我正在研究dragview，因为我想要一个textview，它在中心位置给予（消息点击以便写入），我正在使用以下布局，但textview不会进入中心，它位于布局的顶部，你能建议我吗
以下是我的代码，
<com.snapquote.DragLayer
android:id="@+id/drag_layer"
android:layout_width="fill_parent"
android:layout_centerInParent="true"
android:layout_height="fill_parent" >
<TextView
android:id="@+id/taketext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#80313131"
android:padding="10.0dip"
android:shadowColor="#b3000000"
android:shadowDx="0.0"
android:gravity="center_vertical"
android:shadowDy="-1.0"
android:shadowRadius="1.0"
android:singleLine="false"
android:text="@string/double_tap_to_write"
android:textColor="#b3ffffff"
android:textSize="16.0sp"
android:visibility="visible" />
</com.snapquote.DragLayer>
类：
public class MyAbsoluteLayout extends ViewGroup {
public MyAbsoluteLayout(Context context) {
super(context);
}
public MyAbsoluteLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyAbsoluteLayout(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int count = getChildCount();
int maxHeight = 0;
int maxWidth = 0;
// Find out how big everyone wants to be
measureChildren(widthMeasureSpec, heightMeasureSpec);
// Find rightmost and bottom-most child
for (int i = 0; i < count; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
int childRight;
int childBottom;
MyAbsoluteLayout.LayoutParams lp
= (MyAbsoluteLayout.LayoutParams) child.getLayoutParams();
childRight = lp.x + child.getMeasuredWidth();
childBottom = lp.y + child.getMeasuredHeight();
maxWidth = Math.max(maxWidth, childRight);
maxHeight = Math.max(maxHeight, childBottom);
}
}
// Account for padding too
maxWidth += getPaddingLeft () + getPaddingRight ();
maxHeight += getPaddingTop () + getPaddingBottom ();
/* original
maxWidth += mPaddingLeft + mPaddingRight;
maxHeight += mPaddingTop + mPaddingBottom;
*/
// Check against minimum height and width
maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
setMeasuredDimension(resolveSize(maxWidth, widthMeasureSpec),
resolveSize(maxHeight, heightMeasureSpec));
}
@Override
protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 0, 0);
}
@Override
protected void onLayout(boolean changed, int l, int t,
int r, int b) {
int count = getChildCount();
int paddingL = getPaddingLeft ();
int paddingT = getPaddingTop ();
for (int i = 0; i < count; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
MyAbsoluteLayout.LayoutParams lp =
(MyAbsoluteLayout.LayoutParams) child.getLayoutParams();
int childLeft = paddingL + lp.x;
int childTop = paddingT + lp.y;
/*
int childLeft = mPaddingLeft + lp.x;
int childTop = mPaddingTop + lp.y;
*/
child.layout(childLeft, childTop,
childLeft + child.getMeasuredWidth(),
childTop + child.getMeasuredHeight());
}
}
}
@Override
public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MyAbsoluteLayout.LayoutParams(getContext(), attrs);
}
// Override to allow type-checking of LayoutParams.
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof MyAbsoluteLayout.LayoutParams;
}
@Override
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
return new LayoutParams(p);
}
public static class LayoutParams extends ViewGroup.LayoutParams {
public int x;
public int y;
public LayoutParams(int width, int height, int x, int y) {
super(width, height);
this.x = x;
this.y = y;
}
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
}
public String debug(String output) {
return output + "Absolute.LayoutParams={width="
+ sizeToString(width) + ", height=" + sizeToString(height)
+ " x=" + x + " y=" + y + "}";
}
protected static String sizeToString(int size) {
if (size == WRAP_CONTENT) {
return "wrap-content";
}
if (size == MATCH_PARENT) {
return "match-parent";
}
return String.valueOf(size);
}
} // end class
DragLayer.java
public class DragLayer extends MyAbsoluteLayout
implements DragSource, DropTarget
{
DragController mDragController;
public DragLayer (Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setDragController(DragController controller) {
mDragController = controller;
}
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
return mDragController.dispatchKeyEvent(event) || super.dispatchKeyEvent(event);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return mDragController.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
return mDragController.onTouchEvent(ev);
}
@Override
public boolean dispatchUnhandledMove(View focused, int direction) {
return mDragController.dispatchUnhandledMove(focused, direction);
}
public boolean allowDrag () {
// In this simple demo, any view that you touch can be dragged.
return true;
}
public void onDropCompleted (View target, boolean success)
{
toast ("DragLayer2.onDropCompleted: " + target.getId () + " Check that the view moved.");
}
public void onDrop(DragSource source, int x, int y, int xOffset, int yOffset,
DragView dragView, Object dragInfo)
{
View v = (View) dragInfo;
toast ("DragLayer2.onDrop accepts view: " + v.getId ()
+ "x, y, xO, yO :" + new Integer (x) + ", " + new Integer (y) + ", "
+ new Integer (xOffset) + ", " + new Integer (yOffset));
int w = v.getWidth ();
int h = v.getHeight ();
int left = x - xOffset;
int top = y - yOffset;
DragLayer.LayoutParams lp = new DragLayer.LayoutParams (w, h, left, top);
this.updateViewLayout(v, lp);
}
public void onDragEnter(DragSource source, int x, int y, int xOffset, int yOffset,
DragView dragView, Object dragInfo)
{
}
public void onDragOver(DragSource source, int x, int y, int xOffset, int yOffset,
DragView dragView, Object dragInfo)
{
}
public void onDragExit(DragSource source, int x, int y, int xOffset, int yOffset,
DragView dragView, Object dragInfo)
{
}
public boolean acceptDrop(DragSource source, int x, int y, int xOffset, int yOffset,
DragView dragView, Object dragInfo)
{
return true;
}
public Rect estimateDropLocation(DragSource source, int x, int y, int xOffset, int yOffset,
DragView dragView, Object dragInfo, Rect recycle)
{
return null;
}
public void toast (String msg)
{
if (!DragActivity.Debugging) return;
Toast.makeText (getContext (), msg, Toast.LENGTH_SHORT).show ();
} // end toast
} // end class
答案 0 :(得分：1)
在父布局
中使用以下属性 android:layout_gravity="center"
android:gravity="center"
注意：API level 3中已弃用AbsoluteLayout类。
改为使用FrameLayout, RelativeLayout或custom layout。
MyAbsoluteLayout.java onLayout方法修改
// Use the child's gravity and size to determine its final
// frame within its container.
Gravity.apply(lp.gravity, width, height, mTmpContainerRect, mTmpChildRect);
转到thru this link并进行一些更改，以便为自定义布局应用重力
答案 1 :(得分：0)
AbsoluteLayout已折旧，您应该使用FrameLayout，LinearLayout或RelativeLayout。
如果您使用RelativeLayout，请将以下内容添加到TextView：
android:layout_centerInParent="true"
对于FrameLayout或LinearLayout，将以下内容添加到父级：
android:gravity="center"