滑动的Button

在介绍SwitchButton之前，先来看一下系统Button是如何实现的。源码如下：

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1. @RemoteView
2. public class Button extends TextView {
3. public Button(Context context) {
4. this(context, null);
5. }
6. public Button(Context context, AttributeSet attrs) {
7. this(context, attrs, com.android.internal.R.attr.buttonStyle);
8. }
9. public Button(Context context, AttributeSet attrs, int defStyle) {
10. super(context, attrs, defStyle);
11. }
12. @Override
13. public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
14. super.onInitializeAccessibilityEvent(event);
15. event.setClassName(Button. class.getName());
16. }
17. @Override
18. public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
19. super.onInitializeAccessibilityNodeInfo(info);
20. info.setClassName(Button. class.getName());
21. }
22. }

@RemoteView
public class Button extends TextView {
    public Button(Context context) {
        this(context, null);
    }

    public Button(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.buttonStyle);
    }

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

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        event.setClassName(Button. class.getName());
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        info.setClassName(Button. class.getName());
    }
}

是直接继承于TextView，所不同的是在构造方法中添加了Button的样式，并且在初始化可见性方面交由Button类自己来处理。虽然Button的实现比较简单，但是它的子类并不是这样。看一下：

直接子类只有有一个，CompoundButton。它是一个抽象类，而实现这个类的控件正是CheckBox, RadioButton, Switch, ToggleButton这四个，所以先重点说一下它。源码如下：

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1. /**
2. * <p>
3. * A button with two states, checked and unchecked. When the button is pressed
4. * or clicked, the state changes automatically.
5. * </p>
6. *
7. * <p><strong>XML attributes </strong></p>
8. * <p>
9. * See {@link android.R.styleable#CompoundButton
10. * CompoundButton Attributes}, {@link android.R.styleable#Button Button
11. * Attributes}, {@link android.R.styleable#TextView TextView Attributes}, {@link
12. * android.R.styleable #View View Attributes}
13. * </p>
14. */
15. public abstract class CompoundButton extends Button implements Checkable {
16. private boolean mChecked ;
17. private int mButtonResource ;
18. private boolean mBroadcasting ;
19. private Drawable mButtonDrawable;
20. private OnCheckedChangeListener mOnCheckedChangeListener;
21. private OnCheckedChangeListener mOnCheckedChangeWidgetListener ;
22. private static final int[] CHECKED_STATE_SET = {
23. R.attr.state_checked
24. };
25. public CompoundButton(Context context) {
26. this(context, null);
27. }
28. public CompoundButton(Context context, AttributeSet attrs) {
29. this(context, attrs, 0);
30. }
31. public CompoundButton(Context context, AttributeSet attrs, int defStyle) {
32. super(context, attrs, defStyle);
33. TypedArray a =
34. context.obtainStyledAttributes(
35. attrs, com.android.internal.R.styleable.CompoundButton, defStyle, 0);
36. Drawable d = a.getDrawable(com.android.internal.R.styleable.CompoundButton_button);
37. if (d != null ) {
38. setButtonDrawable(d);
39. }
40. boolean checked = a
41. .getBoolean(com.android.internal.R.styleable.CompoundButton_checked, false);
42. setChecked(checked);
43. a.recycle();
44. }
45. public void toggle() {
46. setChecked(! mChecked);
47. }
48. @Override
49. public boolean performClick() {
50. /*
51. * XXX: These are tiny, need some surrounding ‘expanded touch area‘,
52. * which will need to be implemented in Button if we only override
53. * performClick()
54. */
55. /* When clicked, toggle the state */
56. toggle();
57. return super .performClick();
58. }
59. @ViewDebug.ExportedProperty
60. public boolean isChecked() {
61. return mChecked ;
62. }
63. /**
64. * <p>Changes the checked state of this button.</p>
65. *
66. * @param checked true to check the button, false to uncheck it
67. */
68. public void setChecked(boolean checked) {
69. if (mChecked != checked) {
70. mChecked = checked;
71. refreshDrawableState();
72. notifyViewAccessibilityStateChangedIfNeeded(
73. AccessibilityEvent.CONTENT_CHANGE_TYPE_UNDEFINED );
74. // Avoid infinite recursions if setChecked() is called from a listener
75. if (mBroadcasting ) {
76. return;
77. }
78. mBroadcasting = true ;
79. if (mOnCheckedChangeListener != null) {
80. mOnCheckedChangeListener.onCheckedChanged(this, mChecked);
81. }
82. if (mOnCheckedChangeWidgetListener != null) {
83. mOnCheckedChangeWidgetListener .onCheckedChanged(this, mChecked);
84. }
85. mBroadcasting = false ;
86. }
87. }
88. /**
89. * Register a callback to be invoked when the checked state of this button
90. * changes.
91. *
92. * @param listener the callback to call on checked state change
93. */
94. public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
95. mOnCheckedChangeListener = listener;
96. }
97. /**
98. * Register a callback to be invoked when the checked state of this button
99. * changes. This callback is used for internal purpose only.
100. *
101. * @param listener the callback to call on checked state change
102. * @hide
103. */
104. void setOnCheckedChangeWidgetListener(OnCheckedChangeListener listener) {
105. mOnCheckedChangeWidgetListener = listener;
106. }
107. /**
108. * Interface definition for a callback to be invoked when the checked state
109. * of a compound button changed.
110. */
111. public static interface OnCheckedChangeListener {
112. /**
113. * Called when the checked state of a compound button has changed.
114. *
115. * @param buttonView The compound button view whose state has changed.
116. * @param isChecked  The new checked state of buttonView.
117. */
118. void onCheckedChanged(CompoundButton buttonView, boolean isChecked);
119. }
120. /**
121. * Set the background to a given Drawable, identified by its resource id.
122. *
123. * @param resid the resource id of the drawable to use as the background
124. */
125. public void setButtonDrawable(int resid) {
126. if (resid != 0 && resid == mButtonResource ) {
127. return;
128. }
129. mButtonResource = resid;
130. Drawable d = null;
131. if (mButtonResource != 0) {
132. d = getResources().getDrawable(mButtonResource );
133. }
134. setButtonDrawable(d);
135. }
136. /**
137. * Set the background to a given Drawable
138. *
139. * @param d The Drawable to use as the background
140. */
141. public void setButtonDrawable(Drawable d) {
142. if (d != null ) {
143. if (mButtonDrawable != null) {
144. mButtonDrawable.setCallback(null);
145. unscheduleDrawable( mButtonDrawable);
146. }
147. d.setCallback( this);
148. d.setVisible(getVisibility() == VISIBLE, false);
149. mButtonDrawable = d;
150. setMinHeight(mButtonDrawable .getIntrinsicHeight());
151. }
152. refreshDrawableState();
153. }
154. @Override
155. public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
156. super.onInitializeAccessibilityEvent(event);
157. event.setClassName(CompoundButton.class .getName());
158. event.setChecked( mChecked);
159. }
160. @Override
161. public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
162. super.onInitializeAccessibilityNodeInfo(info);
163. info.setClassName(CompoundButton.class .getName());
164. info.setCheckable( true);
165. info.setChecked( mChecked);
166. }
167. @Override
168. public int getCompoundPaddingLeft() {
169. int padding = super.getCompoundPaddingLeft();
170. if (!isLayoutRtl()) {
171. final Drawable buttonDrawable = mButtonDrawable;
172. if (buttonDrawable != null) {
173. padding += buttonDrawable.getIntrinsicWidth();
174. }
175. }
176. return padding;
177. }
178. @Override
179. public int getCompoundPaddingRight() {
180. int padding = super.getCompoundPaddingRight();
181. if (isLayoutRtl()) {
182. final Drawable buttonDrawable = mButtonDrawable;
183. if (buttonDrawable != null) {
184. padding += buttonDrawable.getIntrinsicWidth();
185. }
186. }
187. return padding;
188. }
189. /**
190. * @hide
191. */
192. @Override
193. public int getHorizontalOffsetForDrawables() {
194. final Drawable buttonDrawable = mButtonDrawable ;
195. return (buttonDrawable != null) ? buttonDrawable.getIntrinsicWidth() : 0;
196. }
197. @Override
198. protected void onDraw(Canvas canvas) {
199. super.onDraw(canvas);
200. final Drawable buttonDrawable = mButtonDrawable ;
201. if (buttonDrawable != null) {
202. final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK ;
203. final int drawableHeight = buttonDrawable.getIntrinsicHeight();
204. final int drawableWidth = buttonDrawable.getIntrinsicWidth();
205. int top = 0;
206. switch (verticalGravity) {
207. case Gravity.BOTTOM :
208. top = getHeight() - drawableHeight;
209. break;
210. case Gravity.CENTER_VERTICAL :
211. top = (getHeight() - drawableHeight) / 2;
212. break;
213. }
214. int bottom = top + drawableHeight;
215. int left = isLayoutRtl() ? getWidth() - drawableWidth : 0;
216. int right = isLayoutRtl() ? getWidth() : drawableWidth;
217. buttonDrawable.setBounds(left, top, right, bottom);
218. buttonDrawable.draw(canvas);
219. }
220. }
221. @Override
222. protected int[] onCreateDrawableState(int extraSpace) {
223. final int [] drawableState = super.onCreateDrawableState(extraSpace + 1);
224. if (isChecked()) {
225. mergeDrawableStates(drawableState, CHECKED_STATE_SET);
226. }
227. return drawableState;
228. }
229. @Override
230. protected void drawableStateChanged() {
231. super.drawableStateChanged();
232. if (mButtonDrawable != null) {
233. int[] myDrawableState = getDrawableState();
234. // Set the state of the Drawable
235. mButtonDrawable.setState(myDrawableState);
236. invalidate();
237. }
238. }
239. @Override
240. protected boolean verifyDrawable(Drawable who) {
241. return super .verifyDrawable(who) || who == mButtonDrawable;
242. }
243. @Override
244. public void jumpDrawablesToCurrentState() {
245. super.jumpDrawablesToCurrentState();
246. if (mButtonDrawable != null) mButtonDrawable.jumpToCurrentState();
247. }
248. static class SavedState extends BaseSavedState {
249. boolean checked ;
250. /**
251. * Constructor called from {@link CompoundButton#onSaveInstanceState()}
252. */
253. SavedState(Parcelable superState) {
254. super(superState);
255. }
256. /**
257. * Constructor called from {@link #CREATOR}
258. */
259. private SavedState(Parcel in) {
260. super(in);
261. checked = (Boolean)in.readValue( null);
262. }
263. @Override
264. public void writeToParcel(Parcel out, int flags) {
265. super.writeToParcel(out, flags);
266. out.writeValue( checked);
267. }
268. @Override
269. public String toString() {
270. return "CompoundButton.SavedState{"
271. + Integer.toHexString(System.identityHashCode(this))
272. + " checked=" + checked + "}" ;
273. }
274. public static final Parcelable.Creator<SavedState> CREATOR
275. = new Parcelable.Creator<SavedState>() {
276. public SavedState createFromParcel(Parcel in) {
277. return new SavedState(in);
278. }
279. public SavedState[] newArray(int size) {
280. return new SavedState[size];
281. }
282. };
283. }
284. @Override
285. public Parcelable onSaveInstanceState() {
286. // Force our ancestor class to save its state
287. setFreezesText( true);
288. Parcelable superState = super.onSaveInstanceState();
289. SavedState ss = new SavedState(superState);
290. ss. checked = isChecked();
291. return ss;
292. }
293. @Override
294. public void onRestoreInstanceState(Parcelable state) {
295. SavedState ss = (SavedState) state;
296. super.onRestoreInstanceState(ss.getSuperState());
297. setChecked(ss. checked);
298. requestLayout();
299. }
300. }

/**
 * <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();
            notifyViewAccessibilityStateChangedIfNeeded(
                    AccessibilityEvent.CONTENT_CHANGE_TYPE_UNDEFINED );

            // 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.setVisible(getVisibility() == VISIBLE, false);
            mButtonDrawable = d;
            setMinHeight(mButtonDrawable .getIntrinsicHeight());
        }

        refreshDrawableState();
    }

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

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

    @Override
    public int getCompoundPaddingLeft() {
        int padding = super.getCompoundPaddingLeft();
        if (!isLayoutRtl()) {
            final Drawable buttonDrawable = mButtonDrawable;
            if (buttonDrawable != null) {
                padding += buttonDrawable.getIntrinsicWidth();
            }
        }
        return padding;
    }

    @Override
    public int getCompoundPaddingRight() {
        int padding = super.getCompoundPaddingRight();
        if (isLayoutRtl()) {
            final Drawable buttonDrawable = mButtonDrawable;
            if (buttonDrawable != null) {
                padding += buttonDrawable.getIntrinsicWidth();
            }
        }
        return padding;
    }

    /**
     * @hide
     */
    @Override
    public int getHorizontalOffsetForDrawables() {
        final Drawable buttonDrawable = mButtonDrawable ;
        return (buttonDrawable != null) ? buttonDrawable.getIntrinsicWidth() : 0;
    }

    @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 drawableHeight = buttonDrawable.getIntrinsicHeight();
            final int drawableWidth = buttonDrawable.getIntrinsicWidth();

            int top = 0;
            switch (verticalGravity) {
                case Gravity.BOTTOM :
                    top = getHeight() - drawableHeight;
                    break;
                case Gravity.CENTER_VERTICAL :
                    top = (getHeight() - drawableHeight) / 2;
                    break;
            }
            int bottom = top + drawableHeight;
            int left = isLayoutRtl() ? getWidth() - drawableWidth : 0;
            int right = isLayoutRtl() ? getWidth() : drawableWidth;

            buttonDrawable.setBounds(left, top, right, bottom);
            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();
    }
}

先从构造方法开始，在构造方法中，

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1. public CompoundButton(Context context, AttributeSet attrs, int defStyle) {
2. super(context, attrs, defStyle);
3. TypedArray a =
4. context.obtainStyledAttributes(
5. attrs, com.android.internal.R.styleable.CompoundButton, defStyle, 0);
6. Drawable d = a.getDrawable(com.android.internal.R.styleable.CompoundButton_button);
7. if (d != null ) {
8. setButtonDrawable(d);
9. }
10. boolean checked = a
11. .getBoolean(com.android.internal.R.styleable.CompoundButton_checked, false);
12. setChecked(checked);
13. a.recycle();
14. }

 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();
    }

先是从attrs中读取定义的属性，一个是Drawable用于设置背景；一个是布尔类型变量用于判断是否check过。设置背景使用的是setButtonDrawable()方法，代码如下：

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1. /**
2. * Set the background to a given Drawable
3. *
4. * @param d The Drawable to use as the background
5. */
6. public void setButtonDrawable(Drawable d) {
7. if (d != null ) {
8. if (mButtonDrawable != null) {
9. mButtonDrawable.setCallback(null);
10. unscheduleDrawable( mButtonDrawable);
11. }
12. d.setCallback( this);
13. d.setVisible(getVisibility() == VISIBLE, false);
14. mButtonDrawable = d;
15. setMinHeight(mButtonDrawable .getIntrinsicHeight());
16. }
17. refreshDrawableState();
18. }

/**
     * 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.setVisible(getVisibility() == VISIBLE, false);
            mButtonDrawable = d;
            setMinHeight(mButtonDrawable .getIntrinsicHeight());
        }

        refreshDrawableState();
    }

这个方法写的就比较完善，可以作为一个学习的典范。首先判断传递过来的Drawable是否为空，如果不为空并且默认的Drawable也不为空，那么取消默认Drawable的callback，然后调用unscheduleDrawable方法。这个方法代码如下：

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1. /**
2. * Unschedule any events associated with the given Drawable.  This can be
3. * used when selecting a new Drawable into a view, so that the previous
4. * one is completely unscheduled.
5. *
6. * @param who The Drawable to unschedule.
7. *
8. * @see #drawableStateChanged
9. */
10. public void unscheduleDrawable(Drawable who) {
11. if (mAttachInfo != null && who != null) {
12. mAttachInfo.mViewRootImpl .mChoreographer.removeCallbacks(
13. Choreographer.CALLBACK_ANIMATION, null, who);
14. }
15. }

 /**
     * Unschedule any events associated with the given Drawable.  This can be
     * used when selecting a new Drawable into a view, so that the previous
     * one is completely unscheduled.
     *
     * @param who The Drawable to unschedule.
     *
     * @see #drawableStateChanged
     */
    public void unscheduleDrawable(Drawable who) {
        if (mAttachInfo != null && who != null) {
            mAttachInfo.mViewRootImpl .mChoreographer.removeCallbacks(
                    Choreographer.CALLBACK_ANIMATION, null, who);
        }
    }

从方法注释中可以看出它的用途，正是更换Drawable时候使用的。接下来开始重新设置Drawable，包括回调、可见性、最小高度。最后调用refreshDrawableState()方法，这个是View类的方法，用于更新Drawable状态。

然后再回过头看一下setChecked(checked)方法，这个用于设置check，也就是button的点击状态。代码如下：

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1. /**
2. * <p>Changes the checked state of this button.</p>
3. *
4. * @param checked true to check the button, false to uncheck it
5. */
6. public void setChecked( boolean checked) {
7. if (mChecked != checked) {
8. mChecked = checked;
9. refreshDrawableState();
10. notifyViewAccessibilityStateChangedIfNeeded(
11. AccessibilityEvent.CONTENT_CHANGE_TYPE_UNDEFINED );
12. // Avoid infinite recursions if setChecked() is called from a listener
13. if (mBroadcasting ) {
14. return;
15. }
16. mBroadcasting = true ;
17. if (mOnCheckedChangeListener != null) {
18. mOnCheckedChangeListener.onCheckedChanged(this, mChecked);
19. }
20. if (mOnCheckedChangeWidgetListener != null) {
21. mOnCheckedChangeWidgetListener .onCheckedChanged(this, mChecked);
22. }
23. mBroadcasting = false ;
24. }
25. }

/**
     * <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();
            notifyViewAccessibilityStateChangedIfNeeded(
                    AccessibilityEvent.CONTENT_CHANGE_TYPE_UNDEFINED );

            // 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 ;
        }
    }

在这个方法中多出了一个接口，这个接口真是check的一个回调接口，代码如下：

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1. /**
2. * Interface definition for a callback to be invoked when the checked state
3. * of a compound button changed.
4. */
5. public static interface OnCheckedChangeListener {
6. /**
7. * Called when the checked state of a compound button has changed.
8. *
9. * @param buttonView The compound button view whose state has changed.
10. * @param isChecked  The new checked state of buttonView.
11. */
12. void onCheckedChanged(CompoundButton buttonView, boolean isChecked);
13. }

/**
     * 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);
    }

这种回调接口在Android中处处可见，之前的文章也有介绍过。但是在上面的方法，它使用了一个mBroadcasting变量，进而巧妙地避免了重复递归的问题，大家自己感受一下。

然后就是ondraw()方法了，把之前的drawable画出来。代码如下：

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1. @Override
2. protected void onDraw(Canvas canvas) {
3. super.onDraw(canvas);
4. final Drawable buttonDrawable = mButtonDrawable ;
5. if (buttonDrawable != null) {
6. final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK ;
7. final int drawableHeight = buttonDrawable.getIntrinsicHeight();
8. final int drawableWidth = buttonDrawable.getIntrinsicWidth();
9. int top = 0;
10. switch (verticalGravity) {
11. case Gravity.BOTTOM :
12. top = getHeight() - drawableHeight;
13. break;
14. case Gravity.CENTER_VERTICAL :
15. top = (getHeight() - drawableHeight) / 2;
16. break;
17. }
18. int bottom = top + drawableHeight;
19. int left = isLayoutRtl() ? getWidth() - drawableWidth : 0;
20. int right = isLayoutRtl() ? getWidth() : drawableWidth;
21. buttonDrawable.setBounds(left, top, right, bottom);
22. buttonDrawable.draw(canvas);
23. }
24. }

  @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 drawableHeight = buttonDrawable.getIntrinsicHeight();
            final int drawableWidth = buttonDrawable.getIntrinsicWidth();

            int top = 0;
            switch (verticalGravity) {
                case Gravity.BOTTOM :
                    top = getHeight() - drawableHeight;
                    break;
                case Gravity.CENTER_VERTICAL :
                    top = (getHeight() - drawableHeight) / 2;
                    break;
            }
            int bottom = top + drawableHeight;
            int left = isLayoutRtl() ? getWidth() - drawableWidth : 0;
            int right = isLayoutRtl() ? getWidth() : drawableWidth;

            buttonDrawable.setBounds(left, top, right, bottom);
            buttonDrawable.draw(canvas);
        }
    }

看得出来，在onDrawable()方法中，最主要的部分还是如何确定上下左右四个参数。确定完后就可以画出来了。但是，CompoundButton是一个抽象类，并不能直接使用，那看一下它的子类是如何实现的：

1、CheckBox

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1. public class CheckBox extends CompoundButton {
2. public CheckBox(Context context) {
3. this(context, null);
4. }
5. public CheckBox(Context context, AttributeSet attrs) {
6. this(context, attrs, com.android.internal.R.attr.checkboxStyle);
7. }
8. public CheckBox(Context context, AttributeSet attrs, int defStyle) {
9. super(context, attrs, defStyle);
10. }
11. @Override
12. public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
13. super.onInitializeAccessibilityEvent(event);
14. event.setClassName(CheckBox. class.getName());
15. }
16. @Override
17. public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
18. super.onInitializeAccessibilityNodeInfo(info);
19. info.setClassName(CheckBox. class.getName());
20. }
21. }

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

    public CheckBox(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.checkboxStyle);
    }

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

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        event.setClassName(CheckBox. class.getName());
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        info.setClassName(CheckBox. class.getName());
    }
}

和Button的实现差不多，使用了一个自己的样式。并且也是重写了那两个方法。再来看一下RadioButton，

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1. public class RadioButton extends CompoundButton {
2. public RadioButton(Context context) {
3. this(context, null);
4. }
5. public RadioButton(Context context, AttributeSet attrs) {
6. this(context, attrs, com.android.internal.R.attr.radioButtonStyle);
7. }
8. public RadioButton(Context context, AttributeSet attrs, int defStyle) {
9. super(context, attrs, defStyle);
10. }
11. /**
12. * {@inheritDoc}
13. * <p>
14. * If the radio button is already checked, this method will not toggle the radio button.
15. */
16. @Override
17. public void toggle() {
18. // we override to prevent toggle when the radio is already
19. // checked (as opposed to check boxes widgets)
20. if (!isChecked()) {
21. super.toggle();
22. }
23. }
24. @Override
25. public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
26. super.onInitializeAccessibilityEvent(event);
27. event.setClassName(RadioButton. class.getName());
28. }
29. @Override
30. public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
31. super.onInitializeAccessibilityNodeInfo(info);
32. info.setClassName(RadioButton. class.getName());
33. }
34. }

public class RadioButton extends CompoundButton {

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

    public RadioButton(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.radioButtonStyle);
    }

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

    /**
     * {@inheritDoc}
     * <p>
     * If the radio button is already checked, this method will not toggle the radio button.
     */
    @Override
    public void toggle() {
        // we override to prevent toggle when the radio is already
        // checked (as opposed to check boxes widgets)
        if (!isChecked()) {
            super.toggle();
        }
    }

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        event.setClassName(RadioButton. class.getName());
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        info.setClassName(RadioButton. class.getName());
    }
}

和CheckBox实现差不多，区别在于多重写了一个方法，用于防止按钮被重复点击。另外还有ToggleButton以及Switch，前者实现也比较简单，后者稍微麻烦了一些，感兴趣可以自己分析。

最后切入正题，看看滑动Button要如何实现呢？首先看一下效果图：

图1-1

图1-2

图1-1所示的滑动Button实现的思路是这样的，背景图片有开和关的文字，一个按钮在其上面左右滑动，遮住相应的部分，使其在一个位置时候只能看到一个开关。

如图1-3，在实现的时候，先画一个开关背景图片只，然后在其上面画一个按钮，滑动开关的时候对上面的按钮进行处理即可。

准备：

1、按钮图片

2、背景图片

编码：

在自定义滑动按钮控件的时候，可以有多种选择，可以继承于Button，也可以继承于Button的子类，也可以继承于View类等。我们知道滑动按钮是一个很简单的控件，就是左右滑动改变显示内容，不需要其他的额外东西在里面，所以直接继承于View来实现即可。如果继承于系统的一些控件，那么有很多东西用不到，会造成浪费。

1、定义一个类继承于View，初始化构造方法，在构造方法中加载图片及其信息。

2、重写onMeasure()方法，计算控件的大小。

3、重写onTouchEvent()方法，对滑动事件进行判别处理。

4、定义接口，实现回调。

5、重写onDraw()方法，动态画出按钮。

代码如下：

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1. /**
2. *
3. */
4. package com.kince.slidebutton;
5. import android.content.Context;
6. import android.graphics.Bitmap;
7. import android.graphics.BitmapFactory;
8. import android.graphics.Canvas;
9. import android.util.AttributeSet;
10. import android.util.Log;
11. import android.view.MotionEvent;
12. import android.view.View;
13. /**
14. * @author kince
15. * @category 左右手势滑动button
16. * @serial 1.0.0
17. * @since 2014.5.17
18. * @see http://blog.csdn.net/wangjinyu501
19. *
20. */
21. public class SlideButton extends View {
22. private Bitmap slideBitMap;// 滑动图片
23. private Bitmap switchBitMap;// 背景图片
24. private int slideBitMapWidth;// 滑动图片宽度
25. private int switchBitMapWidth;// 背景图片宽度
26. private int switchBitMapHeight;// 背景图片高度
27. private boolean currentState;// 开关状态
28. private boolean isSliding = false; // 是否正在滑动中
29. private int currentX; // 当前开关的位置
30. private OnToggleStateChangedListener mChangedListener;// 回调接口
31. /**
32. * @param context
33. *            在java代码中直接调用使用此构造方法
34. */
35. public SlideButton(Context context) {
36. this(context, null);
37. // TODO Auto-generated constructor stub
38. }
39. /**
40. * @param context
41. * @param attrs
42. *            在xml中使用要用到这个方法
43. */
44. public SlideButton(Context context, AttributeSet attrs) {
45. this(context, attrs, 0);
46. // TODO Auto-generated constructor stub
47. }
48. /**
49. * @param context
50. * @param attrs
51. * @param defStyleAttr
52. *            指定一个样式
53. */
54. public SlideButton(Context context, AttributeSet attrs, int defStyleAttr) {
55. super(context, attrs, defStyleAttr);
56. initBitmap();
57. }
58. /**
59. * @category 加载背景图片以及开关图片 然后获取各自的宽高
60. *
61. */
62. private void initBitmap() {
63. // TODO Auto-generated method stub
64. slideBitMap = BitmapFactory.decodeResource(getResources(),
65. R.drawable.slide_button_background);
66. switchBitMap = BitmapFactory.decodeResource(getResources(),
67. R.drawable.switch_background);
68. slideBitMapWidth = slideBitMap.getWidth();
69. switchBitMapWidth = switchBitMap.getWidth();
70. switchBitMapHeight = switchBitMap.getHeight();
71. Log.i("switchBitMapWidth", switchBitMapWidth + "");
72. }
73. @Override
74. protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
75. // TODO Auto-generated method stub
76. super.onMeasure(widthMeasureSpec, heightMeasureSpec);
77. setMeasuredDimension(switchBitMapWidth, switchBitMapHeight);// 设置控件的宽高
78. }
79. @Override
80. protected void onDraw(Canvas canvas) {
81. // 绘制button背景图片
82. canvas.drawBitmap(switchBitMap, 0, 0, null);
83. // 绘制滑动开关
84. if (isSliding) {// 如果当前状态是滑动中 则动态绘制开关
85. int dis = currentX - slideBitMapWidth / 2;
86. if (dis < 0) {
87. dis = 0;
88. } else if (dis > switchBitMapWidth - slideBitMapWidth) {
89. dis = switchBitMapWidth - slideBitMapWidth;
90. }
91. canvas.drawBitmap(slideBitMap, dis, 0, null);
92. } else {
93. if (currentState) { // 绘制开关为开的状态
94. canvas.drawBitmap(slideBitMap, switchBitMapWidth
95. - slideBitMapWidth, 0, null);
96. } else { // 绘制开关为关的状态
97. canvas.drawBitmap(slideBitMap, 0, 0, null);
98. }
99. }
100. super.onDraw(canvas);
101. }
102. @Override
103. public boolean onTouchEvent(MotionEvent event) {
104. // 手势识别 判断滑动方向
105. int action = event.getAction();
106. switch (action) {
107. case MotionEvent.ACTION_DOWN:
108. isSliding = true;
109. currentX = (int) event.getX();
110. break;
111. case MotionEvent.ACTION_MOVE:
112. currentX = (int) event.getX();
113. Log.i("currentX", currentX + "");
114. break;
115. case MotionEvent.ACTION_UP:
116. isSliding = false;
117. int bgCenter = switchBitMapWidth / 2;
118. boolean state = currentX > bgCenter; // 改变后的状态
119. if (state != currentState && mChangedListener != null) {// 添加回调
120. mChangedListener.onToggleStateChanged(state);
121. }
122. currentState = state;
123. break;
124. default:
125. break;
126. }
127. invalidate();
128. return true;
129. }
130. public OnToggleStateChangedListener getmChangedListener() {
131. return mChangedListener;
132. }
133. public void setmChangedListener(
134. OnToggleStateChangedListener mChangedListener) {
135. this.mChangedListener = mChangedListener;
136. }
137. public boolean isToggleState() {
138. return currentState;
139. }
140. public void setToggleState(boolean currentState) {
141. this.currentState = currentState;
142. }
143. }

/**
*
*/
package com.kince.slidebutton;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

/**
* @author kince
* @category 左右手势滑动button
* @serial 1.0.0
* @since 2014.5.17
* @see http://blog.csdn.net/wangjinyu501
*
*/
public class SlideButton extends View {

     private Bitmap slideBitMap;// 滑动图片
     private Bitmap switchBitMap;// 背景图片

     private int slideBitMapWidth;// 滑动图片宽度
     private int switchBitMapWidth;// 背景图片宽度
     private int switchBitMapHeight;// 背景图片高度

     private boolean currentState;// 开关状态
     private boolean isSliding = false; // 是否正在滑动中

     private int currentX; // 当前开关的位置

     private OnToggleStateChangedListener mChangedListener;// 回调接口

     /**
     * @param context
     *            在java代码中直接调用使用此构造方法
     */
     public SlideButton(Context context) {
          this(context, null);
          // TODO Auto-generated constructor stub
     }

     /**
     * @param context
     * @param attrs
     *            在xml中使用要用到这个方法
     */
     public SlideButton(Context context, AttributeSet attrs) {
          this(context, attrs, 0);
          // TODO Auto-generated constructor stub
     }

     /**
     * @param context
     * @param attrs
     * @param defStyleAttr
     *            指定一个样式
     */
     public SlideButton(Context context, AttributeSet attrs, int defStyleAttr) {
          super(context, attrs, defStyleAttr);
          initBitmap();
     }

     /**
     * @category 加载背景图片以及开关图片 然后获取各自的宽高
     *
     */
     private void initBitmap() {
          // TODO Auto-generated method stub
          slideBitMap = BitmapFactory.decodeResource(getResources(),
                    R.drawable.slide_button_background);
          switchBitMap = BitmapFactory.decodeResource(getResources(),
                    R.drawable.switch_background);
          slideBitMapWidth = slideBitMap.getWidth();
          switchBitMapWidth = switchBitMap.getWidth();
          switchBitMapHeight = switchBitMap.getHeight();
          Log.i("switchBitMapWidth", switchBitMapWidth + "");
     }

     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
          // TODO Auto-generated method stub
          super.onMeasure(widthMeasureSpec, heightMeasureSpec);
          setMeasuredDimension(switchBitMapWidth, switchBitMapHeight);// 设置控件的宽高
     }

     @Override
     protected void onDraw(Canvas canvas) {
          // 绘制button背景图片
          canvas.drawBitmap(switchBitMap, 0, 0, null);
          // 绘制滑动开关
          if (isSliding) {// 如果当前状态是滑动中 则动态绘制开关
               int dis = currentX - slideBitMapWidth / 2;
               if (dis < 0) {
                    dis = 0;
               } else if (dis > switchBitMapWidth - slideBitMapWidth) {
                    dis = switchBitMapWidth - slideBitMapWidth;
               }
               canvas.drawBitmap(slideBitMap, dis, 0, null);
          } else {
               if (currentState) { // 绘制开关为开的状态
                    canvas.drawBitmap(slideBitMap, switchBitMapWidth
                              - slideBitMapWidth, 0, null);
               } else { // 绘制开关为关的状态
                    canvas.drawBitmap(slideBitMap, 0, 0, null);
               }
          }
          super.onDraw(canvas);
     }

     @Override
     public boolean onTouchEvent(MotionEvent event) {
          // 手势识别 判断滑动方向
          int action = event.getAction();
          switch (action) {
          case MotionEvent.ACTION_DOWN:
               isSliding = true;
               currentX = (int) event.getX();
               break;

          case MotionEvent.ACTION_MOVE:
               currentX = (int) event.getX();
               Log.i("currentX", currentX + "");

               break;
          case MotionEvent.ACTION_UP:
               isSliding = false;
               int bgCenter = switchBitMapWidth / 2;
               boolean state = currentX > bgCenter; // 改变后的状态
               if (state != currentState && mChangedListener != null) {// 添加回调
                    mChangedListener.onToggleStateChanged(state);
               }
               currentState = state;
               break;
          default:
               break;
          }
          invalidate();
          return true;
     }

     public OnToggleStateChangedListener getmChangedListener() {
          return mChangedListener;
     }

     public void setmChangedListener(
               OnToggleStateChangedListener mChangedListener) {
          this.mChangedListener = mChangedListener;
     }

     public boolean isToggleState() {
          return currentState;
     }

     public void setToggleState(boolean currentState) {
          this.currentState = currentState;
     }

}

回调接口，

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1. package com.kince.slidebutton;
2. **
3. * @author kince
4. *
5. */
6. ublic interface OnToggleStateChangedListener {
7. /**
8. * @category
9. * @param state
10. */
11. public void onToggleStateChanged(boolean state);

  package com.kince.slidebutton;

/**
 * @author kince
 *
 */
public interface OnToggleStateChangedListener {

     /**
      * @category
      * @param state
      */
     public void onToggleStateChanged(boolean state);

}

Activity代码，

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1. package com.kince.slidebutton;
2. import android.support.v7.app.ActionBarActivity;
3. import android.support.v7.app.ActionBar;
4. import android.support.v4.app.Fragment;
5. import android.support.v4.app.FragmentActivity;
6. import android.os.Bundle;
7. import android.view.LayoutInflater;
8. import android.view.Menu;
9. import android.view.MenuItem;
10. import android.view.View;
11. import android.view.ViewGroup;
12. import android.widget.Toast;
13. import android.os.Build;
14. public class MainActivity extends ActionBarActivity {
15. @Override
16. protected void onCreate(Bundle savedInstanceState) {
17. super.onCreate(savedInstanceState);
18. setContentView(R.layout.activity_main);
19. if (savedInstanceState == null) {
20. getSupportFragmentManager().beginTransaction()
21. .add(R.id.container, new PlaceholderFragment()).commit();
22. }
23. }
24. @Override
25. public boolean onCreateOptionsMenu(Menu menu) {
26. // Inflate the menu; this adds items to the action bar if it is present.
27. getMenuInflater().inflate(R.menu.main, menu);
28. return true;
29. }
30. @Override
31. public boolean onOptionsItemSelected(MenuItem item) {
32. // Handle action bar item clicks here. The action bar will
33. // automatically handle clicks on the Home/Up button, so long
34. // as you specify a parent activity in AndroidManifest.xml.
35. int id = item.getItemId();
36. if (id == R.id.action_settings) {
37. return true;
38. }
39. return super.onOptionsItemSelected(item);
40. }
41. /**
42. * A placeholder fragment containing a simple view.
43. */
44. public static class PlaceholderFragment extends Fragment implements
45. OnToggleStateChangedListener {
46. private SlideButton slidebutton;
47. public PlaceholderFragment() {
48. }
49. @Override
50. public View onCreateView(LayoutInflater inflater, ViewGroup container,
51. Bundle savedInstanceState) {
52. View rootView = inflater.inflate(R.layout.fragment_main, container,
53. false);
54. slidebutton = (SlideButton) rootView.findViewById(R.id.slidebutton1);
55. // 设置一下开关的状态
56. slidebutton.setToggleState(true); // 设置开关的状态为打开
57. slidebutton.setmChangedListener(this);
58. return rootView;
59. }
60. @Override
61. public void onToggleStateChanged(boolean state) {
62. // TODO Auto-generated method stub
63. FragmentActivity activity = getActivity();
64. if (state) {
65. Toast.makeText(activity, "开关打开", 0).show();
66. } else {
67. Toast.makeText(activity, "开关关闭", 0).show();
68. }
69. }
70. }
71. }

package com.kince.slidebutton;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);

          if (savedInstanceState == null) {
               getSupportFragmentManager().beginTransaction()
                         .add(R.id.container, new PlaceholderFragment()).commit();
          }
     }

     @Override
     public boolean onCreateOptionsMenu(Menu menu) {

          // Inflate the menu; this adds items to the action bar if it is present.
          getMenuInflater().inflate(R.menu.main, menu);
          return true;
     }

     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
          // Handle action bar item clicks here. The action bar will
          // automatically handle clicks on the Home/Up button, so long
          // as you specify a parent activity in AndroidManifest.xml.
          int id = item.getItemId();
          if (id == R.id.action_settings) {
               return true;
          }
          return super.onOptionsItemSelected(item);
     }

     /**
     * A placeholder fragment containing a simple view.
     */
     public static class PlaceholderFragment extends Fragment implements
               OnToggleStateChangedListener {

          private SlideButton slidebutton;

          public PlaceholderFragment() {
          }

          @Override
          public View onCreateView(LayoutInflater inflater, ViewGroup container,
                    Bundle savedInstanceState) {
               View rootView = inflater.inflate(R.layout.fragment_main, container,
                         false);
               slidebutton = (SlideButton) rootView.findViewById(R.id.slidebutton1);
               // 设置一下开关的状态
               slidebutton.setToggleState(true); // 设置开关的状态为打开
               slidebutton.setmChangedListener(this);
               return rootView;
          }

          @Override
          public void onToggleStateChanged(boolean state) {
               // TODO Auto-generated method stub
               FragmentActivity activity = getActivity();
               if (state) {
                    Toast.makeText(activity, "开关打开", 0).show();
               } else {
                    Toast.makeText(activity, "开关关闭", 0).show();
               }
          }
     }

}

未完待续。