自定义View点击生成随机数

最新推荐文章于 2020-12-16 01:11:33 发布

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最新推荐文章于 2020-12-16 01:11:33 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/taa1007/article/details/78182257

本文介绍了一个自定义View的实现过程，包括如何通过XML定义样式属性并读取这些属性，以及如何在View中进行绘图操作。该View可以显示带有特定样式的文本，并实现了点击后随机更新文本的功能。

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//首先创建自定义View类继承 view

public class CustomTitleView extends View {
    /**
     * 文本
     */
    private String mTitleText;
    /**
     * 文本的颜色
     */
    private int mTitleTextColor;
    /**
     * 文本的大小
     */
    private int mTitleTextSize;

    /**
     * 绘制时控制文本绘制的范围
     */
    private Rect mBound;
    private Paint mPaint;

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

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

    /**
     * 获得我自定义的样式属性
     *
     * @param context
     * @param attrs
     * @param defStyle
     */
    public CustomTitleView(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        /**
         * 获得我们所定义的自定义样式属性
         */
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomTitleView, defStyle, 0);
        int n = a.getIndexCount();
        for (int i = 0; i < n; i++)
        {
            int attr = a.getIndex(i);
            switch (attr)
            {
                case R.styleable.CustomTitleView_titleText:
                    mTitleText = a.getString(attr);
                    break;
                case R.styleable.CustomTitleView_titleTextColor:
                    // 默认颜色设置为黑色
                    mTitleTextColor = a.getColor(attr, Color.BLACK);
                    break;
                case R.styleable.CustomTitleView_titleTextSize:
                    // 默认设置为16sp，TypeValue也可以把sp转化为px
                    mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(
                            TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
                    break;

            }

        }
        a.recycle();

        /**
         * 获得绘制文本的宽和高
         */
        mPaint = new Paint();
        mPaint.setTextSize(mTitleTextSize);
        // mPaint.setColor(mTitleTextColor);
        mBound = new Rect();
        mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        mPaint.setColor(Color.YELLOW);
        canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);

        mPaint.setColor(mTitleTextColor);
        canvas.drawText(mTitleText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint);
        this.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                mTitleText = randomText();
                postInvalidate();
            }
        });
    }
    private String randomText() {
        Random random = new Random();
        Set<Integer> set = new HashSet<Integer>();
        while (set.size() < 4)
        {
            int randomInt = random.nextInt(10);
            set.add(randomInt);
        }
        StringBuffer sb = new StringBuffer();
        for (Integer i : set)
        {
            sb.append("" + i);
        }

        return sb.toString();
    }
}

//创建attrs

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

        <attr name="titleText" format="string" />
        <attr name="titleTextColor" format="color" />
        <attr name="titleTextSize" format="dimension" />

        <declare-styleable name="CustomTitleView">
            <attr name="titleText" />
            <attr name="titleTextColor" />
            <attr name="titleTextSize" />
        </declare-styleable>

</resources>

//布局

注意：一定要加（后面为包名）

xmlns:custom="http://schemas.android.com/apk/res/com.tangao.dianjiview"

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:custom="http://schemas.android.com/apk/res/com.tangao.dianjiview"
    android:layout_width="match_parent"
    android:background="@color/colorPrimaryDark"
    android:layout_height="match_parent" >

    <com.tangao.dianjiview.CustomTitleView
        android:id="@+id/tangao"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_centerInParent="true"
        custom:titleText="3712"
        custom:titleTextColor="#ff0000"
        custom:titleTextSize="40sp" />

</RelativeLayout>