Bitmaps and Pixel Maps
QuickDraw 3D defines bitmaps and pixmaps to specify the images used to define markers, textures, and other objects. A bitmap is a two-dimensional array of values, each of which represents the state of one pixel. A bitmap is defined by the TQ3Bitmap data type.
typedef struct TQ3Bitmap {
unsigned char *image;
unsigned long width;
unsigned long height;
unsigned long rowBytes;
TQ3Endian bitOrder;
} TQ3Bitmap;
Field Description
image
- The address of a two-dimensional block of memory that contains the bitmap image. The size, in bytes, of this block must be exactly the product of the values in the
height and rowBytes fields.
width
- The width, in bits, of the bitmap.
height
- The height of the bitmap.
rowBytes
- The distance, in bytes, from the beginning of one row of the image data to the beginning of the next row of the image data. Each new row in the image begins at an unsigned character that follows (but not necessarily immediately follows) the last unsigned character of the previous row. The minimum value of this field is the size of the image (as returned, for example, by the
Q3Bitmap_GetImageSize function) divided by the value of the height field.
bitOrder
- The order in which the bits in a byte are addressed. This field must contain one of these constants:
typedef enum TQ3Endian {
kQ3EndianBig,
kQ3EndianLittle
} TQ3Endian;
-
- The constant
kQ3EndianBig indicates that the bits are addressed in a big-endian manner. The constant kQ3EndianLittle indicates that the bits are addressed in a little-endian manner.
A pixel map (or, more briefly, a pixmap) is a two-dimensional array of values, each of which represents the color of one pixel. A pixmap is defined by the TQ3Pixmap data type.
typedef struct TQ3Pixmap {
void *image;
unsigned long width;
unsigned long height;
unsigned long rowBytes;
unsigned long pixelSize;
TQ3PixelType pixelType;
TQ3Endian bitOrder;
TQ3Endian byteOrder;
} TQ3Pixmap;
Field Description
image
- The address of a two-dimensional block of memory that contains the pixmap image. The size, in bytes, of this block must be exactly the product of the values in the
height and rowBytes fields.
width
- The width, in pixels, of the pixmap.
height
- The height, in pixels, of the pixmap.
rowBytes
- The distance, in bytes, from the beginning of one row of the image data to the beginning of the next row of the image data. The minimum value of this field depends on the values of the
width and pixelSize fields. You can use the following C language macro to determine a value for this field:
#define Pixmap_GetRowBytes(width, pixelSize) \
((pixelSize) < 8) \
? (((width) / (8 / (pixelSize))) + \
((width) % (8 / (pixelSize)) > 0)) \
: (width * ((pixelSize) / 8))
pixelSize
- The size, in bits, of a pixel.
pixelType
- The type of a pixel. This field must contain one of these constants (which must match the size specified in the
pixelSize field):
typedef enum TQ3PixelType {
kQ3PixelTypeRGB32 /*32 bits per pixel*/
} TQ3PixelType;
bitOrder
- The order in which the bits in a byte are addressed. This field must contain one of these constants:
typedef enum TQ3Endian {
kQ3EndianBig,
kQ3EndianLittle
} TQ3Endian;
-
- The constant
kQ3EndianBig indicates that the bits are addressed in a big-endian manner. The constant kQ3EndianLittle indicates that the bits are addressed in a little-endian manner.
byteOrder
- The order in which the bytes in a word are addressed. This field must contain
kQ3EndianBig or kQ3EndianLittle.
A storage pixel map (or, more briefly, a storage pixmap) is a pixmap whose data is contained in a storage object. A storage pixmap is defined by the TQ3StoragePixmap data type.
typedef struct TQ3StoragePixmap {
TQ3StorageObject image;
unsigned long width;
unsigned long height;
unsigned long rowBytes;
unsigned long pixelSize;
TQ3PixelType pixelType;
TQ3Endian bitOrder;
TQ3Endian byteOrder;
} TQ3StoragePixmap;
Field Description
image
- A storage object that contains the pixmap image. The size, in bytes, of this file must be exactly the product of the values in the
height and rowBytes fields.
width
- The width, in pixels, of the pixmap.
height
- The height, in pixels, of the pixmap.
rowBytes
- The distance, in bytes, from the beginning of one row of the image data to the beginning of the next row of the image data. The minimum value of this field depends on the values of the
width and pixelSize fields. You can use the following C language macro to determine a value for this field:
#define Pixmap_GetRowBytes(width, pixelSize) \
((pixelSize) < 8) \
? (((width) / (8 / (pixelSize))) + \
((width) % (8 / (pixelSize)) > 0)) \
: (width * ((pixelSize) / 8))
pixelSize
- The size, in bits, of a pixel.
pixelType
- The type of a pixel. This field must contain one of these constants (which must match the size specified in the
pixelSize field):
typedef enum TQ3PixelType {
kQ3PixelTypeRGB32 /*32 bits per pixel*/
} TQ3PixelType;
bitOrder
- The order in which the bits in a byte are addressed. This field must contain one of these constants:
typedef enum TQ3Endian {
kQ3EndianBig,
kQ3EndianLittle
} TQ3Endian;
-
- The constant
kQ3EndianBig indicates that the bits are addressed in a big-endian manner. The constant kQ3EndianLittle indicates that the bits are addressed in a little-endian manner.
byteOrder
- The order in which the bytes in a word are addressed. This field must contain
kQ3EndianBig or kQ3EndianLittle.
