c# - Clearing image and draw information on it -

hi want draw information on image in c#. wrote code , works:

bitmap bmp = new bitmap(@"g:\cert_template.png"); graphics g = graphics.fromimage(bmp); g.drawstring(cert_id, new font("b  zar", 3,system.drawing.fontstyle.bold), brushes.black, new point(85, 95)); g.drawstring(date_cert, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(85, 135)); g.drawstring(s1 + s3, new font("b  zar", 4, system.drawing.fontstyle.bold), brushes.black, new point(90, 290)); g.drawstring(s4, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(480, 360)); g.drawstring(date_exam, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(170, 515)); g.drawstring(convert.tostring(mark), new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(520, 600)); g.drawstring(lvl, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(150, 600)); g.drawstring(prvnc, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(170, 780)); g.drawstring(center, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(310, 870)); g.drawstring(inst, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(150, 870)); capturescreen(g,imgcounter); 

my image same information write. i've put code in loop , draws image different information overwrites previous image. want clear image , write on again without overwriting.

edit

after send g function show in picture box:

 private void capturescreen(graphics g,int imgcounter)     {         /*this method captures snapshot of screen ,           * adds imageflowlayoutpanel          */           bmp.save("snap" + imgcounter.tostring() + ".png", system.drawing.imaging.imageformat.png);          //creating picturebox control , add flowlayoutpanel         picturebox temppicturebox = new picturebox();          //generates thumbnail image of specified size         temppicturebox.sizemode = pictureboxsizemode.stretchimage;         temppicturebox.image = bmp.getthumbnailimage(600, 700,                                new image.getthumbnailimageabort(thumbnailcallback),                                intptr.zero);         temppicturebox.size = new system.drawing.size(50,50);          temppicturebox.click += new eventhandler(this.temppicturebox_click);         imageflowlayoutpanel.controls.add(temppicturebox);      }      //this click event used display enlarged images     private void temppicturebox_click(object sender, eventargs e)     {         previewpicturebox.image = ((picturebox)sender).image;     }     public bool thumbnailcallback()     {         return true;     } 

one possibility create temporary bitmap, based on original one, each cycle.

please not made graphics instance disposed when no longer needed (by means of using clause) , note graphics instance build on top of newbitmap not of original one.

also make sure consume newbitmap reference, @ end of cycle instead of bmp reference holds original background.

bitmap bmp = new bitmap(@"g:\cert_template.png");   ( ... ) {    bitmap newbitmap = new bitmap(bmp);   using (graphics g = graphics.fromimage(newbitmap)) {      // somehow alter cert_id, date_cert, etc...      g.drawstring(cert_id, new font("b  zar", 3,system.drawing.fontstyle.bold), brushes.black, new point(85, 95));     g.drawstring(date_cert, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(85, 135));     g.drawstring(s1 + s3, new font("b  zar", 4, system.drawing.fontstyle.bold), brushes.black, new point(90, 290));     g.drawstring(s4, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(480, 360));     g.drawstring(date_exam, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(170, 515));     g.drawstring(convert.tostring(mark), new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(520, 600));     g.drawstring(lvl, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(150, 600));     g.drawstring(prvnc, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(170, 780));     g.drawstring(center, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(310, 870));     g.drawstring(inst, new font("b  zar", 3, system.drawing.fontstyle.bold), brushes.black, new point(150, 870));      // , here newbitmap instance     // (for example: save filename)    }  }