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);
}