SoSFImage(3)

NAME
SoSFImage - The SoSFImage class is used to store pixel images.

The SoSFImage class provides storage for inline 2D image maps. Images in Coin are mainly used for texture mapping support.

SYNOPSIS

#include <Inventor/fields/SoSFImage.h>

Inherits SoSField.

  Public Types
enum CopyPolicy { COPY, NO_COPY, NO_COPY_AND_DELETE, NO_COPY_AND_FREE }

  Public Member Functions
virtual SoType getTypeId (void) const
virtual void copyFrom (const SoField &field)
const SoSFImage & operator= (const SoSFImage &field)
virtual SbBool isSame (const SoField &field) const
const unsigned char * getValue (SbVec2s &size, int &nc) const
const SbImage & getValue () const
void setValue (const SbVec2s &size, const int nc, const unsigned char *pixels, CopyPolicy copypolicy=COPY)
int operator== (const SoSFImage &field) const
int operator!= (const SoSFImage &field) const
unsigned char * startEditing (SbVec2s &size, int &nc)
void finishEditing (void)
void setSubValue (const SbVec2s &dims, const SbVec2s &offset, unsigned char *pixels)
void setSubValues (const SbVec2s *dims, const SbVec2s *offsets, int num, unsigned char **pixelblocks)
unsigned char * getSubTexture (int idx, SbVec2s &dims, SbVec2s &offset) const
SbBool hasSubTextures (int &numsubtextures)
void setNeverWrite (SbBool flag)
SbBool isNeverWrite (void) const
SbBool hasTransparency (void) const

  Static Public Member Functions
static void * createInstance (void)
static SoType getClassTypeId (void)
static void initClass (void)

  Additional Inherited Members

Detailed Description

The SoSFImage class is used to store pixel images.

The SoSFImage class provides storage for inline 2D image maps. Images in Coin are mainly used for texture mapping support. SoSFImage instances can be exported and imported as any other field class in Coin.

The components of an SoSFImage is: its image dimensions (width and height), the number of bytes used for describing each pixel (number of components) and an associated pixel buffer. The size of the pixel buffer will be width*height*components.

For texture maps, the components / bytes-per-pixel setting translates as follows: use 1 for a grayscale imagemap, 2 for grayscale + opacity (i.e. alpha value), 3 for RGB (1 byte each for red, green and blue) and 4 components means 3 bytes for RGB + 1 byte opacity value (aka RGBA).

This field is serializable into the Inventor / Coin file format in the following manner:

FIELDNAME X Y C 0xRRGGBBAA 0xRRGGBBAA ...

For 3-component images, the pixel-format is 0xXXRRGGBB, where the byte in the pixel color value marked as 'XX' is ignored and can be left out.

For 2-component images, the pixel-format is 0xXXXXGGAA, where the bytes in the pixel color values marked as 'XX' are ignored and can be left out. 'GG' is the part which gives a grayscale value and 'AA' is for opacity.

For 1-component images, the pixel-format is 0xXXXXXXGG, where the bytes in the pixel color values marked as 'XX' are ignored and can be left out.

The pixels are read as being ordered in rows along X (width) and columns along Y (height, bottom to top).

Here's a simple example of the file format serialization, for a 2x2 RGB-image inside an SoTexture2 node, as mapped onto an SoCube:

Complexity { textureQuality 0.1 }   # set low to avoid smoothing
Texture2 {
   image 2 2 4
   0xffffffff 0x00ff0088   # white   semi-transparent green
   0xff0000ff 0xffff00ff   #  red    yellow
}
Cube { }

The mini-scenegraph above results in the following mapping on the cube:

The cube has only been slightly rotated, so as you can see from the snapshot, the Y-rows are mapped from bottom to top, while the X-column pixels are mapped onto the cube from left to right.

See also:
    SoTexture2, SoSFImage3

Member Function Documentation

  SoType SoSFImage::getTypeId (void) const [virtual]
Returns the type identification instance which uniquely identifies the Coin field class the object belongs to.

See also:
    getClassTypeId(), SoType

Implements SoField.

  void SoSFImage::copyFrom (const SoField & f) [virtual]
Copy value(s) from f into this field. f must be of the same type as this field.

Implements SoField.

  SbBool SoSFImage::isSame (const SoField & f) const [virtual]
Check for equal type and value(s).

Implements SoField.

  const unsigned char * SoSFImage::getValue (SbVec2s & size, int & nc) const
Return pixel buffer, set size to contain the image dimensions and nc to the number of components in the image.

  const SbImage & SoSFImage::getValue (void) const

Return values:
    SbImage contained by this SoSFImage

  void SoSFImage::setValue (const SbVec2s & size, const int nc, const unsigned char * pixels, SoSFImage::CopyPolicy copypolicy = COPY)
Initialize this field to size and nc.

If pixels is not NULL, the image data is copied from pixels into this field. If pixels is NULL, the image data is cleared by setting all bytes to 0 (note that the behavior on passing a NULL pointer is specific for Coin, Open Inventor will crash if you try it).

The image dimensions is given by the size argument, and the nc argument specifies the number of bytes-pr-pixel. A 24-bit RGB image would for instance have an nc equal to 3.

The copypolicy argument makes it possible to share image data with SoSFImage without the data being copied (thereby using less memory resources). The default is to copy image data from the pixels source into an internal copy.

Important note: if you call this with copypolicy as either NO_COPY_AND_DELETE or NO_COPY_AND_FREE, and your application is running on Mirosoft Windows, be aware that you will get mysterious crashes if your application is not using the same C library run-time as the Coin library.

The cause of this is that a memory block would then be allocated by the application on the memory heap of one C library run-time (say, for instance MSVCRT.LIB), but attempted deallocated in the memory heap of another C library run-time (e.g. MSVCRTD.LIB), which typically leads to hard-to-debug crashes.

Since:
    The CopyPolicy argument was added in Coin 2.0.

    CopyPolicy was added to TGS Inventor 3.0.

  int SoSFImage::operator== (const SoSFImage & field) const
Compare image of field with the image in this field and return TRUE if they are equal.

  int SoSFImage::operator!= (const SoSFImage & field) const [inline]
Compare image of field with the image in this field and return FALSE if they are equal.

  unsigned char * SoSFImage::startEditing (SbVec2s & size, int & nc)
Return pixel buffer. Return the image size and components in size and nc.

You can not use this method to set a new image size. Use setValue() to change the size of the image buffer.

The field's container will not be notified about the changes until you call finishEditing().

  void SoSFImage::finishEditing (void)
Notify the field's auditors that the image data has been modified.

  void SoSFImage::setSubValue (const SbVec2s & dims, const SbVec2s & offset, unsigned char * pixels)
Not yet implemented for Coin. Get in touch if you need this method.

Since:
    Coin 2.0

    TGS Inventor 3.0

  void SoSFImage::setSubValues (const SbVec2s * dims, const SbVec2s * offsets, int num, unsigned char ** pixelblocks)
Not yet implemented for Coin. Get in touch if you need this method.

Since:
    Coin 2.0

    TGS Inventor 3.0

  unsigned char * SoSFImage::getSubTexture (int idx, SbVec2s & dims, SbVec2s & offset) const
Not yet implemented for Coin. Get in touch if you need this method.

Since:
    Coin 2.0

    TGS Inventor 3.0

  SbBool SoSFImage::hasSubTextures (int & numsubtextures)
Returns whether or not sub textures was set up for this field.

If TRUE is returned, the numsubtextures argument will be set to the number of sub textures in this image. This number can be used for iterating over all textures with the SoSFImage::getSubTextures() method.

Since:
    Coin 2.0

    TGS Inventor 3.0

  void SoSFImage::setNeverWrite (SbBool flag)
Set this flag to true to avoid writing out the texture to file. This can save a lot on file size.

Default value is FALSE (i.e. write texture data to file.)

(Note: yet unimplemented for Coin.)

Since:
    Coin 2.0

    TGS Inventor ?.?

  SbBool SoSFImage::isNeverWrite (void) const
Returns value of 'never write texture data' flag.

See also:
    SoSFImage::setNeverWrite()

Since:
    Coin 2.0

    TGS Inventor ?.?

  SbBool SoSFImage::hasTransparency (void) const
Returns TRUE if at least one pixel of the image in this field is not completely opaque, otherwise FALSE.

Since:
    Coin 2.0

    TGS Inventor ?.?

Author

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