Backends: GLFW: Fix CTRL+A, CTRL+Y, CTRL+Z to match keyboard layout. …

…Converting GLFW untranslated keycodes back to translated keycodes. (#456, #2625)

backends/imgui_impl_glfw.cpp

@@ -16,6 +16,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2022-01-05: Inputs: Converting GLFW untranslated keycodes back to translated keycodes (in the ImGui_ImplGlfw_KeyCallback() function) in order to match the behavior of every other backend, and facilitate the use of GLFW with lettered-shortcuts API.
 //  2021-08-17: *BREAKING CHANGE*: Now using glfwSetWindowFocusCallback() to calling io.AddFocusEvent(). If you called ImGui_ImplGlfw_InitXXX() with install_callbacks = false, you MUST install glfwSetWindowFocusCallback() and forward it to the backend via ImGui_ImplGlfw_WindowFocusCallback().
 //  2021-07-29: *BREAKING CHANGE*: Now using glfwSetCursorEnterCallback(). MousePos is correctly reported when the host platform window is hovered but not focused. If you called ImGui_ImplGlfw_InitXXX() with install_callbacks = false, you MUST install glfwSetWindowFocusCallback() callback and forward it to the backend via ImGui_ImplGlfw_CursorEnterCallback().
 //  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
@@ -66,6 +67,7 @@
 #else
 #define GLFW_HAS_NEW_CURSORS    (0)
 #endif
+#define GLFW_HAS_GET_KEY_NAME   (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3200) // 3.2+ glfwGetKeyName()
 
 // GLFW data
 enum GlfwClientApi
@@ -147,6 +149,25 @@ void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int a
     if (bd->PrevUserCallbackKey != NULL && window == bd->Window)
         bd->PrevUserCallbackKey(window, key, scancode, action, mods);
 
+#if GLFW_HAS_GET_KEY_NAME
+    // GLFW 3.1+ attempts to "untranslate" keys, which goes the opposite of what every other framework does, making using lettered shortcuts difficult.
+    // (It had reasons to do so: namely GLFW is/was more likely to be used for WASD-type game controls rather than lettered shortcuts, but IHMO the 3.1 change could have been done differently)
+    // See https://github.com/glfw/glfw/issues/1502 for details.
+    // Adding a workaround to undo this (so our keys are translated->untranslated->translated, likely a lossy process).
+    // This won't cover edge cases but this is at least going to cover common cases.
+    const char* key_name = glfwGetKeyName(key, scancode);
+    if (key_name && key_name[0] != 0 && key_name[1] == 0)
+    {
+        const char char_names[] = "'-=[]\\,;\'./";
+        const int char_keys[] = { GLFW_KEY_GRAVE_ACCENT, GLFW_KEY_MINUS, GLFW_KEY_EQUAL, GLFW_KEY_LEFT_BRACKET, GLFW_KEY_RIGHT_BRACKET, GLFW_KEY_BACKSLASH, GLFW_KEY_COMMA, GLFW_KEY_SEMICOLON, GLFW_KEY_APOSTROPHE, GLFW_KEY_PERIOD, GLFW_KEY_SLASH, 0 };
+        IM_ASSERT(IM_ARRAYSIZE(char_names) == IM_ARRAYSIZE(char_keys));
+        if (key_name[0] >= '0' && key_name[0] <= '9')               { key = GLFW_KEY_0 + (key_name[0] - '0'); }
+        else if (key_name[0] >= 'A' && key_name[0] <= 'Z')          { key = GLFW_KEY_A + (key_name[0] - 'A'); }
+        else if (const char* p = strchr(char_names, key_name[0]))   { key = char_keys[p - char_names]; }
+    }
+    // if (action == GLFW_PRESS) printf("key %d scancode %d name '%s'\n", key, scancode, key_name);
+#endif
+
     ImGuiIO& io = ImGui::GetIO();
     if (key >= 0 && key < IM_ARRAYSIZE(io.KeysDown))
     {

docs/CHANGELOG.txt

@@ -64,6 +64,9 @@ Other Changes:
 - Platform IME: add ImGuiPlatformImeData::WantVisible, hide IME composition window when not used. (#2589) [@actboy168]
 - Platform IME: add ImGuiPlatformImeData::InputLineHeight. (#3113) [@liuliu]
 - Platform IME: [windows] call ImmSetCandidateWindow() to position candidate window.
+- Backends: GLFW: fix CTRL+A, CTRL+Z, CTRL+Y shortcuts to match user keyboard layout. We are now converting GLFW
+  untranslated keycodes back to translated keycodes in order to match the behavior of every other backend, and
+  facilitate the use of GLFW with lettered-shortcuts API. (#456, #2625)
 - Backends: OpenGL3: Fixed a buffer overflow in imgui_impl_opengl3_loader.h init (added in 1.86). (#4468, #4830) [@dymk]
   It would generally not have noticeable side-effect at runtime but would be detected by runtime checkers.
 - Backends: Metal: Added Apple Metal C++ API support. (#4824, #4746) [@luigifcruz]