小编给大家分享一下Android如何实现文字动态高亮读取进度效果，希望大家阅读完这篇文章之后都有所收获，下面让我们一起去探讨吧！
具体内容如下
1、效果图
类似歌词的效果。播放下面文字的音频，同时音频播放的进度和文字高亮进度保持一致。
2、代码结构和实现
简单的类图：
ISubtitleView接口代码如下：
public interface ISubtitleView { List<SubtitleItem> getSubtitleItemList(); void setSubtitleItemList(List<SubtitleItem> linesTextList); void setDuration(long duration); void updatePts(long pts); void reset();}EMSubtitleView类的代码如下：public class EMSubtitleView extends android.support.v7.widget.AppCompatTextView implements ISubtitleView{ private int mMeasuredWidth; private int mMeasuredHeight; private List<SubtitleItem> mSubtitleItemList; private List<LineEntity> mLinesTextList; private Paint mNormalPaint; private Paint mHLPaint; private long mPts = 0; private int mCurHLLine; private float mReadSubtitleCount; private Rect mLastHLRect; private int mHLTextColor; private long mDuration; private boolean mIsPlain = false; public EMSubtitleView(Context context) { this(context , null); } public EMSubtitleView(Context context, AttributeSet attrs) { this(context, attrs , 0); } public EMSubtitleView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); mSubtitleItemList = new ArrayList<>(); mLinesTextList = null; mLastHLRect = new Rect(); mNormalPaint = null; initAttrs(attrs , defStyleAttr); } private void initAttrs(AttributeSet attrs , int defStyleAttr) { TypedArray ta = getContext().obtainStyledAttributes(attrs , R.styleable.EMSubtitleView , defStyleAttr , R.style.EMSubtitleViewDefaultTheme); for(int i = 0 ; i < ta.getIndexCount() ; i++){ int index = ta.getIndex(i); if (index == R.styleable.EMSubtitleView_highLightTextColor) { mHLTextColor = ta.getColor(index, getResources().getColor(R.color.emvideovisit_color_FF9000)); } } ta.recycle(); } private void initHLPaint() { mHLPaint = new Paint(mNormalPaint); mHLPaint.setColor(mHLTextColor); mHLPaint.setTextSize(getTextSize()); } public void setRichText(String text){ mIsPlain = false; reset(); setText(text); setDuration(mDuration , true); } public void setPlainText(String text){ mIsPlain = true; reset(); setText(text); } @Override protected void onDraw(Canvas canvas) { if (mMeasuredWidth == 0 || mMeasuredHeight == 0) { mMeasuredWidth = getMeasuredWidth(); mMeasuredHeight = getMeasuredHeight(); } if(mIsPlain){ super.onDraw(canvas); return; } if(mNormalPaint == null){ super.onDraw(canvas); mNormalPaint = getPaint(); initHLPaint(); return; } if(mLinesTextList == null){ fillLinesEntityListJustOnce(); } //没有pts，绘制 if(mPts <= 0){ drawNormalText(canvas); return; } drawNormalText(canvas); calculateReadLineAndWordsCount(); //绘制高亮部分歌词 drawHLText(canvas); } private void drawHLText(Canvas canvas) { if(mCurHLLine >= 0){ int curLineTextCount = 0; for(int i = 0 ; i < mLinesTextList.size() ; ++i){ LineEntity entity = mLinesTextList.get(i); if(mCurHLLine > i){ canvas.drawText( entity.lineText , entity.left , entity.baseLine , mHLPaint); }else if(mCurHLLine == i && mReadSubtitleCount > 0 ){ canvas.save(); mLastHLRect.set(entity.left , entity.top , entity.left + (int) (mHLPaint.measureText(entity.lineText)*1.0f/entity.lineText.length()*(mReadSubtitleCount-curLineTextCount)), entity.bottom); canvas.clipRect(mLastHLRect ); canvas.drawText( entity.lineText , entity.left , entity.baseLine , mHLPaint); canvas.restore(); //遮挡的话需要滚动 if(entity.baseLine > getHeight()){ if(getScrollY() != entity.bottom - getHeight() + 1){ setScrollY( entity.bottom - getHeight() + 1); } } break; } curLineTextCount += entity.lineText.length(); } } } private void calculateReadLineAndWordsCount() { float curSubtitleCount = 0; for(SubtitleItem subtitleItem : mSubtitleItemList){ //文字之间不可以有空隙，否则mCurHLLine可能一直为-1； if(mPts >= subtitleItem.getStartTime() && mPts < subtitleItem.getEndTime()){ float lineOffset = (subtitleItem.getWords().length()*1.0f/(subtitleItem.getEndTime() - subtitleItem.getStartTime()))*(mPts-subtitleItem.getStartTime()); curSubtitleCount += lineOffset; int curLineTextCount = 0; for(int i = 0 ; i < mLinesTextList.size() ; ++i){ curLineTextCount += mLinesTextList.get(i).lineText.length(); if(curLineTextCount > curSubtitleCount){ mCurHLLine = i; break; } } break; } curSubtitleCount += subtitleItem.getWords().length(); } mReadSubtitleCount = curSubtitleCount; } private void fillLinesEntityListJustOnce() { if(mLinesTextList != null){ return; } mLinesTextList = new ArrayList<>(); Layout layout = getLayout(); int line=getLayout().getLineCount(); String text=layout.getText().toString(); for(int i=0;i<line;i++){ int start=layout.getLineStart(i); int end=layout.getLineEnd(i); int left = (int) layout.getLineLeft(i); int baseLine = layout.getLineBaseline(i); Paint.FontMetrics fontMetrics = getPaint().getFontMetrics(); int top = (int) (baseLine + fontMetrics.top); int bottom = (int) (baseLine + fontMetrics.bottom); int ascent = (int) (baseLine + fontMetrics.ascent); int descent = (int) (baseLine + fontMetrics.descent); mLinesTextList.add(new LineEntity(text.substring(start, end) , top , bottom , ascent , descent ,baseLine , left)); } } private void drawNormalText(Canvas canvas) { for(LineEntity entity : mLinesTextList){ canvas.drawText(entity.lineText, entity.left, entity.baseLine , mNormalPaint); } } public List<SubtitleItem> getSubtitleItemList() { return mSubtitleItemList; } public void setSubtitleItemList(List<SubtitleItem> linesTextList) { if(mSubtitleItemList != null){ mSubtitleItemList.clear(); mSubtitleItemList.addAll(linesTextList); }else{ this.mSubtitleItemList = linesTextList; } } public void setDuration(long duration){ setDuration( duration , false); } private void setDuration(long duration , boolean force){ if((duration > 0 && mDuration != duration) || force){ mDuration = duration; if(mSubtitleItemList != null){ mSubtitleItemList.clear(); }else{ this.mSubtitleItemList = new ArrayList<>(); } mSubtitleItemList.add(new SubtitleItem(getText().toString() , 0 , duration)); } } public void updatePts(long pts){ mPts = pts; postInvalidate(); } public void reset(){ mPts = 0; mCurHLLine = 0; mReadSubtitleCount = 0; mLinesTextList = null; mNormalPaint = null; setScrollY(0); postInvalidate(); } static class LineEntity{ String lineText; int top; int bottom; int ascent; int descent; int baseLine; int left; public LineEntity(String lineText, int top, int bottom, int ascent, int descent, int baseLine, int left) { this.lineText = lineText; this.top = top; this.bottom = bottom; this.ascent = ascent; this.descent = descent; this.baseLine = baseLine; this.left = left; } }}布局文件里使用类似如下：
<com.eastmoney.emvideovisit.view.EMSubtitleView android:id="@+id/play_text" android:layout_width="match_parent" android:layout_height="@dimen/emvideovisit_dp_60" android:layout_marginLeft="@dimen/emvideovisit_dp_60" android:layout_marginRight="@dimen/emvideovisit_dp_60" android:gravity="center_horizontal" android:layout_marginTop="@dimen/emvideovisit_dp_20" android:textColor="#fff" app:highLightTextColor="#A6EA5504" android:text="@string/emvideovisit_string_headset_tips" android:textSize="@dimen/emvideovisit_dp_16" android:layout_marginBottom="@dimen/emvideovisit_dp_4"/>3、其它
处理过程中文字位置的参数需要注意：
Android是什么
Android是一种基于Linux内核的自由及开放源代码的操作系统，主要使用于移动设备，如智能手机和平板电脑，由美国Google公司和开放手机联盟领导及开发。
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