Files
assistant-android/app/src/main/java/com/gh/common/view/ExpandTextView.java
2020-07-13 16:01:11 +08:00

303 lines
12 KiB
Java

package com.gh.common.view;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Rect;
import android.os.Build;
import android.text.Layout;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.style.ClickableSpan;
import android.text.style.ForegroundColorSpan;
import android.util.AttributeSet;
import android.view.View;
import androidx.annotation.NonNull;
import androidx.appcompat.widget.AppCompatTextView;
import androidx.core.content.ContextCompat;
import com.gh.gamecenter.R;
public class ExpandTextView extends AppCompatTextView {
private CharSequence mSnapshotText;
private String mEndText = "...";
private CharSequence mShrankText = "";
private String mExpandText = mEndText + "全文";
private CharSequence mExpandedText = "";
private boolean mUseGradientAlphaEndText = false;
private boolean mShowExpandTextRegardlessOfMaxLines = false; // 不论文字超过 maxLines 都显示"...展开"文字
private int mMaxLines = 3; // 由于sdk版本限制(getMaxLines) 这里设置默认值
private boolean mInitLayout = false;
private boolean mIsExpanded = false; // 位于 recyclerView 时需要自行在外层管理是否已展开
private ExpandCallback mExpandCallback;
private SelfCalculateMaxLinesCallback mMaxLinesCalculatedCallback;
private Rect mLastVisibleLineRect;
private Rect mLastActualLineRect;
private static int DEFAULT_ADDITIONAL_END_TEXT_COUNT = 2;
public ExpandTextView(Context context) {
super(context);
}
public ExpandTextView(Context context, AttributeSet attrs) {
super(context, attrs);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
mMaxLines = getMaxLines();
}
mLastVisibleLineRect = new Rect();
mLastActualLineRect = new Rect();
TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ExpandTextView);
mUseGradientAlphaEndText = ta.getBoolean(R.styleable.ExpandTextView_useGradientAlphaEndText, false);
mEndText = ta.getString(R.styleable.ExpandTextView_endText) == null ? mEndText : ta.getString(R.styleable.ExpandTextView_endText);
mExpandText = ta.getString(R.styleable.ExpandTextView_expandText) == null ? mExpandText : ta.getString(R.styleable.ExpandTextView_expandText);
ta.recycle();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (mShowExpandTextRegardlessOfMaxLines && !mIsExpanded) {
updateMaxLines();
}
setMeasuredDimension(getMeasuredWidth(), getMeasuredHeight() - getExtraBottomPadding());
}
private void updateMaxLines() {
mMaxLines = getLineCount() - 1;
setMaxLines(mMaxLines);
mMaxLinesCalculatedCallback.onMaxLinesCalculated(mMaxLines);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (mMaxLines > 0
&& ((mShowExpandTextRegardlessOfMaxLines && !mIsExpanded) || (mInitLayout && !mIsExpanded && getLineCount() > mMaxLines))) {
mSnapshotText = getText();
mInitLayout = false;
showExpandButton();
}
}
public void setExpandText(String text) {
this.mExpandText = text;
}
public void setExpandCallback(ExpandCallback callback) {
this.mExpandCallback = callback;
}
/**
* 适用于不使用 maxLines 而是整段收起时的文字来确定“...更多”的位置的样式
* @param shrankText 收起时的文字 (“...更多”跟在 shrankText 后)
* @param expandedText 展开时的文字
*/
public void setShrankTextAndExpandedText(CharSequence shrankText, CharSequence expandedText) {
mShrankText = shrankText;
mExpandedText = expandedText;
mShowExpandTextRegardlessOfMaxLines = !TextUtils.isEmpty(shrankText);
if (!mIsExpanded && mShowExpandTextRegardlessOfMaxLines) {
setText(mShrankText);
} else {
setText(mExpandedText);
}
}
@Override
public void setText(CharSequence text, BufferType type) {
mInitLayout = true;
super.setText(text, type);
}
private void showExpandButton() {
String finalEndText = "";
TextPaint paint = getPaint();
Layout layout = getLayout();
int start = layout.getLineStart(0);
int lastLineEnd = layout.getLineEnd(mMaxLines - 1);
int lastLineStart = layout.getLineStart(mMaxLines - 1);
float lastLineRight = layout.getLineRight(mMaxLines - 1);
int viewWidth = getWidth() - getPaddingRight() - getPaddingLeft();
int additionalEndTextCount = 0;
float expandTextWidth;
if (mUseGradientAlphaEndText) {
additionalEndTextCount = DEFAULT_ADDITIONAL_END_TEXT_COUNT;
expandTextWidth = paint.measureText(mEndText + mExpandText);
} else {
expandTextWidth = paint.measureText(mExpandText);
}
CharSequence content = mSnapshotText.subSequence(start, lastLineEnd);
if (viewWidth - lastLineRight > expandTextWidth) {
if (mUseGradientAlphaEndText) {
finalEndText = content.toString()
.substring(content.length() - additionalEndTextCount, content.length()) + mEndText;
finalEndText = finalEndText.replace("\n", "");
content = content.subSequence(0, content.length() - additionalEndTextCount) + finalEndText + mExpandText;
} else {
content = content.toString().trim() + mExpandText;
}
} else {
CharSequence lastLineText = mSnapshotText.subSequence(lastLineStart, lastLineEnd);
CharSequence subSequence;
float subSequenceWidth;
for (int i = lastLineText.length() - 1; i > 0; i--) {
if (mUseGradientAlphaEndText) {
subSequence = lastLineText.subSequence(0, i - additionalEndTextCount);
subSequenceWidth = paint.measureText(subSequence.toString());
finalEndText = lastLineText.subSequence(i - additionalEndTextCount, i) + mEndText;
expandTextWidth = paint.measureText(finalEndText + mExpandText);
if (viewWidth - subSequenceWidth > expandTextWidth) {
finalEndText = finalEndText.replace("\n", "");
content = mSnapshotText.subSequence(start, lastLineStart + i - additionalEndTextCount) + finalEndText + mExpandText;
break;
}
} else {
subSequence = lastLineText.subSequence(0, i);
subSequenceWidth = paint.measureText(subSequence.toString());
if (viewWidth - subSequenceWidth > expandTextWidth) {
content = mSnapshotText.subSequence(start, lastLineStart + i) + mExpandText;
break;
}
}
}
}
SpannableStringBuilder msp = new SpannableStringBuilder(mSnapshotText);
int length = msp.length();
int expandTextStartPosition;
expandTextStartPosition = content.length() - finalEndText.length() - mExpandText.length();
expandTextStartPosition = Math.max(expandTextStartPosition, 0);
// 避免越界
if (expandTextStartPosition >= length) return;
msp.replace(expandTextStartPosition, length, finalEndText + mExpandText);
if (expandTextStartPosition + mEndText.length() >= msp.length()) return;
msp.setSpan(new ClickableSpan() {
@Override
public void updateDrawState(@NonNull TextPaint ds) {
super.updateDrawState(ds);
ds.setColor(ContextCompat.getColor(getContext(), R.color.theme_font));
ds.setUnderlineText(false);
}
@Override
public void onClick(@NonNull View widget) {
mIsExpanded = true;
setMaxLines(Integer.MAX_VALUE);
if (mShowExpandTextRegardlessOfMaxLines) {
setText(mExpandedText);
} else {
setText(mSnapshotText);
}
if (mExpandCallback != null) {
mExpandCallback.onExpand();
}
}
}, expandTextStartPosition + mEndText.length(), msp.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
int paintColor = 0;
// 找到第一个位置与 endTextStartPosition 贴合的 ForegroundSpan / ClickableSpan ,
// 获取颜色赋值给 GradientAlphaTextSpan
Object[] objects = msp.getSpans(0, expandTextStartPosition, Object.class);
if (objects.length != 0) {
for (Object span : objects) {
int startPosition = msp.getSpanStart(span);
int endPosition = msp.getSpanEnd(span);
if (expandTextStartPosition >= startPosition && expandTextStartPosition <= endPosition) {
if (span instanceof ForegroundColorSpan) {
paintColor = ((ForegroundColorSpan) span).getForegroundColor();
break;
} else if (span instanceof ClickableSpan) {
paintColor = getResources().getColor(R.color.theme_font);
break;
}
}
}
}
msp.setSpan(new GradientAlphaTextSpan(paintColor), expandTextStartPosition, expandTextStartPosition + finalEndText.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
setText(msp);
setMovementMethod(CustomLinkMovementMethod.getInstance());
}
/**
* 获取 maxLines + lineSpacingExtra + movementMethod 一起使用时产生的大小与 lineSpacingExtra 一样的底部空间
*/
private int getExtraBottomPadding() {
int result = 0;
// 界面上显示的最后一行的 index
int lastVisibleLineIndex = Math.min(getMaxLines(), getLineCount()) - 1;
// 获取实际文字的最后一行的 index
int lastActualLineIndex = getLineCount() - 1;
if (lastVisibleLineIndex >= 0) {
Layout layout = getLayout();
int lastVisibleLineBaseline = getLineBounds(lastVisibleLineIndex, mLastVisibleLineRect);
getLineBounds(lastActualLineIndex, mLastActualLineRect);
int heightBetweenLastVisibleLineRectAndLastActualLineRect = (mLastActualLineRect.bottom - mLastVisibleLineRect.bottom);
if (getMeasuredHeight() == getLayout().getHeight() - heightBetweenLastVisibleLineRectAndLastActualLineRect) {
result = mLastVisibleLineRect.bottom - (lastVisibleLineBaseline + layout.getPaint()
.getFontMetricsInt().descent + getPaddingBottom());
if (getLineSpacingExtra() > result) {
result = 0;
} else {
result = (int) getLineSpacingExtra();
}
}
}
return result;
}
/**
* 此方法仅更改标记,不做实际展开的操作
*/
public void setIsExpanded(boolean isExpanded) {
mIsExpanded = isExpanded;
}
public void setExpandMaxLines(int maxLines) {
mMaxLines = maxLines;
setMaxLines(maxLines);
}
public void setSelfCalculateMaxLinesCallback(SelfCalculateMaxLinesCallback callback) {
mMaxLinesCalculatedCallback = callback;
}
public interface ExpandCallback {
void onExpand();
}
public interface SelfCalculateMaxLinesCallback {
void onMaxLinesCalculated(int maxLines);
}
}