Creazione di una casella di controllo a tre stati su Android

Question

Sono bloccato di fronte a un grosso problema: Vorrei fare tre checkbox su Android. È una casella di controllo su una ListView con caselle di controllo. Dovrebbe consente all'utente di passare da tre stati:

• tutte controllate
• nessuna controllato
• misc controllato

E opzionalmente mantengono lo stato misc sul cambiamento.

Se ho ragione, dovrei creare una sottoclasse della classe CompoundButton e implementare un int mstate intead del controllo booleano. Quindi dovrei sovrascrivere il listener di eventi, le funzioni per salvare lo stato e il getter e setter dello stato.

La mia domanda è fondamentalmente come posso implementarlo? Come passare da uno stato all'altro? (Ho implementato il middle_state in xml) e come implementare correttamente il gestore di eventi?

Ecco l'attuazione ho iniziato:

public class TriStateCheckBox extends CompoundButton{ 
    private int state; 

    public TriStateCheckBox(Context context) { 
     super(context); 
    } 
    public static interface onCheckChangedListener{ 
     void onCheckChanged(TriStateCheckBox view, int state); 
    } 

    public void onCheckChanged(TriStateCheckBox view, int state){ 
     this.state = state; 
    } 
} 

ecco il codice del titolo CompoundButton:

/* 
* Copyright (C) 2007 The Android Open Source Project 
* 
* Licensed under the Apache License, Version 2.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
*  http://www.apache.org/licenses/LICENSE-2.0 
* 
* Unless required by applicable law or agreed to in writing, software 
* distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
* limitations under the License. 
*/ 

package android.widget; 

import com.android.internal.R; 

import android.content.Context; 
import android.content.res.TypedArray; 
import android.graphics.Canvas; 
import android.graphics.drawable.Drawable; 
import android.os.Parcel; 
import android.os.Parcelable; 
import android.util.AttributeSet; 
import android.view.Gravity; 
import android.view.ViewDebug; 
import android.view.accessibility.AccessibilityEvent; 
import android.view.accessibility.AccessibilityNodeInfo; 

/** 
* <p> 
* A button with two states, checked and unchecked. When the button is pressed 
* or clicked, the state changes automatically. 
* </p> 
* 
* <p><strong>XML attributes</strong></p> 
* <p> 
* See {@link android.R.styleable#CompoundButton 
* CompoundButton Attributes}, {@link android.R.styleable#Button Button 
* Attributes}, {@link android.R.styleable#TextView TextView Attributes}, {@link 
* android.R.styleable#View View Attributes} 
* </p> 
*/ 
public abstract class CompoundButton extends Button implements Checkable { 
    private boolean mChecked; 
    private int mButtonResource; 
    private boolean mBroadcasting; 
    private Drawable mButtonDrawable; 
    private OnCheckedChangeListener mOnCheckedChangeListener; 
    private OnCheckedChangeListener mOnCheckedChangeWidgetListener; 

    private static final int[] CHECKED_STATE_SET = { 
     R.attr.state_checked 
    }; 

    public CompoundButton(Context context) { 
     this(context, null); 
    } 

    public CompoundButton(Context context, AttributeSet attrs) { 
     this(context, attrs, 0); 
    } 

    public CompoundButton(Context context, AttributeSet attrs, int defStyle) { 
     super(context, attrs, defStyle); 

     TypedArray a = 
       context.obtainStyledAttributes(
         attrs, com.android.internal.R.styleable.CompoundButton, defStyle, 0); 

     Drawable d = a.getDrawable(com.android.internal.R.styleable.CompoundButton_button); 
     if (d != null) { 
      setButtonDrawable(d); 
     } 

     boolean checked = a 
       .getBoolean(com.android.internal.R.styleable.CompoundButton_checked, false); 
     setChecked(checked); 

     a.recycle(); 
    } 

    public void toggle() { 
     setChecked(!mChecked); 
    } 

    @Override 
    public boolean performClick() { 
     /* 
     * XXX: These are tiny, need some surrounding 'expanded touch area', 
     * which will need to be implemented in Button if we only override 
     * performClick() 
     */ 

     /* When clicked, toggle the state */ 
     toggle(); 
     return super.performClick(); 
    } 

    @ViewDebug.ExportedProperty 
    public boolean isChecked() { 
     return mChecked; 
    } 

    /** 
    * <p>Changes the checked state of this button.</p> 
    * 
    * @param checked true to check the button, false to uncheck it 
    */ 
    public void setChecked(boolean checked) { 
     if (mChecked != checked) { 
      mChecked = checked; 
      refreshDrawableState(); 

      // Avoid infinite recursions if setChecked() is called from a listener 
      if (mBroadcasting) { 
       return; 
      } 

      mBroadcasting = true; 
      if (mOnCheckedChangeListener != null) { 
       mOnCheckedChangeListener.onCheckedChanged(this, mChecked); 
      } 
      if (mOnCheckedChangeWidgetListener != null) { 
       mOnCheckedChangeWidgetListener.onCheckedChanged(this, mChecked); 
      } 

      mBroadcasting = false;    
     } 
    } 

    /** 
    * Register a callback to be invoked when the checked state of this button 
    * changes. 
    * 
    * @param listener the callback to call on checked state change 
    */ 
    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) { 
     mOnCheckedChangeListener = listener; 
    } 

    /** 
    * Register a callback to be invoked when the checked state of this button 
    * changes. This callback is used for internal purpose only. 
    * 
    * @param listener the callback to call on checked state change 
    * @hide 
    */ 
    void setOnCheckedChangeWidgetListener(OnCheckedChangeListener listener) { 
     mOnCheckedChangeWidgetListener = listener; 
    } 

    /** 
    * Interface definition for a callback to be invoked when the checked state 
    * of a compound button changed. 
    */ 
    public static interface OnCheckedChangeListener { 
     /** 
     * Called when the checked state of a compound button has changed. 
     * 
     * @param buttonView The compound button view whose state has changed. 
     * @param isChecked The new checked state of buttonView. 
     */ 
     void onCheckedChanged(CompoundButton buttonView, boolean isChecked); 
    } 

    /** 
    * Set the background to a given Drawable, identified by its resource id. 
    * 
    * @param resid the resource id of the drawable to use as the background 
    */ 
    public void setButtonDrawable(int resid) { 
     if (resid != 0 && resid == mButtonResource) { 
      return; 
     } 

     mButtonResource = resid; 

     Drawable d = null; 
     if (mButtonResource != 0) { 
      d = getResources().getDrawable(mButtonResource); 
     } 
     setButtonDrawable(d); 
    } 

    /** 
    * Set the background to a given Drawable 
    * 
    * @param d The Drawable to use as the background 
    */ 
    public void setButtonDrawable(Drawable d) { 
     if (d != null) { 
      if (mButtonDrawable != null) { 
       mButtonDrawable.setCallback(null); 
       unscheduleDrawable(mButtonDrawable); 
      } 
      d.setCallback(this); 
      d.setState(getDrawableState()); 
      d.setVisible(getVisibility() == VISIBLE, false); 
      mButtonDrawable = d; 
      mButtonDrawable.setState(null); 
      setMinHeight(mButtonDrawable.getIntrinsicHeight()); 
     } 

     refreshDrawableState(); 
    } 

    @Override 
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 
     super.onInitializeAccessibilityEvent(event); 
     event.setChecked(mChecked); 
    } 

    @Override 
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 
     super.onInitializeAccessibilityNodeInfo(info); 
     info.setCheckable(true); 
     info.setChecked(mChecked); 
    } 

    @Override 
    protected void onDraw(Canvas canvas) { 
     super.onDraw(canvas); 

     final Drawable buttonDrawable = mButtonDrawable; 
     if (buttonDrawable != null) { 
      final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK; 
      final int height = buttonDrawable.getIntrinsicHeight(); 

      int y = 0; 

      switch (verticalGravity) { 
       case Gravity.BOTTOM: 
        y = getHeight() - height; 
        break; 
       case Gravity.CENTER_VERTICAL: 
        y = (getHeight() - height)/2; 
        break; 
      } 

      buttonDrawable.setBounds(0, y, buttonDrawable.getIntrinsicWidth(), y + height); 
      buttonDrawable.draw(canvas); 
     } 
    } 

    @Override 
    protected int[] onCreateDrawableState(int extraSpace) { 
     final int[] drawableState = super.onCreateDrawableState(extraSpace + 1); 
     if (isChecked()) { 
      mergeDrawableStates(drawableState, CHECKED_STATE_SET); 
     } 
     return drawableState; 
    } 

    @Override 
    protected void drawableStateChanged() { 
     super.drawableStateChanged(); 

     if (mButtonDrawable != null) { 
      int[] myDrawableState = getDrawableState(); 

      // Set the state of the Drawable 
      mButtonDrawable.setState(myDrawableState); 

      invalidate(); 
     } 
    } 

    @Override 
    protected boolean verifyDrawable(Drawable who) { 
     return super.verifyDrawable(who) || who == mButtonDrawable; 
    } 

    @Override 
    public void jumpDrawablesToCurrentState() { 
     super.jumpDrawablesToCurrentState(); 
     if (mButtonDrawable != null) mButtonDrawable.jumpToCurrentState(); 
    } 

    static class SavedState extends BaseSavedState { 
     boolean checked; 

     /** 
     * Constructor called from {@link CompoundButton#onSaveInstanceState()} 
     */ 
     SavedState(Parcelable superState) { 
      super(superState); 
     } 

     /** 
     * Constructor called from {@link #CREATOR} 
     */ 
     private SavedState(Parcel in) { 
      super(in); 
      checked = (Boolean)in.readValue(null); 
     } 

     @Override 
     public void writeToParcel(Parcel out, int flags) { 
      super.writeToParcel(out, flags); 
      out.writeValue(checked); 
     } 

     @Override 
     public String toString() { 
      return "CompoundButton.SavedState{" 
        + Integer.toHexString(System.identityHashCode(this)) 
        + " checked=" + checked + "}"; 
     } 

     public static final Parcelable.Creator<SavedState> CREATOR 
       = new Parcelable.Creator<SavedState>() { 
      public SavedState createFromParcel(Parcel in) { 
       return new SavedState(in); 
      } 

      public SavedState[] newArray(int size) { 
       return new SavedState[size]; 
      } 
     }; 
    } 

    @Override 
    public Parcelable onSaveInstanceState() { 
     // Force our ancestor class to save its state 
     setFreezesText(true); 
     Parcelable superState = super.onSaveInstanceState(); 

     SavedState ss = new SavedState(superState); 

     ss.checked = isChecked(); 
     return ss; 
    } 

    @Override 
    public void onRestoreInstanceState(Parcelable state) { 
     SavedState ss = (SavedState) state; 

     super.onRestoreInstanceState(ss.getSuperState()); 
     setChecked(ss.checked); 
     requestLayout(); 
    } 
} 

Ecco il mio xml implementazione dello stato-Lista (di lavoro):

<?xml version="1.0" encoding="utf-8"?> 
<selector xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"> 

    <item android:state_checked="false" 
      android:state_pressed="true" 
      android:drawable="@drawable/btn_check_off_pressed" /> <!-- unchecked pressed --> 

    <item android:state_checked="false" 
      android:state_selected="true" 
      android:drawable="@drawable/btn_check_off_selected" /> <!-- unchecked selected --> 

    <item android:state_checked="true" 
      android:state_pressed="false" 
      android:state_focused="false" 
      android:drawable="@drawable/btn_check_on" /> <!-- checked --> 

    <item android:state_checked="true" 
      android:state_pressed="true" 
      android:drawable="@drawable/btn_check_on_pressed" /> <!-- checked pressed--> 

    <item android:state_checked="true" 
      android:state_selected="true" 
      android:drawable="@drawable/btn_check_on_selected" /> <!-- checked selected--> 

    <item android:state_middle="true" 
      android:state_pressed="false" 
      android:state_focused="false" 
      android:drawable="@drawable/btn_check_middle" /> <!-- middle -->   

    <item android:state_middle="true" 
      android:state_pressed="true" 
      android:drawable="@drawable/btn_check_middle_pressed" /> <!-- middle pressed--> 

    <item android:state_middle="true" 
      android:state_selected="true" 
      android:drawable="@drawable/btn_check_middle_selected" /> <!-- middle selected--> 

    <item android:drawable="@drawable/btn_check_off" /> <!-- unchecked --> 
</selector> 

Ed ecco l'implementazione xml di riserva per la casella di controllo:

<?xml version="1.0" encoding="utf-8"?> 
<!-- Copyright (C) 2008 The Android Open Source Project 

    Licensed under the Apache License, Version 2.0 (the "License"); 
    you may not use this file except in compliance with the License. 
    You may obtain a copy of the License at 

      http://www.apache.org/licenses/LICENSE-2.0 

    Unless required by applicable law or agreed to in writing, software 
    distributed under the License is distributed on an "AS IS" BASIS, 
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
    See the License for the specific language governing permissions and 
    limitations under the License. 
--> 

<selector xmlns:android="http://schemas.android.com/apk/res/android"> 

    <!-- Enabled states --> 

    <item android:state_checked="true" android:state_window_focused="false" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_on" /> 
    <item android:state_checked="false" android:state_window_focused="false" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_off" /> 

    <item android:state_checked="true" android:state_pressed="true" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_on_pressed" /> 
    <item android:state_checked="false" android:state_pressed="true" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_off_pressed" /> 

    <item android:state_checked="true" android:state_focused="true" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_on_selected" /> 
    <item android:state_checked="false" android:state_focused="true" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_off_selected" /> 

    <item android:state_checked="false" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_off" /> 
    <item android:state_checked="true" 
      android:state_enabled="true" 
      android:drawable="@drawable/btn_check_on" /> 


    <!-- Disabled states --> 

    <item android:state_checked="true" android:state_window_focused="false" 
      android:drawable="@drawable/btn_check_on_disable" /> 
    <item android:state_checked="false" android:state_window_focused="false" 
      android:drawable="@drawable/btn_check_off_disable" /> 

    <item android:state_checked="true" android:state_focused="true" 
      android:drawable="@drawable/btn_check_on_disable_focused" /> 
    <item android:state_checked="false" android:state_focused="true" 
      android:drawable="@drawable/btn_check_off_disable_focused" /> 

    <item android:state_checked="false" android:drawable="@drawable/btn_check_off_disable" /> 
    <item android:state_checked="true" android:drawable="@drawable/btn_check_on_disable" /> 

</selector> 

Answer 1

Se proprio insistete sul usando un CheckBox dove ogni elemento ha 3 stati allora quanto segue potrebbe funzionare, ma io non l'ho provato: - Fare una classe che estende la classe CheckBox. - Aggiungi una variabile: "checkstate" di tipo int o byte. La classe dovrebbe avere una variabile booleana "isChecked". - Sovrascrivi il metodo onClick o onCheck in modo che cambi la variabile dello stato di controllo tra i 3 stati invece di alternare la variabile isChecked. - Sul display, selezionare "checkstate" e fare un po 'di effetto visivo per mostrare il 3 ° stato. - Infine, dimmi se funziona.

Answer 2

argomento vecchio, ma io do la mia soluzione per chi si interessed:

public class CheckBoxTriStates extends CheckBox 
{ 
static private final int UNKNOW = -1; 
static private final int UNCHECKED = 0; 
static private final int CHECKED = 1; 
private int state; 

public CheckBoxTriStates(Context context) { 
    super(context); 
    init(); 
} 

public CheckBoxTriStates(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    init(); 
} 

public CheckBoxTriStates(Context context, AttributeSet attrs, int defStyleAttr) { 
    super(context, attrs, defStyleAttr); 
    init(); 
} 

private void init() 
{ 
    state = UNKNOW; 
    updateBtn(); 

    setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() { 

     // checkbox status is changed from uncheck to checked. 
     public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) 
     { 
      switch (state) 
      { 
       case UNKNOW: 
        state = UNCHECKED; 
        break; 
       case UNCHECKED: 
        state = CHECKED; 
        break; 
       case CHECKED: 
        state = UNKNOW; 
        break; 
      } 
      updateBtn(); 
     } 
    }); 

} 

private void updateBtn() 
{ 
    int btnDrawable = R.drawable.ic_checkbox_indeterminate_black; 
    switch (state) 
    { 
     case UNKNOW: 
      btnDrawable = R.drawable.ic_checkbox_indeterminate_black; 
      break; 
     case UNCHECKED: 
      btnDrawable = R.drawable.ic_checkbox_unchecked_black; 
      break; 
     case CHECKED: 
      btnDrawable = R.drawable.ic_checkbox_checked_black; 
      break; 
    } 
    setButtonDrawable(btnDrawable); 

} 
public int getState() 
{ 
    return state; 
} 

public void setState(int state) 
{ 
    this.state = state; 
    updateBtn(); 
} 

}

È possibile trovare le risorse pulsante Here. Funziona perfettamente.