Android自定义控件之刻度尺控件

今天我做的是一个自定义刻度尺控件，由于项目需求需要使用刻度尺那样滑动选择，由于对自定义控件的认识还不够深入，于是花了一周多时间才把这个控件给整出来，也是呕心沥血的经历啊，也让我对自定义控件有了自己的认识，废话不多说，先上一个简单的效果图，大家可以看看，如有需求可以直接拿去使用

效果图如下：只是我的一个简单Demo，效果有点丑陋了点，希望海涵！

效果已经出来接下来就是代码部分了，一看就只是一般的控件很难实现，于是就开始了我的自定义View之旅，每次自定义完后总是会收获很多东西，如下是我的代码：

package android.tst.com.myapplication;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.text.Layout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.Scroller;

/**
 * 卷尺控件类。由于时间比较紧，只有下班后有时间，因此只实现了基本功能。<br>
 * 细节问题包括滑动过程中widget边缘的刻度显示问题等<br>
 * @version create：2014年8月26日
 */
@SuppressLint("ClickableViewAccessibility")
public class RulerView extends View {

 public interface OnValueChangeListener {
 public void onValueChange(float value);
 }

 public static final int MOD_TYPE_HALF = 2;
 public static final int MOD_TYPE_ONE = 10;
 private static final int ITEM_HALF_DIVIDER = 10;
 private static final int ITEM_ONE_DIVIDER = 10;
 private static final int ITEM_MAX_HEIGHT = 20;
 private static final int ITEM_MIN_HEIGHT = 10;
 private static final int TEXT_SIZE = 7;
 private float mDensity;
 private int mValue = 50, mMaxValue = 100, mModType = MOD_TYPE_HALF,
 mLineDivider = ITEM_HALF_DIVIDER;
 // private int mValue = 50, mMaxValue = 500, mModType = MOD_TYPE_ONE,
 // mLineDivider = ITEM_ONE_DIVIDER;

 private int mLastX, mMove;
 private int mWidth, mHeight;

 private int mMinVelocity;
 private Scroller mScroller;
 private VelocityTracker mVelocityTracker;

 private OnValueChangeListener mListener;

 @SuppressWarnings("deprecation")
 public RulerView(Context context, AttributeSet attrs) {
 super(context, attrs);

 mScroller = new Scroller(getContext());
 mDensity = getContext().getResources().getDisplayMetrics().density;
 mMinVelocity = ViewConfiguration.get(getContext())
 .getScaledMinimumFlingVelocity();
 }

 /**
 *
 * 考虑可扩展，但是时间紧迫，只可以支持两种类型效果图中两种类型
 *
 * @param value
 *   初始值
 * @param maxValue
 *   最大值
 * @param model
 *   刻度盘精度：<br>
 *   {@link MOD_TYPE_HALF}<br>
 *   {@link MOD_TYPE_ONE}<br>
 */
 public void initViewParam(int defaultValue, int maxValue, int model) {
 switch (model) {
 case MOD_TYPE_HALF:
 mModType = MOD_TYPE_HALF;
 mLineDivider = ITEM_HALF_DIVIDER;
 mValue = defaultValue * 2;
 mMaxValue = maxValue * 2;
 break;
 case MOD_TYPE_ONE:
 mModType = MOD_TYPE_ONE;
 mLineDivider = ITEM_ONE_DIVIDER;
 mValue = defaultValue;
 mMaxValue = maxValue;
 break;

 default:
 break;
 }
 invalidate();

 mLastX = 0;
 mMove = 0;
 notifyValueChange();
 }

 /**
 * 设置用于接收结果的监听器
 *
 * @param listener
 */
 public void setValueChangeListener(OnValueChangeListener listener) {
 mListener = listener;
 }

 /**
 * 获取当前刻度值
 *
 * @return
 */
 public float getValue() {
 return mValue;
 }
 public void setValue(int value){
 mValue = value;
 notifyValueChange();
 postInvalidate();
 }
 public void setValueToChange(int what) {
 mValue += what;
 notifyValueChange();
 postInvalidate();
 }

 @Override
 protected void onLayout(boolean changed, int left, int top, int right,
 int bottom) {
 mWidth = getWidth();
 mHeight = getHeight();
 super.onLayout(changed, left, top, right, bottom);
 }

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 drawScaleLine(canvas);
 // drawWheel(canvas);
 drawMiddleLine(canvas);
 }

 /**
 * 从中间往两边开始画刻度线
 *
 * @param canvas
 */
 private void drawScaleLine(Canvas canvas) {
 canvas.save();
 Paint linePaint = new Paint();
 linePaint.setStrokeWidth(2);
 linePaint.setColor(Color.rgb(141, 189, 225));

 TextPaint textPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
 textPaint.setColor(Color.rgb(68, 135, 188));
 textPaint.setTextSize(TEXT_SIZE * mDensity);

 int width = mWidth, drawCount = 0;
 float xPosition = 0, textWidth = Layout.getDesiredWidth("0", textPaint);

 for (int i = 0; drawCount <= 4 * width; i++) {
 int numSize = String.valueOf(mValue + i).length();
 // 前
 xPosition = (width / 2 - mMove) + i * mLineDivider * mDensity;
 if (xPosition + getPaddingRight() < mWidth) {
 if ((mValue + i) % mModType == 0) {
  linePaint.setColor(Color.rgb(68, 135, 188));
  canvas.drawLine(xPosition, getPaddingTop(), xPosition,
  mDensity * ITEM_MAX_HEIGHT, linePaint);

  if (mValue + i <= mMaxValue) {
  switch (mModType) {
  case MOD_TYPE_HALF:
  canvas.drawText(
   String.valueOf((mValue + i) / 2),
   countLeftStart(mValue + i, xPosition,
   textWidth),
   getHeight() - textWidth, textPaint);
  break;
  case MOD_TYPE_ONE:
  canvas.drawText(String.valueOf(mValue + i),
   xPosition - (textWidth * numSize / 2),
   getHeight() - textWidth, textPaint);
  break;
  default:
  break;
  }
  }
 } else {
  linePaint.setColor(Color.rgb(141, 189, 225));
  // linePaint.setColor(Color.rgb(68, 135, 188));
  canvas.drawLine(xPosition, getPaddingTop(), xPosition,
  mDensity * ITEM_MIN_HEIGHT, linePaint);
 }
 }
 // 后
 xPosition = (width / 2 - mMove) - i * mLineDivider * mDensity;
 if (xPosition > getPaddingLeft()) {
 if ((mValue - i) % mModType == 0) {
  linePaint.setColor(Color.rgb(68, 135, 188));
  canvas.drawLine(xPosition, getPaddingTop(), xPosition,
  mDensity * ITEM_MAX_HEIGHT, linePaint);

  if (mValue - i >= 0) {
  switch (mModType) {
  case MOD_TYPE_HALF:
  canvas.drawText(
   String.valueOf((mValue - i) / 2),
   countLeftStart(mValue - i, xPosition,
   textWidth),
   getHeight() - textWidth, textPaint);
  break;
  case MOD_TYPE_ONE:
  canvas.drawText(String.valueOf(mValue - i),
   xPosition - (textWidth * numSize / 2),
   getHeight() - textWidth, textPaint);
  break;

  default:
  break;
  }
  }
 } else {
  linePaint.setColor(Color.rgb(141, 189, 225));
  canvas.drawLine(xPosition, getPaddingTop(), xPosition,
  mDensity * ITEM_MIN_HEIGHT, linePaint);
 }
 }

 drawCount += 2 * mLineDivider * mDensity;
 }

 canvas.restore();
 }

 /**
 * 计算没有数字显示位置的辅助方法
 *
 * @param value
 * @param xPosition
 * @param textWidth
 * @return
 */
 private float countLeftStart(int value, float xPosition, float textWidth) {
 float xp = 0f;
 if (value < 20) {
 xp = xPosition - (textWidth * 1 / 2);
 } else {
 xp = xPosition - (textWidth * 2 / 2);
 }
 return xp;
 }

 /**
 * 画中间的红色指示线、阴影等。指示线两端简单的用了两个矩形代替
 *
 * @param canvas
 */
 private void drawMiddleLine(Canvas canvas) {
 // TOOD 常量太多，暂时放这，最终会放在类的开始，放远了怕很快忘记
 int gap = 12, indexWidth = 2, indexTitleWidth = 24, indexTitleHight = 10, shadow = 6;
 String color = "#66999999";

 canvas.save();

 Paint redPaint = new Paint();
 redPaint.setStrokeWidth(indexWidth);
 redPaint.setColor(Color.RED);
 canvas.drawLine(mWidth / 2, 0, mWidth / 2, mHeight, redPaint);

 canvas.restore();
 }

 @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:
 getParent().requestDisallowInterceptTouchEvent(true);
 mMove += (mLastX - xPosition);
 changeMoveAndValue();
 break;
 case MotionEvent.ACTION_UP:
 case MotionEvent.ACTION_CANCEL:
 countMoveEnd();
 countVelocityTracker(event);
 getParent().requestDisallowInterceptTouchEvent(false);
 return false;
 // break;
 default:
 break;
 }

 mLastX = xPosition;
 return true;
 }

 private void countVelocityTracker(MotionEvent event) {
 mVelocityTracker.computeCurrentVelocity(1000);
 float xVelocity = mVelocityTracker.getXVelocity();
 if (Math.abs(xVelocity) > mMinVelocity) {
 mScroller.fling(0, 0, (int) xVelocity, 0, Integer.MIN_VALUE,
  Integer.MAX_VALUE, 0, 0);
 }
 }

 private void changeMoveAndValue() {
 int tValue = (int) (mMove / (mLineDivider * mDensity));
 if (Math.abs(tValue) > 0) {
 mValue += tValue;
 mMove -= tValue * mLineDivider * mDensity;
 if (mValue <= 0 || mValue > mMaxValue) {
 mValue = mValue <= 0 ? 0 : mMaxValue;
 mMove = 0;
 mScroller.forceFinished(true);
 }
 notifyValueChange();
 }
 postInvalidate();
 }

 private void countMoveEnd() {
 int roundMove = Math.round(mMove / (mLineDivider * mDensity));
 mValue = mValue + roundMove;
 mValue = mValue <= 0 ? 0 : mValue;
 mValue = mValue > mMaxValue ? mMaxValue : mValue;

 mLastX = 0;
 mMove = 0;

 notifyValueChange();
 postInvalidate();
 }

 private void notifyValueChange() {
 if (null != mListener) {
 if (mModType == MOD_TYPE_ONE) {
 mListener.onValueChange(mValue);
 }
 if (mModType == MOD_TYPE_HALF) {
 mListener.onValueChange(mValue / 2f);
 }
 }
 }

 @Override
 public void computeScroll() {
 super.computeScroll();
 if (mScroller.computeScrollOffset()) {
 if (mScroller.getCurrX() == mScroller.getFinalX()) { // over
 countMoveEnd();
 } else {
 int xPosition = mScroller.getCurrX();
 mMove += (mLastX - xPosition);
 changeMoveAndValue();
 mLastX = xPosition;
 }
 }
 }

 @Override
 public boolean dispatchTouchEvent(MotionEvent event) {
 getParent().requestDisallowInterceptTouchEvent(true);
 return super.dispatchTouchEvent(event);
 }
}

这是我的自定义View部分的代码，下面就是在布局中的使用了

<TextView
  android:id="@+id/tv_values"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:padding="10dp"
  android:gravity="center"
  android:textColor="@android:color/holo_red_dark"/>
 <android.tst.com.myapplication.RulerView
  android:id="@+id/rv_view"
  android:layout_width="match_parent"
  android:layout_height="60dp"/>

<LinearLayout
 android:layout_width="match_parent"
 android:orientation="horizontal"
 android:layout_height="wrap_content">

 <Button
  android:id="@+id/btn_jia"
  android:layout_width="0dp"
  android:layout_height="wrap_content"
  android:text="+"
  android:textSize="25sp"
  android:gravity="center"
  android:layout_marginRight="15dp"
  android:layout_weight="1"/>
 <Button
  android:id="@+id/btn_jian"
  android:layout_width="0dp"
  android:layout_height="wrap_content"
  android:text="-"
  android:layout_marginLeft="15dp"
  android:textSize="25sp"
  android:gravity="center"
  android:layout_weight="1"/>
</LinearLayout>

如上根据效果图，我需要一个TextView进行显示，还有就是我的自定义刻度尺控件了，接下来就是两个Button控件加减。

接下来就是在Activity中的使用了，

首先需要一个Handler进行更新TextView中的值

Handler handler = new Handler() {
  @Override
  public void handleMessage(Message msg) {
   tv_values.setText(rv_view.getValue() + "Kg");
  };
 };

其次就是初始化相关的操作了，

private void deployRulerView(){
  rv_view= (RulerView) findViewById(R.id.rv_view);
  btn_jia= (Button) findViewById(R.id.btn_jia);
  btn_jian= (Button) findViewById(R.id.btn_jian);
  tv_values= (TextView) findViewById(R.id.tv_values);
  //设置RulerView的初始值
  rv_view.setValue(60);
  //初始化刻度尺范围
  rv_view.initViewParam(60, 200, RulerView.MOD_TYPE_ONE);
  rv_view.setValueChangeListener(new RulerView.OnValueChangeListener() {
   @Override
   public void onValueChange(float value) {
    handler.sendMessage(new Message());
   }
  });
  tv_values.setText(60+"KG");
  //给两个控件添加监听事件
  btn_jia.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    rv_view.setValueToChange(1);
   }
  });
  btn_jian.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    rv_view.setValueToChange(-1);
   }
  });
 }

到这里整个过程已经完成了，如果不好的地方尽情吐槽，真个过程，最复杂的莫过于自定义中的绘制过程，但是一切的问题当你静下心好好去实现时，那一切的问题都就不存在了

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