在 android 上创建一个三态复选框

Question

我遇到了一个大问题：我想在 android 上创建三个 state 复选框。这是一个带有复选框的 ListView 上的复选框。 它应该允许用户在三种状态之间切换：

• 全部勾选
• 没有检查
• 杂项检查

并可选择在更改时保留 misc state。

如果我是对的，我应该创建 CompoundButton class 的子类并实现 boolean mchecked 的 int mstate intead。 然后我应该覆盖事件侦听器、保存 state 的函数以及 state getter 和 setter。

我的问题基本上是我该如何实施？ 如何在可绘制状态之间切换？ （我已经在xml中实现了middle_state）以及如何正确实现事件处理器？

这是我开始的实现：

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;
    }
}

这是股票 CompoundButton 的代码：

/*
 * 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();
    }
}

这是我的 xml 状态列表实现（有效）：

<?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>

这是复选框的库存 xml 实现：

<?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

旧话题，但我为感兴趣的人提供了解决方案：

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) {
                    default:
                    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) {
            default:
            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();
    }
}

您可以在此处找到按钮资源。 它工作完美。

Answer 2

如果您想要在更改状态时没有矢量动画的复选框，请尝试使用这个简单的自定义类来设置状态不确定的复选框

在此处查看github示例

Answer 3

如果您真的坚持使用 CheckBox，其中每个元素都有 3 个状态，那么以下可能有效，但我还没有尝试过： - 创建一个扩展 CheckBox 类的类。 - 添加一个变量：int 或 byte 类型的“checkstate”。 该类应该有一个布尔值“isChecked”变量。 - 覆盖 onClick 或 onCheck 方法，以便它在 3 个状态之间更改 checkstate 变量，而不是切换 isChecked 变量。 - 显示时，检查“checkstate”并做一些视觉效果以显示第三个状态。 - 最后，告诉我它是否有效。

Answer 4

以前我想做同样的事情。 在做了一些艰苦的研究之后，我接近了这个。

优点：

• 动画按钮
• 材料设计

---

TriStateMaterialCheckBox.kt：

import android.content.Context
import android.util.AttributeSet
import androidx.annotation.StyleableRes
import com.google.android.material.checkbox.MaterialCheckBox

class TriStateMaterialCheckBox : MaterialCheckBox {
    constructor(context: Context) : this(context, null)
    constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, com.google.android.material.R.attr.checkboxStyle)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
        val sets = intArrayOf(R.attr.state)
        
        val typedArray = context.obtainStyledAttributes(attrs, sets)
        
        try {
            state = typedArray.getInt(ATTR_STATE, STATE_UNCHECKED)
        } finally {
            typedArray.recycle()
        }
        
        initComponent()
    }
    
    companion object {
        // @formatter:off
        @StyleableRes private const val ATTR_STATE = 0
        // @formatter:on
        
        const val STATE_UNCHECKED: Int = 0
        const val STATE_INDETERMINATE: Int = 1
        const val STATE_CHECKED: Int = 2
        
        private val UNCHECKED = intArrayOf(R.attr.state_unchecked)
        private val INDETERMINATE = intArrayOf(R.attr.state_indeterminate)
        private val CHECKED = intArrayOf(R.attr.state_checked)
    }
    
    private var isChangingState = false
    
    var state: Int
        @Throws(IllegalStateException::class)
        set(value) {
            if (isChangingState) return
            if (field == value) return
            isChangingState = true
            
            field = value
            isChecked = when (value) {
                STATE_UNCHECKED -> false
                STATE_INDETERMINATE -> true
                STATE_CHECKED -> true
                else -> throw IllegalStateException("$value is not a valid state for ${this.javaClass.name}")
            }
            refreshDrawableState()
            
            isChangingState = false
            
            onStateChanged?.let { it(this@TriStateMaterialCheckBox, value) }
        }
    
    var onStateChanged: ((TriStateMaterialCheckBox, Int) -> Unit)? = null
    
    private fun initComponent() {
        setButtonDrawable(R.drawable.tri_state_button)
        setOnCheckedChangeListener { _, _ ->
            state = when (state) {
                STATE_UNCHECKED -> STATE_CHECKED
                STATE_INDETERMINATE -> STATE_CHECKED
                STATE_CHECKED -> STATE_UNCHECKED
                else -> -1
            }
        }
    }
    
    override fun onCreateDrawableState(extraSpace: Int): IntArray {
        val drawableState = super.onCreateDrawableState(extraSpace + 1)
        
        mergeDrawableStates(
            drawableState, when (state) {
                STATE_UNCHECKED -> UNCHECKED
                STATE_INDETERMINATE -> INDETERMINATE
                STATE_CHECKED -> CHECKED
                else -> throw IllegalStateException("$state is not a valid state for ${this.javaClass.name}")
            }
        )
        
        return drawableState
    }
}

attrs.xml：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="state" format="enum">
        <enum name="unchecked" value="0" />
        <enum name="indeterminate" value="1" />
        <enum name="checked" value="2" />
    </attr>
    
    <declare-styleable name="TriStateMaterialCheckBox">
        <attr name="state" />
        <attr name="state_unchecked" format="boolean" />
        <attr name="state_indeterminate" format="boolean" />
        <attr name="state_checked" format="boolean" />
    </declare-styleable>
</resources>

tri_state_button.xml：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:enterFadeDuration="@android:integer/config_shortAnimTime" android:exitFadeDuration="@android:integer/config_shortAnimTime">
    <item android:drawable="@drawable/ic_unchecked" app:state_unchecked="true" />
    <item android:drawable="@drawable/ic_indeterminate" app:state_indeterminate="true" />
    <item android:drawable="@drawable/ic_checked" app:state_checked="true" />
    <item android:drawable="@drawable/ic_unchecked" />
</selector>

Answer 5

最新版本的材质库支持三态复选框。 将此添加到 build.gradle：

implementation 'com.google.android.material:material:1.8.0-rc01'

之后，您可以在 xml 中设置不确定的 state：

  <CheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:checkedState="indeterminate" />

或者通过代码：

    checkbox.checkedState = when (childrenSelected) {
        0 -> MaterialCheckBox.STATE_UNCHECKED
        childrenTotal -> MaterialCheckBox.STATE_CHECKED
        else -> MaterialCheckBox.STATE_INDETERMINATE
    }

其中 childrenSelected 是选中复选框的数量。 您还可以根据需要自定义复选框外观，请在此处查看完整文档： https://developer.android.com/reference/com/google/android/material/checkbox/MaterialCheckBox