Advanced MFC Programming

Chapter 8. DC, Pen, Brush and Palette
Sample 8.11\GDI demonstrates how to check the abilities of a device. It is a standard SDI application
generated from Application Wizard. In the sample, ability checking is implemented in the initialization
stage of the client window.
For this purpose, function CGDIView::OnInitialUpdate() is added to the application through using
Application Wizard. In this function, various device abilities are checked and the result is displayed in a
message box:
void CGDIView::OnInitialUpdate()
{
CClientDC dc(this);
CString szStr;
CString szBuf;
int nRasterCaps;
int nNumOfColors;
int nNumOfReserved;
int nColorRes;
CView::OnInitialUpdate();
}
szStr="My video device's ability:\n";
nRasterCaps=dc.GetDeviceCaps(RASTERCAPS);
if(nRasterCaps & RC_PALETTE)
{
szStr+="\tIt is a palette device\n";
nNumOfColors=dc.GetDeviceCaps(SIZEPALETTE);
szBuf.Format("\tThe device supports %d colors\n", nNumOfColors);
szStr+=szBuf;
szBuf.Empty();
nNumOfReserved=dc.GetDeviceCaps(NUMRESERVED);
szBuf.Format("\tThere are %d static colors\n", nNumOfReserved);
szStr+=szBuf;
nColorRes=dc.GetDeviceCaps(COLORRES);
szBuf.Format("\tColor resolution is %d bits\n", nColorRes);
szStr+=szBuf;
}
else
{
szStr+="\tIt is not a palette device\n";
}
szBuf.Empty();
szBuf.Format
(
"\tHorizontal size is %d mm, %d pixels\n",
dc.GetDeviceCaps(HORZSIZE),
dc.GetDeviceCaps(HORZRES)
);
szStr+=szBuf;
szBuf.Empty();
szBuf.Format
(
"\tVertical size is %d mm, %d pixels\n",
dc.GetDeviceCaps(VERTSIZE),
dc.GetDeviceCaps(VERTRES)
);
szStr+=szBuf;
AfxMessageBox(szStr);
Here we check if the device is a palette device or not. If it is a palette device, we further find out the
maximum number of colors it supports, the number of static colors reserved, and the actual color resolution
for each pixel. Also, the device’s horizontal and vertical sizes are retrieved.
This function is especially useful in finding out if the device is a palette device or not. With this
information, we can decide if the logical palette should be used in the application.
The following lists the capabilities of certain device:
It is a palette device
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