这篇文章给大家介绍android中怎么通过自定义View实现跑马灯效果，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
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 handleMessageandroid.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.sendEmptyMessageDelayed0, spead);
};
};
public MarqueenViewContext context, AttributeSet attrs) {
thiscontext, attrs, 0);
currentLength = length;
}
public MarqueenViewContext context) {
thiscontext, null);
}
public MarqueenViewContext context, AttributeSet attrs, int defStyle) {
supercontext, attrs, defStyle);
TypedArray a = context.getTheme).obtainStyledAttributesattrs, R.styleable.CustomTitleView, defStyle, 0);
int n = a.getIndexCount);
for int i = 0; i < n; i++) {
int attr = a.getIndexi);
switch attr) {
case R.styleable.CustomTitleView_titleText:
mTitleText = a.getStringattr);
break;
case R.styleable.CustomTitleView_titleTextColor:
mTitleTextColor = a.getColorattr, Color.BLACK);
break;
case R.styleable.CustomTitleView_titleTextSize:
mTitleTextSize = a.getDimensionPixelSizeattr,
int) TypedValue.applyDimensionTypedValue.COMPLEX_UNIT_SP, 16, getResources).getDisplayMetrics)));
break;
}
}
a.recycle);
mPaint = new Paint);
mPaint.setTextSizemTitleTextSize);
mBound = new Rect);
usualBound = new Rect);
mPaint.getTextBoundsmTitleText, 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 onMeasureint widthMeasureSpec, int heightMeasureSpec) {
int widthMode = MeasureSpec.getModewidthMeasureSpec);
int widthSize = MeasureSpec.getSizewidthMeasureSpec);
int heightMode = MeasureSpec.getModeheightMeasureSpec);
int heightSize = MeasureSpec.getSizeheightMeasureSpec);
int width;
int height;
if widthMode == MeasureSpec.EXACTLY) {
width = widthSize;
} else {
mPaint.setTextSizemTitleTextSize);
mPaint.getTextBoundsmTitleText, 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.setTextSizemTitleTextSize);
mPaint.getTextBoundsmTitleText, 0, mTitleText.length), mBound);
float textHeight = mBound.height);
int desired = int) getPaddingTop) + textHeight + getPaddingBottom));
height = desired;
}
// setMeasuredDimensionwidth / length) * length, height);
setMeasuredDimensionwidth, height + usualBound.bottom);
}
@Override
protected void onDrawCanvas canvas) {
mPaint.setColormTitleTextColor);
if mBound.width) <= getWidth)) {
if currentLength < mBound.width)) {
canvas.drawTextmTitleText, getPaddingLeft) - currentLength, getHeight) - usualBound.bottom, mPaint);
}
if currentLength >= 120) {
canvas.drawTextmTitleText, getWidth) - currentLength + 120, getHeight) - usualBound.bottom, mPaint);
}
} else {
if currentLength < mBound.width)) {
canvas.drawTextmTitleText, getPaddingLeft) - currentLength, getHeight) - usualBound.bottom, mPaint);
}
if currentLength >= mBound.width) - getWidth) + 120) {
canvas.drawTextmTitleText, 120 - currentLength + mBound.width), getHeight) - usualBound.bottom, mPaint);
}
}
}
public static int getFontHeightInteger textSize) {
Paint paint = new Paint);
if textSize != null) {
paint.setTextSizetextSize);
}
FontMetrics fm = paint.getFontMetrics);
return int) fm.descent - fm.ascent);
}
public void startScroll) {
handler.removeMessages0);
handler.sendEmptyMessage0);
}
public void stopScroll) {
handler.removeMessages0);
currentLength = 0;
invalidate);
}
public void setScrollLengthint length) {
this.length = length;
currentLength = length;
}
public void setSpeadint spead) {
this.spead = spead;
}
public void setTextString msg) {
mTitleText = msg;
mBound = new Rect);
mPaint.getTextBoundsmsg, 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) findViewByIdR.id.main_marquee_view);
mv.stopScroll);
mv.setText"滚动内容");// 设置显示内容
//mv.setSpead15);//滚动频率，默认15毫秒一次，数值太小会影响效率
//mv.setScrollLength3);//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);
}