自定义TextView带滚动字幕

虽然TextView有自带的滚动字幕，但在Listview中，仍需要让TextView能滚动字幕的话，对于焦点的取舍就麻烦了很多。而且若是有多个TextView需要滚动字幕的话，就不行了。正好看到一个帖子里网友提到自定义TextView让其滚动，真是一个非常不错的建议。也提供一下帖子的原地址:http://topic.csdn.net/u/20110728/09/0b52e21d-c609-4643-848b-0f42c28f6e0b.html

下面是我修改过的，把MyTextView作为ListView中的一部分去实现。

package com.abc;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.util.Log;import android.view.Display;import android.view.WindowManager;import android.widget.TextView;public class MyTextView extends TextView {public final static String TAG = MyTextView.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 x = 0f;//不滚动时的横坐标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private boolean first = true;public MyTextView(Context context) {super(context);}public MyTextView(Context context, AttributeSet attrs) {super(context, attrs);}public MyTextView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);}/** * 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();paint.setARGB(255, 0, 255, 0);text = getText().toString();textLength = paint.measureText(text);viewWidth = getWidth();if (viewWidth == 0) {if (windowManager != null) {Display display = windowManager.getDefaultDisplay();viewWidth = display.getWidth();}}if (textLength > viewWidth) {isStarting = true;}step = textLength;temp_view_plus_text_length = viewWidth + textLength;temp_view_plus_two_text_length = viewWidth + textLength * 2;y = getTextSize() + getPaddingTop();x = getPaddingLeft();}public Parcelable onSaveInstanceState() {Parcelable superState = super.onSaveInstanceState();SavedState ss = new SavedState(superState);ss.step = step;ss.isStarting = isStarting;return ss;}public 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);}public 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];}public 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();}public void onDraw(Canvas canvas) {if (first) {viewWidth = getWidth();Log.i("width", "width="+viewWidth);first = false;}if (!isStarting) {canvas.drawText(text, x, y, paint);return;}canvas.drawText(text, temp_view_plus_text_length - step, y, paint);step += 0.5;if (step > temp_view_plus_two_text_length)step = textLength;invalidate();}public void setText(String text) {this.text = text;textLength = paint.measureText(text);if (textLength > viewWidth) {isStarting = true;} else {isStarting = false;}step = textLength;temp_view_plus_text_length = viewWidth + textLength;temp_view_plus_two_text_length = viewWidth + textLength * 2;y = getTextSize() + getPaddingTop();x = getPaddingLeft();invalidate();}}

效果大体如下图：