135 lines
3.9 KiB
Java
135 lines
3.9 KiB
Java
package com.uiuios.aios.view;
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import android.content.Context;
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import android.graphics.Rect;
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import android.text.Layout;
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import android.text.StaticLayout;
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import android.util.AttributeSet;
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import androidx.annotation.Nullable;
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import androidx.appcompat.widget.AppCompatTextView;
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public class ExpandTextView extends AppCompatTextView {
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/**
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* true：展开，false：收起
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*/
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boolean mExpanded;
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/**
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* 状态回调
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*/
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Callback mCallback;
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/**
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* 源文字内容
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*/
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String mText = "";
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/**
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* 最多展示的行数
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*/
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final int maxLineCount = 3;
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/**
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* 省略文字
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*/
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final String ellipsizeText = "...";
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public ExpandTextView(Context context, @Nullable AttributeSet attrs) {
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super(context, attrs);
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}
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@Override
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protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
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super.onMeasure(widthMeasureSpec, heightMeasureSpec);
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// 文字计算辅助工具
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StaticLayout sl = new StaticLayout(mText, getPaint(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()
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, Layout.Alignment.ALIGN_CENTER, 1, 0, true);
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// 总计行数
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int lineCount = sl.getLineCount();
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if (lineCount > maxLineCount) {
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if (mExpanded) {
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setText(mText);
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mCallback.onExpand();
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} else {
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lineCount = maxLineCount;
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// 省略文字的宽度
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float dotWidth = getPaint().measureText(ellipsizeText);
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// 找出第 showLineCount 行的文字
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int start = sl.getLineStart(lineCount - 1);
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int end = sl.getLineEnd(lineCount - 1);
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String lineText = mText.substring(start, end);
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// 将第 showLineCount 行最后的文字替换为 ellipsizeText
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int endIndex = 0;
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for (int i = lineText.length() - 1; i >= 0; i--) {
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String str = lineText.substring(i, lineText.length());
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// 找出文字宽度大于 ellipsizeText 的字符
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if (getPaint().measureText(str) >= dotWidth) {
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endIndex = i;
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break;
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}
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}
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// 新的第 showLineCount 的文字
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String newEndLineText = lineText.substring(0, endIndex) + ellipsizeText;
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// 最终显示的文字
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setText(mText.substring(0, start) + newEndLineText);
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mCallback.onCollapse();
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}
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} else {
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setText(mText);
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mCallback.onLoss();
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}
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// 重新计算高度
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int lineHeight = 0;
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for (int i = 0; i < lineCount; i++) {
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Rect lineBound = new Rect();
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sl.getLineBounds(i, lineBound);
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lineHeight += lineBound.height();
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}
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lineHeight += getPaddingTop() + getPaddingBottom();
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setMeasuredDimension(getMeasuredWidth(), lineHeight);
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}
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/**
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* 设置要显示的文字以及状态
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* @param text
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* @param expanded true：展开，false：收起
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* @param callback
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*/
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public void setText(String text, boolean expanded, Callback callback) {
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mText = text;
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mExpanded = expanded;
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mCallback = callback;
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// 设置要显示的文字，这一行必须要，否则 onMeasure 宽度测量不正确
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setText(text);
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}
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/**
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* 展开收起状态变化
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* @param expanded
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*/
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public void setChanged(boolean expanded) {
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mExpanded = expanded;
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requestLayout();
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}
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public interface Callback {
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/**
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* 展开状态
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*/
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void onExpand();
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/**
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* 收起状态
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*/
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void onCollapse();
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/**
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* 行数小于最小行数，不满足展开或者收起条件
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*/
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void onLoss();
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}
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} |