android进阶-Android控件架构与自定义控件详解（一）

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[demo下载地址]

**(http://download.csdn.net/download/qq_20967339/10010439)

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1.Android控件架构

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2.View的测量

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android系统在绘制view前，要知道需要绘制View的大小，就需要进行测量。测量在onMeasure()方法中进行。

public class TeachingView extends View {

    public TeachingView(Context context) {
        super(context);
    }

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

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

    /**
     * 重写onMeasure方法
     * @param widthMeasureSpec
     * @param heightMeasureSpec
     */
    @Override
    protected void onMeasure(int widthMeasureSpec,
                             int heightMeasureSpec) {
        setMeasuredDimension(
                measureWidth(widthMeasureSpec),
                measureHeight(heightMeasureSpec));
    }

    private int measureWidth(int measureSpec) {
        int result = 0;
        //第一步：从measureSpec对象中提取出具体的测量模式和大小
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        //第二步：通过判断测量的模式，给出不同的测量值。
        //当specMode为EXACTLY时，直接指定的specSize即可，
        //当specMode为其他模式时，需要给它一个默认的大小
        if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        } else {
            result = 200;
            if (specMode == MeasureSpec.AT_MOST) {
                result = Math.min(result, specSize);
            }
        }
        return result;
    }

    private int measureHeight(int measureSpec) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        } else {
            result = 200;
            if (specMode == MeasureSpec.AT_MOST) {
                result = Math.min(result, specSize);
            }
        }
        return result;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.GRAY);
        int width = getWidth();
        int height = getHeight();
        Log.d("xys", "width : " + width + " height : " + height);
    }
}

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3.View的绘制

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4.ViewGroup的测量

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5.ViewGroup的绘制

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6.自定义View

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6.1 对现有控件扩展

public class ShineTextView extends TextView {

    private LinearGradient mLinearGradient;
    private Matrix mGradientMatrix;
    private Paint mPaint;
    private int mViewWidth = 0;
    private int mTranslate = 0;

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

    /**
     * 进行一些对象的初始化工作，并根据View的宽设置一个LinearGradient渐变渲染器
     * @param w
     * @param h
     * @param oldw
     * @param oldh
     */
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        if (mViewWidth == 0) {
            mViewWidth = getMeasuredWidth();
            if (mViewWidth > 0) {
                mPaint = getPaint();
                mLinearGradient = new LinearGradient(
                        0,
                        0,
                        mViewWidth,
                        0,
                        new int[]{
                                Color.BLUE, 0xffffffff,
                                Color.BLUE},
                        null,
                        Shader.TileMode.CLAMP);
                mPaint.setShader(mLinearGradient);
                mGradientMatrix = new Matrix();
            }
        }
    }

    /**
     * 最关键给Paint对象设置原生TextView没有的LinearGradient属性
     * 通过矩阵的方式来不断平移渐变效果
     * @param canvas
     */
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mGradientMatrix != null) {
            mTranslate += mViewWidth / 5;
            if (mTranslate > 2 * mViewWidth) {
                mTranslate = -mViewWidth;
            }
            mGradientMatrix.setTranslate(mTranslate, 0);
            mLinearGradient.setLocalMatrix(mGradientMatrix);
            postInvalidateDelayed(100);
        }
    }
}

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6.2 创建复合控件

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6.2.1 定义属性

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="TopBar">
        <attr name="title" format="string" />
        <attr name="titleTextSize" format="dimension" />
        <attr name="titleTextColor" format="color" />
        <attr name="leftTextColor" format="color" />
        <attr name="leftBackground" format="reference|color" />
        <attr name="leftText" format="string" />
        <attr name="rightTextColor" format="color" />
        <attr name="rightBackground" format="reference|color" />
        <attr name="rightText" format="string" />
    </declare-styleable>

</resources>

6.2.2 组合控件

 // 为组件元素设置相应的布局元素
        mLeftParams = new LayoutParams(
                LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);
        mLeftParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, TRUE);
        // 添加到ViewGroup
        addView(mLeftButton, mLeftParams);

        mRightParams = new LayoutParams(
                LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);
        mRightParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, TRUE);
        addView(mRightButton, mRightParams);

        mTitlepParams = new LayoutParams(
                LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);
        mTitlepParams.addRule(RelativeLayout.CENTER_IN_PARENT, TRUE);
        addView(mTitleView, mTitlepParams);

6.2.3 引用UI模版

public class TopBar extends RelativeLayout {

    // 包含topbar上的元素：左按钮、右按钮、标题
    private Button mLeftButton, mRightButton;
    private TextView mTitleView;

    // 布局属性，用来控制组件元素在ViewGroup中的位置
    private LayoutParams mLeftParams, mTitlepParams, mRightParams;

    // 左按钮的属性值，即我们在atts.xml文件中定义的属性
    private int mLeftTextColor;
    private Drawable mLeftBackground;
    private String mLeftText;
    // 右按钮的属性值，即我们在atts.xml文件中定义的属性
    private int mRightTextColor;
    private Drawable mRightBackground;
    private String mRightText;
    // 标题的属性值，即我们在atts.xml文件中定义的属性
    private float mTitleTextSize;
    private int mTitleTextColor;
    private String mTitle;

    // 映射传入的接口对象
    private topbarClickListener mListener;

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

    public TopBar(Context context) {
        super(context);
    }

    public TopBar(Context context, AttributeSet attrs) {
        super(context, attrs);
        // 设置topbar的背景
        setBackgroundColor(0xFFF59563);
        // 通过这个方法，将你在atts.xml中定义的declare-styleable
        // 的所有属性的值存储到TypedArray中
        TypedArray ta = context.obtainStyledAttributes(attrs,
                R.styleable.TopBar);
        // 从TypedArray中取出对应的值来为要设置的属性赋值
        mLeftTextColor = ta.getColor(
                R.styleable.TopBar_leftTextColor, 0);
        mLeftBackground = ta.getDrawable(
                R.styleable.TopBar_leftBackground);
        mLeftText = ta.getString(R.styleable.TopBar_leftText);

        mRightTextColor = ta.getColor(
                R.styleable.TopBar_rightTextColor, 0);
        mRightBackground = ta.getDrawable(
                R.styleable.TopBar_rightBackground);
        mRightText = ta.getString(R.styleable.TopBar_rightText);

        mTitleTextSize = ta.getDimension(
                R.styleable.TopBar_titleTextSize, 10);
        mTitleTextColor = ta.getColor(
                R.styleable.TopBar_titleTextColor, 0);
        mTitle = ta.getString(R.styleable.TopBar_title);

        // 获取完TypedArray的值后，一般要调用
        // recyle方法来避免重新创建的时候的错误
        ta.recycle();

        mLeftButton = new Button(context);
        mRightButton = new Button(context);
        mTitleView = new TextView(context);

        // 为创建的组件元素赋值
        // 值就来源于我们在引用的xml文件中给对应属性的赋值
        mLeftButton.setTextColor(mLeftTextColor);
        mLeftButton.setBackground(mLeftBackground);
        mLeftButton.setText(mLeftText);

        mRightButton.setTextColor(mRightTextColor);
        mRightButton.setBackground(mRightBackground);
        mRightButton.setText(mRightText);

        mTitleView.setText(mTitle);
        mTitleView.setTextColor(mTitleTextColor);
        mTitleView.setTextSize(mTitleTextSize);
        mTitleView.setGravity(Gravity.CENTER);

        // 为组件元素设置相应的布局元素
        mLeftParams = new LayoutParams(
                LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);
        mLeftParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, TRUE);
        // 添加到ViewGroup
        addView(mLeftButton, mLeftParams);

        mRightParams = new LayoutParams(
                LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);
        mRightParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, TRUE);
        addView(mRightButton, mRightParams);

        mTitlepParams = new LayoutParams(
                LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);
        mTitlepParams.addRule(RelativeLayout.CENTER_IN_PARENT, TRUE);
        addView(mTitleView, mTitlepParams);

        // 按钮的点击事件，不需要具体的实现，
        // 只需调用接口的方法，回调的时候，会有具体的实现
        mRightButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                mListener.rightClick();
            }
        });

        mLeftButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                mListener.leftClick();
            }
        });
    }

    // 暴露一个方法给调用者来注册接口回调
    // 通过接口来获得回调者对接口方法的实现
    public void setOnTopbarClickListener(topbarClickListener mListener) {
        this.mListener = mListener;
    }

    /**
     * 设置按钮的显示与否 通过id区分按钮，flag区分是否显示
     *
     * @param id   id
     * @param flag 是否显示
     */
    public void setButtonVisable(int id, boolean flag) {
        if (flag) {
            if (id == 0) {
                mLeftButton.setVisibility(View.VISIBLE);
            } else {
                mRightButton.setVisibility(View.VISIBLE);
            }
        } else {
            if (id == 0) {
                mLeftButton.setVisibility(View.GONE);
            } else {
                mRightButton.setVisibility(View.GONE);
            }
        }
    }

    // 接口对象，实现回调机制，在回调方法中
    // 通过映射的接口对象调用接口中的方法
    // 而不用去考虑如何实现，具体的实现由调用者去创建
    public interface topbarClickListener {
        // 左按钮点击事件
        void leftClick();
        // 右按钮点击事件
        void rightClick();
    }
}

public class TopBarTest extends Activity {

    private TopBar mTopbar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.topbar_test);
        // 获得我们创建的topbar
        mTopbar = (TopBar) findViewById(R.id.topBar);
        // 为topbar注册监听事件，传入定义的接口
        // 并以匿名类的方式实现接口内的方法
        mTopbar.setOnTopbarClickListener(
                new TopBar.topbarClickListener() {

                    @Override
                    public void rightClick() {
                        Log.e("xyz","1111111111");
                        Toast.makeText(TopBarTest.this,
                                "right", Toast.LENGTH_SHORT)
                                .show();
                    }

                    @Override
                    public void leftClick() {
                        Log.e("xyz","2222222222");
                        Toast.makeText(TopBarTest.this,
                                "left", Toast.LENGTH_SHORT)
                                .show();
                    }
                });
        // 控制topbar上组件的状态
        mTopbar.setButtonVisable(0, true);
        mTopbar.setButtonVisable(1, true);
    }
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="5dp"
    tools:context=".MainActivity">

    <!-- <include layout="@layout/topbar" /> -->

    <com.imooc.systemwidget.TopBar
        android:id="@+id/topBar"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        custom:leftBackground="@drawable/blue_button"
        custom:leftText="Back"
        custom:leftTextColor="#FFFFFF"
        custom:rightBackground="@drawable/blue_button"
        custom:rightText="More"
        custom:rightTextColor="#FFFFFF"
        custom:title="自定义标题"
        custom:titleTextColor="#123412"
        custom:titleTextSize="10sp"/>

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="TopBar">
        <attr name="title" format="string" />
        <attr name="titleTextSize" format="dimension" />
        <attr name="titleTextColor" format="color" />
        <attr name="leftTextColor" format="color" />
        <attr name="leftBackground" format="reference|color" />
        <attr name="leftText" format="string" />
        <attr name="rightTextColor" format="color" />
        <attr name="rightBackground" format="reference|color" />
        <attr name="rightText" format="string" />
    </declare-styleable>

</resources>