我要画一条虚线。我现在用这个来画实线:

LinearLayout divider = new LinearLayout( this );
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams( LinearLayout.LayoutParams.FILL_PARENT, 2 );
divider.setLayoutParams( params );
divider.setBackgroundColor( getResources().getColor( R.color.grey ) );

我需要这样的东西,但不是实心的,而是虚线的。我想避免在透明布局和固体布局之间交替制作数百个布局。


当前回答

无需java代码:

可拉的/ dotted.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line">

    <stroke
       android:color="#FF00FF"
       android:dashWidth="10px"
       android:dashGap="10px"
       android:width="1dp"/>
</shape>

view.xml:

<ImageView
    android:layout_width="match_parent"
    android:layout_height="5dp"
    android:src="@drawable/dotted"
    android:layerType="software" />

效果:

其他回答

我已经创建了一个带有自定义视图的库来解决这个问题,它使用起来应该非常简单。详见https://github.com/Comcast/DahDit。你可以像这样添加虚线:

<com.xfinity.dahdit.DashedLine
    android:layout_width="250dp"
    android:layout_height="wrap_content"
    app:dashHeight="4dp"
    app:dashLength="8dp"
    app:minimumDashGap="3dp"
    app:layout_constraintRight_toRightOf="parent"
    android:id="@+id/horizontal_dashes"/>

通过使用这个类,您可以对多行文本应用“虚线和下划线”效果。使用dashpatheeffect你必须关闭你的TextView的hardwareAccelerated(虽然dashpatheeffect方法有一个长文本的问题)。你可以在这里找到我的示例项目:https://github.com/jintoga/Dashed-Underlined-TextView/blob/master/Untitled.png。

public class DashedUnderlineSpan implements LineBackgroundSpan, LineHeightSpan {

    private Paint paint;
    private TextView textView;
    private float offsetY;
    private float spacingExtra;

    public DashedUnderlineSpan(TextView textView, int color, float thickness, float dashPath,
                               float offsetY, float spacingExtra) {
        this.paint = new Paint();
        this.paint.setColor(color);
        this.paint.setStyle(Paint.Style.STROKE);
        this.paint.setPathEffect(new DashPathEffect(new float[] { dashPath, dashPath }, 0));
        this.paint.setStrokeWidth(thickness);
        this.textView = textView;
        this.offsetY = offsetY;
        this.spacingExtra = spacingExtra;
    }

    @Override
    public void chooseHeight(CharSequence text, int start, int end, int spanstartv, int v,
                             Paint.FontMetricsInt fm) {
        fm.ascent -= spacingExtra;
        fm.top -= spacingExtra;
        fm.descent += spacingExtra;
        fm.bottom += spacingExtra;
    }

    @Override
    public void drawBackground(Canvas canvas, Paint p, int left, int right, int top, int baseline,
                               int bottom, CharSequence text, int start, int end, int lnum) {
        int lineNum = textView.getLineCount();
        for (int i = 0; i < lineNum; i++) {
            Layout layout = textView.getLayout();
            canvas.drawLine(layout.getLineLeft(i), layout.getLineBottom(i) - spacingExtra + offsetY,
                    layout.getLineRight(i), layout.getLineBottom(i) - spacingExtra + offsetY,
                    this.paint);
        }
    }
}

结果:

唯一对我有用的方法,我认为这是最简单的方法,就是使用Path和一个paint对象,就像这样:

    Paint paintDash = new Paint();
    paintDash.setARGB(255, 0, 0, 0);
    paintDash.setStyle(Paint.Style.STROKE);
    paintDash.setPathEffect(new DashPathEffect(new float[]{10f,10f}, 0));
    paintDash.setStrokeWidth(2);
    Path pathDashLine = new Path();

然后onDraw():(重要调用重置,如果你改变这些点之间的onDraw调用,导致路径保存所有的移动)

    pathDashLine.reset();
    pathDashLine.moveTo(porigenX, porigenY);
    pathDashLine.lineTo(cursorX,cursorY);
    c.drawPath(pathDashLine, paintDash);

无需java代码:

可拉的/ dotted.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line">

    <stroke
       android:color="#FF00FF"
       android:dashWidth="10px"
       android:dashGap="10px"
       android:width="1dp"/>
</shape>

view.xml:

<ImageView
    android:layout_width="match_parent"
    android:layout_height="5dp"
    android:src="@drawable/dotted"
    android:layerType="software" />

效果:

对于画布上的点状效果,将此属性设置为paint对象:

paint.setPathEffect(new DashPathEffect(new float[] {0,30}, 0));

并根据你的渲染效果改变值30:它代表每个点之间的“距离”。