Android自定义柱状图表的方法实例

前言

本文将通过示例代码介绍如何自定义简单的直方图表，此图表并非常见的直方图表，而是可以分组的。此文不会过多涉及原理，比较简单，示例图片如下(gif图片没有制作好，有闪烁，请见谅)：

对于该示例的代码实现，其实重点在于坐标轴、文字、直方图的位置控制，需要随滑动距离而动态更新。注意事项会在示例代码中标注。下面贴出示例代码

public class MultiGroupHistogramView extends View {
 private int width;
 private int height;
 // 坐标轴线宽度
 private int coordinateAxisWidth;

 // 组名称字体大小
 private int groupNameTextSize;
 // 小组之间间距
 private int groupInterval;
 // 组内子直方图间距
 private int histogramInterval;
 private int histogramValueTextSize;
 // 图表数值小数点位数
 private int histogramValueDecimalCount;
 private int histogramHistogramWidth;
 private int chartPaddingTop;
 private int histogramPaddingStart;
 private int histogramPaddingEnd;
 // 各组名称到X轴的距离
 private int distanceFormGroupNameToAxis;
 // 直方图上方数值到直方图的距离
 private int distanceFromValueToHistogram;

 // 直方图最大高度
 private int maxHistogramHeight;
 // 轴线画笔
 private Paint coordinateAxisPaint;
 // 组名画笔
 private Paint groupNamePaint;
 private Paint.FontMetrics groupNameFontMetrics;
 private Paint.FontMetrics histogramValueFontMetrics;
 // 直方图数值画笔
 private Paint histogramValuePaint;
 // 直方图画笔
 private Paint histogramPaint;
 // 直方图绘制区域
 private Rect histogramPaintRect;
 // 直方图表视图总宽度
 private int histogramContentWidth;
 // 存储组内直方图shader color，例如，每组有3个直方图，该SparseArray就存储3个相对应的shader color
 private SparseArray<int[]> histogramShaderColorArray;

 private List<MultiGroupHistogramGroupData> dataList;
 private SparseArray<Float> childMaxValueArray;

 private Scroller scroller;
 private int minimumVelocity;
 private int maximumVelocity;
 private VelocityTracker velocityTracker;

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

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

 public MultiGroupHistogramView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  init(attrs);
 }

 private void init(AttributeSet attrs) {
  setLayerType(View.LAYER_TYPE_HARDWARE, null);
  TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.MultiGroupHistogramView);
  coordinateAxisWidth = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_coordinateAxisWidth, DisplayUtil.dp2px(2));
  // 坐标轴线颜色
  int coordinateAxisColor = typedArray.getColor(R.styleable.MultiGroupHistogramView_coordinateAxisColor, Color.parseColor("#434343"));
  // 底部小组名称字体颜色
  int groupNameTextColor = typedArray.getColor(R.styleable.MultiGroupHistogramView_groupNameTextColor, Color.parseColor("#CC202332"));
  groupNameTextSize = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_groupNameTextSize, DisplayUtil.dp2px(15));
  groupInterval = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_groupInterval, DisplayUtil.dp2px(30));
  histogramInterval = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_histogramInterval, DisplayUtil.dp2px(10));
  // 直方图数值文本颜色
  int histogramValueTextColor = typedArray.getColor(R.styleable.MultiGroupHistogramView_histogramValueTextColor, Color.parseColor("#CC202332"));
  histogramValueTextSize = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_histogramValueTextSize, DisplayUtil.dp2px(12));
  histogramValueDecimalCount = typedArray.getInt(R.styleable.MultiGroupHistogramView_histogramValueDecimalCount, 0);
  histogramHistogramWidth = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_histogramHistogramWidth, DisplayUtil.dp2px(20));
  chartPaddingTop = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_chartPaddingTop, DisplayUtil.dp2px(10));
  histogramPaddingStart = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_histogramPaddingStart, DisplayUtil.dp2px(15));
  histogramPaddingEnd = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_histogramPaddingEnd, DisplayUtil.dp2px(15));
  distanceFormGroupNameToAxis = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_distanceFormGroupNameToAxis, DisplayUtil.dp2px(15));
  distanceFromValueToHistogram = typedArray.getDimensionPixelSize(R.styleable.MultiGroupHistogramView_distanceFromValueToHistogram, DisplayUtil.dp2px(10));
  typedArray.recycle();

  coordinateAxisPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
  coordinateAxisPaint.setStyle(Paint.Style.FILL);
  coordinateAxisPaint.setStrokeWidth(coordinateAxisWidth);
  coordinateAxisPaint.setColor(coordinateAxisColor);

  groupNamePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
  groupNamePaint.setTextSize(groupNameTextSize);
  groupNamePaint.setColor(groupNameTextColor);
  groupNameFontMetrics = groupNamePaint.getFontMetrics();

  histogramValuePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
  histogramValuePaint.setTextSize(histogramValueTextSize);
  histogramValuePaint.setColor(histogramValueTextColor);
  histogramValueFontMetrics = histogramValuePaint.getFontMetrics();

  histogramPaintRect = new Rect();
  histogramPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
  scroller = new Scroller(getContext(), new LinearInterpolator());
  ViewConfiguration configuration = ViewConfiguration.get(getContext());
  minimumVelocity = configuration.getScaledMinimumFlingVelocity();
  maximumVelocity = configuration.getScaledMaximumFlingVelocity();
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  width = getMeasuredWidth();
  height = getMeasuredHeight();
  maxHistogramHeight = height - groupNameTextSize - coordinateAxisWidth - distanceFormGroupNameToAxis - distanceFromValueToHistogram - histogramValueTextSize - chartPaddingTop;
 }

 /**
  * 判断是否可以水平滑动
  * @param direction 标识滑动方向 正数：右滑(手指从右至左移动)；负数：左滑(手指由左向右移动)
  * 您可参考ScaollView或HorizontalScrollView理解滑动方向
  */
 @Override
 public boolean canScrollHorizontally(int direction) {
  if (direction > 0) {
   return histogramContentWidth - getScrollX() - width + histogramPaddingStart + histogramPaddingEnd > 0;
  } else {
   return getScrollX() > 0;
  }
 }

 /**
  * 根据滑动方向获取最大可滑动距离
  * @param direction 标识滑动方向 正数：右滑(手指从右至左移动)；负数：左滑(手指由左向右移动)
  * 您可参考ScaollView或HorizontalScrollView理解滑动方向
  */
 private int getMaxCanScrollX(int direction) {
  if (direction > 0) {
   return histogramContentWidth - getScrollX() - width + histogramPaddingStart + histogramPaddingEnd > 0 ?
     histogramContentWidth - getScrollX() - width + histogramPaddingStart + histogramPaddingEnd : 0;
  } else if (direction < 0) {
   return getScrollX();
  }
  return 0;
 }

 private float lastX;

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  initVelocityTrackerIfNotExists();
  velocityTracker.addMovement(event);
  switch (event.getAction()) {
   case MotionEvent.ACTION_DOWN: {
    if (!scroller.isFinished()) {
     scroller.abortAnimation();
    }
    lastX = event.getX();
    return true;
   }
   case MotionEvent.ACTION_MOVE: {
    int deltaX = (int) (event.getX() - lastX);
    lastX = event.getX();
    // 滑动处理
    if (deltaX > 0 && canScrollHorizontally(-1)) {
     scrollBy(-Math.min(getMaxCanScrollX(-1), deltaX), 0);
    } else if (deltaX < 0 && canScrollHorizontally(1)) {
     scrollBy(Math.min(getMaxCanScrollX(1), -deltaX), 0);
    }
    break;
   }
   case MotionEvent.ACTION_UP: {
    velocityTracker.computeCurrentVelocity(1000, maximumVelocity);
    int velocityX = (int) velocityTracker.getXVelocity();
    fling(velocityX);
    recycleVelocityTracker();
    break;
   }
   case MotionEvent.ACTION_CANCEL: {
    recycleVelocityTracker();
    break;
   }
  }
  return super.onTouchEvent(event);
 }

 private void initVelocityTrackerIfNotExists() {
  if (velocityTracker == null) {
   velocityTracker = VelocityTracker.obtain();
  }
 }

 private void recycleVelocityTracker() {
  if (velocityTracker != null) {
   velocityTracker.recycle();
   velocityTracker = null;
  }
 }

 // ACTION_UP事件触发
 private void fling(int velocityX) {
  if (Math.abs(velocityX) > minimumVelocity) {
   if (Math.abs(velocityX) > maximumVelocity) {
    velocityX = maximumVelocity * velocityX / Math.abs(velocityX);
   }
   scroller.fling(getScrollX(), getScrollY(), -velocityX, 0, 0, histogramContentWidth + histogramPaddingStart - width, 0, 0);
  }
 }

 @Override
 public void computeScroll() {
  if (scroller.computeScrollOffset()) {
   scrollTo(scroller.getCurrX(), 0);
  }
 }

 public void setDataList(@NonNull List<MultiGroupHistogramGroupData> dataList) {
  this.dataList = dataList;
  if (childMaxValueArray == null) {
   childMaxValueArray = new SparseArray<>();
  } else {
   childMaxValueArray.clear();
  }
  histogramContentWidth = 0;
  for (MultiGroupHistogramGroupData groupData : dataList) {
   List<MultiGroupHistogramChildData> childDataList = groupData.getChildDataList();
   if (childDataList != null && childDataList.size() > 0) {
    for (int i = 0; i < childDataList.size(); i++) {
     histogramContentWidth += histogramHistogramWidth + histogramInterval;
     MultiGroupHistogramChildData childData = childDataList.get(i);
     Float childMaxValue = childMaxValueArray.get(i);
     if (childMaxValue == null || childMaxValue < childData.getValue()) {
      childMaxValueArray.put(i, childData.getValue());
     }
    }
    histogramContentWidth += groupInterval - histogramInterval;
   }
  }
  histogramContentWidth += -groupInterval;
 }

 /**
  * 设置组内直方图颜色(并不是设置所有直方图颜色，而是根据每组数据内直方图数量设置)
  */
 public void setHistogramColor(int[]... colors) {
  if (colors != null && colors.length > 0) {
   if (histogramShaderColorArray == null) {
    histogramShaderColorArray = new SparseArray<>();
   } else {
    histogramShaderColorArray.clear();
   }
   for (int i = 0; i < colors.length; i++) {
    histogramShaderColorArray.put(i, colors[i]);
   }
  }
 }

 @Override
 protected void onDraw(Canvas canvas) {
  if (width == 0 || height == 0) {
   return;
  }
  int scrollX = getScrollX();
  int axisBottom = height - groupNameTextSize - distanceFormGroupNameToAxis - coordinateAxisWidth / 2;
  canvas.drawLine(coordinateAxisWidth / 2 + scrollX, 0, coordinateAxisWidth / 2 + scrollX, axisBottom, coordinateAxisPaint);
  canvas.drawLine(scrollX, axisBottom, width + scrollX, axisBottom, coordinateAxisPaint);
  if (dataList != null && dataList.size() > 0) {
   int xAxisOffset = histogramPaddingStart; // 每个直方图在x轴的偏移量
   for (MultiGroupHistogramGroupData groupData : dataList) {
    List<MultiGroupHistogramChildData> childDataList = groupData.getChildDataList();
    if (childDataList != null && childDataList.size() > 0) {
     int groupWidth = 0;
     for (int i = 0; i < childDataList.size(); i++) {
      MultiGroupHistogramChildData childData = childDataList.get(i);
      histogramPaintRect.left = xAxisOffset;
      histogramPaintRect.right = histogramPaintRect.left + histogramHistogramWidth;
      int childHistogramHeight;
      if (childData.getValue() <= 0 || childMaxValueArray.get(i) <= 0) {
       childHistogramHeight = 0;
      } else {
       childHistogramHeight = (int) (childData.getValue() / childMaxValueArray.get(i) * maxHistogramHeight);
      }
      histogramPaintRect.top = height - childHistogramHeight - coordinateAxisWidth - distanceFormGroupNameToAxis - groupNameTextSize;
      histogramPaintRect.bottom = histogramPaintRect.top + childHistogramHeight;
      int[] histogramShaderColor = histogramShaderColorArray.get(i);
      LinearGradient shader = null;
      if (histogramShaderColor != null && histogramShaderColor.length > 0) {
       shader = getHistogramShader(histogramPaintRect.left, chartPaddingTop + distanceFromValueToHistogram + histogramValueTextSize,
         histogramPaintRect.right, histogramPaintRect.bottom, histogramShaderColor);
      }
      histogramPaint.setShader(shader);
      canvas.drawRect(histogramPaintRect, histogramPaint);
      String childHistogramHeightValue = StringUtil.NumericScaleByFloor(String.valueOf(childData.getValue()), histogramValueDecimalCount) + childData.getSuffix();

      float valueTextX = xAxisOffset + (histogramHistogramWidth - histogramValuePaint.measureText(childHistogramHeightValue)) / 2;
      // 数值绘制Y轴位置特别处理
      float valueTextY = histogramPaintRect.top - distanceFormGroupNameToAxis + (histogramValueFontMetrics.bottom) / 2;
      canvas.drawText(childHistogramHeightValue, valueTextX, valueTextY, histogramValuePaint);
      int deltaX = i < childDataList.size() - 1 ? histogramHistogramWidth + histogramInterval : histogramHistogramWidth;
      groupWidth += deltaX;
      // 注意此处偏移量累加
      xAxisOffset += i == childDataList.size() - 1 ? deltaX + groupInterval : deltaX;
     }
     String groupName = groupData.getGroupName();
     float groupNameTextWidth = groupNamePaint.measureText(groupName);
     float groupNameTextX = xAxisOffset - groupWidth - groupInterval + (groupWidth - groupNameTextWidth) / 2;
     // 组名绘制Y轴位置特别处理
     float groupNameTextY = (height - groupNameFontMetrics.bottom / 2);
     canvas.drawText(groupName, groupNameTextX, groupNameTextY, groupNamePaint);
    }
   }
  }
 }

 private LinearGradient getHistogramShader(float x0, float y0, float x1, float y1, int[] colors) {
  return new LinearGradient(x0, y0, x1, y1, colors, null, Shader.TileMode.CLAMP);
 }
}

代码就这一点，阅读起来应该不难，如有疑问欢迎留言

自定义属性如下：

<declare-styleable name="MultiGroupHistogramView">
 <attr name="coordinateAxisWidth" format="dimension" />
 <attr name="coordinateAxisColor" format="color" />
 <attr name="groupNameTextColor" format="color" />
 <attr name="groupNameTextSize" format="dimension" />
 <attr name="groupInterval" format="dimension" />
 <attr name="histogramInterval" format="dimension" />
 <attr name="histogramValueTextColor" format="color" />
 <attr name="histogramValueTextSize" format="dimension" />
 <attr name="histogramHistogramWidth" format="dimension" />
 <attr name="histogramPaddingStart" format="dimension" />
 <attr name="histogramPaddingEnd" format="dimension" />
 <attr name="chartPaddingTop" format="dimension" />
 <attr name="distanceFormGroupNameToAxis" format="dimension" />
 <attr name="distanceFromValueToHistogram" format="dimension" />
 <!--图表数值小数点位数-->
 <attr name="histogramValueDecimalCount">
  <enum name="ZERO" value="0" />
  <enum name="ONE" value="1" />
  <enum name="TWO" value="2" />
 </attr>
</declare-styleable>

下面贴出使用方法：

private void initMultiGroupHistogramView() {
 Random random = new Random();
 int groupSize = random.nextInt(5) + 10;
 List<MultiGroupHistogramGroupData> groupDataList = new ArrayList<>();
 // 生成测试数据
 for (int i = 0; i < groupSize; i++) {
  List<MultiGroupHistogramChildData> childDataList = new ArrayList<>();
  MultiGroupHistogramGroupData groupData = new MultiGroupHistogramGroupData();
  groupData.setGroupName("第" + (i + 1) + "组");
  MultiGroupHistogramChildData childData1 = new MultiGroupHistogramChildData();
  childData1.setSuffix("分");
  childData1.setValue(random.nextInt(50) + 51);
  childDataList.add(childData1);

  MultiGroupHistogramChildData childData2 = new MultiGroupHistogramChildData();
  childData2.setSuffix("%");
  childData2.setValue(random.nextInt(50) + 51);
  childDataList.add(childData2);
  groupData.setChildDataList(childDataList);
  groupDataList.add(groupData);
 }
 multiGroupHistogramView.setDataList(groupDataList);
 int[] color1 = new int[]{getResources().getColor(R.color.color_orange), getResources().getColor(R.color.colorPrimary)};

 int[] color2 = new int[]{getResources().getColor(R.color.color_supper_tip_normal), getResources().getColor(R.color.bg_supper_selected)};
 // 设置直方图颜色
 multiGroupHistogramView.setHistogramColor(color1, color2);
}

完整示例：https://github.com/670832188/TestApp

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，如果有疑问大家可以留言交流，谢谢大家对服务器之家的支持。

原文链接：https://www.jianshu.com/p/1595ce6aa3a7