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| Definition:
| | Moved to: [http://www.edm2.com/index.php/GpiEnableYInversion] |
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| BOOL APIENTRY GpiEnableYInversion(HPS hps, LONG lHeight);
| | [[Category:Redirects]] |
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| This function is exported by PMGPI.DLL as ordinal 723.
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| You can use this function by loading it dynamically when needed, for example by the following code. (The code assumes that the program uses other Gpi* functions so PMGPI.DLL is already attached to the process!)
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| static BOOL APIENTRY (*fnGpiEnableYInversion)(HPS hps, LONG lHeight) = NULL;
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| void GpiEnableYInversion(HPS hps, LONG lHeight)
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| {
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| HMODULE hmod;
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| int rc;
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| if (fnGpiEnableYInversion)
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| fnGpiEnableYInversion(hps, lHeight);
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| else
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| {
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| // Interesting, it doesn't work with DosQueryModuleHandle(), even
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| // though it returns the very same handle.
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| // [ rc = DosQueryModuleHandle("PMGPI", &hmod); ]
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| // I have to load and free the module instead...
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| rc = DosLoadModule(NULL, 0, "PMGPI", &hmod);
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| if (rc!=NO_ERROR)
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| return;
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| DosQueryProcAddr(hmod, 723, NULL, (PFN *)&fnGpiEnableYInversion);
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| DosFreeModule(hmod);
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| if (fnGpiEnableYInversion)
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| fnGpiEnableYInversion(hps, lHeight);
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| }
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| }
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| Or you can tell the linker to import it, by adding something like this to your *.def file:
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| IMPORTS
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| GpiEnableYInversion = PMGPI.723
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| Call the function with
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| lHeight = height - 1;
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| GpiEnableYInversion(hps, lHeight);
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| Notes:
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| I think it was introduced with the Open32 API (previously called DAPIE or DAX). It's purpose is to ease the porting of Windows applications to OS/2. Using this API for a given Presentation Space handle (HPS), all the Gpi functions will be inverted using the given lHeight value.
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| Please note that not only the coordinates will be top-left based, but the blitting and handling of bitmaps will also be inverted. For example, using the GpiDrawBits() API expects a pointer to a pixel array, which is bottom-up by default. Once this call is used on the target Presentation Space, you'll have to have the pixels top-up way in your buffer if you want to have your image to be shown correctly.
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| The current setting of Y-Inversion can be queried with the [[GpiQueryYInversion()]] API.
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| '''It seems the aptl[] parameter of GpiBitBlt does ''not'' get inverted! However, the bitmaps themselves ''do''!'''
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| '''The output of GPIPartialArc gets mirrored across the Y-axis - the rotational direction changes!'''
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