c# - PictureBox increases in size with the same inputs when calling FitToScreen() -

i’m having issue functionality in program. supposed fit image screen, does, subsequent calls function cause image increase in size ever slightly. becomes apparent after issuing command 5 times. here’s example gif of bug:

the source program hosted here. make sure in "issue1" branch, geared toward issue. self-contained; download, compile, run. includes test "comic" use.

the fittoscreen() functionality stored in mainwindow.cs:

private void fittoscreen() {     //todo: frameheight (aka height of picture box's tablelayout cell) keeps growing subsequent calls...     // ensure comic has been loaded     if (!_comiccontroller.comicloaded())     {         messagebox.show("no comic loaded!", "cinemastrips");         return;     }      // make window's height tall screen     var screenheight = screen.primaryscreen.workingarea.height;     height = screenheight;     var frameheight = tablelayoutpanel1.getrowheights()[1];      // send comiccontroller size needs try , fit     width = _comiccontroller.fitcomicviewtowindow(frameheight);      // put window location @ 0 height , center width of screen     top = 0;     var screenwidth = screen.primaryscreen.workingarea.width;     left = (screenwidth - width)/2; } 

the call width = _comiccontroller.fitcomicviewtowindow(frameheight) stored in comiccontroller.cs , allows comic displayed correct aspect ratio, based on height given, , returns width window use:

public int fitcomicviewtowindow(int frameheight) {     //take account in margins around comicview     var marginedheight = frameheight - comicview.margin.vertical;     //return image's width if height smaller windowheight     if (marginedheight >= _comic.currentpage.height /* <-- law of demeter?*/) return _comic.currentpage.width;      //calculate aspect ratio     var aspectedwidth = marginedheight * _comic.currentpage.width / _comic.currentpage.height;      //make sure actual page fills inside of picturebox when resizes     comicview.sizemode = pictureboxsizemode.stretchimage;     comicview.size = new size(aspectedwidth, marginedheight);      //return aspected width window can resize     return aspectedwidth; } 

and that's how works! some things note: picturebox displays comic added tablelayoutpanel during initialization. tlp row's height stores picturebox used calculations, though of not modified. stepping through debugger shows row's height increases 1 pixel every function call.

any appreciated , please let me know think!

the answer turned out simpler realized; when getting frameheight, 1 must remember remove additional 1 pixel. gives "inner" height of table layout panel's row containing our picturebox. implementation, removed pixel before passing frameheight width = _comiccontroller.fitcomicviewtowindow(frameheight) call.

the fittoscreen() produces predictable results.