Open GL Super Bible:MFC-Based OpenGL Programming















To access the contents, click the chapter and section titles.


Open GL Super Bible


(Publisher: Macmillan Computer Publishing)

Author(s): Waite group Press

ISBN: 1571690735

Publication Date: 08/01/96



function isIE4()
{
return( navigator.appName.indexOf("Microsoft") != -1 && (navigator.appVersion.charAt(0)==
'4')
); }
function
bookMarkit() {varurl="http://www.itknowledge.com/PSUser/EWBookMarks.html?url="+window.location+"&isbn=0";
parent.location.href=url;
//var win = window.open(url,"myitk");
//if(!isIE4())
// win.focus();

}

 




Previous
Table of Contents
Next




Listing 21-2 CPalette creation and initialization code

// Initializes the CPalette object
void CMfcglView::InitializePalette(void)
{
PIXELFORMATDESCRIPTOR pfd; // Pixel format descriptor
LOGPALETTE *pPal; // Pointer to memory for logical
palette
int nPixelFormat; // Pixel format index
int nColors; // Number of entries in palette
int i; // Counting variable

BYTE RedRange,GreenRange,BlueRange;
// Range for each color entry (7,7,and 3)

// Get the pixel format index and retrieve the pixel format
description
nPixelFormat = GetPixelFormat(m_hDC);
DescribePixelFormat(m_hDC, nPixelFormat,
sizeof(PIXELFORMATDESCRIPTOR), &pfd);

// Does this pixel format require a palette? If not, do not
create a
// palette and just return NULL
if(!(pfd.dwFlags & PFD_NEED_PALETTE))
return;

// Number of entries in palette. 8-bit yields 256 entries
nColors = 1 << pfd.cColorBits;

// Allocate space for a logical palette structure plus all the
// palette entries
pPal = (LOGPALETTE*)malloc(sizeof(LOGPALETTE)
+nColors*sizeof(PALETTEENTRY));

// Fill in palette header
pPal->palVersion = 0x300; // Windows 3.0
pPal->palNumEntries = nColors; // table size

// Build mask of all 1's. This creates a number represented
by having
// the low-order x bits set, where x = pfd.cRedBits,
pfd.cGreenBits,
// and pfd.cBlueBits.
RedRange = (1 << pfd.cRedBits) - 1;
GreenRange = (1 << pfd.cGreenBits) - 1;
BlueRange = (1 << pfd.cBlueBits) - 1;

// Loop through all the palette entries
for(i = 0; i < nColors; i++)
{
// Fill in the 8-bit equivalents for each component
pPal->palPalEntry[i].peRed = (i >> pfd.cRedShift) &
RedRange;
pPal->palPalEntry[i].peRed = (unsigned char)(
(double) pPal->palPalEntry[i].peRed * 255.0 /
RedRange);

pPal->palPalEntry[i].peGreen = (i >> pfd.cGreenShift) &
GreenRange;
pPal->palPalEntry[i].peGreen = (unsigned char)(
(double)pPal->palPalEntry[i].peGreen * 255.0/
GreenRange);

pPal->palPalEntry[i].peBlue = (i >> pfd.cBlueShift) &
BlueRange;
pPal->palPalEntry[i].peBlue = (unsigned char)(
(double)pPal->palPalEntry[i].peBlue * 255.0 /
BlueRange);

pPal->palPalEntry[i].peFlags = (unsigned char) NULL;
}

// Create the palette
m_GLPalette.CreatePalette(pPal);

// Go ahead and select and realize the palette for this device context
SelectPalette(m_hDC,(HPALETTE)m_GLPalette,FALSE);
RealizePalette(m_hDC);

// Free the memory used for the logical palette structure
free(pPal);
}

Using the Class Wizard again to add message response functions for WM_QUERYNEWPALETTE and WM_PALETTECHANGED, our code to realize the palette is shown in Listing 21-3.

Listing 21-3 Code to realize CPalette for the view class

BOOL CMfcglView::OnQueryNewPalette()
{
// If the palette was created.
if((HPALETTE)m_GLPalette)
{
int nRet;

// Selects the palette into the current device context
SelectPalette(m_hDC, (HPALETTE)m_GLPalette, FALSE);

// Map entries from the currently selected palette to
// the system palette. The return value is the number
// of palette entries modified.
nRet = RealizePalette(m_hDC);

// Repaint, forces remap of palette in current window
InvalidateRect(NULL,FALSE);
return nRet;
}

return CView::OnQueryNewPalette();
}

void CMfcglView::OnPaletteChanged(CWnd* pFocusWnd)
{
if(((HPALETTE)m_GLPalette != NULL) && (pFocusWnd != this))
{
// Select the palette into the device context
SelectPalette(m_hDC,(HPALETTE)m_GLPalette,FALSE);

// Map entries to system palette
RealizePalette(m_hDC);

// Remap the current colors to the newly realized palette
UpdateColors(m_hDC);
return;
}

CView::OnPaletteChanged(pFocusWnd);
}

This code to realize the palette is very much like that in Chapter 8. Here, though, Windows does not send these messages to the CView-derived class directly, but rather to the applicationłs CMainFrame class. This is because Windows only sends palette messages to the applicationłs main window; it is this windowłs responsibility to route the messages to any child windows that need to be notified.




Previous
Table of Contents
Next














 


Use of this site is subject to certain Terms & Conditions, Copyright © 1996-2000 EarthWeb Inc.
All rights reserved. Reproduction whole or in part in any form or medium without express written permission of EarthWeb is prohibited. Read EarthWeb's privacy statement.