//布局文件<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.avi.myapplication5.app.MainActivity"> <com.avi.myapplication5.app.DrawActivity android:layout_width="wrap_content" android:layout_height="wrap_content" /></FrameLayout>
//MainActivity类package com.avi.myapplication5.app;import android.app.Activity;import android.os.Bundle;public class MainActivity extends Activity{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); }}//DrawActivity类package com.avi.myapplication5.app;import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;/** * Created by Administrator on 14-4-18. */public class DrawActivity extends View implements View.OnTouchListener{ float PI=(float)Math.PI;//PI=3.1415那个什么的每次调用(float)Math.PI太麻烦，自定义一个。 float canvasWidth,canvasHeight;//画布宽、高 float width,height;//自定义长宽 float left,up;//自定义左上角位置 public DrawActivity(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onDraw(Canvas canvas){ super.onDraw(canvas); //开始一定要先调用Init()初始化参数。我自定义的参数没有默认值。 Init(canvas); Render(canvas); } @Override public boolean onTouch(View view, MotionEvent event) { return false; } //初始化全局参数。 //建议不要在其它函数里更改在这里初始化的参数，以免得不出正确结果 void Init(Canvas canvas){ //获取画布宽、高 canvasWidth=(float)canvas.getWidth(); canvasHeight=(float)canvas.getHeight(); //自定义长宽 width=2*PI;height=2*PI*canvasHeight/canvasWidth; // 自定义左上角位置 left=-width/2;up=height/2; } //渲染画面。 //画图步骤在这里。 void Render(Canvas canvas){ //新建画笔 Paint paint=new Paint(); //画网格线。 paint.setARGB(255, 255, 0, 0); DrawGrid(canvas,0.3f,0.3f,paint); //画坐标线。 paint.setARGB(255,0,0,0); DrawCoord(canvas,paint); //显示横、纵坐标轴名称和原点名称。(重要提示:这里就是你想要的新东西) paint.setARGB(255,100,100,100); DrawCoordName(canvas,paint,"t","f(t)","O"); //画曲线 DrawCurve(canvas, paint); } //画网格线。 //要先画网格再画坐标，不然网格线会把坐标线覆盖掉从而看不到坐标线 //dx,dy: void DrawGrid(Canvas canvas,float dx,float dy,Paint paint){ //画纵向网格线 //左侧 float x=0; while (x>left){ canvas.drawLine(PX(x),PY(up),PX(x),PY(up-height),paint); x-=dx; } //右侧 x=0; while (x<width+left){ canvas.drawLine(PX(x),PY(up),PX(x),PY(up-height),paint); x+=dx; } //画横向网格线 //上侧 float y=0; while (y<up){ canvas.drawLine(PX(left),PY(y),PX(left+width),PY(y),paint); y+=dy; } //下侧 y=0; while (y>up-height){ canvas.drawLine(PX(left),PY(y),PX(left+width),PY(y),paint); y-=dy; } } //画坐标线。 void DrawCoord(Canvas canvas,Paint paint){ //画x,y坐标 canvas.drawLine(PX(left),PY(0f),PX(left+width),PY(0f),paint); canvas.drawLine(PX(0f),PY(up),PX(0f),PY(up-height),paint); } //(重要提示:这里就是你想要的新东西) //显示横、纵坐标轴名称和原点名称。 void DrawCoordName(Canvas canvas,Paint paint,String xAxisName,String yAxisName,String originName){ //设置文字大小 paint.setTextSize(40f); //在适当位置显示x,y,O名称 canvas.drawText(xAxisName,PX(left+width)-30f,PY(0f)+30f,paint); canvas.drawText(yAxisName,PX(0f),PY(up)+30f,paint); canvas.drawText(originName,PX(0f),PY(0f)+30f,paint); } //画点函数。使用自定义坐标。 void DrawPoint(Canvas canvas,float x,float y,Paint paint){ canvas.drawPoint(PX(x),PY(y),paint); } //(重要提示:所有你想画的曲线都在这里进行。) //画曲线函数。 //使用画布坐标。所以要调用PX(x),PY(y)把自定义坐标里的量(如x,y)转换成画布坐标。 void DrawCurve(Canvas canvas,Paint paint){//绘制曲线 paint.setARGB(255,0,0,255); for(float x=left;x<left+width;x+=0.001f){ float y=(float)Math.sin(x); DrawPoint(canvas,x,y,paint); } //因为x,y是自定义坐标，canvas.drawText()是系统提供的函数， // 所以要调用PX(),PY()将(PI/2,sin(PI/2))转换成画布坐标； canvas.drawText("f(t)=sin(t)",PX(PI/2),PY((float)Math.sin(PI/2)),paint); } //将自定义坐标转换成画布坐标的函数， //当要用自定义坐标在系统提供的函数上绘图时，要调用这两个函数把自定义坐标转换成画布坐标 float PX(float x){ return (x-left)*canvasWidth/width; } float PY(float y){ return (up-y)*canvasHeight/height; }}
0 0
