Android文字跑马灯控件（文本自动水平滚动）

代码如下：

AutoScrollTextView.java

package com.cn.lhq;import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.os.Parcel;import android.os.Parcelable;import android.util.AttributeSet;import android.view.Display;import android.view.View;import android.view.WindowManager;import android.view.View.OnClickListener;import android.widget.TextView;/** * TODO 单行文本跑马灯控件 */public class AutoScrollTextView extends TextView implements OnClickListener {//public final static String TAG = AutoScrollTextView.class.getSimpleName();private float textLength = 0f;// 文本长度private float viewWidth = 0f;private float step = 0f;// 文字的横坐标private float y = 0f;// 文字的纵坐标private float temp_view_plus_text_length = 0.0f;// 用于计算的临时变量private float temp_view_plus_two_text_length = 0.0f;// 用于计算的临时变量public boolean isStarting = false;// 是否开始滚动private Paint paint = null;// 绘图样式private String text = "";// 文本内容public AutoScrollTextView(Context context) {super(context);initView();}public AutoScrollTextView(Context context, AttributeSet attrs) {super(context, attrs);initView();}public AutoScrollTextView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initView();}/** * 初始化控件 */private void initView() {setOnClickListener(this);}/** * 文本初始化，每次更改文本内容或者文本效果等之后都需要重新初始化一下 */public void init(WindowManager windowManager) {paint = getPaint();text = getText().toString();textLength = paint.measureText(text);viewWidth = getWidth();if (viewWidth == 0) {if (windowManager != null) {Display display = windowManager.getDefaultDisplay();viewWidth = display.getWidth();}}step = textLength;temp_view_plus_text_length = viewWidth + textLength;temp_view_plus_two_text_length = viewWidth + textLength * 2;y = getTextSize() + getPaddingTop();}@Overridepublic Parcelable onSaveInstanceState() {Parcelable superState = super.onSaveInstanceState();SavedState ss = new SavedState(superState);ss.step = step;ss.isStarting = isStarting;return ss;}@Overridepublic void onRestoreInstanceState(Parcelable state) {if (!(state instanceof SavedState)) {super.onRestoreInstanceState(state);return;}SavedState ss = (SavedState) state;super.onRestoreInstanceState(ss.getSuperState());step = ss.step;isStarting = ss.isStarting;}public static class SavedState extends BaseSavedState {public boolean isStarting = false;public float step = 0.0f;SavedState(Parcelable superState) {super(superState);}@Overridepublic void writeToParcel(Parcel out, int flags) {super.writeToParcel(out, flags);out.writeBooleanArray(new boolean[] { isStarting });out.writeFloat(step);}public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {public SavedState[] newArray(int size) {return new SavedState[size];}@Overridepublic SavedState createFromParcel(Parcel in) {return new SavedState(in);}};private SavedState(Parcel in) {super(in);boolean[] b = null;in.readBooleanArray(b);if (b != null && b.length > 0)isStarting = b[0];step = in.readFloat();}}/** * 开始滚动 */public void startScroll() {isStarting = true;invalidate();}/** * 停止滚动 */public void stopScroll() {isStarting = false;invalidate();}@Overridepublic void onDraw(Canvas canvas) {canvas.drawText(text, temp_view_plus_text_length - step, y, paint);if (!isStarting) {return;}step += 0.5;if (step > temp_view_plus_two_text_length)step = textLength;invalidate();}@Overridepublic void onClick(View v) {if (isStarting)stopScroll();elsestartScroll();}}

实现了宽度的判断，文本自动滚动及开始和停止滚动等功能。

在UI xml中的配置如下：

<com.cn.lhq.AutoScrollTextView android:id="@+id/TextViewNotice"android:layout_height="30px" android:layout_width="fill_parent"android:text="abcdefghijklmn" android:textColor="#000" android:inputType="text"android:background="#EEE" android:textSize="20px"/>

在Activity中的使用方法如下：

//启动公告滚动条autoScrollTextView = (AutoScrollTextView)findViewById(R.id.TextViewNotice);autoScrollTextView.init(getWindowManager());autoScrollTextView.startScroll();

如果想改变跑马灯的文字内容或者文字效果，则在调用完setText方法之后，需要再调用一下init(WindowManager windowManager)方法，重新进行初始化和相关参数的计算。

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