Add IME support for all platforms (#3)

* Apply shibukawa's fix of GLFW for Windows

This fix is based on shibukawa's fix:
  glfw#658
  shibukawa@d36a164

Some minor coding style changes are made, but not yet follow glfw's one,
and some comments doesn't follow recent changes. So further work is
needed.

Co-authored-by: Yoshiki Shibukawa <yoshiki@shibu.jp>
Co-authored-by: Takuro Ashie <ashie@clear-code.com>

* Win32: Support IME

This commit re-organizes 9d9af13.

* Use dynamic load for Imm32.
* Generalize platform-specific features to _GLFWplatform.
* Add caret-position info to preedit-callback.
* Add cursorWidth to preeditCursor and related APIs.
* Handle UTF16 data correctly.
* Handle GCS_RESULTSTR so that committed texts are processed correctly.
* Handle WM_IME_ENDCOMPOSITION to clear preedit.
* Handle WM_IME_SETCONTEXT.
    * https://learn.microsoft.com/en-us/windows/win32/intl/wm-ime-setcontext#remarks
* Refactor code shapes and variable names.

Co-authored-by: Takuro Ashie <ashie@clear-code.com>

* Apply shibukawa's fix of GLFW for MacOS

This fix is based on shibukawa's fix:
  glfw#658
  shibukawa@d36a164

Co-authored-by: Yoshiki Shibukawa <yoshiki@shibu.jp>
Co-authored-by: Takuro Ashie <ashie@clear-code.com>

* macOS: Support IME

This commit re-organizes 31b12b7.

* Use dynamic load for TIS functions and stop using Carbon.
* Generalize platform-specific features to _GLFWplatform.
* Add caret-position info to preedit-callback.
* Handle UTF16 data correctly.
* Implement `firstRectForCharacterRange:actualRange:` to display preedit candidate window correctly.
* Suppress _glfwInputKey during preediting.
* Ensure preedit cleared after committed.
* Fix wrong length of markedRange.
* Improve IME status APIs.
* Refactor code shapes and variable names.

Co-authored-by: Takuro Ashie <ashie@clear-code.com>
Co-authored-by: xfangfang <2553041586@qq.com>

* Apply shibukawa's fix of GLFW for X11

This fix is based on shibukawa's fix:
  glfw#658

The differences is the following.

* Remove `X_HAVE_UTF8_STRING` branching since the current logic doesn't use it
* Replace `XNDestroyCallback` for `XNPreeditAttributes` in `XCreateIC`

Co-authored-by: Yoshiki Shibukawa <yoshiki@shibu.jp>
Co-authored-by: Takuro Ashie <ashie@clear-code.com>

* X11: Support IME

This commit re-organizes 6e7f939.

* Load missing XIM related function symbols.
* Generalize platform-specific features to _GLFWplatform.
* Change the defalut input style to over-the-spot style.
* Rename `decodeUTF8()` to `_glfwDecodeUTF8()` to make it as internal API.
    * It will be also needed to implment input method for Wayland.
* Refactor code shapes and variable names.

About over-the-spot style and on-the-spot style on X11:

* In over-the-spot mode, almost all APIs are disabled since applications only
  need to specify the preedit candidate window position by `glfwSetPreeditCursorPos()`.
* We can change the style by enabling `GLFW_X11_ONTHESPOT` init hint, but it
  has the following problems.
    * Status APIs don't work because status callbacks don't work.
      (at least in my ibus environment).
    * Can't specify the candidate window position.

Known problems:

* Some keys (arrow, Enter, BackSpace, ...) are passed to applications during preediting.
    * This will be fixed in PR glfw#1972 : glfw#1972

Co-authored-by: Takuro Ashie <ashie@clear-code.com>

* Wayland: Support text_input_unstable_v3 and text_input_unstable_v1

They are wayland protocols to support input methods:
https://cgit.freedesktop.org/wayland/wayland-protocols/tree/unstable/text-input/text-input-unstable-v3.xml
https://cgit.freedesktop.org/wayland/wayland-protocols/tree/unstable/text-input/text-input-unstable-v1.xml

text_input_unstable_v3 is widely supported by major desktop environment
on GNU/Linux such as GNOME or KDE.

text_input_unstable_v1 isn't so popular but Weston which is the
reference Wayland implementation supports only it and doesn't support
text_input_unstable_v3 so that we also implement it.

* tests: Add tests for IME features

Co-authored-by: Takuro Ashie <ashie@clear-code.com>

* Apply shibukawa's document fix

This fix is from shibukawa's fix:
  glfw#658
  shibukawa@d36a164

* Doc: Improve document about IME features

* Add credit

new

- Daijiro Fukuda
- Ryo Ichinose (from glfw#658)
- Yasutaka Kumei (from glfw#658)
- xfangfang

already in the list

- Takuro Ashie
- Yoshiki Shibukawa

* Add change log entries

* Win32: Support preedit candidate feature

You can use this feature when you need to manage the drawing of
the preedit candidates on the application side.

* Don't link Fontconfig

Load it dynamically instead.

* WIN32: Better support for IME

---------

Co-authored-by: Daijiro Fukuda <fukuda@clear-code.com>
Co-authored-by: Yoshiki Shibukawa <yoshiki@shibu.jp>
Co-authored-by: Takuro Ashie <ashie@clear-code.com>
Co-authored-by: xfangfang <2553041586@qq.com>

Author: 5 people

CONTRIBUTORS.md

@@ -82,7 +82,7 @@ video tutorials.
  - Jason Francis
  - Gerald Franz
  - Mário Freitas
- - Friz64
+ - Daijiro Fukuda
  - GeO4d
  - Marcus Geelnard
  - Gegy
@@ -112,6 +112,7 @@ video tutorials.
  - Charles Huber
  - Brent Huisman
  - Florian Hülsmann
+ - Ryo Ichinose
  - illustris
  - InKryption
  - IntellectualKitty
@@ -131,6 +132,7 @@ video tutorials.
  - knokko
  - Peter Knut
  - Christoph Kubisch
+ - Yasutaka Kumei
  - Yuri Kunde Schlesner
  - Rokas Kupstys
  - Konstantin Käfer
@@ -298,6 +300,7 @@ video tutorials.
  - Andy Williams
  - Joel Winarske
  - Richard A. Wilkes
+ - xfangfang
  - Tatsuya Yatagawa
  - Ryogo Yoshimura
  - Lukas Zanner

README.md

@@ -169,6 +169,28 @@ information on what to include when reporting a bug.
  - [Null] Added EGL context creation on Mesa via `EGL_MESA_platform_surfaceless`
  - [EGL] Allowed native access on Wayland with `GLFW_CONTEXT_CREATION_API` set to
    `GLFW_NATIVE_CONTEXT_API` (#2518)
+ - Added `glfwSetPreeditCallback` function and `GLFWpreeditfun` type for
+   preedit of input method (#2130)
+ - Added `glfwSetIMEStatusCallback` function and `GLFWimestatusfun` type for
+   status of input method (#2130)
+ - Added `glfwSetPreeditCursorRectangle` function to set the preedit cursor
+   area that is used to decide the position of the candidate window of input
+   method (#2130)
+ - Added `glfwGetPreeditCursorRectangle` function to get the preedit cursor
+   area (#2130)
+ - Added `glfwResetPreeditText` function to reset preedit of input method
+   (#2130)
+ - Added `glfwSetPreeditCandidateCallback` function and
+   `GLFWpreeditcandidatefun` type for preedit candidates (#2130)
+ - Added `glfwGetPreeditCandidate` function to get a preeidt candidate text
+   (#2130)
+ - Added `GLFW_IME` input mode for `glfwGetInputMode` and `glfwSetInputMode`
+   (#2130)
+ - Added `GLFW_X11_ONTHESPOT` init hint for using on-the-spot input method
+   style on X11 (#2130)
+ - Added `GLFW_MANAGE_PREEDIT_CANDIDATE` init hint for displaying preedit
+   candidates on the application side (supported only on Windows currently)
+   (#2130)
 
 
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