Thread: Unknown GDI Object Leak in Paint Routine

Hi. I don't know why, but unless I delete a HBitmap twice my paint routines leak GDI Objects. Can anyone tell me what's going on? Here's the code -

Code:

case WM_PAINT:
            /*Called when the window needs to be painted (redrawn). */
            
            
            /* Starts painting. */  
            hdc = BeginPaint (hwnd, &ps);
            
                 //Sets up the off-screen drawing variables.
                 hdcMem = CreateCompatibleDC(hdc);
                 hdc_hbm = CreateCompatibleBitmap(hdc,640,480);
                 DeleteObject(SelectObject(hdcMem,hdc_hbm));
                 
                 //Fill in the background.
                 FillRect(hdcMem,&Background_Area,wincl.hbrBackground);
                
                 // Sets the colour of the text
                 switch(Position_Type){case -2: SetTextColor(hdcMem,RGB(atoi(separators[266]+1),atoi(separators[267]+1),atoi(separators[268]+1))); break;
                           case -1: SetTextColor(hdcMem,RGB(atoi(separators[274]+1),atoi(separators[275]+1),atoi(separators[276]+1))); break;
                           case 0: SetTextColor(hdcMem,RGB(atoi(separators[282]+1),atoi(separators[283]+1),atoi(separators[284]+1))); break;
                           case 1: SetTextColor(hdcMem,RGB(atoi(separators[290]+1),atoi(separators[291]+1),atoi(separators[292]+1))); break;
                           case 2: SetTextColor(hdcMem,RGB(atoi(separators[298]+1),atoi(separators[299]+1),atoi(separators[300]+1))); break;
                           case 3: SetTextColor(hdcMem,RGB(atoi(separators[306]+1),atoi(separators[307]+1),atoi(separators[308]+1))); break;
                           case 4: SetTextColor(hdcMem,RGB(atoi(separators[314]+1),atoi(separators[315]+1),atoi(separators[316]+1))); break;} 
                
                 // Sets the Font.
                 DeleteObject(SelectObject(hdcMem,Font));
                 SetBkMode(hdcMem,TRANSPARENT);
                
                 // Draws the text.
                 TB_Title->TB_Draw(hdcMem);
                 TB_Status->TB_Draw(hdcMem);
                 TB_Level->TB_Draw(hdcMem);
                 TB_Position->TB_Draw(hdcMem);
                 TB_Commands->TB_Draw(hdcMem);
                 TB_Message->TB_Draw(hdcMem);
                 TB_Battle1->TB_Draw(hdcMem);
                 TB_Battle2->TB_Draw(hdcMem);
                
                 // Draws the sword and shield.
                 hdcMem2 = CreateCompatibleDC(hdcMem);
                 DeleteObject(SelectObject(hdcMem2,Image1));
                 BitBlt(hdcMem,10,360,bm.bmWidth,bm.bmHeight,hdcMem2,0,0,SRCCOPY);
                 DeleteObject(SelectObject(hdcMem2,Image2));
                 BitBlt(hdcMem,490,360,bm.bmWidth,bm.bmHeight,hdcMem2,0,0,SRCCOPY);
                 DeleteDC(hdcMem2);
                 
                 //Copies the bitmap drawn off-screen to the screen
                 BitBlt(ps.hdc,ps.rcPaint.left,ps.rcPaint.top,ps.rcPaint.right-ps.rcPaint.left,ps.rcPaint.bottom-ps.rcPaint.top,hdcMem,ps.rcPaint.left,ps.rcPaint.top,SRCCOPY);
                 
                 //Deletes the hdc made for drawing in memory.
                 DeleteDC(hdcMem);
                 DeleteObject(hdc_hbm);
                
            /* Stops painting. */
            EndPaint (hwnd, &ps);
            
            return 1;
        break;
        
        case WM_ERASEBKGND: return 1; // Say we handled it.

When you select a new object into a DC, you must save the old object and select it back in later.

Code:

// Set up a DC and select a new DC into it.
HBITMAP hdcMem = CreateCompatibleDC(hdc);
HBITMAP hdc_hbm = CreateCompatibleBitmap(hdc,640,480);
HBITMAP hbmOld = SelectObject(hdcMem,hdc_hbm);

// Use here.

// Select old bmp back into DC.
SelectObject(hdcMem, hbmOld);
// Now you can delete the bmp and the DC.
DeleteObject(hdc_hbm);
DeleteDC(hdcMem);

That same pattern applies for the font and the image you select into hdcMem2.