Brian

Here it is:

sub PrintBitmap(byval hPrintBitmap as dword, byval hDCprint as dword, byval xTop as long, byval yTop as long, byval fxSize as long, byval fySize as long)

    local bm as BITMAP
    local dcBitmap as dword
    dcBitmap = CreateCompatibleDC(%NULL)
    GetObject(hPrintBitmap, sizeof(bm), bm)

    local bi as BITMAPINFO
    bi.bmiHeader.biSize = sizeof(bi.bmiHeader)
    bi.bmiHeader.biWidth = bm.bmWidth
    bi.bmiHeader.biHeight = bm.bmHeight
    bi.bmiHeader.biPlanes = 1
    bi.bmiHeader.biBitCount = bm.bmBitsPixel
    bi.bmiHeader.biCompression = %BI_RGB

    '// Calculate space needed for the dib bits
    local nBufSize as long
    nBufSize = (bi.bmiHeader.biWidth + 1) * (bi.bmiHeader.biBitCount / 8)
    nBufSize = ((nBufSize + 3) / 4) * 4
    nBufSize *= bi.bmiHeader.biHeight

    local ghnd, gptr as dword
    ghnd = GlobalAlloc(%GMEM_MOVEABLE, nBufSize)
    gptr = GlobalLock(ghnd)

    local nDI as long
    nDI = GetDIBits(dcBitmap, hPrintBitmap, 0, bm.bmHeight, byval gptr, bi, %DIB_RGB_COLORS)

    '// Use this to print a full bitmap
    nDI = StretchDIBits(hDCprint, xTop, yTop, fxSize, fySize, 0, 0, bm.bmWidth, bm.bmHeight, BYVAL gptr, bi, %DIB_RGB_COLORS, %SRCCOPY)
    GlobalUnlock(ghnd)
    GlobalFree(ghnd)
    DeleteDC(dcBitmap)
end sub

function SendToPrinter() as long
    local nRet, Wdth, Hght, X, Y, hSize, vSize, hRes, vRes, Landscape as long
    local hTmp as dword
    local sFilName as string

    local rc as RECT
    GetWindowRect (gP.hMain, rc)
    Wdth = ((rc.nRight - rc.left) - 438) / 2 - 48
    Hght = ((rc.nBottom - rc.top) - 314) / 2 - 52
    X = rc.left + Wdth
    Y = rc.top + Hght
    hTmp = CreateWindowEx(0, "STATIC", "", %WS_POPUP, X, Y, 0, 0, gP.hMain, 0, gP.hinstance, byval %NULL)

    '// Setup the print common dialog
    local pd as PRINTDLGAPI
    pd.lStructSize = sizeof(pd)
    pd.hwndOwner = hTmp
    pd.hDevMode = 0
    pd.hDevNames = 0
    pd.nFromPage = 0
    pd.nToPage = 0
    pd.nMinPage = 0
    pd.nMaxPage = 0
    pd.nCopies = 0
    pd.hInstance = gP.hinstance
    pd.Flags = %PD_RETURNDC or %PD_NOPAGENUMS or %PD_PRINTSETUP
    pd.lpfnSetupHook = 0
    pd.lpPrintSetupTemplateName = 0
    pd.lpfnPrintHook = 0
    pd.lpPrintTemplateName = 0
    if (PrintDlg(pd)) then

        hSize = GetDeviceCaps(pd.hDC, %HORZSIZE)
        vSize = GetDeviceCaps(pd.hDC, %VERTSIZE)
        hRes  = GetDeviceCaps(pd.hDC, %HORZRES)
        vRes  = GetDeviceCaps(pd.hDC, %VERTRES)

        sFilName = EXE.Name$ + "_output"
        local dinfo as DOCINFO
        dinfo.cbSize = sizeof(dinfo)
        dinfo.lpszDocName = strptr(sFilName)
        dinfo.lpszOutput = 0
        '// Detect printer orientation mode
        Landscape = -1: if (vSize > hSize) then Landscape = 0
        '// Compute the printing size
        local offsetX, offsetY as long
        if (Landscape) then
            offsetX = 60: offsetY = 0
        else
            offsetX = 15: offsetY = 60
        end if

        local img as dword
        GetClientRect(gP.hGL, rc)
        dim buffer(rc.nRight * rc.nBottom * 3) as byte
        glPixelStorei(GL_PACK_ALIGNMENT, 1)
        glReadPixels(0, 0, rc.nRight, rc.nBottom, GL_BGR, GL_UNSIGNED_BYTE, byval varptr(buffer(0)))
        if (GdipCreateBitmapFromScan0(rc.nRight, rc.nBottom, rc.nRight * 3, %PixelFormat24bppRGB, buffer(0), img) = 0) then
            if (img) then
                if (GdipImageRotateFlip(img, 6) = 0) then

                    local hPrintBitmap as dword
                    local background as long
                    if (GdipCreateHBITMAPFromBitmap(img, hPrintBitmap, background) = 0) then
                        local rCoef as single
                        rCoef = min((hRes - (offsetX * 2)) / rc.nRight, (vRes - (offsetY * 2)) / rc.nBottom)
                        local fxSize, fySize, xTop, yTop as long
                        fxSize = (rc.nRight * rCoef)
                        fySize = (rc.nBottom * rCoef)
                        xTop = (hRes - fxSize) \ 2 + offsetX
                        yTop = (vRes - fySize) \ 2 + offsetY

                        if (StartDoc(pd.hDC, dinfo) > 0) then
                            if (StartPage(pd.hDC) > 0) then

                                '// Paint the DIB bitmap
                                PrintBitmap(hPrintBitmap, pd.hDC, xTop, yTop, fxSize, fySize)

                                if (EndPage(pd.hDC) > 0) then
                                    nRet = -1
                                    EndDoc(pd.hDC)
                                end if

                            end if
                        end if
                        DeleteObject(hPrintBitmap)
                    end if
                end if
                GdipDisposeImage(img)
            end if
        end if
        DeleteDC(pd.hDC)
    end if
    DestroyWindow(hTmp)
    function = nRet
end function


The complete source code of the PowerBASIC version (discontinued since may 2016) is available on my private forum there:
http://www.objreader.com/index.php?topic=268.0
in the section named "Post Your Questions & Comments Here".

Patrice, do you have a PowerBASIC example that i can try to compile here?

From ObjReader, to print the OpenGL display...

// 05-22-2015
long SendToPrinter() {
    long nRet = 0;

    RECT rc = { 0 };
    GetWindowRect(gP.hMain, &rc);
    long Wdth = ((rc.right - rc.left) - 438) / 2 - 48;
    long Hght = ((rc.bottom - rc.top) - 314) / 2 - 52;
    long X = rc.left + Wdth;
    long Y = rc.top + Hght;
    HWND hTmp = CreateWindowEx(0, L"STATIC", $NULL, WS_POPUP, X, Y, 0, 0, gP.hMain, 0, gP.hInstance, NULL);

    // Setup the print common dialog
    PRINTDLG pd;
    pd.lStructSize = sizeof(pd);
    pd.hwndOwner = hTmp;
    pd.hDevMode = NULL;
    pd.hDevNames = NULL;
    pd.nFromPage = 0;
    pd.nToPage = 0;
    pd.nMinPage = 0;
    pd.nMaxPage = 0;
    pd.nCopies = 0;
    pd.hInstance = gP.hInstance;
    pd.Flags = PD_RETURNDC | PD_NOPAGENUMS | PD_PRINTSETUP;
    pd.lpfnSetupHook = NULL;
    pd.lpSetupTemplateName = NULL;
    pd.lpfnPrintHook = NULL;
    pd.lpPrintTemplateName = NULL;
    if (PrintDlg(&pd)) {

        long hSize = GetDeviceCaps(pd.hDC, HORZSIZE);
        long vSize = GetDeviceCaps(pd.hDC, VERTSIZE);
        long hRes = GetDeviceCaps(pd.hDC, HORZRES);
        long vRes = GetDeviceCaps(pd.hDC, VERTRES);

        WCHAR PathName[MAX_PATH] = { 0 };
        WCHAR FilName[MAX_PATH] = { 0 };
        zSplitN(zExeName(), &PathName[0], &FilName[0]);

        Add_Str(FilName, L"_output");
        DOCINFO dinfo;
        dinfo.cbSize = sizeof(dinfo);
        dinfo.lpszDocName = &FilName[0];
        dinfo.lpszOutput = NULL;
        // Detect printer orientation mode
        long Landscape = -1; if (vSize > hSize) { Landscape = 0; }
        // Compute the printing size
        long offsetX, offsetY;
        if (Landscape) {
            offsetX = 60; offsetY = 0;
        } else {
            offsetX = 15; offsetY = 60;
        }

        LONG_PTR img = 0;
        GetClientRect(gP.hGL, &rc);

        // 07-17-2017 respect boundary alignment
        rc.right = (rc.right / 4) * 4;
        rc.bottom = (rc.bottom / 4) * 4;

        BYTE* buffer = new BYTE[rc.right * rc.bottom * 3];
        glPixelStorei(GL_PACK_ALIGNMENT, 1);
        glReadPixels(0, 0, rc.right, rc.bottom, GL_BGR, GL_UNSIGNED_BYTE, &buffer[0]);
        if (GdipCreateBitmapFromScan0(rc.right, rc.bottom, rc.right * 3, PixelFormat24bppRGB, &buffer[0], img) == 0) {

            if (img) {
                if (GdipImageRotateFlip(img, 6) == 0) {

                    HBITMAP hPrintBitmap = 0; long background = 0;
                    if (GdipCreateHBITMAPFromBitmap(img, hPrintBitmap, background) == 0) {
                        float rCoef = min((float)((hRes - (offsetX * 2)) / (float)rc.right), (float)((vRes - (offsetY * 2)) / (float)rc.bottom));
                        long fxSize = (long)(rc.right * rCoef);
                        long fySize = (long)(rc.bottom * rCoef);
                        long xTop = (hRes - fxSize) / 2 + offsetX;
                        long yTop = (vRes - fySize) / 2 + offsetY;

                        if (StartDoc(pd.hDC, &dinfo) > 0) {
                            if (StartPage(pd.hDC) > 0) {

                                // Paint the DIB bitmap
                                PrintBitmap(hPrintBitmap, pd.hDC, xTop, yTop, fxSize, fySize);
                                nRet = EndPage(pd.hDC);
                                if (nRet > 0) {
                                    nRet = -1;
                                    EndDoc(pd.hDC);
                                } else {
                                    nRet = 0;
                                }

                            }
                        }
                        DeleteObject(hPrintBitmap);
                    }
                }
                GdipDisposeImage(img);
            }
        }
        delete[] buffer;
        DeleteDC(pd.hDC);
    }
    DestroyWindow(hTmp);
    return nRet;
}

See the attachment of my current Work In Progress, that 3D model should be completed soon.
I have to add some more stickers, extra ambient occlusion, lighting, and ground shadow...

Our o2 Opengl framework uses GDI+ both for loading textures and producing image files.

Currently, the opengl buffer bits are transferred pixel by pixel into a gdi+ bitmap. Though I wonder if there is a more efficient way of making the transfer, bearing in mind that the red and blue colors of each pixel have to be swapped.

Sending GDI+ to a printer looks simple enough:
https://docs.microsoft.com/en-us/windows/win32/gdiplus/-gdiplus-sending-gdi-output-to-a-printer-use

 Sure, no problem. In the other thread i posted an example for a game, that writes directly to a Window DC.
Writinig to a printer DC should be no problem.

QuoteThese could be useful for an XPRINT implementation.

XPRINT is proprietary, what about writing to a printer DC

Good to hear that Thanxx Charles

Thanxx a lot  Charles

That's a beauty mate 

Excellent job that you had done with no equals

We have some classical graphics adapted to OpenGl, primarily for making graphs and diagrams:

examples/OpenGl/DataGraphs/

move
rotate
scale
color
line
thickness
point
pointsize
fan
print
etc.

These could be useful for an XPRINT implementation.

Yes, o2 is in the beta phase, currently 0.2.7. This means minimal changes to keywords and syntax, along with self-compiling, and some extended capabilities and bug-fixes.

The main changes have been:

• Equates default to 32bits in 64bit system
• Support for UTF-16 source code.
• Ability to pass and return UDTs by value
• Adapt Operator system to support variants as well as other UDT types
• Removal of automatic scoping inside procedures
• Built-in RES file linkage