GetGlyphOutline

GetGlyphOutline

The GetGlyphOutline function retrieves the outline or bitmap for a character in the TrueType font that is selected into the specified device context.

DWORD GetGlyphOutline(

HDC hdc,	// handle of device context
UINT uChar,	// character to query
UINT uFormat,	// format of data to return
LPGLYPHMETRICS lpgm,	// address of structure for metrics
DWORD cbBuffer,	// size of buffer for data
LPVOID lpvBuffer,	// address of buffer for data
CONST MAT2 *lpmat2	// address of transformation matrix structure
);

Parameters

hdc

Identifies the device context.

uChar

Specifies the character for which data is to be returned.

uFormat

Specifies the format of the data that the function retrieves. Use one of the following values:

Value	Meaning
GGO_BITMAP	The function retrieves the glyph bitmap. For information about memory allocation, see the following Remarks section.
GGO_NATIVE	The function retrieves the curve data points in the rasterizer's native format and uses the font's design units. When this value is specified, any transformation specified in the lpMatrix parameter is ignored.
GGO_METRICS	The function only retrieves the GLYPHMETRICS structure specified by lpgm. The other buffers are ignored. This value affects the meaning of the function's return value upon failure; see the following Return Value section.
GGO_GRAY2_BITMAP	The function retrieves a glyph bitmap that contains 5 levels of gray.
GGO_GRAY4_BITMAP	The function retrieves a glyph bitmap that contains 17 levels of gray.
GGO_GRAY8_BITMAP	The function retrieves a glyph bitmap that contains 65 levels of gray.

Note that, for the GGO_GRAYn_BITMAP values, the function retrieves a glyph bitmap that contains n^2+1 (n squared plus one) levels of gray.

lpgm

Points to the GLYPHMETRICS structure describing the placement of the glyph in the character cell.

cbBuffer

Specifies the size of the buffer where the function is to copy information about the outline character. If this value is zero, the function returns the required size of the buffer.

lpvBuffer

Points to the buffer where the function is to copy information about the outline character. If this value is NULL, the function returns the required size of the buffer.

lpmat2

Points to a MAT2 structure specifying a transformation matrix for the character.

Return Values

If GGO_BITMAP, GGO_GRAY2_BITMAP, GGO_GRAY4_BITMAP, GGO_GRAY8_BITMAP, or GGO_NATIVE is specified and the function succeeds, the return value is greater than zero; otherwise, the return value is GDI_ERROR. If one of these flags is specified and the buffer size or address is zero, the return value specifies the required buffer size, in bytes.

If GGO_METRICS is specified and the function fails, the return value is GDI_ERROR.

Remarks

The glyph outline returned by the GetGlyphOutline function is for a grid-fitted glyph. (A grid-fitted glyph is a glyph that has been modified so that its bitmapped image conforms as closely as possible to the original design of the glyph.) If an application needs an unmodified glyph outline, it can request the glyph outline for a character in a font whose size is equal to the font's em unit. The value for a font's em unit is stored in the otmEMSquare member of the OUTLINETEXTMETRIC structure.

The glyph bitmap returned by GetGlyphOutline when GGO_BITMAP is specified is a doubleword-aligned, row-oriented, monochrome bitmap. When GGO_GRAY2_BITMAP is specified, the bitmap returned is a doubleword-aligned, row-oriented array of bytes whose values range from 0 to 4. When GGO_GRAY4_BITMAP is specified, the bitmap returned is a doubleword-aligned, row-oriented array of bytes whose values range from 0 to 16. When GGO_GRAY8_BITMAP is specified, the bitmap returned is a doubleword-aligned, row-oriented array of bytes whose values range from 0 to 255.

An application can rotate characters retrieved in bitmap format by specifying a 2-by-2 transformation matrix in the lpMatrix parameter.