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本文实例为大家分享了Android实现滑动标尺选择值，效果图
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1.自定义属性attrs.xml
2.自定义RulerView
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.Scroller;
public class RulerView extends View {
private int mMinVelocity;
private Scroller mScroller; //Scroller是一个专门用于处理滚动效果的工具类 用mScroller记录/计算View滚动的位置，再重写View的computeScroll()，完成实际的滚动
private VelocityTracker mVelocityTracker; //主要用跟踪触摸屏事件（flinging事件和其他gestures手势事件）的速率。
private int mWidth;
private int mHeight;
private float mSelectorValue = 50.0f; // 未选择时 默认的值 滑动后表示当前中间指针正在指着的值
private float mMaxValue = 200; // 最大数值
private float mMinValue = 100.0f; //最小的数值
private float mPerValue = 1; //最小单位 如 1:表示 每2条刻度差为1. 0.1:表示 每2条刻度差为0.1
// 在demo中 身高mPerValue为1 体重mPerValue 为0.1
private float mLineSpaceWidth = 5; // 尺子刻度2条线之间的距离
private float mLineWidth = 4; // 尺子刻度的宽度
private float mLineMaxHeight = 420; // 尺子刻度分为3中不同的高度。 mLineMaxHeight表示最长的那根(也就是 10的倍数时的高度)
private float mLineMidHeight = 30; // mLineMidHeight 表示中间的高度(也就是 5 15 25 等时的高度)
private float mLineMinHeight = 17; // mLineMinHeight 表示最短的那个高度(也就是 1 2 3 4 等时的高度)
private float mTextMarginTop = 10; //o
private float mTextSize = 30; //尺子刻度下方数字 textsize
private boolean mAlphaEnable = false; // 尺子 最左边 最后边是否需要透明 (透明效果更好点)
private float mTextHeight; //尺子刻度下方数字 的高度
private Paint mTextPaint; // 尺子刻度下方数字( 也就是每隔10个出现的数值) paint
private Paint mLinePaint; // 尺子刻度 paint
private int mTotalLine; //共有多少条 刻度
private int mMaxOffset; //所有刻度 共有多长
private float mOffset; // 默认状态下，mSelectorValue所在的位置 位于尺子总刻度的位置
private int mLastX, mMove;
private OnValueChangeListener mListener; // 滑动后数值回调
private int mLineColor = Color.GRAY; //刻度的颜色
private int mTextColor = Color.BLACK; //文字的颜色
public RulerView(Context context) {
this(context, null);
}
public RulerView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public RulerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context, attrs);
}
protected void init(Context context, AttributeSet attrs) {
mScroller = new Scroller(context);
this.mLineSpaceWidth = myfloat(25.0F);
this.mLineWidth = myfloat(2.0F);
this.mLineMaxHeight = myfloat(100.0F);
this.mLineMidHeight = myfloat(60.0F);
this.mLineMinHeight = myfloat(40.0F);
this.mTextHeight = myfloat(40.0F);
final TypedArray typedArray = context.obtainStyledAttributes(attrs,
R.styleable.RulerView);
mAlphaEnable = typedArray.getBoolean(R.styleable.RulerView_alphaEnable, mAlphaEnable);
mLineSpaceWidth = typedArray.getDimension(R.styleable.RulerView_lineSpaceWidth, mLineSpaceWidth);
mLineWidth = typedArray.getDimension(R.styleable.RulerView_lineWidth, mLineWidth);
mLineMaxHeight = typedArray.getDimension(R.styleable.RulerView_lineMaxHeight, mLineMaxHeight);
mLineMidHeight = typedArray.getDimension(R.styleable.RulerView_lineMidHeight, mLineMidHeight);
mLineMinHeight = typedArray.getDimension(R.styleable.RulerView_lineMinHeight, mLineMinHeight);
mLineColor = typedArray.getColor(R.styleable.RulerView_lineColor, mLineColor);
mTextSize = typedArray.getDimension(R.styleable.RulerView_textSize, mTextSize);
mTextColor = typedArray.getColor(R.styleable.RulerView_textColor, mTextColor);
mTextMarginTop = typedArray.getDimension(R.styleable.RulerView_textMarginTop, mTextMarginTop);
mSelectorValue = typedArray.getFloat(R.styleable.RulerView_selectorValue, 0.0f);
mMinValue = typedArray.getFloat(R.styleable.RulerView_minValue, 0.0f);
mMaxValue = typedArray.getFloat(R.styleable.RulerView_maxValue, 100.0f);
mPerValue = typedArray.getFloat(R.styleable.RulerView_perValue, 0.1f);
mMinVelocity = ViewConfiguration.get(getContext()).getScaledMinimumFlingVelocity();
mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mTextPaint.setTextSize(mTextSize);
mTextPaint.setColor(mTextColor);
mTextHeight = getFontHeight(mTextPaint);
mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mLinePaint.setStrokeWidth(mLineWidth);
mLinePaint.setColor(mLineColor);
// setValue(1990, 1940, 2016, 1);
}
public static int myfloat(float paramFloat) {
return (int) (0.5F + paramFloat * 1.0f);
}
private float getFontHeight(Paint paint) {
Paint.FontMetrics fm = paint.getFontMetrics();
return fm.descent - fm.ascent;
}
/**
* @param selectorValue 未选择时 默认的值 滑动后表示当前中间指针正在指着的值
* @param minValue 最大数值
* @param maxValue 最小的数值
* @param per 最小单位 如 1:表示 每2条刻度差为1. 0.1:表示 每2条刻度差为0.1 在demo中 身高mPerValue为1 体重mPerValue 为0.1
*/
public void setValue(float selectorValue, float minValue, float maxValue, float per) {
this.mSelectorValue = selectorValue;
this.mMaxValue = maxValue;
this.mMinValue = minValue;
this.mPerValue = (int) (per * 10.0f);
this.mTotalLine = ((int) ((mMaxValue * 10 - mMinValue * 10) / mPerValue)) + 1;
mMaxOffset = (int) (-(mTotalLine - 1) * mLineSpaceWidth);
mOffset = (mMinValue - mSelectorValue) / mPerValue * mLineSpaceWidth * 10;
invalidate();
setVisibility(VISIBLE);
}
public void setOnValueChangeListener(OnValueChangeListener listener) {
mListener = listener;
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (w > 0 && h > 0) {
mWidth = w;
mHeight = h;
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
float left, height;
String value;
int alpha = 0;
float scale;
int srcPointX = mWidth / 2;
for (int i = 0; i < mTotalLine; i++) {
left = srcPointX + mOffset + i * mLineSpaceWidth;
if (left < 0 || left > mWidth) {
continue; // 先画默认值在正中间，左右各一半的view。 多余部分暂时不画(也就是从默认值在中间，画旁边左右的刻度线)
}
/*文字*/
if (i % 10 == 0) {
value = String.valueOf((int) (mMinValue + i * mPerValue / 10));
if (mAlphaEnable) {
mTextPaint.setAlpha(alpha);
}
canvas.drawText(value, left - mTextPaint.measureText(value) / 2,
mTextHeight, mTextPaint); // 在为整数时,画 数值
}
/*线条*/
if (i % 10 == 0) {
height = mLineMinHeight;
} else if (i % 5 == 0) {
height = mLineMidHeight;
} else {
height = mLineMaxHeight;
}
if (mAlphaEnable) {
scale = 1 - Math.abs(left - srcPointX) / srcPointX;
alpha = (int) (255 * scale * scale);
mLinePaint.setAlpha(alpha);
}
canvas.drawLine(left, mLineMaxHeight + mTextMarginTop + mTextHeight, left, height, mLinePaint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
int xPosition = (int) event.getX();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);
switch (action) {
case MotionEvent.ACTION_DOWN:
mScroller.forceFinished(true);
mLastX = xPosition;
mMove = 0;
break;
case MotionEvent.ACTION_MOVE:
mMove = (mLastX - xPosition);
changeMoveAndValue();
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
countMoveEnd();
countVelocityTracker();
return false;
default:
break;
}
mLastX = xPosition;
return true;
}
private void countVelocityTracker() {
mVelocityTracker.computeCurrentVelocity(1000); //初始化速率的单位
float xVelocity = mVelocityTracker.getXVelocity(); //当前的速度
if (Math.abs(xVelocity) > mMinVelocity) {
mScroller.fling(0, 0, (int) xVelocity, 0, Integer.MIN_VALUE, Integer.MAX_VALUE, 0, 0);
}
}
/**
* 滑动结束后，若是指针在2条刻度之间时，改变mOffset 让指针正好在刻度上。
*/
private void countMoveEnd() {
mOffset -= mMove;
if (mOffset <= mMaxOffset) {
mOffset = mMaxOffset;
} else if (mOffset >= 0) {
mOffset = 0;
}
mLastX = 0;
mMove = 0;
mSelectorValue = mMinValue + Math.round(Math.abs(mOffset) * 1.0f / mLineSpaceWidth) * mPerValue / 10.0f;
mOffset = (mMinValue - mSelectorValue) * 10.0f / mPerValue * mLineSpaceWidth;
notifyValueChange();
postInvalidate();
}
/**
* 滑动后的操作
*/
private void changeMoveAndValue() {
mOffset -= mMove;
if (mOffset <= mMaxOffset) {
mOffset = mMaxOffset;
mMove = 0;
mScroller.forceFinished(true);
} else if (mOffset >= 0) {
mOffset = 0;
mMove = 0;
mScroller.forceFinished(true);
}
mSelectorValue = mMinValue + Math.round(Math.abs(mOffset) * 1.0f / mLineSpaceWidth) * mPerValue / 10.0f;
notifyValueChange();
postInvalidate();
}
private void notifyValueChange() {
if (null != mListener) {
mListener.onValueChange(mSelectorValue);
}
}
/**
* 滑动后的回调
*/
public interface OnValueChangeListener {
void onValueChange(float value);
}
@Override
public void computeScroll() {
super.computeScroll();
if (mScroller.computeScrollOffset()) { //mScroller.computeScrollOffset()返回 true表示滑动还没有结束
if (mScroller.getCurrX() == mScroller.getFinalX()) {
countMoveEnd();
} else {
int xPosition = mScroller.getCurrX();
mMove = (mLastX - xPosition);
changeMoveAndValue();
mLastX = xPosition;
}
}
}
}
3.xml中使用activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
4.Activity中使用MainActivity
public class MainActivity extends AppCompatActivity {
private int maxValue = 250;
private int minValue = 80;
private RulerView rulerHeight;
private TextView tvHeightValue;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
rulerHeight = (RulerView) findViewById(R.id.ruler_height);
tvHeightValue = (TextView) findViewById(R.id.tv_info_height_value);
showNumInt();
findViewById(R.id.click).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showNumInt();
}
});
rulerHeight.setOnValueChangeListener(new RulerView.OnValueChangeListener() {
@Override
public void onValueChange(float value) {
tvHeightValue.setText(String.valueOf(value));
}
});
}
private void showNumInt() {
Random rand = new Random();
int value = rand.nextInt(maxValue - minValue + 1) + minValue;
rulerHeight.setValue(value, minValue, maxValue, 1);
tvHeightValue.setText(String.valueOf(Integer.valueOf(value)));
}
}
PS:可自行根据需要绘制线条和文字，上下选择文字位置。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持创新互联。