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：
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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：
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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服务器之家。
原文链接：https://blog.csdn.net/qq_33022345/article/details/52459232
