Is there any function that removes icon, using visual studio 6.0? - c++

Question

I couldn't find any function which removes a loaded icon. Please help me:))
Or is there any other function which makes an icon hidden such as setVisible(false), or delete?
if(GetDlgItem (IDC_BUTTON1)->IsWindowEnabled())
{
m_hIcon = AfxGetApp()->LoadIcon(IDI_ICON1);
dc.DrawIcon(DT_CENTER,DT_CENTER, m_hIcon);
}
if(GetDlgItem (IDC_BUTTON1)->IsWindowEnabled()==0) //disabled
{ dc.SetTextColor(RGB(192,192,192));
m_hIcon = AfxGetApp()->RemoveIcon(IDI_ICON1);//HERE! // I try another icon
//which is null, however it didn't work because it is transparent.
}

Answer 1

Instead of painting another icon when the button is disabled, either draw a rectangle using a null pen and a brush of the background colour or just invalidate the icon-rectangle with bErase as TRUE when you disable the button

Answer 2

This code is a bit strange, especially since you don't give us any context. What is dc, a device context? Is this code inside of a OnPaint message handler function? And either way, why are you drawing the icon manually instead of letting the button control do it automatically?
The simpler approach is to monitor the enabled state of the control by listening for WM_ENABLE messages via the OnEnable member function, and calling the SetIcon member function to update the button's icon. This way, the button control keeps track of the icon, so there's no need to keep it in a member variable (m_hIcon). And removing an icon is as simple as setting it to display a null icon. There's no need or all of these ugly hacks, like using a second transparent icon, or drawing over the icon with a solid color rectangle.
Sample code, where CMyButton extends CButton:
void CMyButton::OnEnable(BOOL bEnable)
{
CButton::OnEnable(bEnable); // call the base class
if (bEnable)
{
// The button was enabled, so load and set the icon.
const HICON hIcon = AfxGetApp()->LoadIcon(IDI_ICON1);
this->SetIcon(hIcon);
}
else
{
// The button was disabled.
// First, retrieve the current icon from the button.
const HICON hIcon = this->GetIcon();
// Then, remove the icon from the button by setting a null icon.
this->SetIcon(NULL);
// Finally, delete the original icon to prevent memory leaks.
::DestroyIcon(hIcon);
}
}
It is, of course, possible to do it your way inside of the OnPaint function, if you absolutely must (though this is poor design). The trick is that the icon only gets drawn if the code to draw it gets executed. Otherwise, no icon gets drawn. The base class will not draw an icon.
So all you need is:
void CMyWindow::OnPaint()
{
CPaintDC dc(this);
const CWnd* pBtn = GetDlgItem(IDC_BUTTON1);
if (pBtn->IsWindowEnabled())
{
m_hIcon = AfxGetApp()->LoadIcon(IDI_ICON1);
dc.DrawIcon(DT_CENTER, DT_CENTER, m_hIcon);
// make sure that you delete m_hIcon when the window is destroyed!
}
else
{
// Do not draw the icon here!
// But write whatever other code you want, like...
dc.SetTextColor(RGB(192,192,192));
}
}
Obviously this tactic will only work if your code is inside of the OnPaint function, but that is where you should do all of your drawing. Otherwise it will be lost whenever the window is repainted. For a demonstration, just try minimizing the window or moving it off the screen. Force a repaint by calling CWnd::Invalidate, followed by CWnd::UpdateWindow (or alternatively `CWnd::RedrawWindow).