AndroidRecyclerBarChart绘制使用教程

//绘制柱状图, mYAxis这个坐标会实时变动，所以通过 BarChartItemDecoration 传过来的精确值。
    final public void drawBarChart(final canvas canvas, @NonNull final RecyclerView parent, final YAxis mYAxis) {
        final float parentRight = parent.getWidth() - parent.getPaddingRight();
        final float parentLeft = parent.getPaddingLeft();
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            BarEntry barChart = (BarEntry) child.getTag();
            RectF rectF = ChartComputeUtil.getBarChartRectF(child, parent, mYAxis, mBarChartAttrs, barChart);
            drawChart(canvas, rectF, parentLeft, parentRight);
        }
    }

public static <T extends BarEntry, V extends BaseYAxis, E extends BaseChartAttrs> RectF getBarChartRectF(View child, final RecyclerView parent, V mYAxis, E chartAttrs, T barEntry) {
        final RectF rectF = new RectF();
        float contentBottom = parent.getHeight() - parent.getPaddingBottom() - chartAttrs.contentPaddingBottom;
        float realYAxisLabelHeight = contentBottom - parent.getPaddingTop() - chartAttrs.contentPaddingTop;
        float width = child.getWidth();
        float barSpaceWidth = width * chartAttrs.barSpace;
        float barChartWidth = width - barSpaceWidth;//柱子的宽度
        final float left = child.getLeft() + barSpaceWidth / 2;
        final float right = left + barChartWidth;
        float height = barEntry.getY() / mYAxis.getAxisMaximum() * realYAxisLabelHeight;
        if (chartAttrs.yAxisReverse && barEntry.getY() > 0) {
            float valueTemp = mYAxis.getAxisMaximum() - barEntry.getY();
            height = valueTemp / mYAxis.getAxisMaximum() * realYAxisLabelHeight;
        }
        final float top = Math.max(contentBottom - height, parent.getPaddingTop());
        rectF.set(left, top, right, contentBottom);
        return rectF;
    }

private void drawChart(Canvas canvas, RectF rectF, float parentLeft, float parentRight) {
    float radius = (rectF.right - rectF.left) *mBarChartAttrs.barChartRoundRectRadiusRatio;
    // 浮点数的 == 比较需要注意
    if (DecimalUtil.smallOrEquals(rectF.right, parentLeft)) {
      //continue 会闪，原因是end == parentLeft 没有过滤掉，显示出来柱状图了。
      return;
    } else if (rectF.left < parentLeft && rectF.right > parentLeft) {
      //左边部分滑入的时候，处理柱状图的显示
      rectF.left = parentLeft;
      Path path = CanvasUtil.createRectRoundPath(rectF, radius, RoundRectType.TYPE_RIGHT);
      mBarChartPaint.setColor(mBarChartAttrs.chartEdgeColor);
      canvas.drawPath(path, mBarChartPaint);
    } else if (DecimalUtil.biGorEquals(rectF.left, parentLeft) && DecimalUtil.smallOrEquals(rectF.right, parentRight)) {
      //中间的; 浮点数的 == 比较需要注意
      mBarChartPaint.setColor(mBarChartAttrs.chartColor);
      Path path = CanvasUtil.createRectRoundPath(rectF, radius);
      canvas.drawPath(path, mBarChartPaint);
    } else if (DecimalUtil.smallOrEquals(rectF.left, parentRight) && 
               rectF.right > parentRight) {
      //右边部分滑出的时候，处理柱状图，文字的显示
      float distance = (parentRight - rectF.left);
      rectF.right = rectF.left + distance;
      Path path = CanvasUtil.createRectRoundPath(rectF, radius, RoundRectType.TYPE_LEFT);
            mBarChartPaint.setColor(mBarChartAttrs.chartEdgeColor);
            canvas.drawPath(path, mBarChartPaint);
        }
   }

//绘制选中时 highLight 标线及浮框。
public <E extends BaseYAxis> void drawHighLight(Canvas canvas, @NonNull RecyclerView parent, E yAxis) {
  if (mBarChartAttrs.enableValueMark) {
    int childCount = parent.getChildCount();
    View child;
    for (int i = 0; i < childCount; i++) {
      child = parent.getChildAt(i);
      T entry = (T) child.getTag();
      RectF rectF = ChartComputeUtil.getBarChartRectF(child, parent, yAxis, mBarChartAttrs, entry);
      float width = child.getWidth();
      float childCenter = child.getLeft() + width / 2;
      String valueStr = mHighLightValueFORMatter.getBarLabel(entry);
      if (entry.isSelected() && !TextUtils.isEmpty(valueStr)) {
        int chartColor = getChartColor(entry);
        float rectHeight = drawHighLightValue(canvas, valueStr, childCenter, parent, chartColor);//绘制顶部的poupWindow，高亮矩形框及drawText
        float[] points = new float[]{childCenter, rectF.top, childCenter, rectHeight};
        drawHighLightLine(canvas, points, chartColor);//绘制底部的Line
      }
    }
  }
}

//绘制柱状图选中浮框
protected float drawHighLightValue(Canvas canvas, String valueStr, float childCenter,
                                   RecyclerView parent, int barChartColor) {
  float parentTop = parent.getPaddingTop();
  float contentRight = parent.getWidth() - parent.getPaddingRight();
  float contentLeft = parent.getPaddingLeft();
  String[] strings = valueStr.split(DefaultHighLightMarkValueFormatter.CONNECT_STR);
  float leftEdgeDistance = Math.abs(childCenter - contentLeft);
  float rightEdgeDistance = Math.abs(contentRight - childCenter);
  float leftPadding = DisplayUtil.dip2px(8);
  float rightPadding = DisplayUtil.dip2px(8);
  float centerPadding = DisplayUtil.dip2px(16);
  float rectBottom = parentTop;
  float txtTopPadding = DisplayUtil.dip2px(8);
  String leftStr = strings[0];
  String rightStr = strings[1];
  float txtLeftWidth = mHighLightValuePaint.measureText(leftStr);
  float txtRightWidth = mHighLightValuePaint.measureText(rightStr);
  float rectFHeight = TextUtil.getTxtHeight1(mHighLightValuePaint) + txtTopPadding * 2;
  float txtWidth = txtLeftWidth + txtRightWidth + leftPadding +
    rightPadding + centerPadding;
  float edgeDistance = txtWidth / 2.0f;
  float rectTop = parentTop - rectFHeight;
  //绘制RectF
  RectF rectF = new RectF();
  mBarChartPaint.setColor(barChartColor);
  if (leftEdgeDistance <= edgeDistance) {//矩形框靠左对齐
    rectF.set(contentLeft, rectTop, contentLeft + txtWidth, rectBottom);
    float radius = DisplayUtil.dip2px(8);
    canvas.drawRoundRect(rectF, radius, radius, mBarChartPaint);
  } else if (rightEdgeDistance <= edgeDistance) {//矩形框靠右对齐
    rectF.set(contentRight - txtWidth, rectTop, contentRight, rectBottom);
    float radius = DisplayUtil.dip2px(8);
    canvas.drawRoundRect(rectF, radius, radius, mBarChartPaint);
  } else {//居中对齐。
    rectF.set(childCenter - edgeDistance, rectTop, childCenter + edgeDistance, rectBottom);
    float radius = DisplayUtil.dip2px(8);
    canvas.drawRoundRect(rectF, radius, radius, mBarChartPaint);
  }
  //绘文字
  RectF leftRectF = new RectF(rectF.left + leftPadding, rectTop + txtTopPadding,
                              rectF.left + leftPadding + 
                              txtLeftWidth, rectTop + txtTopPadding + rectFHeight);
  mHighLightValuePaint.setTextAlign(Paint.Align.LEFT);
  Paint.FontMetrics fontMetrics = mHighLightValuePaint.getFontMetrics();
  float top = fontMetrics.top;//为基线到字体上边框的距离,即上图中的top
  float bottom = fontMetrics.bottom;//为基线到字体下边框的距离,即上图中的bottom
  int baseLineY = (int) (leftRectF.centerY() + (top + bottom) / 2);//基线中间点的y轴计算公式
  canvas.drawText(leftStr, rectF.left + leftPadding, baseLineY, mHighLightValuePaint);
  float dividerLineStartX = rectF.left + leftPadding + txtLeftWidth + centerPadding / 2.0f;
  float dividerLineStartY = rectTop + DisplayUtil.dip2px(10);
  float dividerLineEndX = dividerLineStartX;
  float dividerLineEndY = rectBottom - DisplayUtil.dip2px(10);
  float[] lines = new float[]{dividerLineStartX, dividerLineStartY, 
                              dividerLineEndX, dividerLineEndY};
  canvas.drawLines(lines, mHighLightValuePaint);
  float rightRectFStart = rectF.left + leftPadding + txtLeftWidth + centerPadding;
  RectF rightRectF = new RectF(rightRectFStart, rectTop + txtTopPadding,
                               rectF.right - rightPadding, rectBottom - txtTopPadding);
  canvas.drawText(rightStr, rightRectF.left, baseLineY, mHighLightValuePaint);
  return rectFHeight;
}