public class NestRadioGroup extends LinearLayout {
// holds the checked id; the selection is empty by default
private int mCheckedId = -1;
// tracks children radio buttons checked state
private CompoundButton.OnCheckedChangeListener mChildOnCheckedChangeListener;
// when true, mOnCheckedChangeListener discards events
private boolean mProtectFromCheckedChange = false;
private OnCheckedChangeListener mOnCheckedChangeListener;
private PassThroughHierarchyChangeListener mPassThroughListener;
public NestRadioGroup(Context context) {
super(context);
init();
}
public NestRadioGroup(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
mCheckedId = View.NO_ID;
setOrientation(HORIZONTAL);
mChildOnCheckedChangeListener = new CheckedStateTracker();
mPassThroughListener = new PassThroughHierarchyChangeListener();
super.setOnHierarchyChangeListener(mPassThroughListener);
}
/**
* {@inheritDoc}
*/
@Override
public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
// the user listener is delegated to our pass-through listener
mPassThroughListener.mOnHierarchyChangeListener = listener;
}
/**
* {@inheritDoc}
*/
@Override
protected void onFinishInflate() {
super.onFinishInflate();
// checks the appropriate radio button as requested in the XML file
if (mCheckedId != View.NO_ID) {
mProtectFromCheckedChange = true;
setCheckedStateForView(mCheckedId, true);
mProtectFromCheckedChange = false;
setCheckedId(mCheckedId);
}
}
/** 递归查找具有选中属性的子控件 */
private static CompoundButton findCheckedView(View child) {
if (child instanceof CompoundButton)
return (CompoundButton) child;
if (child instanceof ViewGroup) {
ViewGroup group = (ViewGroup) child;
for (int i = 0, j = group.getChildCount(); i < j; i++) {
CompoundButton check = findCheckedView(group.getChildAt(i));
if (check != null)
return check;
}
}
return null;//没有找到
}
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
final CompoundButton view = findCheckedView(child);
if (view != null) {
if (view.isChecked()) {
mProtectFromCheckedChange = true;
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
mProtectFromCheckedChange = false;
setCheckedId(view.getId());
}
}
super.addView(child, index, params);
}
/**
* <p>Sets the selection to the radio button whose identifier is passed in
* parameter. Using -1 as the selection identifier clears the selection;
* such an operation is equivalent to invoking {@link #clearCheck()}.</p>
*
* @param id the unique id of the radio button to select in this group
*
* @see #getCheckedRadioButtonId()
* @see #clearCheck()
*/
public void check(int id) {
// don‘t even bother
if (id != -1 && (id == mCheckedId)) {
return;
}
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
if (id != -1) {
setCheckedStateForView(id, true);
}
setCheckedId(id);
}
private void setCheckedId(int id) {
mCheckedId = id;
if (mOnCheckedChangeListener != null) {
mOnCheckedChangeListener.onCheckedChanged(this, mCheckedId);
}
}
private void setCheckedStateForView(int viewId, boolean checked) {
View checkedView = findViewById(viewId);
if (checkedView != null && checkedView instanceof CompoundButton) {
((CompoundButton) checkedView).setChecked(checked);
}
}
/**
* <p>Returns the identifier of the selected radio button in this group.
* Upon empty selection, the returned value is -1.</p>
*
* @return the unique id of the selected radio button in this group
*
* @see #check(int)
* @see #clearCheck()
*
* @attr ref android.R.styleable#NestRadioGroup_checkedButton
*/
public int getCheckedRadioButtonId() {
return mCheckedId;
}
/**
* <p>Clears the selection. When the selection is cleared, no radio button
* in this group is selected and {@link #getCheckedRadioButtonId()} returns
* null.</p>
*
* @see #check(int)
* @see #getCheckedRadioButtonId()
*/
public void clearCheck() {
check(-1);
}
/**
* <p>Register a callback to be invoked when the checked radio button
* changes in this group.</p>
*
* @param listener the callback to call on checked state change
*/
public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
mOnCheckedChangeListener = listener;
}
/**
* {@inheritDoc}
*/
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new NestRadioGroup.LayoutParams(getContext(), attrs);
}
/**
* {@inheritDoc}
*/
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof NestRadioGroup.LayoutParams;
}
@Override
protected LinearLayout.LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}
/**
* <p>This set of layout parameters defaults the width and the height of
* the children to {@link #WRAP_CONTENT} when they are not specified in the
* XML file. Otherwise, this class ussed the value read from the XML file.</p>
*
* <p>See
* {@link android.R.styleable#LinearLayout_Layout LinearLayout Attributes}
* for a list of all child view attributes that this class supports.</p>
*
*/
public static class LayoutParams extends LinearLayout.LayoutParams {
/**
* {@inheritDoc}
*/
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}
/**
* {@inheritDoc}
*/
public LayoutParams(int w, int h) {
super(w, h);
}
/**
* {@inheritDoc}
*/
public LayoutParams(int w, int h, float initWeight) {
super(w, h, initWeight);
}
/**
* {@inheritDoc}
*/
public LayoutParams(ViewGroup.LayoutParams p) {
super(p);
}
/**
* {@inheritDoc}
*/
public LayoutParams(MarginLayoutParams source) {
super(source);
}
/**
* <p>Fixes the child‘s width to
* {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} and the child‘s
* height to {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT}
* when not specified in the XML file.</p>
*
* @param a the styled attributes set
* @param widthAttr the width attribute to fetch
* @param heightAttr the height attribute to fetch
*/
@Override
protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) {
if (a.hasValue(widthAttr)) {
width = a.getLayoutDimension(widthAttr, "layout_width");
} else {
width = WRAP_CONTENT;
}
if (a.hasValue(heightAttr)) {
height = a.getLayoutDimension(heightAttr, "layout_height");
} else {
height = WRAP_CONTENT;
}
}
}
/**
* <p>Interface definition for a callback to be invoked when the checked
* radio button changed in this group.</p>
*/
public interface OnCheckedChangeListener {
/**
* <p>Called when the checked radio button has changed. When the
* selection is cleared, checkedId is -1.</p>
*
* @param group the group in which the checked radio button has changed
* @param checkedId the unique identifier of the newly checked radio button
*/
public void onCheckedChanged(NestRadioGroup group, int checkedId);
}
private class CheckedStateTracker implements CompoundButton.OnCheckedChangeListener {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// prevents from infinite recursion
if (mProtectFromCheckedChange) {
return;
}
mProtectFromCheckedChange = true;
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
mProtectFromCheckedChange = false;
int id = buttonView.getId();
setCheckedId(id);
}
}
/**
* <p>A pass-through listener acts upon the events and dispatches them
* to another listener. This allows the table layout to set its own internal
* hierarchy change listener without preventing the user to setup his.</p>
*/
private class PassThroughHierarchyChangeListener implements ViewGroup.OnHierarchyChangeListener {
private ViewGroup.OnHierarchyChangeListener mOnHierarchyChangeListener;
/**
* {@inheritDoc}
*/
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
public void onChildViewAdded(View parent, View child) {
if (parent == NestRadioGroup.this) {
CompoundButton view = findCheckedView(child);//查找子控件
if (view != null) {
int id = view.getId();
// generates an id if it‘s missing
if (id == View.NO_ID && Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
id = View.generateViewId();
view.setId(id);
}
view.setOnCheckedChangeListener(mChildOnCheckedChangeListener);
}
}
if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewAdded(parent, child);
}
}
/**
* {@inheritDoc}
*/
public void onChildViewRemoved(View parent, View child) {
if (parent == NestRadioGroup.this) {
CompoundButton view = findCheckedView(child);//查找子控件
if (view != null) {
view.setOnCheckedChangeListener(null);
}
}
if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewRemoved(parent, child);
}
}
}
