Docking: Added Docking system. Enable with io.ConfigFlags |= ImGuiCon…

…figFlags_DockingEnable. (Part 1) (#351)

docs/CHANGELOG.txt

@@ -33,9 +33,19 @@ HOW TO UPDATE?
  DOCKING BRANCH (In Progress)
 -----------------------------------------------------------------------
 
+- Added ImGuiConfigFlags_DockingEnable flag to enable Docking. [BETA]
+  Set with `io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;`.
 - Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API. (#261, #351)
+- Added DockSpace() API. (#351)
+- Added SetNextWindowDock() API. (#351)
+- Added IsWindowDocked() API. (#351)
+- Added ImGuiWindowFlags_NoDocking window flag to disable the possibility for a window to be docked.
+  Popup, Menu and Child windows always have the ImGuiWindowFlags_NoDocking flag set. (#351)
 - Added ImGuiWindowFlags_UnsavedDocument window flag to append '*' to title without altering the ID, 
   as a convenience to avoid using the ### operator. 
+- Added io.ConfigDockingWithKeyMod option to configure docking mode.
+- Style: Added ImGuiCol_DockingPreview, ImGuiCol_DockingBg colors. (#351)
+- Style: Added ImGuiCol_Tab, ImGuiCol_TabHovered, ImGuiCol_TabActive, ImGuiCol_TabUnfocused, ImGuiCol_TabUnfocusedActive colors. (#261, #351)
 - Demo: Added Layout->Tabs demo code. (#261, #351)
 - Demo: Added "Documents" example app showcasing possible use for tabs. (#261, #351)
 

imgui.h

@@ -26,6 +26,7 @@
 #define IMGUI_VERSION               "1.66 WIP"
 #define IMGUI_VERSION_NUM           16600
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert))
+#define IMGUI_HAS_DOCK              1 // Docking WIP branch
 #define IMGUI_HAS_TABS              1 // Docking WIP branch
 
 // Define attributes of all API symbols declarations (e.g. for DLL under Windows)
@@ -209,7 +210,9 @@ namespace ImGui
     IMGUI_API bool          IsWindowCollapsed();
     IMGUI_API bool          IsWindowFocused(ImGuiFocusedFlags flags=0); // is current window focused? or its root/child, depending on flags. see flags for options.
     IMGUI_API bool          IsWindowHovered(ImGuiHoveredFlags flags=0); // is current window hovered (and typically: not blocked by a popup/modal)? see flags for options. NB: If you are trying to check whether your mouse should be dispatched to imgui or to your app, you should use the 'io.WantCaptureMouse' boolean for that! Please read the FAQ!
-    IMGUI_API ImDrawList*   GetWindowDrawList();                        // get draw list associated to the window, to append your own drawing primitives
+    IMGUI_API bool          IsWindowDocked();
+    IMGUI_API ImDrawList*   GetWindowDrawList();                        // get draw list associated to the current window, to append your own drawing primitives
+
     IMGUI_API ImVec2        GetWindowPos();                             // get current window position in screen space (useful if you want to do your own drawing via the DrawList API)
     IMGUI_API ImVec2        GetWindowSize();                            // get current window size
     IMGUI_API float         GetWindowWidth();                           // get current window width (shortcut for GetWindowSize().x)
@@ -228,6 +231,7 @@ namespace ImGui
     IMGUI_API void          SetNextWindowCollapsed(bool collapsed, ImGuiCond cond = 0);                 // set next window collapsed state. call before Begin()
     IMGUI_API void          SetNextWindowFocus();                                                       // set next window to be focused / front-most. call before Begin()
     IMGUI_API void          SetNextWindowBgAlpha(float alpha);                                          // set next window background color alpha. helper to easily modify ImGuiCol_WindowBg/ChildBg/PopupBg.
+    IMGUI_API void          SetNextWindowDock(ImGuiID dock_id, ImGuiCond cond = 0);                     // set next window dock id (FIXME-DOCK)
     IMGUI_API void          SetWindowPos(const ImVec2& pos, ImGuiCond cond = 0);                        // (not recommended) set current window position - call within Begin()/End(). prefer using SetNextWindowPos(), as this may incur tearing and side-effects.
     IMGUI_API void          SetWindowSize(const ImVec2& size, ImGuiCond cond = 0);                      // (not recommended) set current window size - call within Begin()/End(). set to ImVec2(0,0) to force an auto-fit. prefer using SetNextWindowSize(), as this may incur tearing and minor side-effects.
     IMGUI_API void          SetWindowCollapsed(bool collapsed, ImGuiCond cond = 0);                     // (not recommended) set current window collapsed state. prefer using SetNextWindowCollapsed().
@@ -499,12 +503,18 @@ namespace ImGui
 
     // Tabs
     // [BETA API] API may evolve.
+    // Note: Tabs are automatically created by the docking system. Use this to create tab bars/tabs yourself without docking being involved.
     IMGUI_API bool          BeginTabBar(const char* str_id, ImGuiTabBarFlags flags = 0);        // create and append into a TabBar
     IMGUI_API void          EndTabBar();
     IMGUI_API bool          BeginTabItem(const char* label, bool* p_open = NULL, ImGuiTabItemFlags = 0);// create a Tab. Returns true if the Tab is selected.
     IMGUI_API void          EndTabItem();                                                       // only call EndTabItem() if BeginTabItem() returns true!
     IMGUI_API void          SetTabItemClosed(const char* tab_or_docked_window_label);           // notify TabBar or Docking system of a closed tab/window ahead (useful to reduce visual flicker on reorderable tab bars). For tab-bar: call after BeginTabBar() and before Tab submissions. Otherwise call with a window name.
 
+    // Docking 
+    // [BETA API] Enable with io.ConfigFlags |= ImGuiConfigFlags_DockingEnable.
+    // Note: you DO NOT need to call DockSpace() to use most Docking facilities! You can hold SHIFT anywhere while moving windows. Use DockSpace() if you need to create an explicit docking space _within_ an existing window. See Docking demo for details)
+    IMGUI_API void          DockSpace(const char* str_id, const ImVec2& size = ImVec2(0, 0));
+
     // Logging/Capture: all text output from interface is captured to tty/file/clipboard. By default, tree nodes are automatically opened during logging.
     IMGUI_API void          LogToTTY(int max_depth = -1);                                       // start logging to tty
     IMGUI_API void          LogToFile(int max_depth = -1, const char* filename = NULL);         // start logging to file
@@ -635,15 +645,17 @@ enum ImGuiWindowFlags_
     ImGuiWindowFlags_NoNavInputs            = 1 << 18,  // No gamepad/keyboard navigation within the window
     ImGuiWindowFlags_NoNavFocus             = 1 << 19,  // No focusing toward this window with gamepad/keyboard navigation (e.g. skipped by CTRL+TAB)
     ImGuiWindowFlags_NoNav                  = ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,
-    ImGuiWindowFlags_UnsavedDocument        = 1 << 20,  // Append '*' to title without altering the ID, as a convenience to avoid using the ### operator. When used in a tab/docking context, tab is selected on closure and closure is deferred by one frame to allow code to cancel the closure (with a confirmation popup, etc.) without flicker.
+    ImGuiWindowFlags_UnsavedDocument        = 1 << 20,  // Append '*' to title without affecting the ID, as a convenience to avoid using the ### operator. When used in a tab/docking context, tab is selected on closure and closure is deferred by one frame to allow code to cancel the closure (with a confirmation popup, etc.) without flicker.
+    ImGuiWindowFlags_NoDocking              = 1 << 21,  // Disable docking of this window
 
     // [Internal]
     ImGuiWindowFlags_NavFlattened           = 1 << 23,  // [BETA] Allow gamepad/keyboard navigation to cross over parent border to this child (only use on child that have no scrolling!)
     ImGuiWindowFlags_ChildWindow            = 1 << 24,  // Don't use! For internal use by BeginChild()
     ImGuiWindowFlags_Tooltip                = 1 << 25,  // Don't use! For internal use by BeginTooltip()
     ImGuiWindowFlags_Popup                  = 1 << 26,  // Don't use! For internal use by BeginPopup()
     ImGuiWindowFlags_Modal                  = 1 << 27,  // Don't use! For internal use by BeginPopupModal()
-    ImGuiWindowFlags_ChildMenu              = 1 << 28   // Don't use! For internal use by BeginMenu()
+    ImGuiWindowFlags_ChildMenu              = 1 << 28,  // Don't use! For internal use by BeginMenu()
+    ImGuiWindowFlags_DockNodeHost           = 1 << 29   // Don't use! For internal use by Begin()/NewFrame()
 
     // [Obsolete]
     //ImGuiWindowFlags_ShowBorders          = 1 << 7,   // --> Set style.FrameBorderSize=1.0f / style.WindowBorderSize=1.0f to enable borders around windows and items
@@ -897,6 +909,9 @@ enum ImGuiConfigFlags_
     ImGuiConfigFlags_NoMouse                = 1 << 4,   // Instruct imgui to clear mouse position/buttons in NewFrame(). This allows ignoring the mouse information set by the back-end.
     ImGuiConfigFlags_NoMouseCursorChange    = 1 << 5,   // Instruct back-end to not alter mouse cursor shape and visibility. Use if the back-end cursor changes are interfering with yours and you don't want to use SetMouseCursor() to change mouse cursor. You may want to honor requests from imgui by reading GetMouseCursor() yourself instead.
 
+    // [BETA] Docking
+    ImGuiConfigFlags_DockingEnable          = 1 << 6,   // Docking enable flags. Use SHIFT to dock window into another (or without SHIFT if io.ConfigDockingWithKeyMod = false).
+
     // User storage (to allow your back-end/engine to communicate to code that may be shared between multiple projects. Those flags are not used by core ImGui)
     ImGuiConfigFlags_IsSRGB                 = 1 << 20,  // Application is SRGB-aware.
     ImGuiConfigFlags_IsTouchScreen          = 1 << 21   // Application is using a touch screen instead of a mouse.
@@ -951,6 +966,8 @@ enum ImGuiCol_
     ImGuiCol_TabActive,
     ImGuiCol_TabUnfocused,
     ImGuiCol_TabUnfocusedActive,
+    ImGuiCol_DockingPreview,
+    ImGuiCol_DockingBg,             // Empty node
     ImGuiCol_PlotLines,
     ImGuiCol_PlotLinesHovered,
     ImGuiCol_PlotHistogram,
@@ -1150,6 +1167,7 @@ struct ImGuiIO
 
     // Miscellaneous configuration options
     bool          MouseDrawCursor;              // = false          // Request ImGui to draw a mouse cursor for you (if you are on a platform without a mouse cursor). Cannot be easily renamed to 'io.ConfigXXX' because this is frequently used by back-end implementations.
+    bool          ConfigDockingWithKeyMod;      // = true           // Enable docking with holding Shift key (reduce visual noise, allows dropping in wider space)
     bool          ConfigMacOSXBehaviors;        // = defined(__APPLE__) // OS X style: Text editing cursor movement using Alt instead of Ctrl, Shortcuts using Cmd/Super instead of Ctrl, Line/Text Start and End using Cmd+Arrows instead of Home/End, Double click selects by word instead of selecting whole text, Multi-selection in lists uses Cmd/Super instead of Ctrl (was called io.OptMacOSXBehaviors prior to 1.63)
     bool          ConfigInputTextCursorBlink;   // = true           // Set to false to disable blinking cursor, for users who consider it distracting. (was called: io.OptCursorBlink prior to 1.63)
     bool          ConfigResizeWindowsFromEdges; // = false          // [BETA] Enable resizing of windows from their edges and from the lower-left corner. This requires (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors) because it needs mouse cursor feedback. (This used to be the ImGuiWindowFlags_ResizeFromAnySide flag)