实现思路:测量好我们的Text长度,使用onDraw方法绘制
[代码]java代码:
public class AutoScrollTextView extends TextView { 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 public boolean isStarting = false;//是否开始滚动 private Paint paint = null;//绘图样式 private float speed = 0.8f; private int textColor=0xFF000000; private boolean isMeasure = false; public int getTextColor() { return textColor; } public void setTextColor(int color) { this.textColor = color; } public float getSpeed() { return speed; } public void setSpeed(float speed) { this.speed = speed; } public void measureText() { paint = getPaint(); if(paint!=null){ paint.setColor(textColor); textLength = paint.measureText(getText().toString()); } viewWidth = getWidth(); step = textLength; temp_view_plus_text_length = viewWidth + textLength; y = getTextSize()+getPaddingTop(); } public void startScroll(float speed) { isStarting = true; this.speed = speed; invalidate(); } public void stopScroll() { isStarting = false; invalidate(); } @Override public void onDraw(Canvas canvas) { if(getText() == null) return; if(isStarting){ if (!isMeasure) {// 文字宽度只需获取一次 isMeasure = true; measureText(); } //水平方向由右向左 CharSequence text = getText().toString(); if (text != null&& !TextUtils.isEmpty(text)) { canvas.drawText(text,0,text.length(),temp_view_plus_text_length - step, y, paint); } if (!isStarting) { return; } step += speed; if (step > temp_view_plus_text_length +viewWidth) step = textLength; invalidate(); }else{ super.onDraw(canvas); } } }
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