Q83034: Reading and Converting Between the Three GDI Resources

Article: Q83034
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): kbfile kbsample kb16bitonly kbOSWin310 kbOSWin300
Last Modified: 06-DEC-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SUMMARY
=======

Gdirsrcs.exe is a file in the Microsoft Software Library that demonstrates the
following three techniques:

1. Reading a device independent bitmap (DIB) resource from a file and using that
  data to create one of the following:

   - A device dependent bitmap (DDB)

   - A cursor

   - An icon

2. Reading a cursor resource from a file and using that data to create one of
  the following:

   - A device dependent bitmap

   - A device independent bitmap

   - An icon

   - Another cursor

3. Reading an icon resource from a file and using that data to create one of the
  following:

   - A device dependent bitmap

   - A device independent bitmap

   - A cursor

   - Another icon

MORE INFORMATION
================

The following files are available for download from the Microsoft Download
Center:

Gdirsrcs.exe

For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.


Reading icon and cursor resources from a file is straightforward. However,
reading a device independent bitmap resource from a file is not so
straightforward for the following two reasons:

- The bitmap may be larger than 64K bytes. Therefore, an application must use a
  custom file-reading function that can deal with the 64K-byte limit.

- The device independent bitmap resource-file header has two different formats:
  one for OS/2 and another for Windows version 3.x. While the GDIRSRCS sample
  reads both formats, it stores bitmap information only in the Windows 3.x
  format.

Creating a Device Dependent Bitmap
----------------------------------

The process to create a DDB using the information in a DIB is straightforward.
Call the CreateBitmap() function to create a bitmap, then read the image data
from the DIB into the DDB.

Creating a DDB from a cursor or from an icon is also straightforward. Note that a
cursor and an icon each contain two bitmaps (the AND and XOR bit masks) in a
DIB. Extract the XOR bit mask and use it to create a DDB.

In the GDIRSRCS sample, the functions that create bitmaps are in the BMP.C file.

Creating a Cursor
-----------------

In the GDIRSRCS sample, the functions that create cursors are in the CUR.C file.

The procedure to create a cursor based on a DIB obtained from a cursor or icon
resource file has eight steps. While the following discussion describes the
process of creating a cursor based on a DIB from an icon file, the procedure to
create a cursor based on a DIB from another cursor is the same.

1. Obtain a pointer to the bits of the device independent bitmap from the icon.

2. Divide the height of the DIB by two because the DIB contains both the AND and
  XOR masks.

3. Calculate the offset to the AND mask bits.

4. Calculate the offset to the XOR mask bits.

5. Create a device dependent monochrome bitmap with the bits of the XOR mask.

6. Obtain the contents of the device dependent XOR bit mask and store it in
  memory. The AND bit mask is a monochrome bitmap. Because device independent
  and device dependent monochrome bitmaps share the same format, there is no
  need to convert the AND bit mask.

7. Because the image of a DIB is stored from bottom to top, flip the scanlines
  of the AND bit mask.

8. Create a cursor by calling the CreateCursor() function, specifying the AND
  and XOR bit masks.

To create a cursor from a bitmap DIB, use the following eight steps:

1. Obtain a handle to the DIB in the bitmap.

2. Call the GetSystemMetrics() function with the SM_CXCURSOR and SM_CYCURSOR
  indexes to determine the width and height of cursors supported by the
  installed video driver.

3. Change the size of the bitmap to match the size of the system's cursors.

4. If the bitmap is a color bitmap, convert it to monochrome. (All cursors are
  monochrome.)

5. Save the XOR mask bits in memory.

6. Create a monochrome bitmap for the AND bit mask. Fill it with any desired
  pattern.

7. Save the AND mask bits in memory.

8. Create a cursor by calling the CreateCursor() function, specifying the AND
  and XOR bit masks.

Creating Icons
--------------

In the GDIRSRCS sample, the functions that create icons are in the ICON.C file.

The process to create an icon from a cursor or from another icon resource file
has eight steps. While the following discussion describes the process of
creating an icon based on a cursor, the process to create an icon based on
another icon is the same.

1. Obtain a pointer to the bits of the DIB in the cursor.

2. Divide the height of the DIB by two because the DIB contains both the AND and
  XOR bitmaps.

3. Calculate the offset to the AND mask bits.

4. Calculate the offset to the XOR mask bits.

5. Create a device dependent monochrome bitmap with the bits of the XOR mask.

6. Obtain the contents of the device dependent XOR bit mask and store it in
  memory. The AND bit mask is a monochrome bitmap. Because device independent
  and device dependent monochrome bitmaps share the same format, there is no
  need to convert the AND bit mask.

7. Because the image of a DIB is stored from bottom to top, flip the scanlines
  of the AND bit mask.

8. Create a cursor by calling the CreateCursor() function, and specifying the
  AND and XOR bit masks.

To create an icon from a bitmap DIB, use the following seven steps:

1. Obtain a handle to the DIB in the bitmap.

2. Call the GetSystemMetrics() function with the SM_CXICON and SM_CYICON indexes
  to determine the width and height of icons supported by the installed video
  driver.

3. Change the size of the bitmap to match the size of the system's icons.

4. Save the XOR mask bits in memory.

5. Create a monochrome bitmap for the AND bit mask. Fill it with any desired
  pattern.

6. Save the AND mask bits in memory.

7. Create an icon by calling the CreateIcon() function, and specifying the AND
  and XOR bit masks.

Additional query words: softlib GDIRSRCS.EXE

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Keywords          : kbfile kbsample kb16bitonly kbOSWin310 kbOSWin300 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

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