本文实例讲述了Android基于TextView实现的跑马灯效果。分享给大家供大家参考，具体如下：
package sweet.venst.act; import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.os.Parcel; import android.os.Parcelable; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.view.Display; import android.view.View; import android.view.WindowManager; import android.view.View.MeasureSpec; import android.view.View.OnClickListener; import android.widget.TextView; public class AutoScrollTextView extends TextView { public final static String TAG = AutoScrollTextView.class.getSimpleName(); private float textLength = 0f;// 文本长度 private int viewWidth = 0; private int viewHight = 300; 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); } public AutoScrollTextView(Context context, AttributeSet attrs) { super(context, attrs); } public AutoScrollTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // TODO Auto-generated method stub super.onMeasure(widthMeasureSpec, heightMeasureSpec); int measureWidth = measureWidth(widthMeasureSpec); int measureHight = measureHeight(heightMeasureSpec); // int measureWidth = 1024; // int measureHight = 300; viewWidth = measureWidth; viewHight = measureHight; setMeasuredDimension(viewWidth, viewHight); } private int measureWidth(int widthMeasureSpec) { int specMode = MeasureSpec.getMode(widthMeasureSpec); int specSize = MeasureSpec.getSize(widthMeasureSpec); if (specMode == MeasureSpec.UNSPECIFIED) { return viewWidth; } else { return viewWidth; } } private int measureHeight(int widthMeasureSpec) { int specMode = MeasureSpec.getMode(widthMeasureSpec); int specSize = MeasureSpec.getSize(widthMeasureSpec); if (specMode == MeasureSpec.UNSPECIFIED) { return viewHight; } else { return viewHight; } } public void setScrollText(String text) { this.text = text; inittextLength(text); // invalidate(); } public void init(Context cx) { paint = getPaint(); paint.setTextSize(40); paint.setColor(Color.WHITE); text = getText().toString(); textLength = paint.measureText(text); viewWidth = getWidth(); if (viewWidth == 0) { DisplayMetrics dm = new DisplayMetrics(); dm = cx.getApplicationContext().getResources().getDisplayMetrics(); viewWidth = dm.widthPixels; } step = textLength; temp_view_plus_text_length = viewWidth + textLength; temp_view_plus_two_text_length = viewWidth + textLength * 2; y = getTextSize() + getPaddingTop(); } private void inittextLength(String text) { textLength = paint.measureText(text); step = textLength; temp_view_plus_text_length = viewWidth + textLength; temp_view_plus_two_text_length = viewWidth + textLength * 2; } @Override public Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState ss = new SavedState(superState); ss.step = step; ss.isStarting = isStarting; return ss; } @Override 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); } @Override 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(); } } public void startScroll() { isStarting = true; // invalidate(); } public void stopScroll() { isStarting = false; // invalidate(); } public void onDraw(Canvas canvas) { canvas.save(); canvas.drawText(text, temp_view_plus_text_length - step, y, paint); if (!isStarting) { return; } step += 3.2;// 0.5为文字滚动速度。 if (step > temp_view_plus_two_text_length) step = textLength; canvas.restore(); // invalidate(); postInvalidate(); } }
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希望本文所述对大家Android程序设计有所帮助。