我如何测量ListView
的FPS?
请查看来自http://code.google.com/events/io/2010/sessions/world-of-listview-android.html的幻灯片13-17。
我如何测量ListView
的FPS?
请查看来自http://code.google.com/events/io/2010/sessions/world-of-listview-android.html的幻灯片13-17。
View
的性能。它以毫秒为单位提供测量、计算布局和绘制每个View
所需时间,并通过显示黄色和红色圆圈来帮助您找到性能差的View
对象。请注意保留HTML标签。import android.database.DataSetObserver;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
public class VpsAdapter implements ListAdapter {
protected int vpsViewCount = 0;
protected long vpsStartTimeNanos = System.nanoTime();
protected ListAdapter delegate;
public VpsAdapter(ListAdapter delegate) {
super();
this.delegate = delegate;
}
public void resetViewsPerSecond() {
vpsViewCount = 0;
vpsStartTimeNanos = System.nanoTime();
}
public double getViewsPerSecond() {
final long now = System.nanoTime();
return (vpsViewCount / (double)(now - vpsStartTimeNanos)) * 1e9;
}
public int getViewsPerSecondViewCount() {
return vpsViewCount;
}
@Override
public boolean areAllItemsEnabled() {
return delegate.areAllItemsEnabled();
}
@Override
public int getCount() {
return delegate.getCount();
}
@Override
public Object getItem(int i) {
return delegate.getItem(i);
}
@Override
public long getItemId(int i) {
return delegate.getItemId(i);
}
@Override
public int getItemViewType(int i) {
return delegate.getItemViewType(i);
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
++vpsViewCount;
Log.d("VpsAdapter", String.format("VpsAdapter: %.2f views per second (%s views)", getViewsPerSecond(), getViewsPerSecondViewCount()));
return delegate.getView(i, view, viewGroup);
}
@Override
public int getViewTypeCount() {
return delegate.getViewTypeCount();
}
@Override
public boolean hasStableIds() {
return delegate.hasStableIds();
}
@Override
public boolean isEmpty() {
return delegate.isEmpty();
}
@Override
public boolean isEnabled(int i) {
return delegate.isEnabled(i);
}
@Override
public void registerDataSetObserver(DataSetObserver dataSetObserver) {
delegate.registerDataSetObserver(dataSetObserver);
}
@Override
public void unregisterDataSetObserver(DataSetObserver dataSetObserver) {
delegate.unregisterDataSetObserver(dataSetObserver);
}
}
使用方法很简单,只需将现有的ListAdapter包装在VpsAdapter中即可,例如:
setListAdapter( new VpsAdapter( myAdapter ) );
当你准备好计时时,请调用resetViewsPerSecond()
,并在准备检索结果时调用getViewsPerSecond()
。适配器还将记录每次调用getView()
的当前vps到控制台。
我与ListView.smoothScrollTo( adapter.getCount()-1 )
一起使用此适配器,以便以编程方式将列表滚动到底部并获取平均vps。