android 怎么设置popupwindow可以拉动

设置popupwindow可以拉动
public void update(int x, int y, int width, int height, boolean force) {
if (width != -1) {
mLastWidth = width;
setWidth(width);
}
if (height != -1) {
mLastHeight = height;
setHeight(height);
}
if (!isShowing() || mContentView == null) {
return;
}
WindowManager.LayoutParams p = (WindowManager.LayoutParams) mPopupView.getLayoutParams();
boolean update = force;
final int finalWidth = mWidthMode < 0 ? mWidthMode : mLastWidth;
if (width != -1 && p.width != finalWidth) {
p.width = mLastWidth = finalWidth;
update = true;
}
final int finalHeight = mHeightMode < 0 ? mHeightMode : mLastHeight;
if (height != -1 && p.height != finalHeight) {
p.height = mLastHeight = finalHeight;
update = true;
}
if (p.x != x) {
p.x = x;
update = true;
}
if (p.y != y) {
p.y = y;
update = true;
}
final int newAnim = computeAnimationResource();
if (newAnim != p.windowAnimations) {
p.windowAnimations = newAnim;
update = true;
}
final int newFlags = computeFlags(p.flags);
if (newFlags != p.flags) {
p.flags = newFlags;
update = true;
}
if (update) {
setLayoutDirectionFromAnchor();
mWindowManager.updateViewLayout(mPopupView, p);
}
}