Using Win32 functions in Visual FoxPro Image Gallery
Code examples:
How to change display settings: screen resolution, screen refresh rate
Capturing keyboard activity of another application with the Raw Input API (VFP9)
Converting Unicode data from the Clipboard to a character string using a given code page
Copying picture of the active form to the Clipboard using Enhanced Metafile API functions
GDI+: copying to the Clipboard (a) image of active FoxPro window/form, (b) image file
Enumerating raw input devices attached to the system (keyboard, mouse, human interface device)
Disabling mouse and keyboard input for the main VFP window (with the app still running)
Enumerating data formats currently available on the clipboard
Using Beep and Sleep functions to make the old tin buzz sing (WinNT only?)
Displaying icons in the system tray (VFP9)
How to register custom Event Log source
Storing content of the Clipboard to a bitmap file
Attaching menu to a top-level form
Current keyboard type
Storing screen shot of a form to bitmap file
How to activate Windows Calculator
Custom HttpRequest class (WinINet)
Drawing Windows predefined bitmaps using the LoadBitmap functions
Using InternetSetFilePointer when resuming interrupted download from the Internet
Minimizing all running applications
How to print a bitmap file
Sending email messages with Simple MAPI
Using IsChild() for testing ThisForm.ShowWindow property
Building a tree of subdirectories for a given path using FindFile functions
How to convert a bitmap file to monochrome format (1 bpp)

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Before you begin:
It all started with a question a developer posted in the Universal Thread Visual FoxPro forum:
Does anyone know how to create a monochrome bitmap or monochrome tiff file from a VFP report?
I need to automate the process. We are using this for a faxing application and it must work in a multi-user environment
Well, there is ReportListener object in VFP9 that can solve at least a part of this task. Its OutputPage method can render the output of a report to a bitmap file. The code is very simple (requires VFP9):

LOCAL oListener As ReportListener, nPageIndex
oListener = CREATEOBJECT("ReportListener")
oListener.ListenerType=3 && renders all pages at once

* make sure the report can load and run

FOR nPageIndex=1 TO oListener.PageTotal
        cOutputFile = "tmp"+TRANS(nPageIndex)+".bmp"
                cOutputFile, 105, 0,0,768,1024) && 105=bitmap

I run the code and voila! It created one bitmap file for each page of my report. But the output files were nothing but small: 32 bits per pixel, 3.28 MB each. Still I was half way through.

Then I spent some time in Visual FoxPro trying in vain to convert bitmaps to monochromes using GDI+ API along with several GDI calls like CreateCompatibleBitmap, BitBlt and so on. The GdipGetImageGraphicsContext absolutely refused to accept monochrome HBITMAP handles.

After that I tried to find a solution using C# .NET, any solution at all. The Bitmap object did not help either. It failed to Clone to the PixelFormat.Format1bppIndexed, each time producing the System.OutOfMemoryException. That appeared consistent with GpStatus=3 returned by the GdipGetImageGraphicsContext function in my VFP tests.

Finally I gave up on GDI+ and switched to good old GDI API calls. And they worked perfectly, credits to the LoadImage for doing the actual conversion.
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5268 bytes  
Created: 2005-09-08 15:31:56  
Modified: 2010-01-14 12:01:18  
Visits in 7 days: 226  
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My comment:
The code above implements:

PROCEDURE SaveBitmapAsMonochrome(srcfile As String, dstfile As String)

To create HBITMAP from a bitmap file I use the LoadImage with LR_LOADFROMFILE and LR_MONOCHROME flags. This way, it takes care of all color-to-monochrome mumbo-jumbos, which fact I am very happy with.

The source HBITMAP is selected into a memory device context. Then both of them are passed to the SaveBitmapToFile procedure.

The procedure is a bit hard-coded, which means it produces monochrome bitmap files only. It creates BITMAPINFOHEADER and BITMAPFILEHEADER structures, extracts bitmap binary data using the GetDIBits function and then saves everything to a file.

* * *
The writing and reading from temporary file makes the C# code noticeably slow on large files, which appears to be an unavoidable pay-off for the utter simplicity of this approach.
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User Contributed Notes:
A.M. | 2007-10-31 11:05:13
Bit2Mono.exe Changes Color Bitmaps to Monochrome

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