wpf - Showing part of UserControl like CroppedBitmap -

i can't english yet. please understand if can't understand me clearly.

i have huge data table in usercontrol.xaml, downscale usercontrol object showing whole in mainwindow.

i want same size datatable showing of partially usercontrol in mainwindow.

like image display way:

<image>     <image.source>         <croppedbitmap source="<path source image>" sourcerect="20,20,50,50"/>     </image.source> </image> 

showing usercontrol in mainwindow sourcerect.

if understand correctly, have several options. first way, , think easiest use viewbox control.

1. viewbox

the viewbox control inherited decorator used stretch or scale child element, scaled proportionally, ie can not set him size such 300x100.

example

<viewbox width="300"          height="300">      <datagrid>     ...     </datagrid> </viewbox> 

the second way use screen capture of control, show, , if want use croppedbitmap.

2. capturing screen

i found great article pete brown on subject here:

capturing screen images in wpf using gdi, win32 , little wpf interop help

in article example, , looks this:

screencapture

class screencapture {     public static bitmapsource capturefullscreen(bool addtoclipboard)     {         return captureregion(             user32.getdesktopwindow(),             (int)systemparameters.virtualscreenleft,             (int)systemparameters.virtualscreentop,             (int)systemparameters.virtualscreenwidth,             (int)systemparameters.virtualscreenheight,             addtoclipboard);     }      // capture window. doesn't alt-prtscrn version loses window shadow.     // version captures shadow , optionally inserts blank (usually white) area behind     // keep screen shot clean     public static bitmapsource capturewindow(intptr hwnd, bool recolorbackground, color substitutebackgroundcolor, bool addtoclipboard)     {         int32rect rect = getwindowactualrect(hwnd);          window blankingwindow = null;          if (recolorbackground)         {             blankingwindow = new window();              blankingwindow.windowstyle = windowstyle.none;             blankingwindow.title = string.empty;             blankingwindow.showintaskbar = false;             blankingwindow.allowstransparency = true;             blankingwindow.background = new solidcolorbrush(substitutebackgroundcolor);             blankingwindow.show();              int fudge = 20;              blankingwindow.left = rect.x - fudge / 2;             blankingwindow.top = rect.y - fudge / 2;             blankingwindow.width = rect.width + fudge;             blankingwindow.height = rect.height + fudge;          }          // bring to-be-captured window capture foreground         // there's race condition here blanking window         // comes top. hate those. there surely         // non-wpf native solution blanking window         // involves drawing directly on desktop or target window          user32.setforegroundwindow(hwnd);          bitmapsource captured = captureregion(             hwnd,             rect.x,             rect.y,             rect.width,             rect.height,              true);          if (blankingwindow != null)             blankingwindow.close();          return captured;     }      // capture region of full screen     public static bitmapsource captureregion(int x, int y, int width, int height, bool addtoclipboard)     {         return captureregion(user32.getdesktopwindow(), x, y, width, height, addtoclipboard);     }      // capture region of screen, defined hwnd     public static bitmapsource captureregion(         intptr hwnd, int x, int y, int width, int height, bool addtoclipboard)     {         intptr sourcedc = intptr.zero;         intptr targetdc = intptr.zero;         intptr compatiblebitmaphandle = intptr.zero;         bitmapsource bitmap = null;          try         {             // gets main desktop , open windows             sourcedc = user32.getdc(user32.getdesktopwindow());             //sourcedc = user32.getdc(hwnd);             targetdc = gdi32.createcompatibledc(sourcedc);              // create bitmap compatible our target dc             compatiblebitmaphandle = gdi32.createcompatiblebitmap(sourcedc, width, height);              // gets bitmap target device context             gdi32.selectobject(targetdc, compatiblebitmaphandle);              // copy source destination             gdi32.bitblt(targetdc, 0, 0, width, height, sourcedc, x, y, gdi32.srccopy);              // here's wpf glue make work. converts              // hbitmap bitmapsource. love wpf interop functions             bitmap = system.windows.interop.imaging.createbitmapsourcefromhbitmap(                 compatiblebitmaphandle, intptr.zero, int32rect.empty,                 bitmapsizeoptions.fromemptyoptions());              if (addtoclipboard)             {                 //clipboard.setimage(bitmap); // high memory usage large images                 idataobject data = new dataobject();                 data.setdata(dataformats.dib, bitmap, false);                 clipboard.setdataobject(data, false);             }          }         catch (exception ex)         {             throw new screencaptureexception(string.format("error capturing region {0},{1},{2},{3}", x, y, width, height), ex);         }                 {             gdi32.deleteobject(compatiblebitmaphandle);              user32.releasedc(intptr.zero, sourcedc);             user32.releasedc(intptr.zero, targetdc);         }          return bitmap;     }      // accounts border , shadow. serious fudgery here.     private static int32rect getwindowactualrect(intptr hwnd)     {         win32rect windowrect = new win32rect();         win32rect clientrect = new win32rect();          user32.getwindowrect(hwnd, out windowrect);         user32.getclientrect(hwnd, out clientrect);          int sideborder = (windowrect.width - clientrect.width)/2 + 1;             // sooo, yeah.         const int hacktoaccountforshadow = 4;          win32point topleftpoint = new win32point(windowrect.left - sideborder, windowrect.top - sideborder);          //user32.clienttoscreen(hwnd, ref topleftpoint);          int32rect actualrect = new int32rect(             topleftpoint.x,              topleftpoint.y,             windowrect.width + sideborder * 2 + hacktoaccountforshadow,             windowrect.height + sideborder * 2 + hacktoaccountforshadow);          return actualrect;     } } 

example of using:

private void captureregionbutton_click(object sender, routedeventargs e) {     capturedimage.source = screencapture.captureregion(100, 100, 500, 500, true); }  private void capturescreenbutton_click(object sender, routedeventargs e) {     capturedimage.source = screencapture.capturefullscreen(true); }