canvas - Android drawing on bitmap is disappear after touch up event -

i trying implement application image device , add canvas start drawing on using brush , eraser (like snapchat idea) used drawing app base

http://code.tutsplus.com/series/create-a-drawing-app-on-android--cms-704

my problem when draw on bitmap start drawing when finished , touch drawing disappear.

this video problem

https://vid.me/rgnf (try mute sound there noise :) )

‏any appreciated. thank you

public class drawingview extends view {        //drawing path     private path drawpath;     //drawing , canvas paint     private paint drawpaint, canvaspaint;     //initial color     private int paintcolor = 0xff660000;     //canvas     private canvas drawcanvas;     //canvas bitmap     public bitmap canvasbitmap;     //brush sizes     private float brushsize, lastbrushsize;     //erase flag     private boolean erase=false;      public drawingview(context context, attributeset attrs){     super(context, attrs);     setupdrawing(); }      //setup drawing private void setupdrawing(){      //prepare drawing , setup paint stroke properties     brushsize = getresources().getinteger(r.integer.medium_size);     lastbrushsize = brushsize;     drawpath = new path();     drawpaint = new paint();     drawpaint.setcolor(paintcolor);     drawpaint.setantialias(true);     drawpaint.setstrokewidth(brushsize);     drawpaint.setstyle(paint.style.stroke);     drawpaint.setstrokejoin(paint.join.round);     drawpaint.setstrokecap(paint.cap.round);     canvaspaint = new paint(paint.dither_flag); }  //size assigned view @override protected void onsizechanged(int w, int h, int oldw, int oldh) {     super.onsizechanged(w, h, oldw, oldh);     canvasbitmap = bitmap.createbitmap(w, h, bitmap.config.argb_8888);         drawcanvas = new canvas(canvasbitmap);   }  //draw view - called after touch event @override protected void ondraw(canvas canvas) {     super.ondraw(canvas);        canvas.drawbitmap(canvasbitmap, 0, 0, canvaspaint);     canvas.drawpath(drawpath, drawpaint);  }  @override public boolean ontouchevent(motionevent event) {     float touchx = event.getx();     float touchy = event.gety();     //respond down, move , events     switch (event.getaction()) {         case motionevent.action_down:             drawpath.moveto(touchx, touchy);             break;         case motionevent.action_move:             drawpath.lineto(touchx, touchy);             break;         case motionevent.action_up:             drawpath.lineto(touchx, touchy);             drawcanvas.drawpath(drawpath, drawpaint);         drawpath.reset();              break;         default:             return false;     }     //redraw     invalidate();     return true;  }  //update color public void setcolor(string newcolor){     invalidate();     paintcolor = color.parsecolor(newcolor);     drawpaint.setcolor(paintcolor); }  //set brush size public void setbrushsize(float newsize){     float pixelamount = typedvalue.applydimension(typedvalue.complex_unit_dip,             newsize, getresources().getdisplaymetrics());     brushsize=pixelamount;     drawpaint.setstrokewidth(brushsize); }  //get , set last brush size public void setlastbrushsize(float lastsize){     lastbrushsize=lastsize; } public float getlastbrushsize(){     return lastbrushsize; }  //set erase true or false public void seterase(boolean iserase){     erase=iserase;     if(erase) drawpaint.setxfermode(new porterduffxfermode(porterduff.mode.clear));     else drawpaint.setxfermode(null); }  //start new drawing public void startnew(){     drawcanvas.drawcolor(0, porterduff.mode.clear);     invalidate(); } 

}

public class mainactivity extends activity implements onclicklistener {  //custom drawing view private drawingview drawview; //buttons private imagebutton currpaint, drawbtn, erasebtn, newbtn, savebtn; //sizes private float smallbrush, mediumbrush, largebrush; button mbtnpick; int mwidth; int mheight; @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);     mwidth = mheight = 0;     //get drawing view     drawview = (drawingview)findviewbyid(r.id.drawing);      //get palette , first color button     linearlayout paintlayout = (linearlayout)findviewbyid(r.id.paint_colors);     currpaint = (imagebutton)paintlayout.getchildat(0);     currpaint.setimagedrawable(getresources().getdrawable(r.drawable.paint_pressed));      //sizes dimensions     smallbrush = getresources().getinteger(r.integer.small_size);     mediumbrush = getresources().getinteger(r.integer.medium_size);     largebrush = getresources().getinteger(r.integer.large_size);      //draw button     drawbtn = (imagebutton)findviewbyid(r.id.draw_btn);     drawbtn.setonclicklistener(this);      //set initial size     drawview.setbrushsize(mediumbrush);      //erase button     erasebtn = (imagebutton)findviewbyid(r.id.erase_btn);     erasebtn.setonclicklistener(this);      //new button     newbtn = (imagebutton)findviewbyid(r.id.new_btn);     newbtn.setonclicklistener(this);      //save button     savebtn = (imagebutton)findviewbyid(r.id.save_btn);     savebtn.setonclicklistener(this);     // getting reference button "pick image"     mbtnpick = (button) findviewbyid(r.id.button);      // setting onclicklistener button     mbtnpick.setonclicklistener(new onclicklistener() {          @override         public void onclick(view v) {             intent = new intent();             i.settype("image/*");             i.setaction(intent.action_get_content);              intent customchooserintent = intent.createchooser(i, "pick image");             startactivityforresult(customchooserintent, 10);         }     });      if(savedinstancestate!=null){         mwidth = savedinstancestate.getint("width");         mheight = savedinstancestate.getint("height");         bitmap bitmap = savedinstancestate.getparcelable("bitmap");         if(bitmap!=null){             drawview.canvasbitmap=bitmap;         }     } }   @override public boolean oncreateoptionsmenu(menu menu) {     // inflate menu; adds items action bar if present.     getmenuinflater().inflate(r.menu.menu_main, menu);     return true; }  //user clicked paint public void paintclicked(view view){     //use chosen color      //set erase false     drawview.seterase(false);     drawview.setbrushsize(drawview.getlastbrushsize());      if(view!=currpaint){         imagebutton imgview = (imagebutton)view;         string color = view.gettag().tostring();         drawview.setcolor(color);         //update ui         imgview.setimagedrawable(getresources().getdrawable(r.drawable.paint_pressed));         currpaint.setimagedrawable(getresources().getdrawable(r.drawable.paint));         currpaint=(imagebutton)view;     } }  @override public void onclick(view view){      if(view.getid()==r.id.draw_btn){         //draw button clicked         final dialog brushdialog = new dialog(this);         brushdialog.settitle("brush size:");         brushdialog.setcontentview(r.layout.brush_chooser);         //listen clicks on size buttons         imagebutton smallbtn = (imagebutton)brushdialog.findviewbyid(r.id.small_brush);         smallbtn.setonclicklistener(new onclicklistener(){             @override             public void onclick(view v) {                 drawview.seterase(false);                 drawview.setbrushsize(smallbrush);                 drawview.setlastbrushsize(smallbrush);                 brushdialog.dismiss();             }         });         imagebutton mediumbtn = (imagebutton)brushdialog.findviewbyid(r.id.medium_brush);         mediumbtn.setonclicklistener(new onclicklistener(){             @override             public void onclick(view v) {                 drawview.seterase(false);                 drawview.setbrushsize(mediumbrush);                 drawview.setlastbrushsize(mediumbrush);                 brushdialog.dismiss();             }         });         imagebutton largebtn = (imagebutton)brushdialog.findviewbyid(r.id.large_brush);         largebtn.setonclicklistener(new onclicklistener(){             @override             public void onclick(view v) {                 drawview.seterase(false);                 drawview.setbrushsize(largebrush);                 drawview.setlastbrushsize(largebrush);                 brushdialog.dismiss();             }         });         //show , wait user interaction         brushdialog.show();     }     else if(view.getid()==r.id.erase_btn){         //switch erase - choose size         final dialog brushdialog = new dialog(this);         brushdialog.settitle("eraser size:");         brushdialog.setcontentview(r.layout.brush_chooser);         //size buttons         imagebutton smallbtn = (imagebutton)brushdialog.findviewbyid(r.id.small_brush);         smallbtn.setonclicklistener(new onclicklistener(){             @override             public void onclick(view v) {                 drawview.seterase(true);                 drawview.setbrushsize(smallbrush);                 brushdialog.dismiss();             }         });         imagebutton mediumbtn = (imagebutton)brushdialog.findviewbyid(r.id.medium_brush);         mediumbtn.setonclicklistener(new onclicklistener(){             @override             public void onclick(view v) {                 drawview.seterase(true);                 drawview.setbrushsize(mediumbrush);                 brushdialog.dismiss();             }         });         imagebutton largebtn = (imagebutton)brushdialog.findviewbyid(r.id.large_brush);         largebtn.setonclicklistener(new onclicklistener(){             @override             public void onclick(view v) {                 drawview.seterase(true);                 drawview.setbrushsize(largebrush);                 brushdialog.dismiss();             }         });         brushdialog.show();     }     else if(view.getid()==r.id.new_btn){         //new button     alertdialog.builder newdialog = new alertdialog.builder(this);         newdialog.settitle("new drawing");         newdialog.setmessage("start new drawing (you lose current drawing)?");         newdialog.setpositivebutton("yes", new dialoginterface.onclicklistener(){             public void onclick(dialoginterface dialog, int which){                 drawview.startnew();                 dialog.dismiss();             }         });         newdialog.setnegativebutton("cancel", new dialoginterface.onclicklistener(){             public void onclick(dialoginterface dialog, int which){                 dialog.cancel();             }         });          newdialog.show();       }     else if(view.getid()==r.id.save_btn){         //save drawing         alertdialog.builder savedialog = new alertdialog.builder(this);         savedialog.settitle("save drawing");         savedialog.setmessage("save drawing device gallery?");         savedialog.setpositivebutton("yes", new dialoginterface.onclicklistener(){             public void onclick(dialoginterface dialog, int which){                 //save drawing                 drawview.setdrawingcacheenabled(true);                 //attempt save                 string imgsaved = mediastore.images.media.insertimage(                         getcontentresolver(), drawview.getdrawingcache(),                         uuid.randomuuid().tostring()+".png", "drawing");                 //feedback                 if(imgsaved!=null){                     toast savedtoast = toast.maketext(getapplicationcontext(),                             "drawing saved gallery!", toast.length_short);                     savedtoast.show();                 }                 else{                     toast unsavedtoast = toast.maketext(getapplicationcontext(),                             "oops! image not saved.", toast.length_short);                     unsavedtoast.show();                 }                 drawview.destroydrawingcache();             }         });         savedialog.setnegativebutton("cancel", new dialoginterface.onclicklistener(){             public void onclick(dialoginterface dialog, int which){                 dialog.cancel();             }         });         savedialog.show();     } } // courtesy : developer.android.com/training/displaying-bitmaps/load-bitmap.html public static int calculateinsamplesize(          bitmapfactory.options options, int reqwidth, int reqheight) {     // raw height , width of image     final int height = options.outheight;     final int width = options.outwidth;     int insamplesize = 1;      if (height > reqheight || width > reqwidth) {          // calculate ratios of height , width requested height , width         final int heightratio = math.round((float) height / (float) reqheight);         final int widthratio = math.round((float) width / (float) reqwidth);          // choose smallest ratio insamplesize value, guarantee         // final image both dimensions larger or equal         // requested height , width.         insamplesize = heightratio < widthratio ? heightratio : widthratio;     }      return insamplesize; }   private bitmap getbitmapfromuri(uri data){     bitmap bitmap = null;      // starting fetch image file     inputstream is=null;     try {          = getcontentresolver().openinputstream(data);          // first decode injustdecodebounds=true check dimensions         final bitmapfactory.options options = new bitmapfactory.options();         options.injustdecodebounds = true;          // bitmapfactory.decodefile(path, options);         bitmapfactory.decodestream(is, null, options);          // calculate insamplesize         options.insamplesize = calculateinsamplesize(options, mwidth, mheight);          // decode bitmap insamplesize set         options.injustdecodebounds = false;          = getcontentresolver().openinputstream(data);          bitmap = bitmapfactory.decodestream(is,null,options);           if(bitmap==null){             toast.maketext(getbasecontext(), "image not loaded",toast.length_short).show();             return null;         }          is.close();     }catch (ioexception e) {         // todo auto-generated catch block         e.printstacktrace();     }catch(nullpointerexception e){         e.printstacktrace();     }     return bitmap; }   @override protected void onactivityresult(int requestcode, int resultcode, intent intent) {     // todo auto-generated method stub     super.onactivityresult(requestcode, resultcode, intent);     if (requestcode == 10 && resultcode == result_ok && null != intent) {         uri data = intent.getdata();         bitmap bitmap = getbitmapfromuri(data);         if(bitmap!=null){             drawview.canvasbitmap=bitmap;         }     } }   @override public void onwindowfocuschanged(boolean hasfocus) {     // todo auto-generated method stub     super.onwindowfocuschanged(hasfocus);     mwidth = drawview.getwidth();     mheight = drawview.getheight(); }  @override protected void onsaveinstancestate(bundle outstate) {      outstate.putint("width", mwidth);     outstate.putint("height", mheight);     if(drawview.canvasbitmap!=null){         outstate.putparcelable("bitmap", drawview.canvasbitmap);     }      super.onsaveinstancestate(outstate);  } 

}

what doing getting canvas of image via drawcanvas object , drawing on canvas , drawing path on it.

try way, canvas of image via drawcanvas object , draw path on , draw resultant image on canvas. see following code

// draw path on canvasbitmap drawcanvas.drawpath(drawpath, drawpaint);  //now draw canvasbitmap on canvas canvas.drawbitmap(canvasbitmap, 0, 0, canvaspaint);  //canvas.drawpath(drawpath, drawpaint); // no need line 

what happening draw path on canvas on action_up , reset path object, see following code of yours

    case motionevent.action_up:         drawpath.lineto(touchx, touchy);         drawcanvas.drawpath(drawpath, drawpaint);     drawpath.reset(); 

according android reset() follows:

clear lines , curves path, making empty.

after above code call invalidate(); clears canvas , redraw empty path object because have called drawpath.reset(). main reason why lines disappearing.