自定义RadioGroup
在Android系统中，自带的RadioGroup只能指定横向和纵向两种布局，所以有的时候我们需要自定义RadioGroup。
首先分析一下，就是在系统自带的RadioGroup中，如果我们嵌套了，LinearLayout的话，就会失效，因为系统的RadioGroup没有考虑到这种情况，所以我们需要自定义一个Group，初步的打算是继承自LinearLayout。
具体代码如下：
package linsir.fuyizhulao.com.love_map;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.CompoundButton;
import android.widget.LinearLayout;
import android.widget.RadioButton;
/**
* <p>This class is used to create a multiple-exclusion scope for a set of radio
* buttons. Checking one radio button that belongs to a radio group unchecks
* any previously checked radio button within the same group.</p>
*
* <p>Intially, all of the radio buttons are unchecked. While it is not possible
* to uncheck a particular radio button, the radio group can be cleared to
* remove the checked state.</p>
*
* <p>The selection is identified by the unique id of the radio button as defined
* in the XML layout file.</p>
*
* <p><strong>XML Attributes</strong></p>
* <p>See {@link android.R.styleable#RadioGroup RadioGroup Attributes},
* {@link android.R.styleable#LinearLayout LinearLayout Attributes},
* {@link android.R.styleable#ViewGroup ViewGroup Attributes},
* {@link android.R.styleable#View View Attributes}</p>
* <p>Also see
* {@link android.widget.LinearLayout.LayoutParams LinearLayout.LayoutParams}
* for layout attributes.</p>
*
* @see RadioButton
*
*/
public class RadioGroup 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;
/**
* {@inheritDoc}
*/
public RadioGroup(Context context) {
super(context);
setOrientation(VERTICAL);
init();
}
/**
* {@inheritDoc}
*/
public RadioGroup(Context context, AttributeSet attrs) {
super(context, attrs);
mCheckedId = View.NO_ID;
final int index = VERTICAL;
setOrientation(index);
init();
}
private void init() {
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 != -1) {
mProtectFromCheckedChange = true;
setCheckedStateForView(mCheckedId, true);
mProtectFromCheckedChange = false;
setCheckedId(mCheckedId);
}
}
@Override
public void addView(final View child, int index, ViewGroup.LayoutParams params) {
if (child instanceof RadioButton) {
((RadioButton) child).setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
((RadioButton) child).setChecked(true);
checkRadioButton((RadioButton) child);
if(mOnCheckedChangeListener != null){
mOnCheckedChangeListener.onCheckedChanged(RadioGroup.this, child.getId());
}
return true;
}
});
} else if(child instanceof LinearLayout){
int childCount = ((LinearLayout) child).getChildCount();
for(int i = 0; i < childCount; i++){
View view = ((LinearLayout) child).getChildAt(i);
if (view instanceof RadioButton) {
final RadioButton button = (RadioButton) view;
((RadioButton) button).setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
((RadioButton) button).setChecked(true);
checkRadioButton((RadioButton) button);
if(mOnCheckedChangeListener != null){
mOnCheckedChangeListener.onCheckedChanged(RadioGroup.this, button.getId());
}
return true;
}
});
}
}
}
super.addView(child, index, params);
}
private void checkRadioButton(RadioButton radioButton){
View child;
int radioCount = getChildCount();
for(int i = 0; i < radioCount; i++){
child = getChildAt(i);
if (child instanceof RadioButton) {
if(child == radioButton){
// do nothing
} else {
((RadioButton) child).setChecked(false);
}
} else if(child instanceof LinearLayout){
int childCount = ((LinearLayout) child).getChildCount();
for(int j = 0; j < childCount; j++){
View view = ((LinearLayout) child).getChildAt(j);
if (view instanceof RadioButton) {
final RadioButton button = (RadioButton) view;
if(button == radioButton){
// do nothing
} else {
((RadioButton) button).setChecked(false);
}
}
}
}
}
}
/**
* <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;
}
private void setCheckedStateForView(int viewId, boolean checked) {
View checkedView = findViewById(viewId);
if (checkedView != null && checkedView instanceof RadioButton) {
((RadioButton) 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#RadioGroup_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 RadioGroup.LayoutParams(getContext(), attrs);
}
/**
* {@inheritDoc}
*/
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof RadioGroup.LayoutParams;
}
@Override
protected LinearLayout.LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}
@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setClassName(RadioGroup.class.getName());
}
@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(info);
info.setClassName(RadioGroup.class.getName());
}
/**
* <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(RadioGroup 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}
*/
public void onChildViewAdded(View parent, View child) {
if (parent == RadioGroup.this && child instanceof RadioButton) {
int id = child.getId();
// generates an id if it's missing
if (id == View.NO_ID) {
id = child.hashCode();
child.setId(id);
}
((RadioButton) child).setOnCheckedChangeListener(
mChildOnCheckedChangeListener);
}
if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewAdded(parent, child);
}
}
/**
* {@inheritDoc}
*/
public void onChildViewRemoved(View parent, View child) {
if (parent == RadioGroup.this && child instanceof RadioButton) {
((RadioButton) child).setOnCheckedChangeListener(null);
}
if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewRemoved(parent, child);
}
}
}
}
这样我们的RadioGroup下面就可以使用布局了，不过目前仅对LinearLayout做了兼容，一般来说这样，就已经可以满足我们的需求了，当然如果我们喜欢的话，也可以对其他的布局进行兼容。
