How does Android draw a bar chart? android bar chart

How does Android draw a bar chart? android bar chart

The following figure shows how the bar chart changes based on the SeekBar Sliding Mode:

Effect:

Code for custom View:

Package com. example. coustomviewdemo; import android. r. color; import android. content. context; import android. graphics. canvas; import android. graphics. color; import android. graphics. paint; import android. graphics. rect; import android. graphics. paint. align; import android. graphics. paint. fontMetrics; import android. util. attributeSet; import android. view. view; public class StatscsView extends View {public StatscsVi Ew (Context context) {super (context); // TODO Auto-generated constructor stubinit (context, null);} public StatscsView (Context context, AttributeSet attrs) {super (context, attrs); // TODO Auto-generated constructor stubinit (context, attrs);} // axis brush: private Paint axisLinePaint; // horizontal dotted line inside the Axis brush private Paint hLinePaint; // Paint brush private Paint titlePaint for text painting; // style information of the rectangular Paint bar chart private Paint recPaint; private void Init (Context context, AttributeSet attrs) {axisLinePaint = new Paint (); hLinePaint = new Paint (); titlePaint = new Paint (); recPaint = new Paint (); axisLinePaint. setColor (Color. DKGRAY); hLinePaint. setColor (Color. LTGRAY); titlePaint. setColor (Color. BLACK);} // 7 private int [] thisYear; // 7 private int [] lastYear;/*** re-paint the new data with the View subclass. ** Called when the main thread refreshes the control: * this. invalidate (); invalid meaning. * This. postInvalidate (); you can call a subthread to update the view method. * ** // Updata this year datapublic void updateThisData (int [] thisData) {thisYear = thisData; // this. invalidate (); // invalid meaning. This. postInvalidate (); // you can call a method to update the view in a subthread .} // Updata last year datapublic void updateLastData (int [] lastData) {lastYear = lastData; // this. invalidate (); // invalid meaning. This. postInvalidate (); // you can call a method to update the view in a subthread .} Private String [] yTitlesStrings = new String [] {"80000", "60000", "40000", "20000", "0 "}; private String [] xTitles = new String [] {"1", "2", "3", "4", "5", "6", "7 "}; @ Overrideprotected void onDraw (Canvas canvas) {// TODO Auto-generated method stubsuper. onDraw (canvas); int width = getWidth (); int height = getHeight (); // 1 draw the coordinate line: canvas. drawLine (100, 10,100,320, axisLinePaint); canvas. drawLine (100,320, width-10, 320, axisLinePaint); // 2 draw the horizontal line inside the coordinate int leftHeight = 300; // the height to be divided on the left peripheral: int hPerHeight = leftHeight/4; hLinePaint. setTextAlign (Align. CENTER); for (int I = 0; I <4; I ++) {canvas. drawLine (100, 20 + I * hPerHeight, width-10, 20 + I * hPerHeight, hLinePaint);} // 3 draw Y week coordinates FontMetrics metrics = titlePaint. getFontMetrics (); int descent = (int) metrics. descent; titlePaint. setTextAlign (Align. RIGHT); for (int I = 0; I <yTitlesStrin Gs. length; I ++) {canvas. drawText (yTitlesStrings [I], 80, 20 + I * hPerHeight + descent, titlePaint);} // 4 draw X-week coordinates int xAxisLength = width-110; int columCount = xTitles. length + 1; int step = xAxisLength/columCount; for (int I = 0; I <columCount-1; I ++) {canvas. drawText (xTitles [I], 100 + step * (I + 1), 360, titlePaint);} // 5 draw a rectangle if (thisYear! = Null & thisYear. length> 0) {int thisCount = thisYear. length; for (int I = 0; I <thisCount; I ++) {int value = thisYear [I]; int num = 8-value/10000; recPaint. setColor (0xFF1078CF); Rect rect = new Rect (); rect. left = 100 + step * (I + 1)-10; rect. right = 100 + step * (I + 1) + 10; // current relative height: int rh = (leftHeight * num)/8; rect. top = rh + 20; rect. bottom = 320; canvas. drawRect (rect, recPaint) ;}} if (lastYear! = Null & lastYear. length> 0) {int thisCount = lastYear. length; for (int I = 0; I <thisCount; I ++) {int value = lastYear [I]; int num = 8-value/10000; recPaint. setColor (0xFFAA1122); Rect rect = new Rect (); rect. left = 100 + step * (I + 1)-10; rect. right = 100 + step * (I + 1) + 10; // current relative height: int rh = (leftHeight * num)/8; rect. top = rh + 20; rect. bottom = 320; canvas. drawRect (rect, recPaint );}}}}

Activity:

package com.example.coustomviewdemo;import android.app.Activity;import android.os.Bundle;import android.widget.SeekBar;import android.widget.SeekBar.OnSeekBarChangeListener;public class StatscsActivity extends Activity implementsOnSeekBarChangeListener {private SeekBar seekBar;private StatscsView statscsView;public StatscsActivity() {// TODO Auto-generated constructor stub}@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.sycts);seekBar = (SeekBar) this.findViewById(R.id.seekBar);statscsView = (StatscsView) this.findViewById(R.id.statscsView1);// seekerBarseekBar.setOnSeekBarChangeListener(this);}private int[] lastData0 = new int[] { 70000, 10000, 20000, 40000, 50000,80000, 40000 };private int[] thisData0 = new int[] { 40000, 10000, 10000, 20000, 30000,50000, 30000 };private int[] lastData1 = new int[] { 70000, 60000, 60000, 40000, 50000,80000, 80000 };private int[] thisData1 = new int[] { 40000, 30000, 30000, 20000, 30000,50000, 30000 };private int[] lastData2 = new int[] { 70000, 50000, 70000, 80000, 80000,80000, 70000 };private int[] thisData2 = new int[] { 40000, 10000, 40000, 40000, 30000,40000, 10000 };private int[] lastData3 = new int[] { 70000, 80000, 70000, 40000, 50000,80000, 40000 };private int[] thisData3 = new int[] { 10000, 10000, 10000, 20000, 30000,10000, 30000 };@Overridepublic void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {// TODO Auto-generated method stubint cc = progress / 4;switch (cc) {case 0:statscsView.updateThisData(lastData0);statscsView.updateLastData(thisData0);break;case 1:statscsView.updateThisData(lastData1);statscsView.updateLastData(thisData1);break;case 2:statscsView.updateThisData(lastData2);statscsView.updateLastData(thisData2);break;case 3:statscsView.updateThisData(lastData3);statscsView.updateLastData(thisData3);break;default:break;}}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}}

Main. xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >        <SeekBar         android:id="@+id/seekBar"        android:layout_width="match_parent"        android:layout_height="wrap_content"         android:max="48"                />        <LinearLayout         android:orientation="horizontal"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_marginLeft="10dp"        android:gravity="center"        >                <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="1"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="2"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="3"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="4"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="5"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="6"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="7"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="8"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="9"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="10"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="11"            />        <TextView             android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1" android:gravity="center"            android:text="12"            />                    </LinearLayout>        <com.example.coustomviewdemo.StatscsView        android:id="@+id/statscsView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content" /></LinearLayout>

How can I create a bar chart for android to display listening events for each column?

Whether your image is self-painted or an image. If your View is self-painted, listen to it.
Listening for touchEvent, rewriting onKeyDown and other functions

How does Android create a bar chart?

Android bar chart
Package org. achartengine. chartdemo. demo. chart;
Import org. achartengine. chartFactory; import org. achartengine. chart. barChart. type; import org. achartengine. chartdemo. demo. r; import org. achartengine. model. rangeCategorySeries; import org. achartengine. model. XYMultipleSeriesDataset; import org. achartengine. renderer. simpleSeriesRenderer; import org. achartengine. renderer. XYMultipleSeriesRenderer; import android. app. activity; import android. graphics. color; import android. graphics. paint. align; import android. OS. bundle; import android. view. view;

Public class TemperatureChart extends Activity {
@ Overrideprotected void onCreate (Bundle savedInstanceState) {// TODO Auto-generated method stub super. onCreate (savedInstanceState); setContentView (R. layout. main );
Double [] minValues = new double [] {55,50, 40,30, 20,20, 30,40, 50,55}; double [] maxValues = new double [] {95,100, 95,85 };
// Used to save the point set data, including the X and Y coordinates of each curve XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset (); // use RangeCategorySeries = new RangeCategorySeries ("your consumption record for the current month") with the bar chart; // the text at the bottom of the chart in parentheses is for (int k = 0; k <minValues. length; k ++) {series. add (minValues [k], maxValues [k]);} dataset. addSeries (series. toXYSeries (); int [] colors = new int [] {Color. CYAN}; // blue-green XYMultipleSeriesRenderer renderer = buildBarRenderer (colors); setChartSettings (renderer, "title", "x", "y", 0.5, 12.5, 0,150, Color. GRAY, Color. LTGRAY); // color pre-paint ...... remaining full text>