GreGetBitmapBits

GreGetBitmapBits can be called for two reasons. If the pointer to application storage (pBitmap) is not NULL, the function transfers bit-map data from a bit map to application storage. If pBitmap is NULL, this function must only fill in the RGB values in the BITMAPINFO or BITMAPINFO2 data structure, which is pointed to by pInfo, and then return the value 0.

This function must be supported by the presentation driver. GreGetBitmapBits is called from GpiQueryBitmapBits, and is used to transfer bit-map data from the device context to application storage. It can be handled by bit-map simulation.

Simulation support

None. This function is mandatory for all drivers.

Syntax

GreGetBitmapBits(hdc, hbm, lScanStart, cScanCount, pBitmap, pInfo, pInstance, lFunction)

Parameters

hdc (HDC) - input

Device context handle.

hbm (HBITMAP) - input

Bit-map handle.

If 0, the DC bit map is used.

lScanStart (LONG) - input

Scan line number from where data transfer starts.

0 is the first scan line number.

cScanCount (LONG) - input

Number of scan lines to be transferred.

pBitmap (PBYTE) - input

Pointer to bit-map data or NULL.

Pointer to the pel data of the bit map. This data is stored in the order that the coordinates appear on a display screen, that is, the pel in the lower-left corner is the first in the bit map. Pels are scanned to the right, and upward, from that position. The bits of the first pel are stored beginning with the most significant bits of the first byte. The data for pels in each scan line is packed together tightly. However, all scan lines are padded at the end so that each one begins on a ULONG boundary. That is, three bytes of pel data will hold one 24-bit pel, three 8-bit pels, six 4-bit pels, or twenty-four 1-bit pels. If those three bytes are the only pel data for that scan line, one more byte of 0s would be required to pad the line to a ULONG boundary.

pInfo (PBITMAPINFO) - input

Pointer to BITMAPINFO or BITMAPINFO2 structure.

pInstance (PVOID) - input

Pointer to instance data.

lFunction (ULONG) - input

High-order WORD=flags; low-order WORD=NGreGetBitmapBits.

Returns

rc (LONG) - returns

Return Code.

On completion, the handling routine must return a LONG value (lLines), indicating the number of lines transferred, or GPI_ALTERROR if an error occurred.

Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. Error codes for conditions that the handling routine is expected to check include:

• PMERR_BITMAP_NOT_SELECTED
• PMERR_DEV_FUNC_NOT_INSTALLED
• PMERR_INCORRECT_DC_TYPE
• PMERR_INV_HBITMAP
• PMERR_INV_IN_AREA
• PMERR_INV_IN_PATH
• PMERR_INV_INFO_TABLE
• PMERR_INV_LENGTH_OR_COUNT
• PMERR_INV_SCAN_START

Refer to the "Error Explanations" section in the Presentation Manager Programming Reference for further explanation.

Sample

#define INCL_GRE_BITMAPS
#include <os2.h>

HDC            hdc;         /*  Device context handle. */
HBITMAP        hbm;         /*  Bit-map handle. */
LONG           lScanStart;  /*  Scan line number from where data transfer starts. */
LONG           cScanCount;  /*  Number of scan lines to be transferred. */
PBYTE          pBitmap;     /*  Pointer to bit-map data or NULL. */
PBITMAPINFO    pInfo;       /*  Pointer to BITMAPINFO or BITMAPINFO2 structure. */
PVOID          pInstance;   /*  Pointer to instance data. */
ULONG          lFunction;   /*  High-order WORD=flags; low-order WORD=NGreGetBitmapBits. */
LONG           rc;          /*  Return Code. */

rc = GreGetBitmapBits(hdc, hbm, lScanStart,
       cScanCount, pBitmap, pInfo, pInstance, lFunction);

Remarks

The bit map can be specified by a bit-map handle, or (if this is NULL) a DC handle, in which case the device context must be a memory DC with a bit map currently selected.

When the bit-map handle is NULL, the DC must be a memory DC with a bit map currently selected. Otherwise, the DC handle must be valid for that device. The BITMAPINFO or BITMAPINFO2 structure must be initialized with the values of cPlanes and cBitcount for the format of data required. This must be one of the standard formats or a device-specific format that matches the DC. On return, cx, cy, and argbColors are supplied by the system. Conversion of the bit-map data is carried out, if necessary.

pBitmap must point to a storage area large enough to contain data for the requested number of scan lines. The amount of storage required for one scan line can be determined by calling GetBitmapParameters:

((cBitcount * cx + 31)/32) * cPlanes * 4 bytes