很多场景中,我们都会用到TextView,面对如今各种各样的需求,很多人都选择自定义TextView实现各种各样的需求,今天就来实现一个自定义跑马灯的效果。
可实现:不论文字长短,都可有跑马灯效果
可随时暂停跑马灯效果
直接上代码:
public class MyTextView extends TextView implements OnClickListener{
public final static String TAG = MyTextView.class.getSimpleName();
private float textLength = 0f;
private float viewWidth = 0f;
private float step = 0f;
private float y = 0f;
private float temp_view_plus_text_length = 0.0f;
private float temp_view_plus_two_text_length = 0.0f;
public boolean isStarting = false;
private Paint paint = null;
private String text = "";
public MyTextView(Context context) {
super(context);
initView();
}
public MyTextView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
public MyTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
private void initView() {
//点击事件初始化
setOnClickListener(this);
}
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();
}
@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];
}
@Override
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();
}
/**
* 绘制跑动效果
* @param canvas
*/
@Override
public void onDraw(Canvas canvas) {
canvas.drawText(text, temp_view_plus_text_length - step, y, paint);
if(!isStarting)
{
return;
}
step += 3;//速度控制 可调节快慢
if(step > temp_view_plus_two_text_length)
step = textLength;
invalidate();
}
/**
* 点击就可以暂停 如果不需要可以删除
* @param v
*/
@Override
public void onClick(View v) {
if(isStarting)
stopScroll();
else
startScroll();
}
}
可通过onDraw()方法中的step来控制速度
public void onDraw(Canvas canvas) {
canvas.drawText(text, temp_view_plus_text_length - step, y, paint);
if(!isStarting)
{
return;
}
step += 3;//速度控制 可调节快慢 越大越快
if(step > temp_view_plus_two_text_length)
step = textLength;
invalidate();
}
启动
myTextView.setText("哈哈哈哈哈哈哈");
myTextView.init(getWindowManager());
myTextView.startScroll();//启动
myTextView.stopScroll(); //停止
ok,实现了.