Android自定义View-简单折线图

先看效果图：

折线图其实就是对坐标进行计算，实现很简单，下面直接上代码：

package com.example.customeview;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import java.util.ArrayList;

/**
 * 自定义折线图
 */
public class MyView extends View {

    private Paint paint;
//    private int color;
    private ArrayList<Integer> mPoint;
    private ArrayList<String> xText = new ArrayList<>();

    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
//        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.myView);
//        color = typedArray.getColor(R.styleable.myView_TextColor, Color.BLUE);
        paint = new Paint();
        paint.setStrokeWidth(2);
//        typedArray.recycle();
    }

    public MyView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        xText.add("一");
        xText.add("二");
        xText.add("三");
        xText.add("四");
        xText.add("五");
        xText.add("六");
        xText.add("七");
        xText.add("八");

        paint.setColor(Color.BLACK);
        paint.setAntiAlias(true);
        paint.setAntiAlias(true);
        paint.setDither(true);
        canvas.drawLine(50,500,850,500,paint);
        canvas.drawLine(850, 500, 840, 490, paint);
        canvas.drawLine(850, 500, 840, 510, paint);

        canvas.drawLine(50,500,50,0,paint);
        canvas.drawLine(50, 0, 40, 10, paint);
        canvas.drawLine(50, 0, 60, 10, paint);

        for (int i = 0; i < 8; i++) {
            canvas.drawLine(50 + 100*i, 500, 50 + 100*i, 490, paint);
        }

        for (int i = 0; i < 10; i++) {
            canvas.drawLine(50, 50*i, 50 + 10, 50*i, paint);
        }

        paint.setColor(Color.RED);

        if (mPoint.size() != 0){
            for (int i = 0; i < mPoint.size(); i++) {
                if (i == 0){
                    canvas.drawLine(50 + i*100, 500, 50 + i*100 + 100, 500 - mPoint.get(i)*5, paint);
                    canvas.drawCircle(50 + i*100 + 100, 500 - mPoint.get(i)*5,5, paint);
                }
                else{
                    canvas.drawLine(50 + i*100, 500 - mPoint.get(i - 1)*5, 50 + i*100 + 100, 500 - mPoint.get(i)*5, paint);
                    canvas.drawCircle(50 + i*100 + 100, 500 - mPoint.get(i)*5,5, paint);
                }
            }
        }

        paint.setTextSize(25);
        paint.setColor(Color.BLACK);
        for (int i = 0; i < 8; i++) {
            canvas.drawText(xText.get(i), 40+ 100*i, 540 , paint);
        }

        for (int i = 0; i < 10; i++) {
            canvas.drawText(10*i + "", 10, 510 - 50*i , paint);
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    }

    public void setmPoint(ArrayList<Integer> point){
        mPoint = point;
        postInvalidate();
    }
}

布局中代码：

<com.example.customeview.MyView
        android:id="@+id/custom"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        />

在Activity中设置值：

custom = findViewById(R.id.custom);

        mPoint.add(10);
        mPoint.add(50);
        mPoint.add(70);
        mPoint.add(90);
        mPoint.add(60);
        mPoint.add(0);
        custom.setmPoint(mPoint);