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Four characters in DEC Special Graphics (Line Drawing)[⁽¹⁾] charset were translated by Konsole into codepoints in private use area. This patch uses the same code points that xterm uses. | Index | Previously | Should be | | ------ | ---------- | ----------| | `0x6F` | `U+F800` | `U+23BA` | | `0x70` | `U+F801` | `U+23BB` | | `0x72` | `U+F803` | `U+23BC` | | `0x73` | `U+F804` | `U+23BD` | The old behavior used the same mapping used by Linux consoles, as stated in `unicode.txt`[⁽²⁾] in Linux's documents. This has been changed long ago when Unicode 3.2.0 introduced the codepoints `U+23BA`, `U+23BB`, `U+23BC`, `U+23BD`, as the following excerpt of `unicode.txt` says: ``` In addition, the following characters not present in Unicode 1.1.4 have been defined; these are used by the DEC VT graphics map. [v1.2] THIS USE IS OBSOLETE AND SHOULD NO LONGER BE USED; PLEASE SEE BELOW. ====== ====================================== U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1 U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3 U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7 U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9 ====== ====================================== [...] [v1.3]: These characters have been officially added to Unicode 3.2.0; they are added at U+23BA, U+23BB, U+23BC, U+23BD. Linux now uses the new values. ``` [⁽¹⁾]: https://vt100.net/docs/vt220-rm/chapter2.html#T2-4 [⁽²⁾]: https://raw.githubusercontent.com/torvalds/linux/5bfc75d92efd494db37f5c4c173d3639d4772966/Documentation/admin-guide/unicode.rst
115 lines
3.8 KiB
Plaintext
115 lines
3.8 KiB
Plaintext
[README.fonts]
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Fonts need to suit the needs of X11, QT and konsole.
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* the font has to be fixed width.
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This requirement originate both from X11 and
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the way QT and konsole uses it together with
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the very idea of what a terminal emulation is
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about.
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Basically, a terminal emulation is to display
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a character cell oriented screen, meaning that
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all characters in the same column line up
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properly under each other.
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Though one could make this with a variable
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width font (which are preferably used in text
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processing) the outcome would look very poor,
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since the glyphs would have to be placed into
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a cell fitting the widest character in the
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font, which is typically more than two times
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wider than the narrowest glyph. Imagine a text
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with l o t s o f s p a c e s
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inserted between each character to get the idea.
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Further, doing this with a variable width font
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means to do some operations that slow down the
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whole display refreshing dramatically. X11/QT
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performs very poor when one draws characters
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individually while additionally clearing
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background regions instead of drawing a complete
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string (as konsole does). If one draws a string
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with a variable width font, it is of course
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typeset by X11 variable width, not longer
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conforming to the character cell model of a
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terminal emulation.
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So from both perspectives, variable width fonts
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are unsuited for terminal emulation purposes.
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* the font has to contain some graphical characters
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Many full screen applications make use of these
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characters to draw boxes, scroll bars and likely
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pseudo graphical entities.
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Using fonts without this capabilities means to
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break the visual appearance of these products.
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As a minimum the following glyphs have to be
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included within a font to become usable:
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- 0x0b U+2518 : BOX DRAWINGS LIGHT UP AND LEFT
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- 0x0c U+2510 : BOX DRAWINGS LIGHT DOWN AND LEFT
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- 0x0d U+250c : BOX DRAWINGS LIGHT DOWN AND RIGHT
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- 0x0e U+2514 : BOX DRAWINGS LIGHT UP AND RIGHT
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- 0x0f U+253c : BOX DRAWINGS LIGHT VERTICAL AND HORIZONTAL
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- 0x10 U+23ba : HORIZONTAL SCAN LINE-1
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- 0x11 U+23bb : HORIZONTAL SCAN LINE-3
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- 0x12 U+2500 : BOX DRAWINGS LIGHT HORIZONTAL (scan line 5)
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- 0x13 U+23bc : HORIZONTAL SCAN LINE-7
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- 0x14 U+23bd : HORIZONTAL SCAN LINE-9
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- 0x15 U+251c : BOX DRAWINGS LIGHT VERTICAL AND RIGHT
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- 0x16 U+2524 : BOX DRAWINGS LIGHT VERTICAL AND LEFT
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- 0x17 U+2534 : BOX DRAWINGS LIGHT UP AND HORIZONTAL
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- 0x18 U+252c : BOX DRAWINGS LIGHT DOWN AND HORIZONTAL
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- 0x19 U+2502 : BOX DRAWINGS LIGHT VERTICAL
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- 0x01 U+25c6 : BLACK DIAMOND
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- 0x02 U+2592 : MEDIUM SHADE
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- 0x1F U+00b7 : MIDDLE DOT
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Also, the VT100 knows about the following glyphs,
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though omitting them is unlikely to break anything.
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- 0x07 U+00b0 : DEGREE SIGN
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- 0x08 U+00b1 : PLUS-MINUS SIGN
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- 0x1a U+2264 : LESS THAN OR EQUAL TO
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- 0x1b U+2265 : GREATER THAN OR EQUAL TO
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- 0x1c U+03c0 : GREEK SMALL LETTER PI
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- 0x1d U+2260 : NOT EQUAL TO
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- 0x1e U+00a3 : POUND SIGN
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Additionally, digraphs are provided for some
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of the control characters by VT100, too.
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- 0x03 U+2409 : DIGRAPH HT
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- 0x04 U+240c : DIGRAPH FF
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- 0x05 U+240d : DIGRAPH CR
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- 0x06 U+240a : DIGRAPH LF
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- 0x09 U+240d : DIGRAPH NL
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- 0x0a U+240b : DIGRAPH VT
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The mapping of non-iso10646 fonts is extended by konsole
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with the regular xterm fixed font placement of these
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glyphs to 0x00-0x1f.
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* Iso10646 fonts needs to have a fall back character
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to be properly assigned.
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Use the "DEFAULT_CHAR" property with bdf fonts
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to do so. Other font representations provide
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likely means. The unicode assignment is U+fffd.
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If such a character isn't defined, X11 might
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choose to void the character completely, causing
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inconsistent appearance when refreshing the screen.
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One may choose the space glyph to hide the flaw
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or a box like one to exhibit it.
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