Functions | |
void | Draw_DC_Image_Block (HT_Rendition *nr, HT_DC_Point *start, int width, int height, char format, int rowbytes, void **data) |
void | Draw_DC_Image (HT_Rendition *nr, HT_DC_Point *start, HT_DC_Point *end, int hoffset, char format, int rowbytes, void **rasters, const int pattern, HT_Driver_Color *contr_clr, HT_IMAGE *db_image) |
|
Draws a generalized image.
DETAILSHIC_Draw_DC_Image_Block() is the simplest and preferred method of drawing images and rasters. However, it allows drawing only the entire image stored in the data block, and does not provide for Z-buffering tilted images.NOTESThis routine is device-independent, in that it can be called for devices of any visual type.start may be off-screen. format has one of the following values, with the indicated meanings: -------------------------------------------------------------------------- Image_MAPPED_8 One byte per pixel, used as index into current color map. Image_MAPPED_16 Two bytes per pixel, used as 16-bit index into current color map. Image_RGB Three bytes per pixel, giving red, green, and blue values in order. Image_ARGB Four bytes per pixel, giving alpha, red, green, and blue values in order. Image_RGBA Four bytes per pixel, giving red, blue, green, and alpha values in order. -------------------------------------------------------------------------- Currently, the alpha value is used as a stencil. That is, pixels with A=0 are not drawn and pixels with A not zero are drawn.
|
|
Draws a generalized image.
DETAILSHIC_Draw_DC_Image() is a more general image drawing routine. It would be used to draw a sub-block of the stored image, or to apply Z-buffering to a tilted image.In HIC_Draw_DC_Image() , the array of pointers rasters, and the hoffset argument allow for drawing a sub-image of a stored image. Because it has both start and end parameters, it allows for drawing a tilted image that may be subject to Z-buffer comparison, when Z-buffering is in effect. However, Z-buffering of tilted images works only for images consisting of a single scan line, with (start - y) = (end - y). Z-buffering results are unpredictable for multi-line tilted images. NOTESThis routine is device-independent, in that it can be called for devices of any visual type.start may be off-screen. format has one of the following values, with the indicated meanings: -------------------------------------------------------------------------- Image_MAPPED_8 One byte per pixel, used as index into current color map. Image_MAPPED_16 Two bytes per pixel, used as 16-bit index into current color map. Image_RGB Three bytes per pixel, giving red, green, and blue values in order. Image_ARGB Four bytes per pixel, giving alpha, red, green, and blue values in order. Image_RGBA Four bytes per pixel, giving red, blue, green, and alpha values in order. -------------------------------------------------------------------------- Currently, the alpha value is used as a stencil. That is, pixels with A=0 are not drawn and pixels with A not zero are drawn.
|