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notcurses_visual.3: fully detail octant blitter

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nick black 2024-12-25 03:12:26 -05:00
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doc/man/man3/notcurses_visual.3.md
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@ -254,19 +254,20 @@ to work out very well for images, but (depending on the font) can be very
good for plots. good for plots.
A string can be transformed to a blitter with **notcurses_lex_blitter**, A string can be transformed to a blitter with **notcurses_lex_blitter**,
recognizing **ascii**, **half**, **quad**, **sex**, **fourstep**, **braille**, recognizing **ascii**, **half**, **quad**, **sex**, **oct**, **fourstep**,
**eightstep**, and **pixel**. Conversion in the opposite direction is performed **braille**, **eightstep**, and **pixel**. Conversion in the opposite direction
with **notcurses_str_blitter**. is performed with **notcurses_str_blitter**.
In the absence of scaling, for a given set of pixels, more rows and columns in In the absence of scaling, for a given set of pixels, more rows and columns in
the blitter will result in a smaller output image. An image rendered with the blitter will result in a smaller output image. An image rendered with
**NCBLIT_1x1** will be twice as tall as the same image rendered with **NCBLIT_1x1** will be twice as tall as the same image rendered with
**NCBLIT_2x1**, which will be twice as wide as the same image rendered with **NCBLIT_2x1**, which will be twice as wide as the same image rendered with
**NCBLIT_2x2**. The same image rendered with **NCBLIT_3x2** will be one-third **NCBLIT_2x2**, and double the height and width of the same image rendered
as tall and one-half as wide as the original **NCBLIT_1x1** render (again, this with **NCBLIT_4x2**. The same image rendered with **NCBLIT_3x2** will be
depends on **NCSCALE_NONE**). If the output size is held constant (using for one-third as tall and one-half as wide as the original **NCBLIT_1x1** render
instance **NCSCALE_SCALE_HIRES** and a large image), more rows and columns will (again, this depends on **NCSCALE_NONE**). If the output size is held constant
result in more effective resolution. (using for instance **NCSCALE_SCALE_HIRES** and a large image), more rows and
columns will result in more effective resolution.
A string can be transformed to a scaling mode with **notcurses_lex_scalemode**, A string can be transformed to a scaling mode with **notcurses_lex_scalemode**,
recognizing **stretch**, **scalehi**, **hires**, **scale**, and **none**. recognizing **stretch**, **scalehi**, **hires**, **scale**, and **none**.
@ -276,7 +277,9 @@ Assuming a cell is twice as tall as it is wide, **NCBLIT_1x1** (and indeed
any NxN blitter) will stretch an image by a factor of 2 in the vertical any NxN blitter) will stretch an image by a factor of 2 in the vertical
dimension. **NCBLIT_2x1** will not distort the image whatsoever, as it maps a dimension. **NCBLIT_2x1** will not distort the image whatsoever, as it maps a
vector two pixels high and one pixel wide to a single cell. **NCBLIT_3x2** will vector two pixels high and one pixel wide to a single cell. **NCBLIT_3x2** will
stretch an image by a factor of 1.5. stretch an image by a factor of 1.5. **NCBLIT_4x2** will preserve the aspect
ratio similarly to **NCBLIT_2x1**, but can lose color fidelity (there can be
more than two colors in a block of eight pixels).
The cell's dimension in pixels is ideally evenly divisible by the blitter The cell's dimension in pixels is ideally evenly divisible by the blitter
geometry. If **NCBLIT_3x2** is used together with a cell 8 pixels wide and geometry. If **NCBLIT_3x2** is used together with a cell 8 pixels wide and
@ -346,11 +349,10 @@ or if both ***nc*** and ***n*** are **NULL**.
**ncvisual_media_defblitter** returns the blitter selected by **NCBLIT_DEFAULT** **ncvisual_media_defblitter** returns the blitter selected by **NCBLIT_DEFAULT**
in the specified configuration. If UTF8 is not enabled, this will always be in the specified configuration. If UTF8 is not enabled, this will always be
**NCBLIT_1x1**. If ***scale*** is **NCSCALE_NONE** or **NCSCALE_SCALE**, the **NCBLIT_1x1**. If ***scale*** is **NCSCALE_NONE** or **NCSCALE_SCALE**, the
aspect-preserving **NCBLIT_2x1** will be returned. If octants are aspect-preserving **NCBLIT_2x1** will be returned. For **NCSCALE_STRETCH**,
available (see **notcurses_canoctant**), this will be **NCBLIT_4x2**, **NCBLIT_4x2** is chosen if octants are available (see **notcurses_canoctant**),
or otherwise, if sextants are available (see otherwise **NCBLIT_3x2** if sextants are available (see **notcurses_cansextant**),
**notcurses_cansextant**), this will be **NCBLIT_3x2**, or otherwise and otherwise **NCBLIT_2x2**.
**NCBLIT_2x2**.
# NOTES # NOTES
@ -363,11 +365,10 @@ a multimedia backend include **ncvisual_from_file** and
Sixel documentation can be found at [Dankwiki](https://nick-black.com/dankwiki/index.php?title=Sixel). Sixel documentation can be found at [Dankwiki](https://nick-black.com/dankwiki/index.php?title=Sixel).
Kitty's graphics protocol is specified in [its documentation](https://sw.kovidgoyal.net/kitty/graphics-protocol.html). Kitty's graphics protocol is specified in [its documentation](https://sw.kovidgoyal.net/kitty/graphics-protocol.html).
Bad font support can ruin **NCBLIT_2x2**, **NCBLIT_4x2**, **NCBLIT_3x2**, Bad font support can ruin **NCBLIT_2x2**, **NCBLIT_3x2**, **NCBLIT_4x1**,
**NCBLIT_4x1**, **NCBLIT_4x2**, **NCBLIT_BRAILLE**, and **NCBLIT_8x1**. Braille glyphs ought
**NCBLIT_BRAILLE**, and **NCBLIT_8x1**. Braille glyphs ought ideally draw only ideally draw only the raised dots, rather than drawing all eight dots with two
the raised dots, rather than drawing all eight dots with two different styles. different styles. It's often best for the emulator to draw these glyphs itself.
It's often best for the emulator to draw these glyphs itself.
Several emulators claim to implement Sixel, but do so in a more or less broken Several emulators claim to implement Sixel, but do so in a more or less broken
fashion. I consider **XTerm** and **foot** to be reference Sixel fashion. I consider **XTerm** and **foot** to be reference Sixel