android自带的TextView可以实现跑马灯效果，但是有很多的局限性；比如需要设置ellipsize=”marquee”，获取 focusable=”true”，设置singleLine=”true”，控件里的内容需要超过控件本身的长度，无法控制滚动速度和滚动暂停和继续滚动功能，各种限制导致用起来特别不顺手，几乎无法使用到生产环境中，在此背景下，需要自定义View实现跑马灯效果。

使用主要方法：自定义View重写onDraw方法，通过canvas.drawText()方法来显示文字，利用Handler不断地绘制文字，并控制文字开始绘制的X轴的位置，来实现连续滚动的效果。

实现步骤：

1、自定义view的class：

import android.annotation.SuppressLint;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Paint.FontMetrics;import android.graphics.Rect;import android.os.Handler;import android.util.AttributeSet;import android.util.TypedValue;import android.view.View;public class MarqueenView extends View { /* * 1、自定义View的属性 2、在View的构造方法中获得我们自定义的属性 [ 3、重写onMesure ] 4、重写onDraw */ /* * 文本 */ private String mTitleText; /** * 文本的颜色 */ private int mTitleTextColor; /** * 文本的大小 */ private int mTitleTextSize; /** * 绘制时控制文本绘制的范围 */ private Rect mBound, usualBound; // 画笔 private Paint mPaint; private int spead = 15; private int length = 3; private int currentLength; @SuppressLint("HandlerLeak") private Handler handler = new Handler() { @Override public void handleMessage(android.os.Message msg) { if (mBound.width() <= getWidth()) { if (currentLength >= 120 + (getWidth() / length) * length) { currentLength = length; } else { currentLength = currentLength + length; } } else { if (currentLength >= (mBound.width() + 120)) { currentLength = length; } else { currentLength = currentLength + length; } } invalidate(); handler.sendEmptyMessageDelayed(0, spead); }; }; public MarqueenView(Context context, AttributeSet attrs) { this(context, attrs, 0); currentLength = length; } public MarqueenView(Context context) { this(context, null); } public MarqueenView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomTitleView, defStyle, 0); int n = a.getIndexCount(); for (int i = 0; i < n; i++) { int attr = a.getIndex(i); switch (attr) { case R.styleable.CustomTitleView_titleText: mTitleText = a.getString(attr); break; case R.styleable.CustomTitleView_titleTextColor: mTitleTextColor = a.getColor(attr, Color.BLACK); break; case R.styleable.CustomTitleView_titleTextSize: mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics())); break; } } a.recycle(); mPaint = new Paint(); mPaint.setTextSize(mTitleTextSize); mBound = new Rect(); usualBound = new Rect(); mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound); mPaint.getTextBounds("1234567890QqYy你好", 0, 16, usualBound); } /* * EXACTLY：一般是设置了明确的值或者是MATCH_PARENT AT_MOST：表示子布局限制在一个最大值内，一般为WARP_CONTENT * UNSPECIFIED：表示子布局想要多大就多大，很少使用 */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int widthMode = MeasureSpec.getMode(widthMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); int width; int height; if (widthMode == MeasureSpec.EXACTLY) { width = widthSize; } else { mPaint.setTextSize(mTitleTextSize); mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound); float textWidth = mBound.width();// 字体宽度 // 控件padding int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight()); width = desired; } if (heightMode == MeasureSpec.EXACTLY) { height = heightSize; } else { mPaint.setTextSize(mTitleTextSize); mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound); float textHeight = mBound.height(); int desired = (int) (getPaddingTop() + textHeight + getPaddingBottom()); height = desired; } // setMeasuredDimension((width / length) * length, height); setMeasuredDimension(width, height + usualBound.bottom); } @Override protected void onDraw(Canvas canvas) { mPaint.setColor(mTitleTextColor); if (mBound.width() <= getWidth()) { if (currentLength < mBound.width()) { canvas.drawText(mTitleText, getPaddingLeft() - currentLength, getHeight() - usualBound.bottom, mPaint); } if (currentLength >= 120) { canvas.drawText(mTitleText, getWidth() - currentLength + 120, getHeight() - usualBound.bottom, mPaint); } } else { if (currentLength < mBound.width()) { canvas.drawText(mTitleText, getPaddingLeft() - currentLength, getHeight() - usualBound.bottom, mPaint); } if (currentLength >= mBound.width() - getWidth() + 120) { canvas.drawText(mTitleText, 120 - currentLength + mBound.width(), getHeight() - usualBound.bottom, mPaint); } } } public static int getFontHeight(Integer textSize) { Paint paint = new Paint(); if (textSize != null) { paint.setTextSize(textSize); } FontMetrics fm = paint.getFontMetrics(); return (int) (fm.descent - fm.ascent); } public void startScroll() { handler.removeMessages(0); handler.sendEmptyMessage(0); } public void stopScroll() { handler.removeMessages(0); currentLength = 0; invalidate(); } public void setScrollLength(int length) { this.length = length; currentLength = length; } public void setSpead(int spead) { this.spead = spead; } public void setText(String msg) { mTitleText = msg; mBound = new Rect(); mPaint.getTextBounds(msg, 0, mTitleText.length(), mBound); }}

2、在values的attrs.xml文件中需要加入自定义的属性，字体大小、颜色、和初始内容，这里有待改进

<?xml version="1.0" encoding="utf-8"?><resources> <attr name="titleText" format="string" /> <attr name="titleTextColor" format="color" /> <attr name="titleTextSize" format="dimension" /> <declare-styleable name="CustomTitleView"> <attr name="titleText" /> <attr name="titleTextColor" /> <attr name="titleTextSize" /> </declare-styleable></resources>

3、在layout的布局文件中引用此控件

<?xml version="1.0" encoding="utf-8"?><LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android" xmlns:custom="http://schemas.android.com/apk/res/***这里写上自己的包名***" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <com.example.MarqueenView android:id="@+id/main_marquee_view" android:layout_width="fill_parent" android:layout_height="wrap_content" custom:titleText=" " custom:titleTextColor="#666666" custom:titleTextSize="14sp"/> </LinearLayout>

4、上面准备好后，就可以在activity中设置跑马灯并开始滚动了

mv = (MarqueenView) findViewById(R.id.main_marquee_view);mv.stopScroll();mv.setText("滚动内容");// 设置显示内容//mv.setSpead(15);//滚动频率，默认15毫秒一次，数值太小会影响效率//mv.setScrollLength(3);//默认每次左移3px，数值太大会有停顿感，数值太小滚动会变慢mv.startScroll();//记得在Ondestroy中停止滚动，方便回收@Override protected void onDestroy() { try { mv.stopScroll(); mv = null; } catch (Throwable e) { e.printStackTrace(); } super.onDestroy(); }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。