaxX;
mScroller.forceFinished(true);
}
int dx = mCurrentX - mNextX;
removeNonVisibleItems(dx);
fillList(dx);
positionItems(dx);
mCurrentX = mNextX;
if(!mScroller.isFinished()){
post(new Runnable(){
@Override
public void run() {
requestLayout();
}
});
}
}
private void fillList(final int dx) {
int edge = 0;
View child = getChildAt(getChildCount()-1);
if(child != null) {
edge = child.getRight();
}
fillListRight(edge, dx);
edge = 0;
child = getChildAt(0);
if(child != null) {
edge = child.getLeft();
}
fillListLeft(edge, dx);
}
private void fillListRight(int rightEdge, final int dx) {
while(rightEdge + dx < getWidth() && mRightViewIndex <
mAdapter.getCount()) {
View child = mAdapter.getView(mRightViewIndex,
mRemovedViewQueue.poll(), this);
addAndMeasureChild(child, -1);
rightEdge += child.getMeasuredWidth();
if(mRightViewIndex == mAdapter.getCount()-1) {
mMaxX = mCurrentX + rightEdge - getWidth();
}
if (mMaxX < 0) {
mMaxX = 0;
}
mRightViewIndex++;
}
}
private void fillListLeft(int leftEdge, final int dx) {
while(leftEdge + dx > 0 && mLeftViewIndex >= 0) {
View child = mAdapter.getView(mLeftViewIndex,
mRemovedViewQueue.poll(), this);
addAndMeasureChild(child, 0);
leftEdge -= child.getMeasuredWidth();
mLeftViewIndex--;
mDisplayOffset -= child.getMeasuredWidth();
}
}
private void removeNonVisibleItems(final int dx) {
View child = getChildAt(0);
while(child != null && child.getRight() + dx <= 0) {
mDisplayOffset += child.getMeasuredWidth();
mRemovedViewQueue.offer(child);
removeViewInLayout(child);
mLeftViewIndex++;
child = getChildAt(0);
}
child = getChildAt(getChildCount()-1);
while(child != null && child.getLeft() + dx >= getWidth()) {
mRemovedViewQueue.offer(child);
removeViewInLayout(child);
mRightViewIndex--;
child = getChildAt(getChildCount()-1);
}
}
private void positionItems(final int dx) {
if(getChildCount() > 0){
mDisplayOffset += dx;
int left = mDisplayOffset;
for(int i=0;i<getChildCount();i++){
View child = getChildAt(i);
int childWidth = child.getMeasuredWidth();
child.layout(left, 0, left + childWidth,
child.getMeasuredHeight());
left += childWidth + child.getPaddingRight();
}
}
}
public synchronized void scrollTo(int x) {
mScroller.startScroll(mNextX, 0, x - mNextX, 0);
requestLayout();
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
boolean handled = super.dispatchTouchEvent(ev);
handled |= mGesture.onTouchEvent(ev);
return handled;
}
protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
synchronized(HorizontalListView.this){
mScroller.fling(mNextX, 0, (int)-velocityX, 0, 0, mMaxX, 0, 0);
}
requestLayout();
return true;
}
protected boolean onDown(MotionEvent e) {
mScroller.forceFinished(true);
return true;
}
private OnGestureListener mOnGesture = new
GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onDown(MotionEvent e) {
return HorizontalListView.this.onDown(e);
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
return HorizontalListView.this.onFling(e1, e2, velocityX,
velocityY);
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
synchronized(HorizontalListView.this){
mNextX += (int)distanceX;
}
requestLayout();
return true;
}
@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
for(int i=0;i<getChildCount();i++){
View child = getChildAt(i);
if (isEventWithinView(e, child)) {
if(mOnItemClicked != null){
mOnItemClicked.onItemClick(HorizontalListView.this, child, mLeftViewIndex + 1 +
i, mAdapter.getItemId( mLeftViewIndex + 1 + i ));
}
if(mOnItemSelected != null){
mOnItemSelected.onItemSelected(HorizontalListView.this, child, mLeftViewIndex +
1 + i, mAdapter.getItemId( mLeftViewIndex + 1 + i ));
}
break;
}
}
return true;
}
@Override
public void onLongPress(MotionEvent e) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (isEventWithinView(e, child)) {
if (mOnItemLongClicked != null) {
mOnItemLongClicked.onItemLongClick(HorizontalListView.this, child, mLeftViewIndex +
1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));
}
break;
}
}
}
private boolean isEventWithinView(MotionEvent e, View child) {
Rect viewRect = new Rect();
int[] childPosition = new int[2];
child.getLocationOnScreen(childPosition);
int left = childPosition[0];
int right = left + child.getWidth();
int top = childPosition[1];
int bottom = top + child.getHeight();
viewRect.set(left, top, right, bottom);
return viewRect.contains((int) e.getRawX(), (int) e.getRawY());
}
};
}
最佳答案
看一下下面的链接。已经有人为它编写了一个库。
Android Universal Image Loader
我在最近的项目中使用了this库，它可以完美运行。
希望它会有所帮助。
关于android - 如何在自定义ListView中加载动态图像，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17715818/