Android-Tab单选控件

今天看到项目中有一个控件写得很美丽，据说是github上开源的控件，地址没找到，例如以下图所看到的，很常见的效果，几个tab页面来回切换：

转载请标明出处：http://blog.csdn.net/goldenfish1919/article/details/46799341

FlatTabGroup.java:

public class FlatTabGroup extends RadioGroup implements RadioGroup.OnCheckedChangeListener {
    public FlatTabGroup(Context context) {
        this(context, null);
    }

    private int mRadius;
    private int mStroke;
    private int mHighlightColor;
    private String[] mItemString;
    private float mTextSize;
    private ColorStateList mTextColor;
    private int[] mTabViewIds;
    private OnTabCheckedListener mTabCheckedListener;

    public FlatTabGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        setOrientation(HORIZONTAL);
        setGravity(Gravity.CENTER_VERTICAL);
        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.FlatTabGroup);
        mHighlightColor = array.getColor(R.styleable.FlatTabGroup_tab_border_color, Color.WHITE);
        mStroke = array.getDimensionPixelSize(R.styleable.FlatTabGroup_tab_border_width, 2);
        mRadius = array.getDimensionPixelOffset(R.styleable.FlatTabGroup_tab_radius, 5);
        mTextColor = array.getColorStateList(R.styleable.FlatTabGroup_tab_textColor);
        mTextSize = array.getDimensionPixelSize(R.styleable.FlatTabGroup_tab_textSize, 14);
        int id = array.getResourceId(R.styleable.FlatTabGroup_tab_items, 0);
        array.recycle();
        mItemString = isInEditMode() ? new String[] { "TAB A", "TAB B", "TAB C"} : context.getResources().getStringArray(id);
        generateTabView(context, attrs);
        super.setOnCheckedChangeListener(this);
        
    }

    private void generateTabView(Context context, AttributeSet attrs) {
        if (mItemString == null) {
            return;
        }
        mTabViewIds = new int[mItemString.length];
        for (int i=0; i<mItemString.length;i++ ) {
        <span style="white-space:pre">	</span>String text = mItemString[i];
            RadioButton button = new RadioButton(context, attrs);
            button.setGravity(Gravity.CENTER);
            button.setButtonDrawable(android.R.color.transparent);
            button.setText(text);
            button.setTextColor(mTextColor);
            button.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
            button.setId(mTabViewIds[i] = generateViewIds());
            LayoutParams lp = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT, 1);
            if(i < mItemString.length - 1){
            <span style="white-space:pre">	</span>lp.rightMargin = -1 * mStroke;
            }
            addView(button, lp);
        }
    }
    public void setOnTabCheckedListener(OnTabCheckedListener listener) {
        mTabCheckedListener = listener;
    }

    public void setSelection(int position) {
        check(getChildAt(position).getId());
    }

    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        if (mTabCheckedListener != null) {
            int checkedPosition = -1;
            for (int i = 0; i < mTabViewIds.length; i++) {
                if (mTabViewIds[i] == checkedId) {
                    checkedPosition = i;
                    break;
                }
            }
            mTabCheckedListener.onChecked(this, checkedPosition);
        }
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        updateChildBackground();
    }

    @SuppressWarnings("deprecation")
	private void updateChildBackground() {
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            if (child instanceof RadioButton) {
                child.setBackgroundDrawable(generateTabBackground(i, mHighlightColor));
            }
        }
    }

    private Drawable generateTabBackground(int position, int color) {//怎样用代码定义selector
        StateListDrawable stateListDrawable = new StateListDrawable();
        stateListDrawable.addState(new int[] {android.R.attr.state_checked}, generateDrawable(position, color));
        stateListDrawable.addState(new int[] {                            }, generateDrawable(position, Color.TRANSPARENT));
        return stateListDrawable;
    }

    private Drawable generateDrawable(int position, int color) {
        float[] radius;
        if (position == 0) {
            radius = new float[] {
                    mRadius, mRadius,
                    0, 0,
                    0, 0,
                    mRadius, mRadius
            };
        } else if (position == getChildCount() - 1) {
            radius = new float[] {
                    0, 0,
                    mRadius, mRadius,
                    mRadius, mRadius,
                    0, 0
            };
        } else {
            radius = new float[] {
                    0, 0,
                    0, 0,
                    0, 0,
                    0, 0
            };
        }
        GradientDrawable shape = new GradientDrawable();//怎样用代码生成圆角shape
        shape.setCornerRadii(radius);
        shape.setColor(color);
        shape.setStroke(mStroke, mHighlightColor);
        return shape;
    }

    private static final AtomicInteger sNextGeneratedId = new AtomicInteger(1);//怎样使用自己定义的id

    /**
     * Generate a value suitable for use in {@link #setId(int)}. This value will
     * not collide with ID values generated at build time by aapt for R.id.
     * 
     * @return a generated ID value
     */
    public static int generateViewIds() {
        for (;;) {
            final int result = sNextGeneratedId.get();
            // aapt-generated IDs have the high byte nonzero; clamp to the range
            // under that.
            int newValue = result + 1;
            if (newValue > 0x00FFFFFF)
                newValue = 1; // Roll over to 1, not 0.
            if (sNextGeneratedId.compareAndSet(result, newValue)) {
                return result;
            }
        }
    }

    public static interface OnTabCheckedListener {
        public void onChecked(FlatTabGroup group, int position);
    }
}

这里有几个点挺有意思：

（1）怎样用代码做selector

（2）怎样用代码生成圆角

（3）怎样使用自己定义的id

attr_flat_tab_group.xml：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="FlatTabGroup">
        <attr name="tab_items" format="reference" />
        <attr name="tab_border_width" format="dimension|reference" />
        <attr name="tab_border_color" format="color|reference" />
        <attr name="tab_radius" format="dimension|reference" />
        <attr name="tab_textColor" format="reference" />
        <attr name="tab_textSize" format="dimension|reference" />
    </declare-styleable>
</resources>

arrays_flat_tab_group.xml：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="array_tabs_more_video">
        <item>实时直播</item>
        <item>直播预约</item>
        <item>精彩回看</item>
    </string-array>
</resources>

引用的时候：

<com.example.view.FlatTabGroup
         android:id="@+id/flat_tab_group"
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:paddingBottom="5dp"
         android:paddingTop="5dp"
		 android:layout_marginLeft="10dp"
		 android:layout_marginRight="10dp"
         android:layout_gravity="center_vertical"
         app:tab_border_color="#cdcdcd"
         app:tab_border_width="1dp"
         app:tab_items="@array/array_tabs_more_video"
         app:tab_radius="5dp"
         app:tab_textColor="@android:color/black"
         app:tab_textSize="16sp"/>

      FlatTabGroup tabs = (FlatTabGroup)this.findViewById(R.id.flat_tab_group);
      tabs.setOnTabCheckedListener(new OnTabCheckedListener(){
			@Override
			public void onChecked(FlatTabGroup group, int position) {
				Toast.makeText(MainActivity.this, ""+position, Toast.LENGTH_SHORT).show();
			}
      });
      tabs.setSelection(0);