Andorid自定义View实现K线图 代码示例

以下是一个简单的自定义View实现K线图的代码示例：

public class KLineView extends View {
    
    private List<KLineData> mData; // K线数据
    
    private int mWidth, mHeight; // 控件宽度、高度
    private int mTopPadding; // 顶部留白
    private int mBottomPadding; // 底部留白
    
    private Paint mLinePaint; // K线画笔
    private Paint mTextPaint; // 文本画笔
    
    private float mMaxPrice, mMinPrice; // 最高价、最低价
    private float mPriceScale; // 价格缩放比例
    private float mVolumeScale; // 成交量缩放比例
    
    private int mCandleWidth; // K线宽度
    private int mCandleSpace; // K线间隔
    
    public KLineView(Context context) {
        this(context, null);
    }
    
    public KLineView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }
    
    public KLineView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        
        // 初始化画笔
        mLinePaint = new Paint();
        mLinePaint.setStrokeWidth(2f);
        mLinePaint.setAntiAlias(true);
        mLinePaint.setStyle(Paint.Style.STROKE);
        
        mTextPaint = new Paint();
        mTextPaint.setTextSize(24f);
        mTextPaint.setAntiAlias(true);
        mTextPaint.setColor(Color.BLACK);
        
        // 初始化K线宽度、间隔
        mCandleWidth = dp2px(8);
        mCandleSpace = dp2px(4);
        
        // 初始化留白
        mTopPadding = dp2px(20);
        mBottomPadding = dp2px(20);
    }
    
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        
        // 获取控件宽度、高度
        mWidth = MeasureSpec.getSize(widthMeasureSpec);
        mHeight = MeasureSpec.getSize(heightMeasureSpec);
        
        // 计算价格、成交量缩放比例
        mPriceScale = (mHeight - mTopPadding - mBottomPadding) / (mMaxPrice - mMinPrice);
        mVolumeScale = (mHeight - mTopPadding - mBottomPadding) / getMaxVolume();
    }
    
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        
        // 绘制K线图
        drawCandles(canvas);
        
        // 绘制边框
        drawBorder(canvas);
        
        // 绘制Y轴标签
        drawYLabels(canvas);
    }
    
    /**
     * 绘制K线图
     */
    private void drawCandles(Canvas canvas) {
        if (mData == null || mData.size() == 0) {
            return;
        }
        
        mLinePaint.setColor(Color.RED);
        mLinePaint.setStyle(Paint.Style.FILL);
        
        float startX = mCandleWidth / 2 + mCandleSpace; // 第一个K线起始X坐标
        float startY = 0f; // K线起始Y坐标
        float endX, endY; // K线结束X坐标、Y坐标
        
        for (int i = 0; i < mData.size(); i++) {
            KLineData data = mData.get(i);
            
            // 计算K线顶部、底部Y坐标
            float highY = mTopPadding + (mMaxPrice - data.getHigh()) * mPriceScale;
            float lowY = mTopPadding + (mMaxPrice - data.getLow()) * mPriceScale;
            
            // 计算K线开盘、收盘Y坐标
            float openY = mTopPadding + (mMaxPrice - data.getOpen()) * mPriceScale;
            float closeY = mTopPadding + (mMaxPrice - data.getClose()) * mPriceScale;
            
            // 绘制K线实体
            if (data.getOpen() < data.getClose()) {
                mLinePaint.setColor(Color.RED);
            } else {
                mLinePaint.setColor(Color.GREEN);
            }
            canvas.drawRect(startX - mCandleWidth / 2, closeY, startX + mCandleWidth / 2, openY, mLinePaint);
            
            // 绘制K线上下影线
            mLinePaint.setColor(Color.BLACK);
            canvas.drawLine(startX, highY, startX, openY, mLinePaint);
            canvas.drawLine(startX, lowY, startX, closeY, mLinePaint);
            
            // 更新起始X坐标
            startX += mCandleWidth + mCandleSpace;
        }
    }
    
    /**
     * 绘制边框
     */
    private void drawBorder(Canvas canvas) {
        mLinePaint.setColor(Color.BLACK);
        mLinePaint.setStyle(Paint.Style.STROKE);
        canvas.drawRect(0, 0, mWidth, mHeight, mLinePaint);
    }
    
    /**
     * 绘制Y轴标签
     */
    private void drawYLabels(Canvas canvas) {
        float labelHeight = mTextPaint.descent() - mTextPaint.ascent();
        
        // 绘制价格标签
        float priceLabelY = mTopPadding - mTextPaint.ascent();
        for (float price = mMinPrice; price <= mMaxPrice; price += (mMaxPrice - mMinPrice) / 5) {
            float priceY = mTopPadding + (mMaxPrice - price) * mPriceScale;
            canvas.drawText(String.format(Locale.getDefault(), "%.2f", price), 0, priceY + labelHeight / 2, mTextPaint);
            canvas.drawLine(mCandleWidth / 2, priceY, mWidth, priceY, mLinePaint);
        }
        
        // 绘制成交量标签
        float volumeLabelY = mHeight - mBottomPadding - mTextPaint.descent();
        float maxVolume = getMaxVolume();
        for (int i = 0; i < 5; i++) {
            float volumeY = volumeLabelY - i * labelHeight * maxVolume / 5;
            canvas.drawText(String.format(Locale.getDefault(), "%.0f", maxVolume * i / 5), 0, volumeY - labelHeight / 2, mTextPaint);
        }
    }
    
    /**
     * 设置K线数据
     */
    public void setData(List<KLineData> data) {
        mData = data;
        calculateMaxAndMinPrice();
        requestLayout();
        invalidate();
    }
    
    /**
     * 计算最高价、最低价
     */
    private void calculateMaxAndMinPrice() {
        if (mData == null || mData.size() == 0) {
            return;
        }
        
        mMaxPrice = mData.get(0).getHigh();
        mMinPrice = mData.get(0).getLow();
        
        for (int i = 1; i < mData.size(); i++) {
            KLineData data = mData.get(i);
            mMaxPrice = Math.max(mMaxPrice, data.getHigh());
            mMinPrice = Math.min(mMinPrice, data.getLow());
        }
    }
    
    /**
     * 获取最大成交量
     */
    private float getMaxVolume() {
        float maxVolume = 0f;
        
        if (mData != null && mData.size() > 0) {
            for (KLineData data : mData) {
                maxVolume = Math.max(maxVolume, data.getVolume());
            }
        }
        
        return maxVolume;
    }
    
    /**
     * dp转px
     */
    private int dp2px(int dp) {
        return (int) (dp * getContext().getResources().getDisplayMetrics().density + 0.5f);
    }
}

其中，KLineData表示K线数据，包括开盘价、收盘价、最高价、最低价、成交量等属性。可以根据实际需求进行修改。