跑马灯 TextView

朱雀 2023-10-05 14:14 143阅读 0赞

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;
    
    
    /**
     * 跑马灯
     */
    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();
        }
    
    
        private void initView() {
            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();
        }
    
    
        @Override
        public void onDraw(Canvas canvas) {
            canvas.drawText(text, temp_view_plus_text_length - step, y, paint);
            if (!isStarting) {
                return;
            }
            step += 5;//0.5为文字滚动速度。
            if (step > temp_view_plus_two_text_length)
                step = textLength;
            invalidate();
    
        }
    
        @Override
        public void onClick(View v) {
            if (isStarting)
                stopScroll();
            else
                startScroll();
    
        }
    
    }