Adjust active window to SDL "safe area"

Text entry on Android and iOS devices is accomplished by displaying an "Input Method Editor", or IME (soft keyboard), over the running application. The UI model is such that the application is supposed to adjust its graphical layout so that the text-entry field is repositioned to fit above the newly-displayed keyboard. This change adds support for discovering what the IME's insets are, and adjusting the top-level window to be displayed within the area not covered.

Author: tophyr

android/sdl_patches/01-ime-insets.patch

@@ -0,0 +1,20 @@
+Subject: [PATCH] Add consideration for IME insets to Safe Area
+---
+Index: android/src/main/java/org/libsdl/app/SDLSurface.java
+IDEA additional info:
+Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
+<+>UTF-8
+===================================================================
+diff --git a/android/src/main/java/org/libsdl/app/SDLSurface.java b/android/src/main/java/org/libsdl/app/SDLSurface.java
+--- a/android/src/main/java/org/libsdl/app/SDLSurface.java	(revision a162be9609af731e5a0f0b78351fc8d32ee899b0)
++++ b/android/src/main/java/org/libsdl/app/SDLSurface.java	(date 1769037984477)
+@@ -199,7 +199,8 @@
+                                                WindowInsets.Type.systemGestures() |
+                                                WindowInsets.Type.mandatorySystemGestures() |
+                                                WindowInsets.Type.tappableElement() |
+-                                               WindowInsets.Type.displayCutout());
++                                               WindowInsets.Type.displayCutout() |
++                                               WindowInsets.Type.ime());
+ 
+             SDLActivity.onNativeInsetsChanged(combined.left, combined.right, combined.top, combined.bottom);
+         }

android/src/main/java/org/libsdl/app/SDLSurface.java

@@ -199,7 +199,8 @@ public WindowInsets onApplyWindowInsets(View v, WindowInsets insets) {
                                                WindowInsets.Type.systemGestures() |
                                                WindowInsets.Type.mandatorySystemGestures() |
                                                WindowInsets.Type.tappableElement() |
-                                               WindowInsets.Type.displayCutout());
+                                               WindowInsets.Type.displayCutout() |
+                                               WindowInsets.Type.ime());
 
             SDLActivity.onNativeInsetsChanged(combined.left, combined.right, combined.top, combined.bottom);
         }

ui/UISystem.cpp

@@ -173,6 +173,7 @@
 #include "pserror.h"
 #include "renderer.h"
 #include "Macros.h"
+#include "SDLHelpers.h"
 
 constexpr float kDefaultMouseScale = 20;
 
@@ -456,6 +457,7 @@ void ui_DoWindowFocus() {
     UIWindowFocus = NULL;
 }
 //	returns a result and processes input of a window in focus
+extern SDL_Window* GSDLWindow;
 int ui_ProcessFocusedWindow() {
   int res = -1;
   int res2;
@@ -465,6 +467,11 @@ int ui_ProcessFocusedWindow() {
   // get keys.   get mouse while real events (non ui manuipulated) are there.
   ui_MousePoll(false);
   if (UIWindowFocus) {
+    SDL_Rect safeArea{};
+    SDL_GetWindowSafeArea(GSDLWindow, &safeArea);
+    auto const& [safeX, safeY, safeW, safeH] = SDLWindowToGameRenderer(safeArea);
+    UIWindowFocus->AdjustToSafeArea(safeX, safeY, safeW, safeH);
+
     UI_input.b1_count = 0; // button one state reset.
     ui_KeyPoll();
     ui_MousePoll(true);

ui/UIWindow.cpp

@@ -198,6 +198,10 @@ void UIWindow::Create(int x, int y, int w, int h, int flags) {
     y = UI_screen_height / 2 - h / 2;
   }
 
+  m_RealX = x;
+  m_RealY = y;
+  m_RealW = w;
+  m_RealH = h;
   UIObject::Create(x, y, w, h);
 }
 
@@ -216,6 +220,14 @@ void UIWindow::Destroy() {
   UIObject::Destroy();
 }
 
+void UIWindow::Move(int x, int y, int w, int h) {
+  m_RealX = x;
+  m_RealY = y;
+  m_RealW = w;
+  m_RealH = h;
+  UIObject::Move(x, y, w, h);
+}
+
 //	interface functions
 // adds a UIObject to the interface's draw list.
 void UIWindow::AddGadget(UIGadget *gadget) {
@@ -292,6 +304,13 @@ void UIWindow::UnlockFocusOnGadget() { m_LockedGadget = NULL; }
 // forces all keyinput onto one gadget.
 void UIWindow::LockKeyFocusOnGadget(UIGadget *gadget) {}
 
+void UIWindow::AdjustToSafeArea(int safeX, int safeY, int safeW, int safeH) {
+  m_W = std::min(m_RealW, safeW);
+  m_H = std::min(m_RealH, safeH);
+  m_X = std::clamp(m_RealX, safeX, safeX + safeW - m_W);
+  m_Y = std::clamp(m_RealY, safeY, safeY + safeH - m_H);
+}
+
 //	Process
 //		run this to handle user input inside an interface
 //		sets focus on a control

ui/ui.h

@@ -316,7 +316,7 @@ class UIObject {
   int H() const { return m_H; };
 
   //	moves the object.
-  void Move(int x, int y, int w, int h);
+  virtual void Move(int x, int y, int w, int h);
 
   //	inheritable operations
 public:
@@ -1033,6 +1033,8 @@ class UIWindow : public UIObject {
   } m_Accelerators[N_WINDOW_ACCELS]; // used for quick key press interaction
   int m_naccels;
 
+  int m_RealX, m_RealY, m_RealW, m_RealH;
+
   static int m_WindowFont; // global window default font
 
 private:
@@ -1085,6 +1087,9 @@ class UIWindow : public UIObject {
   void Open();           // adds window to ui list.
   void Close();          // removes window from ui list.
 
+  void Move(int x, int y, int w, int h) override;
+  void AdjustToSafeArea(int safeX, int safeY, int safeW, int safeH);
+
   //	settings
   void SetFont(int handle);        // sets window's font.
   void SetBackItem(UIItem *item) { // sets the background drawing item.