Android应用界面开发——自定义控件(实现俯卧撑计数器)

<View
        android:layout_width="match_parent"
        android:layout_height="1px"
        android:background="#000000"/>

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

</resources>

android:theme="@style/AppTheme"

public class CounterView extends View implements View.OnClickListener {

    private Paint mPaint;
    private Rect mRect;
    private int number = Integer.parseInt(PushUpsActivity.number);
    private int mBackgroundColor;
    private int mTextColor;
    private int mTextSize;


    public CounterView(Context context) {
        //在构造器中用this调用后边的构造器，这样只在最后一个构造器中初始化view即可。
        this(context, null);
    }

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

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

    private void init(Context context, AttributeSet attrs) {
        mPaint = new Paint();
        mRect = new Rect();

        this.setOnClickListener(this);

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CounterView);
        mBackgroundColor = typedArray.getColor(R.styleable.CounterView_backgroundColor, Color.BLACK);
        mTextColor= typedArray.getColor(R.styleable.CounterView_textColor, Color.YELLOW);
        mTextSize = (int) typedArray.getDimension(R.styleable.CounterView_textSize, 18);
    }

    /**
     * 在onDraw方法中画圆形按钮和数字
     *
     * @param canvas
     */
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //画图需要画笔，但不能在onDraw中创建Paint，因为onDraw使用频繁，会导致过多的内存消耗，所以创建工作放在了init中。
        mPaint.setColor(mBackgroundColor);
        mPaint.setAntiAlias(false);
        //画圆形按钮
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, getWidth() / 2, mPaint);
        //画白色数字需要将画笔颜色设置为白色
        mPaint.setColor(mTextColor);
        //设置字体大小
        mPaint.setTextSize(mTextSize);
        String text = String.valueOf(number);
        mPaint.getTextBounds(text, 0, text.length(), mRect);

        int textWidth = mRect.width();
        int textHeight = mRect.height();

        canvas.drawText(text, getWidth() / 2 - textWidth / 2, getHeight() / 2 + textHeight / 2, mPaint);//居中显示
    }

    @Override
    public void onClick(View v) {
        if (number > 0) {
            number--;
            invalidate();
        } else if (number == 0) {
            Toast.makeText(getContext(), "训练结束", Toast.LENGTH_LONG).show();
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CounterView">
        <attr name="backgroundColor" format="color"/>
        <attr name="textColor" format="color"/>
        <attr name="textSize" format="dimension"/>
    </declare-styleable>
</resources>

xmlns:app="http://schemas.android.com/apk/res-auto"

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

    <TextView
        android:id="@+id/text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="20dp"
        android:paddingTop="20dp"
        android:text="开始训练吧，练出完美胸肌"
        android:textColor="#000000"
        android:textSize="25sp" />

    <com.trampcr.pushupcounter.CounterView
        android:id="@+id/counter_view"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_below="@+id/text"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="80dp"
        app:backgroundColor="#000000"
        app:textColor="#ffff00"
        app:textSize="80sp" />

    <Button
        android:id="@+id/btn_stop"
        android:layout_width="200dp"
        android:layout_height="60dp"
        android:layout_below="@+id/counter_view"
        android:layout_centerHorizontal="true"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="60dp"
        android:text="结束训练"
        android:textColor="#000000"
        android:textSize="20sp" />

</RelativeLayout>

TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CounterView);
        mBackgroundColor = typedArray.getColor(R.styleable.CounterView_backgroundColor, Color.BLACK);
        mTextColor= typedArray.getColor(R.styleable.CounterView_textColor, Color.YELLOW);
        mTextSize = (int) typedArray.getDimension(R.styleable.CounterView_textSize, 18);