我正在使用 EditText 小部件,希望修改用户长按该视图时显示的上下文菜单。问题在于,我需要知道长按事件发生时光标所在位置的字符位置,以便确定需要添加到上下文菜单中的内容。基础类可以实现这个功能,因为菜单中的一个选项是“将 'word_clicked_on' 添加到字典中”。但是,在文本中设置 ClickableSpans 不是解决办法,因为它会消耗点击事件,从而使得在跨度内移动编辑光标变得不可能。
这是我想到的解决方案,它确实可行,所以我想分享一下:
首先,我得扩展EditText类,以便能够拦截onTouchEvent,捕获ACTION_DOWN事件并保存位置。现在我有了按下点的位置,我可以调用getOffsetForPosition(downPointX, downPointY)并获取长按字符的位置。但是,有一个大问题,getOffsetForPosition功能直到SDK 14才添加!为了使此解决方案起作用,我必须将getOffsetForPosition的功能向后移植,并在当前SDK早于SDK_INT 14时进行分支。以下是新类的源代码:
public class ScrapEditText extends EditText{
protected float LastDownPositionX, LastDownPositionY;
public ScrapEditText(Context context)
{
super(context);
}
public ScrapEditText(Context context, AttributeSet attrs)
{
super(context, attrs);
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
final int action = event.getActionMasked();
if(action == MotionEvent.ACTION_DOWN)
{
LastDownPositionX = event.getX();
LastDownPositionY = event.getY();
}
return super.onTouchEvent(event);
}
public float GetLastDownPositionX()
{
return LastDownPositionX;
}
public float GetLastDownPositionY()
{
return LastDownPositionY;
}
public int GetOffsetForLastDownPosition()
{
if(Build.VERSION.SDK_INT > 13)
{
// as of SDK 14 the getOffsetForPosition was added to TextView
return getOffsetForPosition(LastDownPositionX, LastDownPositionY);
}
else
{
return GetOffsetForPositionOlderSdk();
}
}
public int GetOffsetForPositionOlderSdk()
{
if (getLayout() == null) return -1;
final int line = GetLineAtCoordinateOlderSDK(LastDownPositionY);
final int offset = GetOffsetAtCoordinateOlderSDK(line, LastDownPositionX);
return offset;
}
public int GetLineAtCoordinateOlderSDK(float y)
{
y -= getTotalPaddingTop();
// Clamp the position to inside of the view.
y = Math.max(0.0f, y);
y = Math.min(getHeight() - getTotalPaddingBottom() - 1, y);
y += getScrollY();
return getLayout().getLineForVertical((int) y);
}
protected int GetOffsetAtCoordinateOlderSDK(int line, float x) {
x = ConvertToLocalHorizontalCoordinateOlderSDK(x);
return getLayout().getOffsetForHorizontal(line, x);
}
protected float ConvertToLocalHorizontalCoordinateOlderSDK(float x) {
x -= getTotalPaddingLeft();
// Clamp the position to inside of the view.
x = Math.max(0.0f, x);
x = Math.min(getWidth() - getTotalPaddingRight() - 1, x);
x += getScrollX();
return x;
}
}
ScrapText = (ScrapEditText) findViewById(R.id.sample_text);
ScrapText.setOnCreateContextMenuListener(new View.OnCreateContextMenuListener(){
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo)
{
int charOffset = FileText.GetOffsetForLastDownPosition();
}
});