android在TextView后添加view实现展开收起查看更多

效果如下： 直接上代码：

import android.content.Context; import android.graphics.drawable.Drawable; import android.text.Layout; import android.util.AttributeSet; import android.view.Gravity; import android.view.MotionEvent; import android.view.ViewGroup; import android.view.ViewTreeObserver; import android.widget.FrameLayout; import android.widget.ScrollView; import android.widget.TextView; import androidx.annotation.NonNull; import androidx.annotation.Nullable; import androidx.core.content.ContextCompat; /** * 在超长文本后面加一个view，用来控制文本展示区域，当展开状态时超出的文本将可垂直滚动 * 非长文本内容就像TextView一样 * * @author ly * date 2020/3/9 10:22 */ public class ScrollExpandTextView extends ScrollView implements ViewTreeObserver.OnGlobalLayoutListener { private static final int MAX_LINE_COLLAPSE = 2;//收起时最大展示行数 private static final String TEXT_EXPAND = "展开"; private static final String TEXT_COLLAPSE = "收起"; private static final int MAX_H = 3 * PixelUtil.dp2px(50); private int w; private int minH; private int curH; private int arrowSize; private TextView tv; private TextView tvMore; private State state = State.COLLAPSE; private CharSequence text; private LayoutParams paramsMore; private int space; public enum State { EXPAND, COLLAPSE } public ScrollExpandTextView(@NonNull Context context) { super(context); init(); } public ScrollExpandTextView(@NonNull Context context, @Nullable AttributeSet attrs) { super(context, attrs); init(); } public ScrollExpandTextView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); setMeasuredDimension(w, curH);//固定宽高 } private void init() { w = (int) (0.7 * ScreenUtil.getScreenWidth()); minH = PixelUtil.dp2px(50); curH = minH; arrowSize = PixelUtil.dp2px(7); space = PixelUtil.dp2px(3); FrameLayout flContainer = new FrameLayout(getContext()); tv = new TextView(getContext()); tv.setTextSize(14); tv.setMaxHeight(PixelUtil.dp2px(50)); tv.setMaxLines(MAX_LINE_COLLAPSE); tv.setIncludeFontPadding(true); tv.setLineSpacing(1.0f, 1.2f); tvMore = new TextView(getContext()); tvMore.setBackgroundResource(R.drawable.scroll_expand_tv_more); tvMore.setMaxLines(1); tvMore.setTextSize(12); tvMore.setGravity(Gravity.CENTER); tvMore.setVisibility(GONE); tvMore.setOnClickListener(v -> { if (state == State.COLLAPSE) { state = State.EXPAND; tv.setMaxLines(Integer.MAX_VALUE); tv.setText(text); } else { state = State.COLLAPSE; tv.setMaxLines(MAX_LINE_COLLAPSE); } setMoreViewPosition(); }); tv.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT)); paramsMore = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT); tvMore.setLayoutParams(paramsMore); flContainer.addView(tv); flContainer.addView(tvMore); addView(flContainer); setTextColor(ContextCompat.getColor(getContext(), R.color.white)); setMoreTextColor(ContextCompat.getColor(getContext(), R.color.white)); setOverScrollMode(OVER_SCROLL_NEVER); setVerticalScrollBarEnabled(false); } private void setMoreViewPosition() { Layout layout = tv.getLayout(); if (layout == null) return; int lineCount = layout.getLineCount(); int lineH = layout.getLineBottom(0) - layout.getLineTop(0); minH = MAX_LINE_COLLAPSE * lineH; curH = lineCount * lineH; if (text == null || lineCount <= MAX_LINE_COLLAPSE && tv.length() == text.length()) { tvMore.setVisibility(GONE); } else { if (state == State.COLLAPSE) { curH = minH; float lineWidth = layout.getLineWidth(MAX_LINE_COLLAPSE - 1); //获取第2行最后一个字符的下标 int lineEnd = layout.getLineEnd(MAX_LINE_COLLAPSE - 1); //计算每个字符占的宽度 float widthPerChar = layout.getLineWidth(MAX_LINE_COLLAPSE - 1) / (lineEnd + 1); float diff = lineWidth + tvMore.getMeasuredWidth() + space - (getWidth() - getPaddingLeft() - getPaddingRight()); //第二行展示不下，去掉第二行最后几个字符，用来放展开按钮 if (diff > 0) { int removeCount = (int) (diff / widthPerChar); if (lineEnd > removeCount) { CharSequence t = text.subSequence(0, lineEnd - removeCount) + "..."; setTextAndRefresh(t); return;//setText会重新触发onGlobalLayout } } //获取第二行字符的坐标，设置展开按钮的margin，使展开按钮在文本后面 paramsMore.leftMargin = (int) layout.getLineRight(MAX_LINE_COLLAPSE - 1) + space; paramsMore.topMargin = lineH + tv.getPaddingTop() - space; tvMore.setText(TEXT_EXPAND); drawRight4MoreView(R.drawable.ico_arrowdown); } else { if (curH > MAX_H) curH = MAX_H; float lineWidth = layout.getLineWidth(lineCount - 1); if (lineWidth + tvMore.getMeasuredWidth() - (getWidth() - getPaddingLeft() - getPaddingRight()) > 0) {//最后一行显示不下，将最后一行换行 if (text.length() > 2) { //分两个字符到tvMore那一行，更协调 String tmp = text.subSequence(0, text.length() - 2) + "\n" + text.subSequence(text.length() - 2, text.length()); setTextAndRefresh(tmp); return;//setText会重新触发onGlobalLayout } } tvMore.setText(TEXT_COLLAPSE); drawRight4MoreView(R.drawable.ico_arrowup); paramsMore.leftMargin = (int) layout.getSecondaryHorizontal(layout.getLineEnd(lineCount - 1)) + space; paramsMore.topMargin = layout.getHeight() - tv.getPaddingBottom() - lineH + PixelUtil.dp2px(2); } tvMore.setVisibility(VISIBLE); } getLayoutParams().height = curH; } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); setMoreViewPosition(); } @Override public void onGlobalLayout() { //为保证TextView.getLayout()!=null，在这里再执行相关逻辑 setMoreViewPosition(); //记得移除，不然会一直回调 tv.getViewTreeObserver().removeOnGlobalLayoutListener(this); } public void setText(final CharSequence text) { this.text = text; setTextAndRefresh(text); } public void setTextAndRefresh(CharSequence text) { tv.getViewTreeObserver().addOnGlobalLayoutListener(this); tv.setText(text); } private void drawRight4MoreView(int icRes) { Drawable drawable = getResources().getDrawable(icRes); /// 这一步必须要做,否则不会显示. drawable.setBounds(arrowSize / 3, 0, arrowSize, arrowSize / 3); tvMore.setCompoundDrawables(null, null, drawable, null); } public void setTextColor(int color) { tv.setTextColor(color); } public void setMoreTextColor(int color) { tvMore.setTextColor(color); } //如果不需要处理滑动冲突，去掉下面的代码即可 private int startX, startY; @Override public boolean dispatchTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: startX = (int) ev.getX(); startY = (int) ev.getY(); getParent().requestDisallowInterceptTouchEvent(false); break; case MotionEvent.ACTION_MOVE: int endX = (int) ev.getX(); int endY = (int) ev.getY(); int disX = Math.abs(endX - startX); int disY = Math.abs(endY - startY); if (disX > disY) { getParent().requestDisallowInterceptTouchEvent(canScrollHorizontally(startX - endX)); } else { getParent().requestDisallowInterceptTouchEvent(canScrollVertically(startY - endY)); } break; default: getParent().requestDisallowInterceptTouchEvent(false); break; } return super.dispatchTouchEvent(ev); } }

以上