Android绘制动态折线图

所谓动态折线图，就是折线图能随着手指的滑动进行动态绘制，这里很定会产生动画效果。基于这个效果，这里使用SurfaceView进行制图。

实现步奏如下：

(1): 这里新建一个绘图ChartView，继承SurfaceView并实现SurfaceHolder.Callback , Runnable接口，主要绘图工作在子线程中完成。
(2):现实 SurfaceHolder.Callback接口的三个方法，并在 surfaceCreated中开启子线程进行绘图。
(3):重写onTouchEvent方法，在Move事件中，根据手指的滑动距离计算偏移量，具体实现请看代码。
(4): 这里的折线图的坐标值是随意添加的，可以在实际项目中根据需求自己添加。
(5):此例中有大量从集合中添加和删除元素，建议使用LinkedList来进行保存数据。

自定义ChartView：

public class ChartView extends SurfaceView implements SurfaceHolder.Callback , Runnable
{
 private Context mContext;
 private Paint mPaint;
 private Resources res;
 private DisplayMetrics dm;

 private int canvasHeight;
 private int canvasWidth;
 private int bHeight = 0;
 private int bWidth;
 private boolean isMeasure = true;
 private boolean canScrollRight = true;
 private boolean canScrollLeft = true;

 //y轴最大值
 private int maxValue;
 //y轴间隔值
 private int averageValue;
 private int marginTop = 20;
 private int marginBottom = 80;

 //曲线上的总点数
 private Point[] mPoints;
 //纵坐标值
 private LinkedList<Double> yRawData;
 //横坐标值
 private LinkedList<String> xRawData;
 //根据间隔计算出的每个X的值
 private LinkedList<Integer> xList = new LinkedList<>();
 private LinkedList<String> xPreData = new LinkedList<>();
 private LinkedList<Double> yPreData = new LinkedList<>();

 private LinkedList<String> xLastData = new LinkedList<>();
 private LinkedList<Double> yLastData = new LinkedList<>();
 private int spacingHeight;

 private SurfaceHolder holder;
 private boolean isRunning = true;
 private int lastX;
 private int offSet;
 private Rect mRect;

 private int xAverageValue = 0;


 public ChartView(Context context)
 {
  this(context , null);
 }

 public ChartView(Context context , AttributeSet attrs)
 {
  super(context, attrs);
  this.mContext = context;
  initView();
 }

 private void initView()
 {
  this.res = mContext.getResources();
  this.mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
  dm = new DisplayMetrics();
  WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
  wm.getDefaultDisplay().getMetrics(dm);

  xPreData.add("05-18");
  xPreData.add("05-17");
  xPreData.add("05-16");
  xPreData.add("05-15");
  xPreData.add("05-14");
  xPreData.add("05-13");

  yPreData.add(4.53);
  yPreData.add(3.45);
  yPreData.add(6.78);
  yPreData.add(5.21);
  yPreData.add(2.34);
  yPreData.add(6.32);

  xLastData.add("05-26");
  xLastData.add("05-27");
  xLastData.add("05-28");
  xLastData.add("05-29");
  xLastData.add("05-30");
  xLastData.add("05-31");

  yLastData.add(2.35);
  yLastData.add(5.43);
  yLastData.add(6.23);
  yLastData.add(7.33);
  yLastData.add(3.45);
  yLastData.add(2.45);

  holder = this.getHolder();
  holder.addCallback(this);
 }

 @Override
 protected void onSizeChanged(int w , int h , int oldW , int oldH)
 {
  if (isMeasure)
  {
   this.canvasHeight = getHeight();
   this.canvasWidth = getWidth();
   if (bHeight == 0)
   {
    bHeight = canvasHeight - marginBottom;
   }
   bWidth = dip2px(30);
   xAverageValue = (canvasWidth - bWidth) / 7;
   isMeasure = false;
  }
 }


 @Override
 public void run()
 {
  while (isRunning)
  {
   drawView();
   try
   {
    Thread.sleep(100);
   }
   catch (InterruptedException e)
   {
    e.printStackTrace();
   }
  }
 }

 private void drawView()
 {
  Canvas canvas = holder.lockCanvas();
  canvas.drawColor(Color.WHITE);
  mPaint.setColor(res.getColor(R.color.color_f2f2f2));
  drawAllXLine(canvas);
  mRect = new Rect(bWidth - 3, marginTop - 5 ,
    bWidth + (canvasWidth - bWidth) / yRawData.size() * (yRawData.size() - 1) + 3, bHeight + marginTop + marginBottom);
  //锁定画图区域
  canvas.clipRect(mRect);
  drawAllYLine(canvas);

  mPoints = getPoints();

  mPaint.setColor(res.getColor(R.color.color_ff4631));
  mPaint.setStrokeWidth(dip2px(2.5f));
  mPaint.setStyle(Paint.Style.STROKE);
  drawLine(canvas);

  mPaint.setStyle(Paint.Style.FILL);
  for (int i = 0 ; i < mPoints.length ; i++)
  {
   canvas.drawCircle(mPoints[i].x , mPoints[i].y , 5 , mPaint);
  }

  holder.unlockCanvasAndPost(canvas);
 }

 //绘制折线图
 private void drawLine(Canvas canvas)
 {
  Point startP = null;
  Point endP = null;
  for (int i = 0 ; i < mPoints.length - 1; i++)
  {
   startP = mPoints[i];
   endP = mPoints[i + 1];
   canvas.drawLine(startP.x , startP.y , endP.x , endP.y , mPaint);
  }
 }

 //绘制所有的纵向分割线
 private void drawAllYLine(Canvas canvas)
 {
  for (int i = 0 ; i < yRawData.size() ; i++)
  {
   if (i == 0)
   {
    canvas.drawLine(bWidth, marginTop , bWidth, bHeight + marginTop , mPaint);
   }
   if (i == yRawData.size() - 1)
   {
    canvas.drawLine(bWidth + xAverageValue * i, marginTop , bWidth + xAverageValue * i , bHeight + marginTop , mPaint);
   }
   xList.add(bWidth + xAverageValue * i);
   canvas.drawLine(bWidth + xAverageValue * i + offSet, marginTop , bWidth + xAverageValue * i + offSet , bHeight + marginTop , mPaint);
   drawText(xRawData.get(i) , bWidth + xAverageValue * i - 30 + offSet, bHeight + dip2px(26) , canvas);

  }
 }

 //绘制所有的横向分割线
 private void drawAllXLine(Canvas canvas)
 {
  for (int i = 0 ; i < spacingHeight + 1 ; i++)
  {
   canvas.drawLine(bWidth , bHeight - (bHeight / spacingHeight) * i + marginTop ,
     bWidth + xAverageValue * (yRawData.size() - 1) , bHeight - (bHeight / spacingHeight) * i + marginTop , mPaint);
   drawText(String.valueOf(averageValue * i) , bWidth / 2 , bHeight - (bHeight / spacingHeight) * i + marginTop, canvas);
  }
 }

 //绘制坐标值
 private void drawText(String text , int x , int y , Canvas canvas)
 {
  Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
  p.setTextSize(dip2px(12));
  p.setColor(res.getColor(R.color.color_999999));
  p.setTextAlign(Paint.Align.LEFT);
  canvas.drawText(text , x , y , p);
 }

 @Override
 public void surfaceCreated(SurfaceHolder surfaceHolder)
 {
  new Thread(this).start();
  Log.d("OOK" , "Created");
 }

 @Override
 public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2)
 {
  Log.d("OOK" , "Changed");
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder surfaceHolder)
 {
  isRunning = false;
  try
  {
   Thread.sleep(500);
  }
  catch (InterruptedException e)
  {
   e.printStackTrace();
  }
 }

 @Override
 public boolean onTouchEvent(MotionEvent event)
 {
  int action = event.getAction();
  int rawX = (int) event.getX();
  switch (action)
  {
   case MotionEvent.ACTION_DOWN:
    lastX = rawX;
    break;
   case MotionEvent.ACTION_MOVE:
    int offsetX = rawX - lastX;
    if (xPreData.size() == 0 && offSet > 0)
    {
     offSet = 0;
     canScrollRight = false;
    }
    if (xLastData.size() == 0 && offSet < 0)
    {
     offSet = 0;
     canScrollLeft = false;
    }
    offSet = offSet + offsetX;
    if (offSet > xAverageValue && canScrollRight)
    {
     offSet = offSet % xAverageValue;
     xRawData.addFirst(xPreData.pollFirst());
     yRawData.addFirst(yPreData.pollFirst());
     xLastData.addFirst(xRawData.removeLast());
     yLastData.addFirst(yRawData.removeLast());
     canScrollLeft = true;
    }


    if (offSet < -xAverageValue && canScrollLeft)
    {
     offSet = offSet % xAverageValue;
     xRawData.addLast(xLastData.pollFirst());
     yRawData.addLast(yLastData.pollFirst());
     xPreData.addFirst(xRawData.removeFirst());
     yPreData.addFirst(yRawData.removeFirst());
     canScrollRight = true;
    }
    lastX = rawX;
    break;
   case MotionEvent.ACTION_UP:
    break;
  }
  return true;
 }

 private Point[] getPoints()
 {
  Point[] points = new Point[yRawData.size()];
  for (int i = 0 ; i < yRawData.size() ; i++)
  {
   int ph = bHeight - (int)(bHeight * (yRawData.get(i) / maxValue));

   points[i] = new Point(xList.get(i) + offSet , ph + marginTop);
  }
  return points;
 }

 public void setData(LinkedList<Double> yRawData , LinkedList<String> xRawData , int maxValue , int averageValue)
 {
  this.maxValue = maxValue;
  this.averageValue = averageValue;
  this.mPoints = new Point[yRawData.size()];
  this.yRawData = yRawData;
  this.xRawData = xRawData;
  this.spacingHeight = maxValue / averageValue;
 }

 private int dip2px(float dpValue)
 {
  return (int) (dpValue * dm.density + 0.5f);
 }
}

MainActivity代码：

public class MainActivity extends Activity
{
 LinkedList<Double> yList;
 LinkedList<String> xRawData;
 ChartView chartView;
 @Override
 protected void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main_activity);
  chartView = (ChartView) findViewById(R.id.chartView);

  yList = new LinkedList<>();
  yList.add(2.203);
  yList.add(4.05);
  yList.add(6.60);
  yList.add(3.08);
  yList.add(4.32);
  yList.add(2.0);
  yList.add(5.0);

  xRawData = new LinkedList<>();
  xRawData.add("05-19");
  xRawData.add("05-20");
  xRawData.add("05-21");
  xRawData.add("05-22");
  xRawData.add("05-23");
  xRawData.add("05-24");
  xRawData.add("05-25");

  chartView.setData(yList , xRawData , 8 , 2);
 }
}

此例页面布局比较简单，就是在主页面布局中添加一个自定义的ChartView即可，这里不再贴出。可能写得有点仓促，如果不妥之处，请大家批评指正，谢谢！

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小牛知识库。