Problem with Deleting the GDI object

I want to create my own pen and brush, draw an ellipse, and then delete the brush and pen.

The problem is that when I run my program, the font size of my clock in the system tray, and font size of the windows shows in the task bar also changes. Even when I end my program, it still remains the same until I restart my system. Here is a little hint of what I am doing:

Code:

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HPEN hpen;
HBRUSH hbrush;
hpen = CreatePen(PS_SOLID, 1, RGB(255,0,0));
hbrush = CreateSolidBrush(RGB(0,255,255));

SelectObject(memhdc, hpen);
SelectObject(memhdc, hbrush);

Ellipse(memhdc, 0,0, 20,20);

DeleteObject(hbrush);
DeleteObject(hpen);

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Do you know why it's effecting my whole system?
If you want the full source code then please reply!

Code:

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HBRUSH hOldBr = (HBRUSH)SelectObject(memhdc, hbrush);
HPEN hOldPen = (HPEN)SelectObject(memhdc, hpen);

Ellipse(memhdc, 0,0, 20,20);

SelectObject(memhdc, hOldBr);
SelectObject(memhdc, hOldPen);

DeleteObject(hbrush);
DeleteObject(hpen);

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You need to tidy the DC up first.

But it is not drawing anything in colour. The "memhdc" is a memory hdc and I transfered a bitmap onto it to draw something on it. But when I dont draw anything, it is filled with just 2 types of colours - white and black, right?
How can erase the background and draw with the colours on it - I also want to draw text with different colours.

I know there is an API call called "SetDCPenColor" in windows 2000 but its not available in windows 98 or lower


Please dont ignore that!

It doesn't matter. Bizarre things happen (as documented in MSDN) if you delete a GDI object without removing it from the DC. If you have a memory DC why not set it up when your program loads? That way you won't need SelectObject every time WM_PAINT arrives (speed things up a bit).

Why can't I make a function to make bitmap with the text in it. As I said above, I can't really change the colour in the memory DC and I cannot delete the background from that DC. I want to work with that as I do do with my windows's DC. If you want the whole source code then here it is:

Code:

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#include <windows.h>
#include <wingdi.h>
#include "resource.h"

static char g_szClassName[] = "MyWindowClass";
static HINSTANCE hinst = NULL;
#define ID_FONT1 2
//Function to stretch the bitmap for our menus
HBITMAP StretchBitmap(HBITMAP hbitmap);
//Function to create you own bitmap any type of font

HBITMAP CreateFontBitmap(char *sztext,int fontwidth,int fontheight,char *fontface,
                                                BOOL fontbold, BOOL fontitalic, BOOL fontunderline,
                                                BOOL fontstrikethrough, COLORREF fontcolour);
//Public handle of our window
HWND hwnd;

//Public variables to use in our menus :

HMENU hmenu, hmenupopup;
HBITMAP hfilebmp, heditbmp;


LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
  LPSTR lpCmdLine, int nCmdShow)
{



  WNDCLASSEX WndClass;
  MSG Msg;

  hinst = hInstance;

  WndClass.cbSize        = sizeof(WNDCLASSEX);
  WndClass.style        = CS_HREDRAW | CS_VREDRAW;
  WndClass.lpfnWndProc  = WndProc;
  WndClass.cbClsExtra    = 0;
  WndClass.cbWndExtra    = 0;
  WndClass.hInstance    = hinst;
  WndClass.hIcon        = LoadIcon(NULL, IDI_APPLICATION);
  WndClass.hCursor      = LoadCursor(NULL, IDC_ARROW);
  WndClass.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
  WndClass.lpszMenuName  = NULL;
  WndClass.lpszClassName = g_szClassName;
  WndClass.hIconSm      = LoadIcon(NULL, IDI_APPLICATION);

  if(!RegisterClassEx(&WndClass))
  {
      MessageBox(0, "Window Registration Failed! :(", "Error!",
        MB_ICONEXCLAMATION | MB_OK | MB_SYSTEMMODAL);
      return 0;
  }


  //Create a Menu with first "File" Menu Bar

  hmenu = CreateMenu();

  //Loads the bitmaps from the resource
  hfilebmp = StretchBitmap(LoadBitmap(hinst, MAKEINTRESOURCE(FILEBMP)));
  heditbmp = StretchBitmap(LoadBitmap(hinst, MAKEINTRESOURCE(EDITBMP)));
  /*Loads the whole "File" Menubar and sets it as a popup menu
  for our main menu*/
  hmenupopup = LoadMenu(hinst, MAKEINTRESOURCE(FILEMENU));
  AppendMenu(hmenu, MF_BITMAP| MF_POPUP, (int) hmenupopup, (PSTR)(LONG) hfilebmp);
  /*Loads the whole "Edit" Menubar and sets it as a popup menu
  for our main menu*/
  hmenupopup = LoadMenu(hinst, MAKEINTRESOURCE(EDITMENU));
  AppendMenu(hmenu, MF_BITMAP| MF_POPUP, (int) hmenupopup, (PSTR)(LONG) heditbmp);

  hmenupopup = CreateMenu();

  AppendMenu(hmenupopup, MF_BITMAP, ID_FONT1, (PSTR)(LONG) CreateFontBitmap("The Text",52,152,"Verdana", FALSE,FALSE,FALSE,FALSE, RGB(255,0,0)));
  AppendMenu(hmenu, MF_POPUP | MF_STRING,(int)hmenupopup,"DF");


  hwnd = CreateWindowEx(
      NULL,
      g_szClassName,
      "Coloured Shapes Generator",
      WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, CW_USEDEFAULT, 320, 240,
      NULL, hmenu, hinst, NULL);

  if(hwnd == NULL)
  {
      MessageBox(0, "Window Creation Failed! :(", "Error!",
        MB_ICONEXCLAMATION | MB_OK | MB_SYSTEMMODAL);
      return 0;
  }


  ShowWindow(hwnd, nCmdShow);
  UpdateWindow(hwnd);
       
 
  while(GetMessage(&Msg, NULL, 0, 0))
  {
      TranslateMessage(&Msg);
      DispatchMessage(&Msg);
  }

  //Deletes the bitmaps to free the "Resources"
  DeleteObject(heditbmp);
  DeleteObject(hfilebmp);

  return Msg.wParam;
}






LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wparam, LPARAM lparam)
{
       
  switch(Message)
  {
 
      case WM_CLOSE:
        DestroyWindow(hwnd);
      break;
      case WM_DESTROY:
                  DeleteObject(hmenu);
        PostQuitMessage(0);
      break;
      default:
        return DefWindowProc(hwnd, Message, wparam, lparam);
  }
  return 0;
}



//Function to stretch the bitmap so that it has a minimum of viewable
// size

HBITMAP StretchBitmap(HBITMAP hbitmap)
{
        HBITMAP ReturnBitmap;
        BITMAP bm1, bm2;
        HDC memhdc1, memhdc2, hdc;
        TEXTMETRIC tm;

        hdc = CreateIC("DISPLAY",NULL,NULL,NULL);

        GetTextMetrics(hdc, &tm);

        memhdc1 = CreateCompatibleDC(hdc);
        memhdc2 = CreateCompatibleDC(hdc);

        DeleteDC(hdc);

        GetObject(hbitmap, sizeof(bm1), (LPSTR)&bm1);

        bm2 = bm1;

        bm2.bmHeight = (tm.tmHeight * bm2.bmHeight) / 8;
        bm2.bmWidth = (tm.tmAveCharWidth * bm2.bmWidth) / 4;
        bm2.bmWidthBytes = ((bm2.bmWidth + 15) / 16) * 2;

        ReturnBitmap = CreateBitmapIndirect(&bm2);

        SelectObject(memhdc1, hbitmap);
        SelectObject(memhdc2, ReturnBitmap);

        StretchBlt(memhdc2, 0,0,bm2.bmWidth, bm2.bmHeight,
                                memhdc1, 0,0, bm1.bmWidth, bm1.bmHeight, SRCCOPY);

        DeleteDC(memhdc1);
        DeleteDC(memhdc2);

        DeleteObject(hbitmap);

        return ReturnBitmap;

}

//Function to create you own bitmap any type of font

HBITMAP CreateFontBitmap(char *sztext, int fontwidth,int fontheight,char *fontface,
                                                BOOL fontbold, BOOL fontitalic, BOOL fontunderline,
                                                BOOL fontstrikethrough, COLORREF fontcolour)
{


HFONT hfont; // Handle to our font
SIZE size;  //Holds the size of the string to print
TEXTMETRIC tm; //It is used get get some info about the DISPLAY text
HBITMAP ReturnBitmap; //Bitmap where we print our text
static LOGFONT lf; // Holds all the properties for our font
HDC memhdc, hdc; //The memoryDC and DISPLAY DC
HBRUSH hbrush;
HPEN hpen;
hdc = CreateIC("DISPLAY", NULL,NULL,NULL);
GetTextMetrics(hdc, &tm);
memhdc = CreateCompatibleDC(hdc);
//Now, we set the properties of our font.  EG: size, face


fontheight == -1 ? lf.lfHeight = tm.tmHeight :
                                        lf.lfHeight = fontheight; //The height of font

fontwidth == -1  ? lf.lfWidth = tm.tmAveCharWidth :
                                  lf.lfWidth = fontwidth;//the width of font

//Is the text Italic?
fontitalic ?                lf.lfItalic = TRUE : lf.lfItalic = FALSE;
//Is the text Bold?
fontbold  ?                lf.lfWeight = 800 : lf.lfWeight = 0;
//Is the text Underlined?
fontunderline ?                lf.lfUnderline = TRUE : lf.lfUnderline = FALSE;
// Is the text Striked Out?
fontstrikethrough ?        lf.lfStrikeOut = TRUE : lf.lfUnderline = FALSE;
//Copies  the face of the font into the LOGFONT
strcpy((char*)lf.lfFaceName, fontface);

//Create the font based on the LOGFONT and returns a handle to it
hfont = (HFONT) SelectObject(memhdc, CreateFontIndirect(&lf));
//Gets the x and y coordinates of the text so that our bitmap is the same
// size as the text is
GetTextExtentPoint(memhdc, sztext, strlen(sztext), &size);
//Create a bitmap
ReturnBitmap = CreateBitmap(size.cx + 30, size.cy, 1,1, NULL);
//select the bitmap into the memory so that we can draw on it later
SelectObject(memhdc, ReturnBitmap);


//Draws the text onto the memory DC
/*
NOTE:  When we draw onto the memory DC, we are actually drawing on
                the bitmap.  So whatever we do to the memory DC, it is done to
                the bitmap
*/
hbrush = CreateSolidBrush(RGB(0,255,0));
hpen = CreatePen(PS_SOLID, 2, RGB(0,0,255));
HPEN holdpen = (HPEN)SelectObject(memhdc, hpen);
HBRUSH holdbrush = (HBRUSH)SelectObject(memhdc, hbrush);

Ellipse(memhdc, 0,0,30,size.cy);
TextOut(memhdc, 31,0, sztext, strlen(sztext));
SelectObject(memhdc, holdpen);
SelectObject(memhdc, holdbrush);
//Delete the handle to the font to free up the resources
DeleteObject(SelectObject(memhdc, hfont));
//Delete the memory DC to free up the resources
DeleteDC(memhdc);
//Delete the DISPLAY DC to free up the resources
DeleteDC(hdc);
//Return the actuall bitmap where we "drew" the text
return ReturnBitmap;

}

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