Graphical front-end (GUI-TUI Bridge)

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Terminal users always enter the terminal environment from a graphical environment. The initial interface is always graphical. Until now, we have relied entirely on third-party graphical terminal emulators which significantly limit the capabilities of console applications without providing any way to achieve the required functionality. The only way to overcome these bottlenecks is to create our own bridge from the graphical to the terminal environment.

Our own graphical front-end will open up ways for us to solve the following issues:

• Implementation of full keyboard support. Keyboard-only access #86
• Displaying fragments of characters (halves), as well as subcell-sized text. Tested Terminals #72 (comment)
• Display of extended grapheme clusters in TUI applications.
• Support for pixel graphics. Pixel graphics in terminal #164
• Additional character attributes. Cell background interpolation as SGR attribute #165
• Full support for platform-specific clipboard. Text copied outside vtm cannot be pasted with a right click #273
• Get rid of the 16-color mode in older versions of Windows.
• Support for multiple text cursors and in the correct mode.
• Placing IME in the correct location next to the caret.
• Support for grid lines.

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You can play with a prototype of the vtm graphical window (gui-bridge branch) on various Windows platforms starting with Win8.1 (including Window Server 2019 Core).

If vtm is launched from a graphical shell, or through the start vtm.exe command, then it automatically turns on the graphical mode.

screen_record_Thu_04.18.2024__3-02-53.76.mp4

The vtm server starts in the background, despite the fact that its interface is not yet rendered.

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8x4 character matrix support

screen_record_Mon_05.20.2024_18-27-05.90.mp4

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Of course, along with the character matrix, support for both rotation (pi/2, pi, 3pi/2) and flip (hz/vt) is required.

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At present only standardized variation sequences with VS1, VS2, VS3, VS15 and VS16 have been defined; VS15 and VS16 are reserved to request that a character should be displayed as text or as an emoji) respectively.

VS4–VS14 (U+FE03–U+FE0D) are not used for any variation sequences

• https://en.wikipedia.org/wiki/Variation_Selectors_(Unicode_block)
• https://www.unicode.org/Public/UNIDATA/StandardizedVariants.txt
• https://www.unicode.org/reports/tr51/tr51-16.html#Direction

Let's try to play this way:

VS	Codepoint	Function
VS10	0xFE09	Rotate 90° CCW
VS11	0xFE0A	Rotate 180° CCW
VS12	0xFE0B	Rotate 270° CCW
VS13	0xFE0C	Horizontal flip
VS14	0xFE0D	Vertical flip

# state - is a three bits integer.
VS10(state) = (state & 0b100) | ((state + 0b001) & 0b011)
VS11(state) = (state & 0b100) | ((state + 0b010) & 0b011)
VS12(state) = (state & 0b100) | ((state + 0b011) & 0b011)
VS13(state) = (state ^ 0b100) | ((state + (state & 1 ? 0 : 0b010)) & 0b011)
VS14(state) = (state ^ 0b100) | ((state + (state & 1 ? 0b010 : 0)) & 0b011)

angle = 90 * (state & 0b011)
hflip = state >> 2

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Character rotation support

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