Using Icons
Using Icons

The following topics describe how to perform certain tasks related to icons:

Creating an Icon

To use an icon, your application must get a handle to the icon. The following example shows how to create two different icon handles: one for the standard exclamation icon and one for a custom icon included as a resource in the application's resource-definition file. 

HICON hIcon1;   // icon handle 
HICON hIcon2;   // icon handle 
 
// Create a standard question icon. 
 
hIcon1 = LoadIcon(NULL, IDI_QUESTION); 
 
// Create a custom icon based on a resource. 
 
hIcon2 = LoadIcon(hinst, MAKEINTRESOURCE(460)); 
 
// Create a custom icon at run time.

An application should implement custom icons as resources and should use the LoadIcon or LoadImage  function, rather than create the icons at run-time. This approach avoids device dependence, simplifies localization, and enables applications to share icon bitmaps. However, the following example uses CreateIcon to create a custom icon at run-time, based on bitmap bitmasks; it is included to illustrate how the system interprets icon bitmap bitmasks. 

HICON hIcon3;      // icon handle 
 
// Yang icon AND bitmask 
 
BYTE ANDmaskIcon[] = {0xFF, 0xFF, 0xFF, 0xFF,   // line 1 
                      0xFF, 0xFF, 0xC3, 0xFF,   // line 2 
                      0xFF, 0xFF, 0x00, 0xFF,   // line 3 
                      0xFF, 0xFE, 0x00, 0x7F,   // line 4 
 
                      0xFF, 0xFC, 0x00, 0x1F,   // line 5 
                      0xFF, 0xF8, 0x00, 0x0F,   // line 6 
                      0xFF, 0xF8, 0x00, 0x0F,   // line 7 
                      0xFF, 0xF0, 0x00, 0x07,   // line 8 
 
                      0xFF, 0xF0, 0x00, 0x03,   // line 9 
                      0xFF, 0xE0, 0x00, 0x03,   // line 10 
                      0xFF, 0xE0, 0x00, 0x01,   // line 11 
                      0xFF, 0xE0, 0x00, 0x01,   // line 12 
 
                      0xFF, 0xF0, 0x00, 0x01,   // line 13 
                      0xFF, 0xF0, 0x00, 0x00,   // line 14 
                      0xFF, 0xF8, 0x00, 0x00,   // line 15 
                      0xFF, 0xFC, 0x00, 0x00,   // line 16 
 
                      0xFF, 0xFF, 0x00, 0x00,   // line 17 
                      0xFF, 0xFF, 0x80, 0x00,   // line 18 
                      0xFF, 0xFF, 0xE0, 0x00,   // line 19 
                      0xFF, 0xFF, 0xE0, 0x01,   // line 20 
 
                      0xFF, 0xFF, 0xF0, 0x01,   // line 21 
                      0xFF, 0xFF, 0xF0, 0x01,   // line 22 
                      0xFF, 0xFF, 0xF0, 0x03,   // line 23 
                      0xFF, 0xFF, 0xE0, 0x03,   // line 24 
 
                      0xFF, 0xFF, 0xE0, 0x07,   // line 25 
                      0xFF, 0xFF, 0xC0, 0x0F,   // line 26 
                      0xFF, 0xFF, 0xC0, 0x0F,   // line 27 
                      0xFF, 0xFF, 0x80, 0x1F,   // line 28 
 
                      0xFF, 0xFF, 0x00, 0x7F,   // line 29 
                      0xFF, 0xFC, 0x00, 0xFF,   // line 30 
                      0xFF, 0xF8, 0x03, 0xFF,   // line 31 
                      0xFF, 0xFC, 0x3F, 0xFF};  // line 32 
 
// Yang icon XOR bitmask 
 
BYTE XORmaskIcon[] = {0x00, 0x00, 0x00, 0x00,   // line 1 
                      0x00, 0x00, 0x00, 0x00,   // line 2 
                      0x00, 0x00, 0x00, 0x00,   // line 3 
                      0x00, 0x00, 0x00, 0x00,   // line 4 
 
                      0x00, 0x00, 0x00, 0x00,   // line 5 
                      0x00, 0x00, 0x00, 0x00,   // line 6 
                      0x00, 0x00, 0x00, 0x00,   // line 7 
                      0x00, 0x00, 0x38, 0x00,   // line 8 
 
                      0x00, 0x00, 0x7C, 0x00,   // line 9 
                      0x00, 0x00, 0x7C, 0x00,   // line 10 
                      0x00, 0x00, 0x7C, 0x00,   // line 11 
                      0x00, 0x00, 0x38, 0x00,   // line 12 
 
                      0x00, 0x00, 0x00, 0x00,   // line 13 
                      0x00, 0x00, 0x00, 0x00,   // line 14 
                      0x00, 0x00, 0x00, 0x00,   // line 15 
                      0x00, 0x00, 0x00, 0x00,   // line 16 
 
                      0x00, 0x00, 0x00, 0x00,   // line 17 
                      0x00, 0x00, 0x00, 0x00,   // line 18 
                      0x00, 0x00, 0x00, 0x00,   // line 19 
                      0x00, 0x00, 0x00, 0x00,   // line 20 
 
                      0x00, 0x00, 0x00, 0x00,   // line 21 
                      0x00, 0x00, 0x00, 0x00,   // line 22 
                      0x00, 0x00, 0x00, 0x00,   // line 23 
                      0x00, 0x00, 0x00, 0x00,   // line 24 
 
                      0x00, 0x00, 0x00, 0x00,   // line 25 
                      0x00, 0x00, 0x00, 0x00,   // line 26 
                      0x00, 0x00, 0x00, 0x00,   // line 27 
                      0x00, 0x00, 0x00, 0x00,   // line 28 
 
                      0x00, 0x00, 0x00, 0x00,   // line 29 
                      0x00, 0x00, 0x00, 0x00,   // line 30 
                      0x00, 0x00, 0x00, 0x00,   // line 31 
                      0x00, 0x00, 0x00, 0x00};  // line 32 
 
hIcon3 = CreateIcon(hinst,    // application instance  
             32,              // icon width 
             32,              // icon height 
             1,               // number of XOR planes 
             1,               // number of bits per pixel 
             ANDmaskIcon,     // AND bitmask  
             XORmaskIcon);    // XOR bitmask

To create the icon, CreateIcon applies the following truth table to the AND and XOR bitmasks.

AND bitmaskXOR bitmaskDisplay
00Black
01White
10Screen
11Reverse screen

Before closing, your application must use DestroyIcon to destroy any icon it created by using CreateIconIndirect. It is not necessary to destroy icons created by other functions.

Displaying an Icon

Your application can load and create icons to display in the application's client area or child windows. The following example demonstrates how to draw an icon in the client area of the window whose device context (DC) is identified by the hdc parameter. 

HICON hIcon1;   // icon handle  
HDC hdc;        // handle to display context 
 
DrawIcon(hdc, 10, 20, hIcon1);

The system automatically displays the class icon(s) for a window. Your application can assign class icons while registering a window class. Your application can replace a class icon by using the SetClassLong function. This function changes the default window settings for all windows of a given class. The following example replaces a class icon with the icon whose resource identifier is 480. 

HINSTANCE hinst;            // handle to current instance 
HWND hwnd;                  // main window handle  
 
// Change the icon for hwnd's window class. 
 
SetClassLong(hwnd,          // window handle 
    GCL_HICON,              // changes icon 
    (LONG) LoadIcon(hinst, MAKEINTRESOURCE(480))
   );

For more information about window classes, see Window Classes.

Sharing Icon Resources

The following code uses the functions CreateIconFromResourceEx, DrawIcon, and LookupIconIdFromDirectoryEx, and several of the resource functions, to create an icon handle based on icon data from another executable file. Then, it displays the icon in a window.

security note Security Alert  Using LoadLibrary incorrectly can compromise the security of your application by loading the wrong DLL. Refer to the LoadLibrary documentation for information on how to correctly load DLLs with different versions of Windows.
HICON hIcon1;       // icon handle 
HINSTANCE hExe;     // handle to loaded .EXE file 
HRSRC hResource;    // handle to FindResource  
HRSRC hMem;         // handle to LoadResource 
BYTE *lpResource;   // pointer to resource data  
int nID;            // ID of resource that best fits current screen 
 
HDC hdc;        // handle to display context 
 
// Load the file from which to copy the icon. 
// Note: LoadLibrary should have a fully explicit path.
//
hExe = LoadLibrary("myapp.exe");
if (hExe == NULL)
{
    //Error loading module -- fail as securely as possible
	return;
}
 
 
// Find the icon directory whose identifier is 440. 
 
hResource = FindResource(hExe, 
    MAKEINTRESOURCE(440), 
    RT_GROUP_ICON); 
 
// Load and lock the icon directory. 
 
hMem = LoadResource(hExe, hResource); 
 
lpResource = LockResource(hMem); 
 
// Get the identifier of the icon that is most appropriate 
// for the video display. 
 
nID = LookupIconIdFromDirectoryEx((PBYTE) lpResource, TRUE, 
    CXICON, CYICON, LR_DEFAULTCOLOR); 
 
// Find the bits for the nID icon. 
 
hResource = FindResource(hExe, 
    MAKEINTRESOURCE(nID), 
    MAKEINTRESOURCE(RT_ICON)); 
 
// Load and lock the icon. 
 
hMem = LoadResource(hExe, hResource); 
 
lpResource = LockResource(hMem); 
 
// Create a handle to the icon. 
 
hIcon1 = CreateIconFromResourceEx((PBYTE) lpResource, 
    SizeofResource(hExe, hResource), TRUE, 0x00030000, 
    CXICON, CYICON, LR_DEFAULTCOLOR); 
 
// Draw the icon in the client area. 
 
DrawIcon(hdc, 10, 20, hIcon1);
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Community Content

SRELU
Can I see a CreateIcon sample for a COLOR icon ?

I searched thoroughfully the internet to find one. Nobody has any sample other than the one displayed on this page.
I spent a whole day trying to make CreateIcon work with colour icons. I was only successful with monochrome ones.

While in the monochrome case a correct icon was obtained, in the case of the color icons I was able to obtain only icons consisting of random pixels, all black or white.
No matter what I tried, I was never able to see even a single pixel having a color other than black or white.

I checked each and every byte of the icon files I used, everything was according to the "ico" file format. I checked and triple checked the file loaded in the memory, all the parameters and pointers passed to the function, everything was ok, the function returned a valid icon handle, GetLastError returned zero. Only the pixels displayed on the scren with DrawIcon (also checked carefully) were a total mess.

Just to mention a design problem, the function doesn't receive any pointer to a color table. To me it apears that this function can only work with monochrome icons.

Actually, if the icon is color, you can replace the pointers for the AND and XOR masks with null pointers (normally a huge mistake) and nothing bad will happen, the function doesn't apear to use them in any way.

Null pointers will cause havoc only if a monchrome icon is used (cBitsPixel = 1 and cPlanes = 1).

We are in 2009, I think it's time to switch to color icons. How about a CreateIconEx function with one of the parameters to hold a pointer to a BITMAPINFO structure ? (The simplified structure, as it can be found in the icon files.)

Or, at least, remove any reference to color icons and state clearly that the function can handle only monochrome icons.


Tycho
API with color
Take a look at function CreateIconIndirect http://msdn.microsoft.com/en-us/library/ms648062(VS.85).aspx. This function allows colors to be passed though!
Tags : color icon

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