Android自定义View练习--折线图

本练习参考自定义View练习（二）简易折线图控件，折线图支持设置x轴与y轴的取值范围与递增值，效果如下：

linechart效果图

首先自定义属性，在res/value目录下新建attrs.xml文件，在此文件中申明自定义的属性，除了颜色、padding等外，自定义 x_max_value 与 x_step用来定义x轴的最大值与递增值,y轴同样，xml文件如下：

然后继承自View自定义折线图，在构造方法中获取设置的值，由于设置的x、y轴最大值可能不是递增值的倍数，定义multiple()方法将值转换为小于设置值的递增值最大数，将chartPadding设置为定义的padding值的1.5倍是为了给接下来的刻度值预留空间。

     TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.LineChart, defStyleAttr, 0);
        xStep = ta.getInt(R.styleable.LineChart_x_step, DEFAULT_STEP);
        yStep = ta.getInt(R.styleable.LineChart_y_step, DEFAULT_STEP);
        xMaxValue = multiple(ta.getInt(R.styleable.LineChart_x_max_value, DEFAULT_SCALE_SPACE), xStep);
        yMaxValue = multiple(ta.getInt(R.styleable.LineChart_y_max_value, DEFAULT_SCALE_SPACE), yStep);
        pointRadius = ta.getDimension(R.styleable.LineChart_point_radius, DensityUtils.dp2px(getContext(), DEFAULT_POINT_RADIUS));
        coordinateColor = ta.getColor(R.styleable.LineChart_coordinate_color, Color.BLUE);
        pointColor = ta.getColor(R.styleable.LineChart_point_color, Color.RED);
        lineColor = ta.getColor(R.styleable.LineChart_line_color, Color.MAGENTA);

        float padding = ta.getDimension(R.styleable.LineChart_chart_padding, DensityUtils.dp2px(getContext(), DEFAULT_CHART_PADDING));
        chartPadding = padding + padding / 2; //chartPadding为设置的padding的1.5倍，为刻度值预留空间
        axisStroke = ta.getDimension(R.styleable.LineChart_axis_stroke, DensityUtils.dp2px(getContext(), DEFAULT_AXIS_STROKE));
        lineStroke = ta.getDimension(R.styleable.LineChart_line_stroke, DensityUtils.dp2px(getContext(), DEFAULT_LINE_STROKE));
        scaleNumberSize = ta.getDimension(R.styleable.LineChart_scaleNumberSize, DensityUtils.sp2px(getContext(), DEFAULT_SCALE_NUMBER_SIZE));
        ta.recycle();

    private int multiple(int x, int y) {
        int m = x % y;
        if (m != 0) x -= m;
        return x;
    }

接下来复写onMeasure()方法,当使用折线图时如果选择的是wrap_content，MeasureSpec对应的是AT_MOST模式，那么要为折线图设置默认的大小，这里将长宽都设置为200dp(不考虑MeasureSpec.UNSPECIFIED)，如下所示：

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

    private int measureDimension(int measureSpec) {
        int mode = MeasureSpec.getMode(measureSpec);
        int measureSize = MeasureSpec.getSize(measureSpec);

        int result = 0;
        if (mode == MeasureSpec.EXACTLY) {
            result = measureSize;
        } else {
            result = DensityUtils.dp2px(this.getContext(), DEFAULT_SIZE);

        }
        return result;
    }

最后复写onDraw()方法绘制整个图

1. 绘制坐标轴

        //零点的x，y
        float startXPoint = chartPadding;
        float startYPoint = getHeight() - chartPadding;
        //x轴终点的x,y
        float xAxisEndXPoint = getWidth() - chartPadding;
        float xAxisEndYPoint = getHeight() - chartPadding;
        //y轴终点的x,y
        float yAxisEndXPoint = chartPadding;
        float yAxisEndYPoint = chartPadding;

        //画坐标轴
        coordinatePath.reset();
        coordinatePath.moveTo(xAxisEndXPoint, xAxisEndYPoint);
        coordinatePath.lineTo(startXPoint, startYPoint);
        coordinatePath.lineTo(yAxisEndXPoint, yAxisEndYPoint);
        canvas.drawPath(coordinatePath, coordinatePaint);
        coordinatePath.reset();

        //画箭头
        coordinatePath.moveTo(xAxisEndXPoint, xAxisEndYPoint - 8);
        coordinatePath.lineTo(xAxisEndXPoint + 8, xAxisEndYPoint);
        coordinatePath.lineTo(xAxisEndXPoint, xAxisEndYPoint + 8);
        coordinatePath.close();
        canvas.drawPath(coordinatePath, arrowPaint);

        coordinatePath.moveTo(yAxisEndXPoint - 8, yAxisEndYPoint);
        coordinatePath.lineTo(yAxisEndXPoint, yAxisEndYPoint - 8);
        coordinatePath.lineTo(yAxisEndXPoint + 8, yAxisEndYPoint);
        coordinatePath.close();
        canvas.drawPath(coordinatePath, arrowPaint);

2. 绘制坐标刻度

        //画刻度
        //x轴上的刻度数量
        xCount = xMaxValue / xStep + 1;
        //y轴上的刻度数量
        yCount = yMaxValue / yStep + 1;

        //每个刻度之间的实际间隔，刚开始没有* 1.0f 算出来的间隔是去掉小数的整数，
        //会导致在刻度数量多的情况下每个刻度都向前移了，明显没有用完坐标轴的长度
        xScaleSpace = (getWidth() - 2 * chartPadding) * 1.0f / xCount;
        yScaleSpace = (getHeight() - 2 * chartPadding) * 1.0f / yCount;
        //刻度的起始点
        float xScaleXStart = startXPoint;
        float xScaleYStart = startYPoint;
        //刻度的结束点
        float xScaleXEnd = xScaleXStart;
        float xScaleYEnd = xScaleYStart - coordinateScaleLength;

        //遍历画刻度
        for (int i = 0; i < xCount; i++) {
            canvas.drawLine(xScaleXStart, xScaleYStart, xScaleXEnd, xScaleYEnd, scalePaint);
            String s = String.valueOf(i * xStep);
            //获取刻度值的文本长宽，保存在scaleNumberBounds中
            scaleNumberPaint.getTextBounds(s, 0, s.length(), scaleNumberBounds);
            //画刻度值
            canvas.drawText(s, xScaleXStart - scaleNumberBounds.width() / 2,
                    xScaleYStart  + lineStroke + scaleNumberBounds.height() , scaleNumberPaint);
            //递增
            xScaleXStart += xScaleSpace;
            xScaleXEnd += xScaleSpace;
        }

        //与画x轴刻度值类似
        float yScaleXStart = startXPoint;
        float yScaleYStart = startYPoint;
        float yScaleXEnd = yScaleXStart + coordinateScaleLength;
        float yScaleYEnd = yScaleYStart;

        for (int i = 0; i < yCount; i++) {
            canvas.drawLine(yScaleXStart, yScaleYStart, yScaleXEnd, yScaleYEnd, scalePaint);
            if (i != 0) {
                String s = String.valueOf(i * yStep);
                scaleNumberPaint.getTextBounds(s, 0, s.length(), scaleNumberBounds);
                canvas.drawText(s, yScaleXStart - scaleNumberBounds.width() - lineStroke, yScaleYStart + scaleNumberBounds.height() / 2, scaleNumberPaint);
            }
            yScaleYEnd -= yScaleSpace;
            yScaleYStart -= yScaleSpace;
        }

3. 绘制折线图

定义ChartPoint类

    static class ChartPoint {
        private int x, y;

        public int getX() {
            return x;
        }

        public void setX(int x) {
            this.x = x;
        }

        public int getY() {
            return y;
        }

        public void setY(int y) {
            this.y = y;
        }

        public ChartPoint(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }

对外提供setPoints()方法设置坐标点，mChartPoints保存刚设置的坐标点，mLastChartPoints保存上一次的坐标点，默认list的顺序就是节点的顺序。

    private ArrayList mChartPoints;
    private ArrayList mLastChartPoints;

    public void setPoints(ArrayList newList) {
        if (newList == null) {
            throw new RuntimeException("arrayList is null ");
        } else if (newList.size() < 0) {
            throw new RuntimeException("arrayList.size() < 0 ");
        } else if (newList.size() > xCount) {
            throw new RuntimeException("arrayList.size() > xCount ");
        }
        if (mLastChartPoints == null) {
            mChartPoints = newList;
            invalidate();
        } else {
            mChartPoints = newList;
            startAnimation(mLastChartPoints, mChartPoints);
        }
        mLastChartPoints = mChartPoints;
    }

动画,对于每个节点只演变y轴的值

    private void startAnimation(ArrayList fromPoints, final ArrayList toPoints) {
        for (int i = 0; i < fromPoints.size(); i++) {
            final ChartPoint point = toPoints.get(i);
            ValueAnimator valueAnimator = ValueAnimator.ofInt(fromPoints.get(i).getY(), toPoints.get(i).getY());
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    int val = (int) animation.getAnimatedValue();
                    point.setY(val);
                    invalidate();
                }
            });
            valueAnimator.start();
        }
    }

4.在onDraw()方法中添加绘制折线的代码

        if (mChartPoints != null) {
            float startX = 0, startY = 0;
            for (int i = 0; i < mChartPoints.size(); i++) {
                ChartPoint cp = mChartPoints.get(i);
                //计算节点的确切位置
                float x = startXPoint + cp.getX() / xStep * xScaleSpace;
                float y = startYPoint - cp.getY() / yStep * yScaleSpace;
                canvas.drawCircle(x, y, pointRadius, mPointPaint);
                if (i != 0) {
                    canvas.drawLine(startX, startY, x, y, mLinePoint);
                }
                
                startX = x;
                startY = y;
            }
        }

附代码

import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
import java.util.ArrayList;

public class LineChart extends View {

    private Paint coordinatePaint;

    private static final int DEFAULT_CHART_PADDING = 8;//dp
    private static final int DEFAULT_AXIS_STROKE = 2;//dp
    private static final int DEFAULT_STEP = 10;
    private static final int DEFAULT_SIZE = 200;//dp
    private static final int DEFAULT_SCALE_SPACE = 10;
    private static final int DEFAULT_POINT_RADIUS = 2;//dp
    private static final int DEFAULT_LINE_STROKE = 2;//dp
    private static final int DEFAULT_SCALE_NUMBER_SIZE = 4;//sp
    private int scaleStroke = 3;
    private int coordinateScaleLength = 10;
    private float axisStroke;
    private float xScaleSpace;//px
    private int xStep;
    private float yScaleSpace;
    private int yStep;
    private Paint scalePaint;
    private Paint scaleNumberPaint;

    private Rect scaleNumberBounds;
    private float chartPadding;
    private int xCount, yCount;
    private Paint mPointPaint;
    private Paint mLinePoint;
    private Path coordinatePath;
    private Paint arrowPaint;
    private ArrayList mChartPoints;
    private ArrayList mLastChartPoints;
    private int pointColor;
    private int lineColor;
    private int coordinateColor;
    private int xMaxValue;
    private int yMaxValue;
    private float pointRadius;
    private float lineStroke;
    private float scaleNumberSize;

    static class ChartPoint {
        private int x, y;

        public int getX() {
            return x;
        }

        public void setX(int x) {
            this.x = x;
        }

        public int getY() {
            return y;
        }

        public void setY(int y) {
            this.y = y;
        }

        public ChartPoint(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }


    public void setPoints(ArrayList newList) {
        if (newList == null) {
            throw new RuntimeException("arrayList is null ");
        } else if (newList.size() < 0) {
            throw new RuntimeException("arrayList.size() < 0 ");
        } else if (newList.size() > xCount) {
            throw new RuntimeException("arrayList.size() > xCount ");
        }
        if (mLastChartPoints == null) {
            mChartPoints = newList;
            invalidate();
        } else {
            mChartPoints = newList;
            startAnimation(mLastChartPoints, mChartPoints);
        }
        mLastChartPoints = mChartPoints;
    }

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

    public LineChart(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public LineChart(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.LineChart, defStyleAttr, 0);
        xStep = ta.getInt(R.styleable.LineChart_x_step, DEFAULT_STEP);
        yStep = ta.getInt(R.styleable.LineChart_y_step, DEFAULT_STEP);
        xMaxValue = multiple(ta.getInt(R.styleable.LineChart_x_max_value, DEFAULT_SCALE_SPACE), xStep);
        yMaxValue = multiple(ta.getInt(R.styleable.LineChart_y_max_value, DEFAULT_SCALE_SPACE), yStep);
        pointRadius = ta.getDimension(R.styleable.LineChart_point_radius, DensityUtils.dp2px(getContext(), DEFAULT_POINT_RADIUS));
        coordinateColor = ta.getColor(R.styleable.LineChart_coordinate_color, Color.BLUE);
        pointColor = ta.getColor(R.styleable.LineChart_point_color, Color.RED);
        lineColor = ta.getColor(R.styleable.LineChart_line_color, Color.MAGENTA);

        float padding = ta.getDimension(R.styleable.LineChart_chart_padding, DensityUtils.dp2px(getContext(), DEFAULT_CHART_PADDING));
        chartPadding = padding + padding / 2; //chartPadding为设置的padding的1.5倍，为刻度值预留空间
        axisStroke = ta.getDimension(R.styleable.LineChart_axis_stroke, DensityUtils.dp2px(getContext(), DEFAULT_AXIS_STROKE));
        lineStroke = ta.getDimension(R.styleable.LineChart_line_stroke, DensityUtils.dp2px(getContext(), DEFAULT_LINE_STROKE));
        scaleNumberSize = ta.getDimension(R.styleable.LineChart_scaleNumberSize, DensityUtils.sp2px(getContext(), DEFAULT_SCALE_NUMBER_SIZE));
        ta.recycle();


        coordinatePath = new Path();
        coordinatePaint = new Paint();
        coordinatePaint.setColor(coordinateColor);
        coordinatePaint.setStyle(Paint.Style.STROKE);
        coordinatePaint.setStrokeWidth(axisStroke);

        scalePaint = new Paint();
        scalePaint.setStrokeWidth(scaleStroke);
        scalePaint.setStyle(Paint.Style.STROKE);
        scalePaint.setColor(coordinateColor);

        scaleNumberPaint = new Paint();
        scaleNumberPaint.setStyle(Paint.Style.FILL);
        scaleNumberPaint.setColor(coordinateColor);
        scaleNumberPaint.setTextSize(scaleNumberSize);
        scaleNumberPaint.setAntiAlias(true);

        scaleNumberBounds = new Rect();

        mPointPaint = new Paint();
        mPointPaint.setStyle(Paint.Style.FILL);
        mPointPaint.setColor(pointColor);

        mLinePoint = new Paint();
        mLinePoint.setStyle(Paint.Style.STROKE);
        mLinePoint.setStrokeWidth(lineStroke);
        mLinePoint.setColor(lineColor);
        mLinePoint.setAntiAlias(true);

        arrowPaint = new Paint();
        arrowPaint.setColor(coordinateColor);
        arrowPaint.setStyle(Paint.Style.FILL);
    }

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

    private int measureDimension(int measureSpec) {
        int mode = MeasureSpec.getMode(measureSpec);
        int measureSize = MeasureSpec.getSize(measureSpec);

        int result = 0;
//        MeasureSpec.UNSPECIFIED
        if (mode == MeasureSpec.EXACTLY) {
            result = measureSize;
        } else {
            result = DensityUtils.dp2px(this.getContext(), DEFAULT_SIZE);

        }
        return result;
    }


    @Override
    protected void onDraw(Canvas canvas) {

        xCount = xMaxValue / xStep + 1;
        yCount = yMaxValue / yStep + 1;
        xScaleSpace = (getWidth() - 2 * chartPadding) * 1.0f / xCount;
        yScaleSpace = (getHeight() - 2 * chartPadding) * 1.0f / yCount;

        //零点的x，y
        float startXPoint = chartPadding;
        float startYPoint = getHeight() - chartPadding;
        //x轴终点的x,y
        float xAxisEndXPoint = getWidth() - chartPadding;
        float xAxisEndYPoint = getHeight() - chartPadding;
        //y轴终点的x,y
        float yAxisEndXPoint = chartPadding;
        float yAxisEndYPoint = chartPadding;

        //画坐标轴
        coordinatePath.reset();
        coordinatePath.moveTo(xAxisEndXPoint, xAxisEndYPoint);
        coordinatePath.lineTo(startXPoint, startYPoint);
        coordinatePath.lineTo(yAxisEndXPoint, yAxisEndYPoint);
        canvas.drawPath(coordinatePath, coordinatePaint);
        coordinatePath.reset();

        //画箭头
        coordinatePath.moveTo(xAxisEndXPoint, xAxisEndYPoint - 8);
        coordinatePath.lineTo(xAxisEndXPoint + 8, xAxisEndYPoint);
        coordinatePath.lineTo(xAxisEndXPoint, xAxisEndYPoint + 8);
        coordinatePath.close();
        canvas.drawPath(coordinatePath, arrowPaint);

        coordinatePath.moveTo(yAxisEndXPoint - 8, yAxisEndYPoint);
        coordinatePath.lineTo(yAxisEndXPoint, yAxisEndYPoint - 8);
        coordinatePath.lineTo(yAxisEndXPoint + 8, yAxisEndYPoint);
        coordinatePath.close();
        canvas.drawPath(coordinatePath, arrowPaint);
//        canvas.drawLine(startXPoint, startYPoint, xCoordinateEndXPoint, xCoordinateEndYPoint, mPaint);
//        canvas.drawLine(startXPoint, startYPoint, yCoordinateEndXPoint, yCoordinateEndYPoint, mPaint);

        //画刻度
        float xScaleXStart = startXPoint;
        float xScaleYStart = startYPoint;

        float xScaleXEnd = xScaleXStart;
        float xScaleYEnd = xScaleYStart - coordinateScaleLength;


        for (int i = 0; i < xCount; i++) {
            canvas.drawLine(xScaleXStart, xScaleYStart, xScaleXEnd, xScaleYEnd, scalePaint);
            String s = String.valueOf(i * xStep);
            scaleNumberPaint.getTextBounds(s, 0, s.length(), scaleNumberBounds);
            canvas.drawText(s, xScaleXStart - scaleNumberBounds.width() / 2,
                    xScaleYStart + axisStroke + scaleNumberBounds.height(), scaleNumberPaint);
            xScaleXStart += xScaleSpace;
            xScaleXEnd += xScaleSpace;
        }

        float yScaleXStart = startXPoint;
        float yScaleYStart = startYPoint;
        float yScaleXEnd = yScaleXStart + coordinateScaleLength;
        float yScaleYEnd = yScaleYStart;

        for (int i = 0; i < yCount; i++) {
            canvas.drawLine(yScaleXStart, yScaleYStart, yScaleXEnd, yScaleYEnd, scalePaint);
            if (i != 0) {
                String s = String.valueOf(i * yStep);
                scaleNumberPaint.getTextBounds(s, 0, s.length(), scaleNumberBounds);
                canvas.drawText(s, yScaleXStart - scaleNumberBounds.width() - axisStroke, yScaleYStart + scaleNumberBounds.height() / 2, scaleNumberPaint);
            }
            yScaleYEnd -= yScaleSpace;
            yScaleYStart -= yScaleSpace;
        }


        if (mChartPoints != null) {
            float startX = 0, startY = 0;
            for (int i = 0; i < mChartPoints.size(); i++) {
                ChartPoint cp = mChartPoints.get(i);
                float x = startXPoint + cp.getX() / xStep * xScaleSpace;
                float y = startYPoint - cp.getY() / yStep * yScaleSpace;
                canvas.drawCircle(x, y, pointRadius, mPointPaint);
                if (i != 0) {
                    canvas.drawLine(startX, startY, x, y, mLinePoint);
                }
                startX = x;
                startY = y;
            }
        }


    }


    public int getxStep() {
        return xStep;
    }

    public void setxStep(int xStep) {
        this.xStep = xStep;
    }

    public int getyStep() {
        return yStep;
    }

    public void setyStep(int yStep) {
        this.yStep = yStep;
    }

    public int getxMaxValue() {
        return xMaxValue;
    }

    public void setxMaxValue(int xMaxValue) {
        this.xMaxValue = xMaxValue;
    }

    public int getyMaxValue() {
        return yMaxValue;
    }

    public void setyMaxValue(int yMaxValue) {
        this.yMaxValue = yMaxValue;
    }

    private void startAnimation(ArrayList fromPoints, final ArrayList toPoints) {
        for (int i = 0; i < fromPoints.size(); i++) {
            final ChartPoint point = toPoints.get(i);
            ValueAnimator valueAnimator = ValueAnimator.ofInt(fromPoints.get(i).getY(), toPoints.get(i).getY());
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    int val = (int) animation.getAnimatedValue();
                    point.setY(val);
                    invalidate();
                }
            });
            valueAnimator.start();
        }
    }

    private int multiple(int x, int y) {
        int m = x % y;
        if (m != 0) x -= m;
        return x;
    }
}

public class DensityUtils {
    private DensityUtils() {
        throw new UnsupportedOperationException("can not be instantiated");
    }

    public static int dp2px(Context context, float dpVal) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dpVal, context.getResources().getDisplayMetrics());
    }

    public static int sp2px(Context context, float spVal) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, spVal, context.getResources().getDisplayMetrics());
    }

    public static float px2dp(Context context, float pxVal) {
        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, pxVal, context.getResources().getDisplayMetrics());

    }

    public static float px2sp(Context context, float pxVal) {
        return (pxVal / context.getResources().getDisplayMetrics().scaledDensity);
    }
}

Android自定义View练习--折线图

1. 绘制坐标轴

2. 绘制坐标刻度

3. 绘制折线图

附代码

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