ImageGear for C and C++ on Windows v19.0
LPFNIG_ISIS_AREA
| API Reference Guide > ISIS Component API Reference > ISIS Component Callback Functions Reference > LPFNIG_ISIS_AREA |
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typedef LONG (LPACCUAPI LPFNIG_ISIS_AREA)(
LONG lCommand,
DWORD lData,
DWORD lParam
);
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| Name | Type | Description |
|---|---|---|
| lCommand | LONG | Low word is the command to be executed by the callback function. High word is a sub-command specific to the command. |
| lData | DWORD | 32-bit data associated with the command. |
| lParam | DWORD | 32-bit user data that was passed as the lParam parameter to IG_ISIS_area_dialog_CB_register. |
The possible values for lCommand are:
| lCommand | Meaning |
|---|---|
| IG_ISIS_AREA_INIT Sub-command: unused 0) | Called when the preview window is created.lData is unused. Return IGE_SUCCESS if successful. Any other return value will show the preview rectangle without any preview image and no further messages will be sent to the callback. |
| IG_ISIS_AREA_DONE Sub-command: unused (0) | Called when the preview window is destroyed. lData is unused. |
| IG_ISIS_AREA_PAINT Sub-command: unused (0) | The callback should scale and paint its image into the supplied destRect using the supplied clipping rectangle (clipRect) and device context (hDC).lData is a FAR pointer to a AT_ISIS_AREAPAINTINFO structure which holds these three values. The callback should return IGE_SUCCESS if successful. |
| IG_ISIS_AREA_GET Sub-command: TAG number | Called during dialog initialization to request values from the callback describing the image that will be painted. lData is a FAR pointer which should be cast to point to the data type of the equivalent tag (AT_ISIS_RAT must be converted to IG_ISIS_TAG_TYPE_RATIONAL). If the callback doesn't provide a particular tag, it must not modify the contents of *lData. |
| IG_ISIS_TAG_XRESOLUTION IG_ISIS_TAG_YRESOLUTION |
The callback must provide resolution information so that the area dialog can determine how to scale the drawing rectangle. (Type: IG_ISIS_TAG_TYPE_RATIONAL) |
| IG_ISIS_TAG_IMAGEWIDTH IG_ISIS_TAG_IMAGELENGTH |
The callback must provide the unscaled image size (in pixels). (Type: IG_ISIS_TAG_TYPE_LONG) |
| IG_ISIS_TAG_XPOSITION IG_ISIS_TAG_YPOSITION |
The callback can optionally provide the unscaled X/Y positions (in pixels) used when the preview image was originally scanned. (Type: IG_ISIS_TAG_TYPE_LONG) If the position tags are not provided by the callback, the drawing rectangle will be at the top of the page, centered for centerfeed scanners and left aligned for other scanners. |