How Android draws a histogram-------custom view

The effect of the histogram on the sliding of the Seekbar is realized:

Graphic effect:

To customize the view's code:

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 Statscsview (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 Axis brush: Private Paint axislinepaint;//axis horizontal interior dashed brush private paint hlinepaint;//Draw text Brush private paint titlepaint;//Rectangle Brush Style information for the histogram 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 bar Private int[] lastyear;/** * With the new own data need to redraw the view sub-class.  * * Called when the main thread refreshes the control: * This.invalidate (); The meaning of the expiration.  * This.postinvalidate (); A method call that can update a view by a child thread. * * *///updata this year datapublic void Updatethisdata (int[] thisdata) {thisyear = Thisdata;//this.invalidate ();//meaning of expiration.  This.postinvalidate (); A method call that can update a view by a child thread. }//updata last year datapublic void Updatelastdata (int[] lastdata) {lastyear = Lastdata;//this.invalidate ();//meaning of expiration.  This.postinvalidate (); A method call that can update a view by a child thread. }private string[] ytitlesstrings = new string[]{"80000", "60000", "40000", "20000", "0"};p rivate 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 coordinate lines: canvas.drawline (+, x, +, Axi00;//height of the left peripheral: int hperheight = Leftheight/4;hlinepaint.settextalign (Align.center); for (int i=0;i<4;i++) { Canvas.drawline (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<ytitlesstrings.length;i++) {Canvas.drawtext (yTitlesStrings [i], 20+i*hperheight+descent, titlepaint);} 4 plot X week do coordinate 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), titlepaint);} 5 Draw 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 = + Step * (i+1)-10;rect.right = + Step * (i+1) + 10;//current relative height: int RH = (lef Theight * num)/8; rect.top = RH + 20;rect.bottom = 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 = + Step * (i+1)-10;rect.right = + Step * (i+1) + 10;//current relative height: int RH = (lef Theight * num)/8; rect.top = RH + 20;rect.bottom =; 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};p rivate int[] thisData0 = new int[] {40000, 10000, 10000, 20000, 30000,50000, 30000};p rivate int[] lastData1 = new int[] {70000, 60000, 60000, 40000, 5000 0,80000, 80000};p rivate int[] thisData1 = new INt[] {40000, 30000, 30000, 20000, 30000,50000, 30000};p rivate int[] lastData2 = new int[] {70000, 50000, 70000, 80000, 80000,80000, 70000};p rivate int[] thisData2 = new int[] {40000, 10000, 40000, 40000, 30000,40000, 10000};p rivate int[] LASTDATA3 = new int[] {70000, 80000, 70000, 40000, 50000,80000, 40000};p rivate int[] thisData3 = new int[] {10000, 1000 0, 10000, 20000, 30000,10000, 30000}; @Overridepublic void onprogresschanged (SeekBar SeekBar, int progress,boolean Fromus ER) {//TODO auto-generated method Stubint cc = Progress/4;switch (cc) {case 0:statscsview.updatethisdata (LASTDATA0); STA Tscsview.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= "/> <linearlayout android:orientation=" Horizontal "android:layout_width=" Match_parent "android:layout_height=" Wrap_content "android:layout_m arginleft= "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:layou            t_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 oid:gravity= "Center" android:text= "3"/> <textview android:layout_width= "0d            P "android:layout_height=" Wrap_content "android:layout_weight=" 1 "android:gravity=" center " android:text= "4"/> <textview android:layout_width= "0DP" Android:layout_h            eight= "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"/> <textv Iew android:layout_width= "0DP" android:layout_height= "Wrap_content" Android:layout_weigh t= "1" android:gravity= "center" android:text= "ten"/> <textview android:layou T_width= "0DP" android:layout_height= "Wrap_content" android:layout_weight= "1" android:gravity= "center "Android:text= "One"/> <textview android:layout_width= "0DP" android:layout_height= "WRAP_"                    Content "android:layout_weight=" 1 "android:gravity=" center "android:text="/> </LinearLayout> <com.example.coustomviewdemo.statscsview android:id= "@+id/statscsview 1 "android:layout_width=" wrap_content "android:layout_height=" Wrap_content "/></linearlayout>

How Android draws a histogram-------custom view