本文实例讲述了Android编程实现canvas绘制柱状统计图功能。分享给大家供大家参考，具体如下：
这里实现了一个简单的柱状统计图，如下：
特点：
1.根据数据源自动计算每个条目的高度、宽度、间距，自动计算分度值。
2.当条目数较多时，可左右滑动查看全部内容，图形、文字同步滑动，并且松手后会渐渐的停下来（而不是立刻停下来）。
代码：
（1）核心代码：BarChartView.Java
package com.sina.appbarchart;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.Rect;import android.support.annotation.NonNull;import android.support.v7.app.ActionBar;import android.support.v7.app.ActionBarActivity;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;/** * 自定义组件：条形统计图 * Created by hanj on 14-12-30. */public class BarChartView extends View { private int screenW, screenH; private BarChartItemBean[] mItems; //max value in mItems. private float maxValue; //max height of the bar private int maxHeight; private int[] mBarColors = new int[]{Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW, Color.MAGENTA, Color.CYAN}; private Paint barPaint, linePaint, textPaint; private Rect barRect, leftWhiteRect, rightWhiteRect; private Path textPath; private int leftMargin, topMargin, smallMargin; //the width of one bar item private int barItemWidth; //the spacing between two bar items. private int barSpace; //the width of the line. private int lineStrokeWidth; /** * The x-position of y-index and the y-position of the x-index.. */ private float x_index_startY, y_index_startX; private Bitmap arrowBmp; private Rect x_index_arrowRect, y_index_arrowRect; private static final int BG_COLOR = Color.parseColor("#E5E5E5"); public BarChartView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } private void init(Context context) { screenW = ScreenUtils.getScreenW(context); screenH = ScreenUtils.getScreenH(context); leftMargin = ScreenUtils.dp2px(context, 16); topMargin = ScreenUtils.dp2px(context, 40); smallMargin = ScreenUtils.dp2px(context, 6); barPaint = new Paint(); barPaint.setColor(mBarColors[0]); linePaint = new Paint(); lineStrokeWidth = ScreenUtils.dp2px(context, 1); linePaint.setStrokeWidth(lineStrokeWidth); textPaint = new Paint(); textPaint.setAntiAlias(true); barRect = new Rect(0, 0, 0, 0); textPath = new Path(); leftWhiteRect = new Rect(0, 0, 0, screenH); rightWhiteRect = new Rect(screenW - leftMargin, 0, screenW, screenH); arrowBmp = BitmapFactory.decodeResource(context.getResources(), R.drawable.arrow_up); } //标记是否已经获取过状态拉的高度 private boolean statusHeightHasGet; @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (!statusHeightHasGet) { subStatusBarHeight(); statusHeightHasGet = true; } //draw background canvas.drawColor(BG_COLOR); //bounds checkLeftMoving(); textPaint.setTextSize(ScreenUtils.dp2px(getContext(), 16)); for (int i = 0; i < mItems.length; i++) { //draw bar rect barRect.left = (int) y_index_startX + barItemWidth * i + barSpace * (i + 1) - (int) leftMoving; barRect.top = topMargin * 2 + (int) (maxHeight * (1.0f - mItems[i].itemValue / maxValue)); barRect.right = barRect.left + barItemWidth; barPaint.setColor(mBarColors[i % mBarColors.length]); canvas.drawRect(barRect, barPaint); //draw type text String typeText = mItems[i].itemType; float textPathStartX = barRect.left + barItemWidth / 2 - (float) (Math.sin(Math.PI / 6)) * textPaint.measureText("好") / 2; float textPathStartY = barRect.bottom; textPath.reset(); textPath.moveTo(textPathStartX, textPathStartY); textPath.lineTo(textPathStartX + (float) (1000 * Math.tan(Math.PI / 6)), textPathStartY + 1000); canvas.drawTextOnPath(typeText, textPath, smallMargin * 1.5f, smallMargin * 2, textPaint); //draw value text String valueText = String.valueOf(mItems[i].itemValue); canvas.drawText(valueText, barRect.left - (textPaint.measureText(valueText) - barItemWidth) / 2, barRect.top - smallMargin, textPaint); } //draw left white space and right white space int c = barPaint.getColor(); barPaint.setColor(BG_COLOR); leftWhiteRect.right = (int) y_index_startX; canvas.drawRect(leftWhiteRect, barPaint); canvas.drawRect(rightWhiteRect, barPaint); barPaint.setColor(c); //draw x-index line. canvas.drawLine( y_index_startX - lineStrokeWidth / 2, x_index_startY, screenW - leftMargin, x_index_startY, linePaint); //draw y-index line. canvas.drawLine( y_index_startX, x_index_startY + lineStrokeWidth / 2, y_index_startX, topMargin / 2, linePaint); canvas.drawBitmap(arrowBmp, null, y_index_arrowRect, null); canvas.save(); canvas.rotate(90, (x_index_arrowRect.left + x_index_arrowRect.right) / 2, (x_index_arrowRect.top + x_index_arrowRect.bottom) / 2); canvas.drawBitmap(arrowBmp, null, x_index_arrowRect, null); canvas.restore(); //draw division value int maxDivisionValueHeight = (int) (maxHeight * 1.0f / maxValue * maxDivisionValue); textPaint.setTextSize(ScreenUtils.dp2px(getContext(), 10)); for (int i = 1; i <= 10; i++) { float startY = barRect.bottom - maxDivisionValueHeight * 0.1f * i; if (startY < topMargin / 2) { break; } canvas.drawLine(y_index_startX, startY, y_index_startX + 10, startY, linePaint); String text = String.valueOf(maxDivisionValue * 0.1f * i); canvas.drawText(text, y_index_startX - textPaint.measureText(text) - 5, startY + textPaint.measureText("0") / 2, textPaint); } } private float leftMoving; private float lastPointX; private float movingLeftThisTime = 0.0f; @Override public boolean onTouchEvent(@NonNull MotionEvent event) { int type = event.getAction(); switch (type) { case MotionEvent.ACTION_DOWN: lastPointX = event.getRawX(); break; case MotionEvent.ACTION_MOVE: float x = event.getRawX(); movingLeftThisTime = lastPointX - x; leftMoving += movingLeftThisTime; lastPointX = x; invalidate(); break; case MotionEvent.ACTION_UP: //smooth scroll new Thread(new SmoothScrollThread(movingLeftThisTime)).start(); break; default: return super.onTouchEvent(event); } return true; } /** * Check the value of leftMoving to ensure that the view is not out of the screen. */ private void checkLeftMoving() { if (leftMoving < 0) { leftMoving = 0; } if (leftMoving > (maxRight - minRight)) { leftMoving = maxRight - minRight; } } public BarChartItemBean[] getItems() { return mItems; } public void setItems(BarChartItemBean[] items) { if (items == null) { throw new RuntimeException("BarChartView.setItems(): the param items cannot be null."); } if (items.length == 0) { return; } this.mItems = items; //Calculate the max value. maxValue = items[0].itemValue; for (BarChartItemBean bean : items) { if (bean.itemValue > maxValue) { maxValue = bean.itemValue; } } //Calculate the max division value. getRange(maxValue, 0); //Get the width of each bar. getBarItemWidth(screenW, items.length); //Refresh the view. invalidate(); } private int maxRight, minRight; /** * Get the width of each bar which is depended on the screenW and item count. */ private void getBarItemWidth(int screenW, int itemCount) { //The min width of the bar is 50dp. int minBarWidth = ScreenUtils.dp2px(getContext(), 40); //The min width of spacing. int minBarSpacing = ScreenUtils.dp2px(getContext(), 30); barItemWidth = (screenW - leftMargin * 2) / (itemCount + 3); barSpace = (screenW - leftMargin * 2 - barItemWidth * itemCount) / (itemCount + 1); if (barItemWidth < minBarWidth || barSpace < minBarSpacing) { barItemWidth = minBarWidth; barSpace = minBarSpacing; } maxRight = (int) y_index_startX + lineStrokeWidth + (barSpace + barItemWidth) * mItems.length; minRight = screenW - leftMargin - barSpace; } /** * Sub the height of status bar and action bar to get the accurate height of screen. */ private void subStatusBarHeight() { //The height of the status bar int statusHeight = ScreenUtils.getStatusBarHeight((Activity) getContext()); //The height of the actionBar ActionBar ab = ((ActionBarActivity) getContext()).getSupportActionBar(); int abHeight = ab == null ? 0 : ab.getHeight(); screenH -= (statusHeight + abHeight); barRect.top = topMargin * 2; barRect.bottom = screenH - topMargin * 3; maxHeight = barRect.bottom - barRect.top; x_index_startY = barRect.bottom; x_index_arrowRect = new Rect(screenW - leftMargin, (int) (x_index_startY - 10), screenW - leftMargin + 10, (int) (x_index_startY + 10)); } //The max and min division value. private float maxDivisionValue, minDivisionValue; //Get the max and min division value by the max and min value in mItems. private void getRange(float maxValue, float minValue) { //max int scale = Utility.getScale(maxValue); float unscaledValue = (float) (maxValue / Math.pow(10, scale)); maxDivisionValue = (float) (getRangeTop(unscaledValue) * Math.pow(10, scale)); y_index_startX = getDivisionTextMaxWidth(maxDivisionValue) + 10; y_index_arrowRect = new Rect((int) (y_index_startX - 5), topMargin / 2 - 20, (int) (y_index_startX + 5), topMargin / 2); } private float getRangeTop(float value) { //value: [1,10) if (value < 1.2) { return 1.2f; } if (value < 1.5) { return 1.5f; } if (value < 2.0) { return 2.0f; } if (value < 3.0) { return 3.0f; } if (value < 4.0) { return 4.0f; } if (value < 5.0) { return 5.0f; } if (value < 6.0) { return 6.0f; } if (value < 8.0) { return 8.0f; } return 10.0f; } /** * Get the max width of the division value text. */ private float getDivisionTextMaxWidth(float maxDivisionValue) { Paint textPaint = new Paint(); textPaint.setTextSize(ScreenUtils.dp2px(getContext(), 10)); float max = textPaint.measureText(String.valueOf(maxDivisionValue * 0.1f)); for (int i = 2; i <= 10; i++) { float w = textPaint.measureText(String.valueOf(maxDivisionValue * 0.1f * i)); if (w > max) { max = w; } } return max; } /** * Use this thread to create a smooth scroll after ACTION_UP. */ private class SmoothScrollThread implements Runnable { float lastMoving; boolean scrolling = true; private SmoothScrollThread(float lastMoving) { this.lastMoving = lastMoving; scrolling = true; } @Override public void run() { while (scrolling) { long start = System.currentTimeMillis(); lastMoving = (int) (0.9f * lastMoving); leftMoving += lastMoving; checkLeftMoving(); postInvalidate(); if (Math.abs(lastMoving) < 5) { scrolling = false; } long end = System.currentTimeMillis(); if (end - start < 20) { try { Thread.sleep(20 - (end - start)); } catch (InterruptedException e) { e.printStackTrace(); } } } } } /** * A model class to keep the bar item info. */ static class BarChartItemBean { private String itemType; private float itemValue; public BarChartItemBean(String itemType, float itemValue) { this.itemType = itemType; this.itemValue = itemValue; } }}
（2）该自定义组件的使用：
package com.sina.appbarchart;import android.support.v7.app.ActionBarActivity;import android.os.Bundle;public class MainActivity extends ActionBarActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); BarChartView barChartView = (BarChartView) findViewById(R.id.bar_chart); BarChartView.BarChartItemBean[] items = new BarChartView.BarChartItemBean[]{ new BarChartView.BarChartItemBean("餐饮", 300), new BarChartView.BarChartItemBean("学习", 200), new BarChartView.BarChartItemBean("旅行", 270), new BarChartView.BarChartItemBean("购物", 110), new BarChartView.BarChartItemBean("人际关系", 120), new BarChartView.BarChartItemBean("娱乐", 80), new BarChartView.BarChartItemBean("投资", 110), new BarChartView.BarChartItemBean("教育", 280) }; barChartView.setItems(items); }}
完整实例代码点击此处本站下载。
更多关于Android相关内容感兴趣的读者可查看本站专题：《Android图形与图像处理技巧总结》、《Android开发入门与进阶教程》、《Android调试技巧与常见问题解决方法汇总》、《Android基本组件用法总结》、《Android视图View技巧总结》、《Android布局layout技巧总结》及《Android控件用法总结》
希望本文所述对大家Android程序设计有所帮助。
梦想，并不奢侈，只要勇敢地迈出第一步。
