class HT_Bitonal

class HT_Bitonal_Format

This class enables access to endian and black and white bit swap for Heidi bitonal images. It provides a means for changing the way that bitonal images are packed, in order to further the support for hardcopy drivers. Some devices may prefer less significant bit first (LSB); others most significant bit first (MSB).

For more information, see the settings On_Bit_Black and On_Bit_White in HT_Renderer::draw_dc_bitonal_image, the implementation in HT_Renderer_Options::bitonal_format and the general discussion in the section, "bitonal_format," of chapter 3, "Implementing a New Driver."

Details

Call the HT_Renderer_Options method set_bitonal_format with the proper HT_Bitonal_Format enum to control bitonal image padding. When dithering a true color, index 8, and gray scale image, Heidi standard routines pack the output image based on the new flags HT_Bitional_Format::MSB and HT_Bitonal_Format::On_Bit_Black. Both bits are off by default.

Note: These standard routines will process bitonal images, of different padding, to the proper format. In your device driver's draw_dc_bitonal_image, you should check to see if the new incoming format parameter, bitonal_format, matches your renderer option with the same name. If not, then punt to the HD_Standard_Draw_DC_Bitonal_Image, which will repack the image and call your draw_dc_bitonal_image again.

class HT_Bitonal_Format {
    public:
        enum Enum {
            Default =           0x0000,  // neither MSB nor On_Bit_Black
            MSB =               0x0001,
            On_Bit_Black =      0x0002,
        };
    ENUM_BIT_CLASS_FUNCTIONS (HT_Bitonal_Format);
};

See Also HT_Renderer, HT_Renderer_Options,chapter 3, "Implementing a New Driver."