301 lines
15 KiB
Markdown
301 lines
15 KiB
Markdown
==================================================================
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Notes regarding fonts, code pages, and East Asian character widths
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==================================================================
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Registry settings
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=================
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* There are console registry settings in `HKCU\Console`. That key has many
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default settings (e.g. the default font settings) and also per-app subkeys
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for app-specific overrides.
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* It is possible to override the code page with an app-specific setting.
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* There are registry settings in
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`HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Console`. In particular,
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the `TrueTypeFont` subkey has a list of suitable font names associated with
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various CJK code pages, as well as default font names.
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* There are two values in `HKLM\SYSTEM\CurrentControlSet\Control\Nls\CodePage`
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that specify the current code pages -- `OEMCP` and `ACP`. Setting the
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system locale via the Control Panel's "Region" or "Language" dialogs seems
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to change these code page values.
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Console fonts
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=============
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* The `FontFamily` field of `CONSOLE_FONT_INFOEX` has two parts:
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- The high four bits can be exactly one of the `FF_xxxx` font families:
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FF_DONTCARE(0x00)
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FF_ROMAN(0x10)
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FF_SWISS(0x20)
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FF_MODERN(0x30)
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FF_SCRIPT(0x40)
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FF_DECORATIVE(0x50)
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- The low four bits are a bitmask:
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TMPF_FIXED_PITCH(1) -- actually means variable pitch
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TMPF_VECTOR(2)
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TMPF_TRUETYPE(4)
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TMPF_DEVICE(8)
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* Each console has its own independent console font table. The current font
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is identified with an index into this table. The size of the table is
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returned by the undocumented `GetNumberOfConsoleFonts` API. It is apparently
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possible to get the table size without this API, by instead calling
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`GetConsoleFontSize` on each nonnegative index starting with 0 until the API
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fails by returning (0, 0).
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* The font table grows dynamically. Each time the console is configured with
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a previously-unused (FaceName, Size) combination, two entries are added to
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the font table -- one with normal weight and one with bold weight. Fonts
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added this way are always TrueType fonts.
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* Initially, the font table appears to contain only raster fonts. For
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example, on an English Windows 8 installation, here is the initial font
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table:
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font 0: 4x6
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font 1: 6x8
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font 2: 8x8
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font 3: 16x8
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font 4: 5x12
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font 5: 7x12
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font 6: 8x12 -- the current font
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font 7: 16x12
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font 8: 12x16
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font 9: 10x18
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`GetNumberOfConsoleFonts` returns 10, and this table matches the raster font
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sizes according to the console properties dialog.
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* With a Japanese or Chinese locale, the initial font table appears to contain
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the sizes applicable to both the East Asian raster font, as well as the
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sizes for the CP437/CP1252 raster font.
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* The index passed to `SetCurrentConsoleFontEx` apparently has no effect.
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The undocumented `SetConsoleFont` API, however, accepts *only* a font index,
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and on Windows 8 English, it switches between all 10 fonts, even font index
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#0.
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* If the index passed to `SetConsoleFont` identifies a Raster Font
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incompatible with the current code page, then another Raster Font is
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activated.
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* Passing "Terminal" to `SetCurrentConsoleFontEx` seems to have no effect.
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Perhaps relatedly, `SetCurrentConsoleFontEx` does not fail if it is given a
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bogus `FaceName`. Some font is still chosen and activated. Passing a face
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name and height seems to work reliably, modulo the CP936 issue described
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below.
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Console fonts and code pages
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============================
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* On an English Windows installation, the default code page is 437, and it
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cannot be set to 932 (Shift-JIS). (The API call fails.) Changing the
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system locale to "Japanese (Japan)" using the Region/Language dialog
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changes the default CP to 932 and permits changing the console CP between
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437 and 932.
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* A console has both an input code page and an output code page
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(`{Get,Set}ConsoleCP` and `{Get,Set}ConsoleOutputCP`). I'm not going to
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distinguish between the two for this document; presumably only the output
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CP matters. The code page can change while the console is open, e.g.
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by running `mode con: cp select={932,437,1252}` or by calling
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`SetConsoleOutputCP`.
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* The current code page restricts which TrueType fonts and which Raster Font
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sizes are available in the console properties dialog. This can change
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while the console is open.
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* Changing the code page almost(?) always changes the current console font.
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So far, I don't know how the new font is chosen.
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* With a CP of 932, the only TrueType font available in the console properties
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dialog is "MS Gothic", displayed as "ＭＳ ゴシック". It is still possible to
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use the English-default TrueType console fonts, Lucida Console and Consolas,
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via `SetCurrentConsoleFontEx`.
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* When using a Raster Font and CP437 or CP1252, writing a UTF-16 codepoint not
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representable in the code page instead writes a question mark ('?') to the
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console. This conversion does not apply with a TrueType font, nor with the
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Raster Font for CP932 or CP936.
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ReadConsoleOutput and double-width characters
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==============================================
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* With a Raster Font active, when `ReadConsoleOutputW` reads two cells of a
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double-width character, it fills only a single `CHAR_INFO` structure. The
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unused trailing `CHAR_INFO` structures are zero-filled. With a TrueType
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font active, `ReadConsoleOutputW` instead fills two `CHAR_INFO` structures,
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the first marked with `COMMON_LVB_LEADING_BYTE` and the second marked with
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`COMMON_LVB_TRAILING_BYTE`. The flag is a misnomer--there aren't two
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*bytes*, but two cells, and they have equal `CHAR_INFO.Char.UnicodeChar`
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values.
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* `ReadConsoleOutputA`, on the other hand, reads two `CHAR_INFO` cells, and
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if the UTF-16 value can be represented as two bytes in the ANSI/OEM CP, then
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the two bytes are placed in the two `CHAR_INFO.Char.AsciiChar` values, and
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the `COMMON_LVB_{LEADING,TRAILING}_BYTE` values are also used. If the
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codepoint isn't representable, I don't remember what happens -- I think the
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`AsciiChar` values take on an invalid marker.
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* Reading only one cell of a double-width character reads a space (U+0020)
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instead. Raster-vs-TrueType and wide-vs-ANSI do not matter.
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- XXX: what about attributes? Can a double-width character have mismatched
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color attributes?
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- XXX: what happens when writing to just one cell of a double-width
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character?
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Default Windows fonts for East Asian languages
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==============================================
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CP932 / Japanese: "ＭＳ ゴシック" (MS Gothic)
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CP936 / Chinese Simplified: "新宋体" (SimSun)
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Unreliable character width (half-width vs full-width)
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=====================================================
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The half-width vs full-width status of a codepoint depends on at least these variables:
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* OS version (Win10 legacy and new modes are different versions)
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* system locale (English vs Japanese vs Chinese Simplified vs Chinese Traditional, etc)
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* code page (437 vs 932 vs 936, etc)
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* raster vs TrueType (Terminal vs MS Gothic vs SimSun, etc)
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* font size
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* rendered-vs-model (rendered width can be larger or smaller than model width)
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Example 1: U+2014 (EM DASH): East_Asian_Width: Ambiguous
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--------------------------------------------------------
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rendered modeled
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CP932: Win7/8 Raster Fonts half half
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CP932: Win7/8 Gothic 14/15px half full
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CP932: Win7/8 Consolas 14/15px half full
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CP932: Win7/8 Lucida Console 14px half full
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CP932: Win7/8 Lucida Console 15px half half
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CP932: Win10New Raster Fonts half half
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CP932: Win10New Gothic 14/15px half half
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CP932: Win10New Consolas 14/15px half half
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CP932: Win10New Lucida Console 14/15px half half
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CP936: Win7/8 Raster Fonts full full
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CP936: Win7/8 SimSun 14px full full
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CP936: Win7/8 SimSun 15px full half
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CP936: Win7/8 Consolas 14/15px half full
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CP936: Win10New Raster Fonts full full
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CP936: Win10New SimSum 14/15px full full
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CP936: Win10New Consolas 14/15px half half
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Example 2: U+3044 (HIRAGANA LETTER I): East_Asian_Width: Wide
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-------------------------------------------------------------
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rendered modeled
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CP932: Win7/8/10N Raster Fonts full full
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CP932: Win7/8/10N Gothic 14/15px full full
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CP932: Win7/8/10N Consolas 14/15px half(*2) full
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CP932: Win7/8/10N Lucida Console 14/15px half(*3) full
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CP936: Win7/8/10N Raster Fonts full full
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CP936: Win7/8/10N SimSun 14/15px full full
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CP936: Win7/8/10N Consolas 14/15px full full
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Example 3: U+30FC (KATAKANA-HIRAGANA PROLONGED SOUND MARK): East_Asian_Width: Wide
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----------------------------------------------------------------------------------
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rendered modeled
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CP932: Win7 Raster Fonts full full
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CP932: Win7 Gothic 14/15px full full
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CP932: Win7 Consolas 14/15px half(*2) full
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CP932: Win7 Lucida Console 14px half(*3) full
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CP932: Win7 Lucida Console 15px half(*3) half
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CP932: Win8 Raster Fonts full full
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CP932: Win8 Gothic 14px full half
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CP932: Win8 Gothic 15px full full
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CP932: Win8 Consolas 14/15px half(*2) full
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CP932: Win8 Lucida Console 14px half(*3) full
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CP932: Win8 Lucida Console 15px half(*3) half
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CP932: Win10New Raster Fonts full full
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CP932: Win10New Gothic 14/15px full full
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CP932: Win10New Consolas 14/15px half(*2) half
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CP932: Win10New Lucida Console 14/15px half(*2) half
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CP936: Win7/8 Raster Fonts full full
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CP936: Win7/8 SimSun 14px full full
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CP936: Win7/8 SimSun 15px full half
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CP936: Win7/8 Consolas 14px full full
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CP936: Win7/8 Consolas 15px full half
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CP936: Win10New Raster Fonts full full
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CP936: Win10New SimSum 14/15px full full
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CP936: Win10New Consolas 14/15px full full
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Example 4: U+4000 (CJK UNIFIED IDEOGRAPH-4000): East_Asian_Width: Wide
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----------------------------------------------------------------------
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rendered modeled
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CP932: Win7 Raster Fonts half(*1) half
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CP932: Win7 Gothic 14/15px full full
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CP932: Win7 Consolas 14/15px half(*2) full
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CP932: Win7 Lucida Console 14px half(*3) full
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CP932: Win7 Lucida Console 15px half(*3) half
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CP932: Win8 Raster Fonts half(*1) half
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CP932: Win8 Gothic 14px full half
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CP932: Win8 Gothic 15px full full
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CP932: Win8 Consolas 14/15px half(*2) full
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CP932: Win8 Lucida Console 14px half(*3) full
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CP932: Win8 Lucida Console 15px half(*3) half
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CP932: Win10New Raster Fonts half(*1) half
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CP932: Win10New Gothic 14/15px full full
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CP932: Win10New Consolas 14/15px half(*2) half
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CP932: Win10New Lucida Console 14/15px half(*2) half
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CP936: Win7/8 Raster Fonts full full
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CP936: Win7/8 SimSun 14px full full
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CP936: Win7/8 SimSun 15px full half
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CP936: Win7/8 Consolas 14px full full
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CP936: Win7/8 Consolas 15px full half
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CP936: Win10New Raster Fonts full full
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CP936: Win10New SimSum 14/15px full full
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CP936: Win10New Consolas 14/15px full full
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(*1) Rendered as a half-width filled white box
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(*2) Rendered as a half-width box with a question mark inside
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(*3) Rendered as a half-width empty box
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(!!) One of the only places in Win10New where rendered and modeled width disagree
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Windows quirk: unreliable font heights with CP936 / Chinese Simplified
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======================================================================
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When I set the font to 新宋体 17px, using either the properties dialog or
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`SetCurrentConsoleFontEx`, the height reported by `GetCurrentConsoleFontEx` is
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not 17, but is instead 19. The same problem does not affect Raster Fonts,
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nor have I seen the problem in the English or Japanese locales. I observed
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this with Windows 7 and Windows 10 new mode.
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If I set the font using the facename, width, *and* height, then the
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`SetCurrentConsoleFontEx` and `GetCurrentConsoleFontEx` values agree. If I
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set the font using *only* the facename and height, then the two values
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disagree.
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Windows bug: GetCurrentConsoleFontEx is initially invalid
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=========================================================
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- Assume there is no configured console font name in the registry. In this
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case, the console defaults to a raster font.
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- Open a new console and call the `GetCurrentConsoleFontEx` API.
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- The `FaceName` field of the returned `CONSOLE_FONT_INFOEX` data
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structure is incorrect. On Windows 7, 8, and 10, I observed that the
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field was blank. On Windows 8, occasionally, it instead contained:
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U+AE72 U+75BE U+0001
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The other fields of the structure all appeared correct:
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nFont=6 dwFontSize=(8,12) FontFamily=0x30 FontWeight=400
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- The `FaceName` field becomes initialized easily:
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- Open the console properties dialog and click OK. (Cancel is not
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sufficient.)
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- Call the undocumented `SetConsoleFont` with the current font table
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index, which is 6 in the example above.
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- It seems that the console uncritically accepts whatever string is
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stored in the registry, including a blank string, and passes it on the
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the `GetCurrentConsoleFontEx` caller. It is possible to get the console
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to *write* a blank setting into the registry -- simply open the console
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(default or app-specific) properties and click OK.
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