以编程方式在Android上绘制虚线

Question

我想在编程生成的TextViews之间绘制水平虚线.我试过这段代码:

Paint fgPaintSel = new Paint();
fgPaintSel.setARGB(255, 0, 0, 0);
fgPaintSel.setStyle(Paint.Style.STROKE);
fgPaintSel.setPathEffect(new DashPathEffect(new float[]{5, 10}, 0));

但什么都没发生.我只是复制并粘贴了这段代码.我该怎么画一条虚线？谢谢.

Answer 1

为活动布局指定一个ID.我使用onLlick处理程序PaintDashedLines()使用了一个按钮进行演示.

在content_main.xml布局中.

<LinearLayout android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" .../>

    <Button android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="PaintDashedLines"
        android:text="Press Me"/>
</LinearLayout>

使用静态int来计算demo的目的,使用单独的方法来创建drawable,用于模块化.

在您的活动中:

static int tvCount = 0;

public void PaintDashedLines(View v) {
    LinearLayout ll = (LinearLayout) findViewById(R.id.main);
    TextView tv = new TextView(MainActivity.this);
    tv.setGravity(Gravity.CENTER);
    tv.setTextSize(25);
    tv.setPadding(0, 5, 0, 5);
    ll.addView(tv);
    tv.setText("TextView " + tvCount);
    ImageView divider = new ImageView(MainActivity.this);
    LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
            ll.getWidth(), 2);
    lp.setMargins(0, 5, 0, 5);
    divider.setLayoutParams(lp);
    divider.setBackground(CreateDashedLined());
    ll.addView(divider);
    tvCount++;
}

public static Drawable CreateDashedLined() {
    ShapeDrawable sd = new ShapeDrawable(new RectShape());
    Paint fgPaintSel = sd.getPaint();
    fgPaintSel.setColor(Color.BLACK);
    fgPaintSel.setStyle(Paint.Style.STROKE);
    fgPaintSel.setPathEffect(new DashPathEffect(new float[]{5, 10}, 0));
    return sd;
}

-MyActivity
--int count;
--oncreate
--PaintDashedLines(View v) -
public static Drawable CreateDashedLined()

在build.gradle中(虽然这不是一成不变的)

    minSdkVersion 18
    targetSdkVersion 23

你不需要做任何其他事情.

Answer 2

在drawable文件夹中创建dotted_line.xml文件:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:left="-3px"
        android:right="-3px"
        android:top="-3px">
        <shape xmlns:android="http://schemas.android.com/apk/res/android"
            android:shape="rectangle">

            <stroke
                android:width="2px"
                android:color="@color/dark_blue"
                android:dashGap="2px"
                android:dashWidth="3px" />
        </shape>
    </item>

</layer-list>

添加此drawable作为背景:

view.setBackground(getResources().getDrawable(R.drawable.dotted_line));

结果: