From e2dd2eedab581f688f555a1078bb30278487dc26 Mon Sep 17 00:00:00 2001
From: akallabeth <akallabeth@posteo.net>
Date: Fri, 30 Jan 2026 11:02:07 +0100
Subject: [PATCH] [client,sdl] implement display detection handling

* SdlContext::detectDisplays to create a initial list of displays and
  their rdpMonitor configuration
* SdlContext::getDisplays to query a SDL_DisplayID at runtime
* SdlContext::getDisplayIds to query available SDL_DisplayID at runtime
---
 client/SDL/SDL3/sdl_context.cpp | 41 +++++++++++++++++++++++++++++++++
 client/SDL/SDL3/sdl_context.hpp |  7 ++++++
 2 files changed, 48 insertions(+)

diff --git a/client/SDL/SDL3/sdl_context.cpp b/client/SDL/SDL3/sdl_context.cpp
index 56240c8ac..0a9d65921 100644
--- a/client/SDL/SDL3/sdl_context.cpp
+++ b/client/SDL/SDL3/sdl_context.cpp
@@ -888,6 +888,37 @@ bool SdlContext::removeDisplayWindow(SDL_DisplayID id)
 	return true;
 }
 
+bool SdlContext::detectDisplays()
+{
+	int count = 0;
+	auto display = SDL_GetDisplays(&count);
+	if (!display)
+		return false;
+	for (int x = 0; x < count; x++)
+	{
+		const auto id = display[x];
+		auto monitor = SdlWindow::query(id, false);
+		addOrUpdateDisplay(id, monitor);
+	}
+
+	return true;
+}
+
+rdpMonitor SdlContext::getDisplay(SDL_DisplayID id) const
+{
+	return _displays.at(id);
+}
+
+std::vector<SDL_DisplayID> SdlContext::getDisplayIds() const
+{
+	std::vector<SDL_DisplayID> keys;
+	for (const auto& entry : _displays)
+	{
+		keys.push_back(entry.first);
+	}
+	return keys;
+}
+
 const SdlWindow* SdlContext::getWindowForId(SDL_WindowID id) const
 {
 	auto it = _windows.find(id);
@@ -1091,6 +1122,16 @@ bool SdlContext::handleEvent(const SDL_TouchFingerEvent& ev)
 	return SdlTouch::handleEvent(this, copy.tfinger);
 }
 
+void SdlContext::addOrUpdateDisplay(SDL_DisplayID id, const rdpMonitor& monitor)
+{
+	_displays.emplace(id, monitor);
+}
+
+void SdlContext::deleteDisplay(SDL_DisplayID id)
+{
+	_displays.erase(id);
+}
+
 bool SdlContext::eventToPixelCoordinates(SDL_WindowID id, SDL_Event& ev)
 {
 	auto w = getWindowForId(id);
diff --git a/client/SDL/SDL3/sdl_context.hpp b/client/SDL/SDL3/sdl_context.hpp
index 393feee2c..b225f19ef 100644
--- a/client/SDL/SDL3/sdl_context.hpp
+++ b/client/SDL/SDL3/sdl_context.hpp
@@ -121,6 +121,9 @@ class SdlContext
 
 	[[nodiscard]] bool addDisplayWindow(SDL_DisplayID id);
 	[[nodiscard]] bool removeDisplayWindow(SDL_DisplayID id);
+	[[nodiscard]] bool detectDisplays();
+	[[nodiscard]] rdpMonitor getDisplay(SDL_DisplayID id) const;
+	[[nodiscard]] std::vector<SDL_DisplayID> getDisplayIds() const;
 
 	[[nodiscard]] sdlDispContext& getDisplayChannelContext();
 	[[nodiscard]] sdlInput& getInputChannelContext();
@@ -162,6 +165,9 @@ class SdlContext
 	[[nodiscard]] bool handleEvent(const SDL_MouseWheelEvent& ev);
 	[[nodiscard]] bool handleEvent(const SDL_TouchFingerEvent& ev);
 
+	void addOrUpdateDisplay(SDL_DisplayID id, const rdpMonitor& monitor);
+	void deleteDisplay(SDL_DisplayID id);
+
 	[[nodiscard]] bool createPrimary();
 	[[nodiscard]] std::string windowTitle() const;
 	[[nodiscard]] bool waitForWindowsCreated();
@@ -206,6 +212,7 @@ class SdlContext
 
 	SdlConnectionDialogWrapper _dialog;
 
+	std::map<SDL_DisplayID, rdpMonitor> _displays;
 	std::map<SDL_WindowID, SdlWindow> _windows;
 
 	uint32_t _windowWidth = 0;