icons.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-
"""win32 icons
"""
import itertools

# John Hornick, "Icons in Win32", September 29, 1995
# http://msdn.microsoft.com/en-us/library/ms997538.aspx
# The Old New Thing, "The format of icon resources"
# http://blogs.msdn.com/b/oldnewthing/archive/2012/07/20/10331787.aspx
from . import _wapi

# dwBytesInRes is the size of the ICONIMAGE blob, dwImageOffset is the
# offset in the file or resource where the ICONIMAGE blob starts.
class ICONDIRENTRY(_wapi.Structure):
    _pack_ = 2
    _fields_ = [("bWidth", _wapi.BYTE),
                ("bHeight", _wapi.BYTE),
                ("bColorCount", _wapi.BYTE),
                ("bReserved", _wapi.BYTE),
                ("wPlanes", _wapi.WORD),
                ("wBitCount", _wapi.WORD),
                ("dwBytesInRes", _wapi.DWORD),
                ("dwImageOffset", _wapi.DWORD)]


# An .ico file starts with an ICONDIRHEADER which contains idCount
# ICONDIRENTRY structures that describe the one or more icon images in
# the file.
class ICONDIRHEADER(_wapi.Structure):
    _pack_ = 2
    _fields_ = [("idReserved", _wapi.WORD), # Must be 0
                ("idType", _wapi.WORD), # Should check that this is 1 for icons
                ("idCount", _wapi.WORD), # Number os ICONDIRENTRYs to follow
##                ("idEntries", ICONDIRENTRY * 0)
                ]

    @classmethod
    def readfrom(cls, fileobj):
        header = cls()
        fileobj.readinto(header)
        header.idEntries = []
        for i in range(header.idCount):
            entry = ICONDIRENTRY()
            fileobj.readinto(entry)
            header.idEntries.append(entry)

        header.iconimages = []
        for entry in header.idEntries:
            fileobj.seek(entry.dwImageOffset)
            image = fileobj.read(entry.dwBytesInRes)
            header.iconimages.append(image)
        return header

################################################################

# The RT_GROUP_ICON resource in the exe/dll file is a GRPICONDIR
# structure (see below). The GRPICONDIR structure contains a
# GRPICONDIRENTRY for each icon, the nID members are the resource ids
# of the corresponding RT_ICON resources which are ICONIMAGE
# structures.

class GRPICONDIRENTRY(_wapi.Structure):
    _pack_ = 2
    _fields_ = [("bWidth", _wapi.BYTE),
                ("bHeight", _wapi.BYTE),
                ("bColorCount", _wapi.BYTE),
                ("bReserved", _wapi.BYTE),
                ("wPlanes", _wapi.WORD),
                ("wBitCount", _wapi.WORD),
                ("dwBytesInRes", _wapi.DWORD),
                # nID is the resource id of the RT_ICON resource
                ("nID", _wapi.WORD)]


def CreateGrpIconDirHeader(iconheader, id_generator):
    """Create a GRPICONDIRHEADER from an ICONDIRHEADER.
    """
    # ctypes doesn't support variable type structures; so we
    # create one of the size we want NOW.
    class GRPICONDIRHEADER(_wapi.Structure):
        _pack_ = 2
        _fields_ = [("idReserved", _wapi.WORD),
                    ("idType", _wapi.WORD),
                    ("idCount", _wapi.WORD),
                    ("idEntries", GRPICONDIRENTRY * iconheader.idCount)]
        def tobytes(self):
            return memoryview(self).tobytes()
    if iconheader.idCount > 10:
        raise ValueError("too many images for this icon: %d" % iconheader.idCount)
    grpheader = GRPICONDIRHEADER(
        idReserved = iconheader.idReserved,
        idType = iconheader.idType,
        idCount = iconheader.idCount)
    for i in range(iconheader.idCount):
        dst = grpheader.idEntries[i]
        src = iconheader.idEntries[i]
        dst.bWidth = src.bWidth
        dst.bHeight = src.bHeight
        dst.bColorCount = src.bColorCount
        dst.bReserved = src.bReserved
        dst.wPlanes = src.wPlanes
        dst.wBitCount = src.wBitCount
        dst.dwBytesInRes = src.dwBytesInRes
        dst.nID = next(id_generator)
        if dst.nID > 32767:
            raise ValueError("Invalid resource id %s" % dst.nID)
    return grpheader

################################################################

def BuildIcons(icon_resources):
    """Create RT_ICON and RT_GROUP_ICON resources from a list of
    (icon id, icon file) tuples.
    """
    result = []

    id_generator = itertools.count(10)

    for resource_id, iconpath in icon_resources:
        with open(iconpath, "rb") as iconfile:
            header = ICONDIRHEADER.readfrom(iconfile)

        grp_header = CreateGrpIconDirHeader(header, id_generator)

        for i, entry in enumerate(grp_header.idEntries):
            # type, name, data
            result.append((_wapi.RT_ICON, entry.nID, header.iconimages[i]))

        result.append((_wapi.RT_GROUP_ICON, resource_id, grp_header.tobytes()))

    return result

################################################################

if __name__ == "__main__":
    with open("128.ico", "rb") as ifi:
        hdr = ICONDIRHEADER.readfrom(ifi)

        print(hdr.iconimages)

##        CreateGrpIconDirHeader(hdr, 42)
        print(hdr.idType, hdr.idCount)

        for entry in hdr.idEntries:
            print("ENTRY", entry.bWidth, entry.bHeight, entry.bColorCount,
                  entry.wPlanes, entry.wBitCount,
                  entry.dwBytesInRes,
                  entry.dwImageOffset)

            ifi.seek(entry.dwImageOffset)
            iconimage = ifi.read(entry.dwBytesInRes)
            assert len(iconimage) == entry.dwBytesInRes

        print(ifi.tell())

"""
    /* Each RT_ICON resource in an image file (containing the icon for one
       specific resolution and number of colors) must have a unique id, and
       the id must be in the GRPICONDIRHEADER's nID member.

       So, we use a *static* variable rt_icon_id which is incremented for each
       RT_ICON resource and written into the GRPICONDIRHEADER's nID member.

       XXX Do we need a way to reset the rt_icon_id variable to zero?  If we
       are building a lot of images in one setup script? 
    */
    for (i = 0; i < pidh->idCount; ++i) {
	    pgidh->idEntries[i].nID = rt_icon_id++;
    }
"""
"""
    if (!pfn_UpdateResource(hUpdate,
			    (Py_UNICODE *)MAKEINTRESOURCE(RT_GROUP_ICON),
			    (Py_UNICODE *)MAKEINTRESOURCE(icoid),
			    MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL),
			    pgidh,
			    gidh_size)) {
	SystemError(GetLastError(), "UpdateResource");
	goto failed;
    }
    for (i = 0; i < pidh->idCount; ++i) {
        char *cp = &icodata[pidh->idEntries[i].dwImageOffset];
        int cBytes = pidh->idEntries[i].dwBytesInRes;
        if (!pfn_UpdateResource(hUpdate,
				(Py_UNICODE *)MAKEINTRESOURCE(RT_ICON),
				(Py_UNICODE *)MAKEINTRESOURCE(pgidh->idEntries[i].nID),
				MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL),
				cp,
				cBytes)) {
            SystemError(GetLastError(), "UpdateResource");
            goto failed;
        }
    }
"""