做响应式网站所用的代码,网站建设如何财务处理,wordpress阿里云图片,凡客的官网Android上实现柱状图算法实现 第一步#xff1a; 获取Android设备的屏幕大小 第二步#xff1a; 在View对象中使用Canvas绘制蓝色边框与白色背景XY轴两条线#xff0c;代码如下 第三步#xff1a; 绘制柱状图标题 第四步#xff1a; 根据数据集计算出每个系列数据所占X轴的… Android上实现柱状图算法实现 第一步 获取Android设备的屏幕大小 第二步 在View对象中使用Canvas绘制蓝色边框与白色背景XY轴两条线代码如下 第三步 绘制柱状图标题 第四步 根据数据集计算出每个系列数据所占X轴的大小来绘制X 数据名称 第五步 根据数据集计算出数据单元大小并将数据单元映射为像素单元绘制出标尺单位与 背景虚线 第六步 根据数据集的值来计算出柱状图的高度以及柱状图的宽度大小映射为像素值以后 完成绘制。 程序效果图 技术点详解 在View中获取Android设备屏幕大小的方法为 // get default screen size from system service WindowManager wm (WindowManager) this.getContext().getSystemService(Context.WINDOW_SERVICE); Display display wm.getDefaultDisplay(); int width display.getWidth();在Activity中获取Android设备屏幕大小的方法为 DisplayMetrics displaymetrics new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(displaymetrics); int height displaymetrics.heightPixels; int wwidth displaymetrics.widthPixels;计算X轴中每个系列所占大小的代码为 int count series.getSeriesCount(); int xUnit (width - 2 - xOffset)/count;其中xOffset, yOffset值计算公式如下 int xOffset (int)(width * 0.1); int yOffset (int)(height * 0.1);计算每个系类中每个柱状图之间缝隙大小的为 int barWidth (int)(xUnit/Math.pow(itemList.size(),2)); int startPos xOffset 2 xPadding xUnit*i; int interval barWidth/2;其中barWidth表示每个柱状矩形的宽度interval表示同一数据系列中表示 每个矩形之间的间隔。 另外一些技巧 1.在起始位置填充额外的长度大小让柱状图不会紧贴Y轴看上去更美观 默认的xPadding值等于10 int xPadding 10; 2.使用反锯齿功能让图形看上去更柔和启用反锯齿功能的代码为 myPaint.setAntiAlias(true);3.当要填充一个矩形时候设置Paint的Style myPaint.setStyle(Style.FILL);当要绘制一个边框矩形时候设置Paint的Style myPaint.setStyle(Style.STROKE);4.如何绘制虚线(dotted line, dash line),使用DashPathEffect对象 本文中的实现代码如下 myPaint.setStyle(Style.STROKE); myPaint.setStrokeWidth(1); myPaint.setColor(Color.LTGRAY); myPaint.setPathEffect(new DashPathEffect(new float[] {1,3}, 0));相关的Class说明 DataSeries对象用来构造数据集根据key来得到对应的数据系列。源代码如下 package com.gloomyfish; import java.util.HashMap; import java.util.List; public class DataSeries { private HashMapString, ListDataElement map; public DataSeries() { map new HashMapString, ListDataElement(); } public void addSeries(String key, ListDataElement itemList) { map.put(key, itemList); } public ListDataElement getItems(String key) { return map.get(key); } public int getSeriesCount() { return map.size(); } public String[] getSeriesKeys() { return map.keySet().toArray(new String[0]); } } DataElement数据元素属性有数据名称值大小显示颜色等源代码如下 package com.gloomyfish; public class DataElement { public DataElement(String name, float value, int color) { this.itemName name; this.value value; this.color color; } public String getItemName() { return itemName; } public void setItemName(String itemName) { this.itemName itemName; } public float getValue() { return value; } public void setValue(float value) { this.value value; } public void setColor(int color) { this.color color; } public int getColor() { return this.color; } private String itemName; private int color; private float value; } BarChartPanel独立的组件继承自Android View对象是柱状图的图形组件可以为 任何版本的Android使用。源代码如下 package com.gloomyfish; import java.text.NumberFormat; import java.util.ArrayList; import java.util.List; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.DashPathEffect; import android.graphics.Paint; import android.graphics.Paint.Style; import android.view.Display; import android.view.View; import android.view.WindowManager; public class BarChartPanel extends View{ private String plotTitle; private DataSeries series; public final static int[] platterTable new int[]{Color.RED, Color.BLUE, Color.GREEN, Color.YELLOW, Color.CYAN}; public BarChartPanel(Context context, String plotTitle) { this(context); this.plotTitle plotTitle; } public BarChartPanel(Context context) { super(context); } public void setSeries(DataSeries series) { this.series series; } Override public void onDraw(Canvas canvas) { // get default screen size from system service WindowManager wm (WindowManager) this.getContext().getSystemService(Context.WINDOW_SERVICE); Display display wm.getDefaultDisplay(); int width display.getWidth(); // remove application title height int height display.getHeight() - 80; System.out.println(width width); System.out.println(height height); // draw background Paint myPaint new Paint(); myPaint.setColor(Color.BLUE); myPaint.setStrokeWidth(2); canvas.drawRect(0, 0, width, height, myPaint); myPaint.setColor(Color.WHITE); myPaint.setStrokeWidth(0); canvas.drawRect(2, 2, width-2, height-2, myPaint); // draw XY Axis int xOffset (int)(width * 0.1); int yOffset (int)(height * 0.1); System.out.println(xOffset xOffset); myPaint.setColor(Color.BLACK); myPaint.setStrokeWidth(2); canvas.drawLine(2xOffset, height-2-yOffset, 2xOffset, 2, myPaint); canvas.drawLine(2xOffset, height-2-yOffset, width-2, height-2-yOffset, myPaint); // draw text title myPaint.setAntiAlias(true); myPaint.setStyle(Style.FILL); canvas.drawText(plotTitle, (width-2)/4, 30, myPaint); // draw data series now...... if(series null) { getMockUpSeries(); } int xPadding 10; if(series ! null) { int count series.getSeriesCount(); int xUnit (width - 2 - xOffset)/count; String[] seriesNames series.getSeriesKeys(); for(int i0; iseriesNames.length; i) { canvas.drawText(seriesNames[i], xOffset 2 xPadding xUnit*i, height-yOffset 10, myPaint); } // Y Axis markers float min 0, max 0; for(int i0; iseriesNames.length; i) { ListDataElement itemList series.getItems(seriesNames[i]); if(itemList ! null itemList.size() 0) { for(DataElement item : itemList) { if(item.getValue() max) { max item.getValue(); } if(item.getValue() min) { min item.getValue(); } } } } int yUnit 22; int unitValue (height-2-yOffset)/yUnit; myPaint.setStyle(Style.STROKE); myPaint.setStrokeWidth(1); myPaint.setColor(Color.LTGRAY); myPaint.setPathEffect(new DashPathEffect(new float[] {1,3}, 0)); float ymarkers (max-min)/yUnit; NumberFormat nf NumberFormat.getInstance(); nf.setMinimumFractionDigits(2); nf.setMaximumFractionDigits(2); for(int i0; i20; i) { canvas.drawLine(2xOffset, height-2-yOffset - (unitValue * (i1)), width-2, height-2-yOffset - (unitValue * (i1)), myPaint); } // clear the path effect myPaint.setColor(Color.BLACK); myPaint.setStyle(Style.STROKE); myPaint.setStrokeWidth(0); myPaint.setPathEffect(null); for(int i0; i20; i) { float markValue ymarkers * (i1); canvas.drawText(nf.format(markValue), 3, height-2-yOffset - (unitValue * (i1)), myPaint); } // draw bar chart now myPaint.setStyle(Style.FILL); myPaint.setStrokeWidth(0); String maxItemsKey null; int maxItem 0; for(int i0; iseriesNames.length; i) { ListDataElement itemList series.getItems(seriesNames[i]); int barWidth (int)(xUnit/Math.pow(itemList.size(),2)); int startPos xOffset 2 xPadding xUnit*i; int index 0; int interval barWidth/2; if(itemList.size() maxItem) { maxItemsKey seriesNames[i]; maxItem itemList.size(); } for(DataElement item : itemList) { myPaint.setColor(item.getColor()); int barHeight (int)((item.getValue()/ymarkers) * unitValue); canvas.drawRect(startPos barWidth*index interval*index, height-2-yOffset-barHeight, startPos barWidth*index interval*index barWidth, height-2-yOffset, myPaint); index; } } ListDataElement maxItemList series.getItems(maxItemsKey); int itemIndex 0; int basePos 10; for(DataElement item : maxItemList) { myPaint.setColor(item.getColor()); canvas.drawRect(basePos itemIndex * 10, height-yOffset 15, basePos itemIndex * 10 10, height-yOffset 30, myPaint); myPaint.setColor(Color.BLACK); canvas.drawText(item.getItemName(), basePos (itemIndex1) * 10, height-yOffset 25, myPaint); itemIndex; basePos basePos xUnit*itemIndex; } } } public DataSeries getMockUpSeries() { series new DataSeries(); ListDataElement itemListOne new ArrayListDataElement(); itemListOne.add(new DataElement(shoes,120.0f, platterTable[0])); itemListOne.add(new DataElement(jacket,100.0f, platterTable[1])); series.addSeries(First Quarter, itemListOne); ListDataElement itemListTwo new ArrayListDataElement(); itemListTwo.add(new DataElement(shoes,110.0f, platterTable[0])); itemListTwo.add(new DataElement(jacket,50.0f, platterTable[1])); series.addSeries(Second Quarter, itemListTwo); ListDataElement itemListThree new ArrayListDataElement(); itemListThree.add(new DataElement(shoes,100.0f, platterTable[0])); itemListThree.add(new DataElement(jacket,280.0f, platterTable[1])); series.addSeries(Third Quarter, itemListThree); ListDataElement itemListFour new ArrayListDataElement(); itemListFour.add(new DataElement(shoes,120.0f, platterTable[0])); itemListFour.add(new DataElement(jacket,100.0f, platterTable[1])); series.addSeries(Fourth Quarter, itemListFour); return series; } } BarChartDemoActivity测试该组件的Android Activity启动类。 package com.gloomyfish; import android.app.Activity; import android.os.Bundle; public class BarChartDemoActivity extends Activity { /** Called when the activity is first created. */ Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new BarChartPanel(this, Quarter Vs. sales volume)); } }转载请务必注明出处 转载于:https://blog.51cto.com/gloomyfish/1400363