Android自定义组件系列【9】Canvas绘制折线图_H5之家

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Android自定义组件系列【9】Canvas绘制折线图

作者：发布日期：2014-06-17 21:18:54

Tag标签：线图组件

有时候我们在项目中会遇到使用折线图等图形，Android的开源项目中为我们提供了很多插件，但是很多时候我们需要根据具体项目自定义这些图表，这一篇文章我们一起来看看如何在Android中使用Canvas绘制折线图。先看看绘制的效果：

实现原理很简单，我就直接给出代码：

package com.example.testcanvasdraw; import java.util.ArrayList; import java.util.List; import java.util.Random; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.os.Handler; import android.os.Message; import android.util.AttributeSet; import android.view.View; public class MyView extends View{ private int XPoint = 60; private int YPoint = 260; private int XScale = 8; //刻度长度 private int YScale = 40; private int XLength = 380; private int YLength = 240; private int MaxDataSize = XLength / XScale; private List<Integer> data = new ArrayList<Integer>(); private String[] YLabel = new String[YLength / YScale]; private Handler handler = new Handler(){ public void handleMessage(Message msg) { if(msg.what == 0x1234){ MyView.this.invalidate(); } }; }; public MyView(Context context, AttributeSet attrs) { super(context, attrs); for(int i=0; i<YLabel.length; i++){ YLabel[i] = (i + 1) + "M/s"; } new Thread(new Runnable() { @Override public void run() { while(true){ try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } if(data.size() >= MaxDataSize){ data.remove(0); } data.add(new Random().nextInt(4) + 1); handler.sendEmptyMessage(0x1234); } } }).start(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint(); paint.setStyle(Paint.Style.STROKE); paint.setAntiAlias(true); //去锯齿 paint.setColor(Color.BLUE); //画Y轴 canvas.drawLine(XPoint, YPoint - YLength, XPoint, YPoint, paint); //Y轴箭头 canvas.drawLine(XPoint, YPoint - YLength, XPoint - 3, YPoint-YLength + 6, paint); //箭头 canvas.drawLine(XPoint, YPoint - YLength, XPoint + 3, YPoint-YLength + 6 ,paint); //添加刻度和文字 for(int i=0; i * YScale < YLength; i++) { canvas.drawLine(XPoint, YPoint - i * YScale, XPoint + 5, YPoint - i * YScale, paint); //刻度 canvas.drawText(YLabel[i], XPoint - 50, YPoint - i * YScale, paint);//文字 } //画X轴 canvas.drawLine(XPoint, YPoint, XPoint + XLength, YPoint, paint); System.out.println("Data.size = " + data.size()); if(data.size() > 1){ for(int i=1; i<data.size(); i++){ canvas.drawLine(XPoint + (i-1) * XScale, YPoint - data.get(i-1) * YScale, XPoint + i * XScale, YPoint - data.get(i) * YScale, paint); } } } } 上面绘制折线部分我们还有一种方式同样可以实现：

if(data.size() > 1){ Path path = new Path(); path.moveTo(XPoint, YPoint - data.get(0) * YScale); for(int i=1; i<data.size(); i++){ path.lineTo(XPoint + i * XScale, YPoint - data.get(i) * YScale); } canvas.drawPath(path, paint); } 下面我们将上面代码修改，让折线下面的区域颜色填充

package com.example.testcanvasdraw; import java.util.ArrayList; import java.util.List; import java.util.Random; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Path; import android.os.Handler; import android.os.Message; import android.util.AttributeSet; import android.view.View; /** * * @author 阳光小强 * * */ public class MyView extends View { private int XPoint = 60; private int YPoint = 260; private int XScale = 8; // 刻度长度 private int YScale = 40; private int XLength = 380; private int YLength = 240; private int MaxDataSize = XLength / XScale; private List<Integer> data = new ArrayList<Integer>(); private String[] YLabel = new String[YLength / YScale]; private Handler handler = new Handler() { public void handleMessage(Message msg) { if (msg.what == 0x1234) { MyView.this.invalidate(); } }; }; public MyView(Context context, AttributeSet attrs) { super(context, attrs); for (int i = 0; i < YLabel.length; i++) { YLabel[i] = (i + 1) + "M/s"; } new Thread(new Runnable() { @Override public void run() { while (true) { try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } if (data.size() >= MaxDataSize) { data.remove(0); } data.add(new Random().nextInt(4) + 1); handler.sendEmptyMessage(0x1234); } } }).start(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint(); paint.setStyle(Paint.Style.STROKE); paint.setAntiAlias(true); // 去锯齿 paint.setColor(Color.BLUE); // 画Y轴 canvas.drawLine(XPoint, YPoint - YLength, XPoint, YPoint, paint); // Y轴箭头 canvas.drawLine(XPoint, YPoint - YLength, XPoint - 3, YPoint - YLength + 6, paint); // 箭头 canvas.drawLine(XPoint, YPoint - YLength, XPoint + 3, YPoint - YLength + 6, paint); // 添加刻度和文字 for (int i = 0; i * YScale < YLength; i++) { canvas.drawLine(XPoint, YPoint - i * YScale, XPoint + 5, YPoint - i * YScale, paint); // 刻度 canvas.drawText(YLabel[i], XPoint - 50, YPoint - i * YScale, paint);// 文字 } // 画X轴 canvas.drawLine(XPoint, YPoint, XPoint + XLength, YPoint, paint); // 绘折线 /* * if(data.size() > 1){ for(int i=1; i<data.size(); i++){ * canvas.drawLine(XPoint + (i-1) * XScale, YPoint - data.get(i-1) * * YScale, XPoint + i * XScale, YPoint - data.get(i) * YScale, paint); } * } */ paint.setStyle(Paint.Style.FILL); if (data.size() > 1) { Path path = new Path(); path.moveTo(XPoint, YPoint); for (int i = 0; i < data.size(); i++) { path.lineTo(XPoint + i * XScale, YPoint - data.get(i) * YScale); } path.lineTo(XPoint + (data.size() - 1) * XScale, YPoint); canvas.drawPath(path, paint); } } }

上面的效果有时候还是达不到我们的要求，我们将代码修改后效果如下：