行内标签的实现

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序言

在最近的项目中需要实现行内标签，我原来觉得挺简单的后来,后来试了很多方式发现并没有那么简单。比如想到的几种实现方式和最终的效果如下图，本着辛苦我一个方便千万家的思想，我把我的TagUtil抽取出来了，并上传到GitHub上了。

这里写图片描述

实现思路

1.首先需要一个tag的布局文件

这里写图片描述

2.手动的填充布局文件，生成一个TextView
3.根据这个TextView获取它的截屏，生成一个Bitmap
4.将bitmap设置到需要显示tag的TextView上，这和TextView中显示表情的原理是一样的。

代码如下

package com.trs.nxnews.news.util;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.Rect;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.text.SpannableString;import android.text.TextUtils;import android.text.style.ImageSpan;import android.view.LayoutInflater;import android.view.View;import android.widget.TextView;import com.trs.nxnews.R;import static android.text.Spanned.SPAN_INCLUSIVE_EXCLUSIVE;/** * Created by zhuguohui on 2016/12/12. */public class TagUtil {    public static void setTag(String tag, TextView textView) {        if (TextUtils.isEmpty(tag) || "无".equals(tag)) {            return;        }        //填充tag布局        TextView tv_tag = (TextView) LayoutInflater.from(textView.getContext()).inflate(R.layout.view_tag, null, true);        tv_tag.setText(tag);        //获取View的截图，用来当Tag图标        Bitmap drawingCache = convertViewToBitmap(tv_tag);        //将图片设置到TextView中        BitmapDrawable bitmapDrawable = new BitmapDrawable(drawingCache);        bitmapDrawable.setBounds(0, 0, drawingCache.getWidth(), drawingCache.getHeight());        SpannableString spannableString = new SpannableString(tag + textView.getText());        MyIm imageSpan = new MyIm(bitmapDrawable);        spannableString.setSpan(imageSpan, 0, tag.length(), SPAN_INCLUSIVE_EXCLUSIVE);        textView.setText(spannableString);    }    /**     * 获取tag图标     *     * @param view     * @return     */    public static Bitmap convertViewToBitmap(View view) {        view.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED), View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));        view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());        view.buildDrawingCache();        Bitmap bitmap = view.getDrawingCache();        return bitmap;    }    /**     * 可以居中对齐的ImageSPan     */    public static class MyIm extends ImageSpan {        public MyIm(Context arg0, int arg1) {            super(arg0, arg1);        }        public MyIm(Drawable drawable) {            super(drawable);        }        public int getSize(Paint paint, CharSequence text, int start, int end,                           Paint.FontMetricsInt fm) {            Drawable d = getDrawable();            Rect rect = d.getBounds();            if (fm != null) {                Paint.FontMetricsInt fmPaint = paint.getFontMetricsInt();                int fontHeight = fmPaint.bottom - fmPaint.top;                int drHeight = rect.bottom - rect.top;                int top = drHeight / 2 - fontHeight / 4;                int bottom = drHeight / 2 + fontHeight / 4;                fm.ascent = -bottom;                fm.top = -bottom;                fm.bottom = top;                fm.descent = top;            }            //15为padding            return rect.right + 15;        }        @Override        public void draw(Canvas canvas, CharSequence text, int start, int end,                         float x, int top, int y, int bottom, Paint paint) {            Drawable b = getDrawable();            canvas.save();            int transY = 0;            transY = ((bottom - top) - b.getBounds().bottom) / 2 + top;            canvas.translate(x, transY);            b.draw(canvas);            canvas.restore();        }    }}

源码

TAGDemo

总结

有一些事情并没有想象中那么简单，多积累一点一滴的技术，学会灵活运用技术，这样开发才会越来越简单，与君共勉。

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