android中的<hr>标记用法

Question

我有一个声明,我必须添加一条水平线.但它没有得到Android的支持,似乎有任何方法可以重新创建

---

使用支持的标签在android中标记效果.

String message = "Hello <br> hai<br> I am fine <hr>";
tab.setText(Html.fromHtml(message));

这表明您好
海
我很好

但没有横线.

这里HTML标签"hr"不起作用.有没有办法从支持的标签添加hr标签效果.提前致谢..

Answer 1

Html.fromHtml()目前不支持<hr>标记,因此您需要编写自己的标记处理程序来实现Html.TagHandler.Android中的TextViews使用Spans进行样式设置,因此我们需要创建一个绘制水平线的Span,让我们调用它HrSpan.

Java的

String html = "Hello <br> hai<br> I am fine <hr> And here's another line";

HtmlTagHandler tagHandler = new HtmlTagHandler();
Spanned styledText = HtmlCompat.fromHtml(html, HtmlCompat.FROM_HTML_MODE_LEGACY, null, tagHandler);
textView.setText(styledText);

HtmlTagHandler.java

public class HtmlTagHandler implements Html.TagHandler {

    @Override
    public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader) {
        if (tag.equals("hr")) {
            handleHrTag(opening, output);
        }
    }

    private void handleHrTag(boolean opening, Editable output) {
        final String placeholder = "\n-\n";
        if (opening) {
            output.insert(output.length(), placeholder);
        } else {
            output.setSpan(new HrSpan2(), output.length() - placeholder.length(), output.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        }
    }
}

HrSpan.java

public class HrSpan extends ReplacementSpan {

    @Override
    public int getSize(@NonNull Paint paint, CharSequence text, int start, int end, @Nullable Paint.FontMetricsInt fm) {
        return 0;
    }

    @Override
    public void draw(@NonNull Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, @NonNull Paint paint) {
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(8); // 8px tall line

        int middle = (top + bottom) / 2;
        // Draw a line across the middle of the canvas
        canvas.drawLine(0, middle, canvas.getWidth(), middle, paint);
    }
}

科特林

val html = "Hello <br> hai<br> I am fine <hr> Another line here <hr><hr>"
val tagHandler = HtmlTagHandler()

textView.text = HtmlCompat.fromHtml(html, HtmlCompat.FROM_HTML_MODE_LEGACY, null, tagHandler)

class HtmlTagHandler : Html.TagHandler {

    override fun handleTag(opening: Boolean, tag: String?, output: Editable?, xmlReader: XMLReader?) {
        if (output == null) return

        when (tag) {
            "hr" -> handleHrTag(opening, output)
            // Handle other tags if needed
        }
    }

    private fun handleHrTag(opening: Boolean, output: Editable) {
        val placeholder = "\n-\n" // Makes sure the HR is drawn on a new line
        if (opening) {
            output.insert(output.length, placeholder)
        } else {
            output.setSpan(HrSpan(), output.length - placeholder.length, output.length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
        }
    }
}

class HrSpan : ReplacementSpan() {

    override fun getSize(paint: Paint, text: CharSequence?, start: Int, end: Int, fm: Paint.FontMetricsInt?) = 0

    override fun draw(
        canvas: Canvas, text: CharSequence?, start: Int, end: Int, x: Float, top: Int, y: Int,
        bottom: Int, paint: Paint
    ) {
        paint.style = Paint.Style.STROKE
        paint.strokeWidth = 8f

        // Draw line in the middle of the available space
        val middle = ((top + bottom) / 2).toFloat()

        canvas.drawLine(0f, middle, canvas.width.toFloat(), middle, paint)
    }
}

这会给你一个像这样的结果.它匹配TextView的宽度,因此如果您希望线占据整个宽度,请将TextView width属性更改为match_parent.

Answer 2

您添加高度为 1 或 2、宽度设置为与父级匹配的视图，并指定背景颜色。但这意味着您将有 3 个文本视图。

这是来自工作代码。如您所见，视图的任何子级都会执行以下操作：

        <!-- divider 1 -->
        <LinearLayout
            android:id="@+id/lineA"
            android:layout_width="fill_parent"
            android:layout_height="2dp"
            android:background="#000000" />

另一种选择是使用肯定支持 <hr> 的 WebView，但这很可能是一种矫枉过正。