Syntax
INT is_PrepareStealVideo (HIDS hf, int Mode, ULONG StealColorMode)
Description
When in DirectDraw mode, is_PrepareStealVideo() prepares image acquisition in an image memory which has been allocated with is_AllocImageMem(). During the display of a live image in DirectDraw mode, a number of images can be stolen from the live image acquisition and be copied to an allocated area of memory. The live image acquisition is halted only for this number of images.
As an alternative an automatic steal mode can be used. And thus the number of images which are alternately sent to VGA card and main memory can be set separately between 1 and 255. When starting the automatic steal mode the first image is sent to the VGA card following alternately the set number of frames to the main memory and VGA card. Image acquisition in steal mode can be combined with an image reflection around the horizontal axis (see also is_SetRopEffect()). For this purpose parameter Mode has to be logical "or"-operated with one of the MIRROR constants. The mode set with function is_SetRopEffect() does not affect the “stealing” of the image. A desired ROP effect must be set in is_PrepareStealVideo() through this OR-Operation mentioned above.
The steal mode can only be used in connection with the image acquisition modes IS_SET_CM_FRAME or IS_SET_CM_NEXT_FRAME in the interlaced or non-interlaced representation (see also is_SetCaptureMode()).
Using the sequence event (see also is_InitEvent()) more events as the set number of images acquisited in the image memory can be signalized in connection with the DirectDraw primary surface mode.
Parameters
hf |
Frame grabber handle |
Mode |
Initialization or deinitialization of the mode |
IS_INIT_STEAL_VIDEO |
Initializes the manual steal mode |
IS_INIT_STEAL_VIDEO_MANUAL |
Initializes the manual steal mode |
IS_INIT_STEAL_VIDEO_AUTO |
Initializes the automatic steal mode |
IS_SET_STEAL_RATIO |
Sets the proportion from number of images to VGA card and/or main memory (OR-operation with first three constants) |
IS_EXIT_STEAL_VIDEO |
Deinitializes the steal mode |
Additional reflection around the horizontal axis (OR-operation): |
|
IS_SET_ROP_MIRROR_UPDOWN |
reflect frame |
IS_SET_ROP_MIRROR_UPDOWN_ODD |
reflect odd field |
IS_SET_ROP_MIRROR_UPDOWN_EVEN |
reflect even field |
Steal-image size independent of the current settings (or-linked) |
|
IS_USE_MEM_IMAGE_SIZE |
Acquisition of the Steal-Image in the same size of the corresponding image memory which is allocated for the image |
StealColorMode |
Color mode with which the image should be stolen. (Color mode see is_SetColorMode()). A corresponding image memory must be allocated. |
Return value
IS_SUCCESS, IS_NO_SUCCESS
The number of images to the VGA card and main memory can be set in case of IS_SET_STEAL_RATIO with parameter StealColorMode:
Bits |
31...24 |
23...16 |
15...8 |
7...0 |
Relevance |
reserved |
Number of frames to VGA card |
Number of frames to main memory |
Steal color mode |
Example
•To initialize manual steal mode in Y8 color mode:
is_PrepareStealVideo(hf, IS_INIT_STEAL_VIDEO, IS_SET_CM_Y8)
•To initialize manual steal mode in Y8 color mode with 5 images stolen in main memory:
is_PrepareStealVideo(hf, IS_INIT_STEAL_VIDEO | IS_SET_STEAL_RATIO, IS_SET_CM_Y8 | 0x0500)
0x0500 is the hexadecimal representation of 5 in bits 15…8
| is logical OR-operation
•To initialize automatic steal mode in Y8 color mode with 2 images stolen in main memory and 7 to VGA card:
is_PrepareStealVideo(hf, IS_INIT_STEAL_VIDEO_AUTO | IS_SET_STEAL_RATIO , IS_SET_CM_Y8 | 0x070200)
0x070200 is the hexadecimal representation of 7 in bits 23…16 and of 2 in bits 15…8
| is logical OR-operation
•Sets the values to capture 2 images in main memory and 7 images to VGA card (steal process can be active):
is_PrepareStealVideo(hf, IS_SET_STEAL_RATIO, 0x070200)
0x070200 is the hexadecimal representation of 7 in bits 23…16 and of 2 in bits 15…8
