allow manual setting for GUI screen size (for DPI scaling)

Author: Sascha Brandt

Base/Draw.cpp

@@ -122,6 +122,7 @@ struct DrawContext {
 	uint32_t meshOffset = 0;
 	Geometry::Vec2i position,screenSize;
 	Geometry::Rect_i scissor;
+	Geometry::Vec2 scale;
 
 	RenderingContext* rc;
 	Util::Reference<Shader> shader;
@@ -149,6 +150,7 @@ struct DrawContext {
 	uint32_t meshOffset = 0;
 	Geometry::Vec2i position,screenSize;
 	Geometry::Rect_i scissor;
+	Geometry::Vec2 scale;
 
 	GLuint shaderProg = 0;
 	GLuint vertexBuffer = 0;
@@ -379,7 +381,7 @@ static bool init() {
 #ifdef GUI_BACKEND_RENDERING
 
 //! (static)
-void Draw::beginDrawing(Rendering::RenderingContext& rc, const Geometry::Vec2i & screenSize) {
+void Draw::beginDrawing(Rendering::RenderingContext& rc, const Geometry::Vec2i & screenSize, const Geometry::Vec2 & renderScale) {
 	ctxt.rc = &rc;
 
 	static bool initialized = false;
@@ -391,6 +393,7 @@ void Draw::beginDrawing(Rendering::RenderingContext& rc, const Geometry::Vec2i &
 	ctxt.position = Geometry::Vec2(0,0);
 	ctxt.activeTexture = nullptr;
 	ctxt.screenSize = screenSize;
+	ctxt.scale = renderScale;
 	ctxt.meshOffset = 0;
 
 	rc.pushAndSetDepthBuffer(DepthBufferParameters(false, false, Comparison::ALWAYS));
@@ -401,7 +404,7 @@ void Draw::beginDrawing(Rendering::RenderingContext& rc, const Geometry::Vec2i &
 	rc.pushScissor();
 	resetScissor();	
 	rc.pushAndSetShader(ctxt.shader.get());
-	ctxt.shader->setUniform(rc, Uniform(UNIFORM_SCREEN_SCALE, Geometry::Vec2(2.0f/screenSize.getWidth(),-2.0f/screenSize.getHeight())));
+	ctxt.shader->setUniform(rc, Uniform(UNIFORM_SCREEN_SCALE, Geometry::Vec2(2.0f/screenSize.getWidth(),-2.0f/screenSize.getHeight()) * ctxt.scale));
 
 	GET_GL_ERROR();
 }
@@ -507,9 +510,11 @@ void Draw::flush() {
 	#ifdef GUI_BACKEND_RENDERING
 		BlendingParameters blending(BlendingParameters::SRC_ALPHA, BlendingParameters::ONE_MINUS_SRC_ALPHA);
 		ctxt.mesh->openVertexData().markAsChanged();
+		float yOffset = static_cast<float>(ctxt.screenSize.y()) * ctxt.scale.y() - static_cast<float>(ctxt.screenSize.getHeight());
 		for(const auto& cmd : ctxt.commands) {
 			ctxt.shader->setUniform(*ctxt.rc, {UNIFORM_POS_OFFSET, cmd.offset});
-			ctxt.rc->setScissor(ScissorParameters(cmd.scissor));
+			Geometry::Rect scissor(cmd.scissor.getX() * ctxt.scale.x(), cmd.scissor.getY() * ctxt.scale.y() - yOffset, cmd.scissor.getWidth() * ctxt.scale.x(), cmd.scissor.getHeight() * ctxt.scale.y());
+			ctxt.rc->setScissor(ScissorParameters(Geometry::Rect_i(scissor)));
 			if(cmd.blending)
 				blending.enable();
 			else

Base/Draw.h

@@ -29,7 +29,7 @@ class Draw {
 	public:
 		// general
 #ifdef GUI_BACKEND_RENDERING
-		GUIAPI static void beginDrawing(Rendering::RenderingContext& rc, const Geometry::Vec2i & screenSize);
+		GUIAPI static void beginDrawing(Rendering::RenderingContext& rc, const Geometry::Vec2i & screenSize, const Geometry::Vec2 & renderScale={1.0f,1.0f});
 		GUIAPI static Rendering::RenderingContext& getRenderingContext();
 #else // GUI_BACKEND_RENDERING
 		GUIAPI static void beginDrawing(const Geometry::Vec2i & screenSize);

GUI_Manager.cpp

@@ -293,6 +293,10 @@ Rect GUI_Manager::getScreenRect()const{
 	return globalContainer->getLocalRect();
 }
 
+void GUI_Manager::setScreenSize(const Geometry::Vec2& size) {
+	globalContainer->setSize(size);
+}
+
 // ------------------------------------------------------------------------
 // Event handling & Listener
 bool GUI_Manager::isCtrlPressed() const {
@@ -458,8 +462,9 @@ void GUI_Manager::display()
 
 		#ifdef GUI_BACKEND_RENDERING
 			Geometry::Rect_i viewport = rc.getViewport();
-			globalContainer->setSize(static_cast<float>(viewport.getWidth()), static_cast<float>(viewport.getHeight()));
-			Draw::beginDrawing(rc, Geometry::Vec2i(viewport.getWidth(),viewport.getHeight()));
+			//globalContainer->setSize(static_cast<float>(viewport.getWidth()), static_cast<float>(viewport.getHeight()));
+			Geometry::Vec2 renderScale(static_cast<float>(viewport.getWidth()) / globalContainer->getWidth(), static_cast<float>(viewport.getHeight()) / globalContainer->getHeight());
+			Draw::beginDrawing(rc, Geometry::Vec2i(viewport.getWidth(),viewport.getHeight()), renderScale);
 		#else // GUI_BACKEND_RENDERING
 			Geometry::Rect_i viewport = Draw::queryViewport();
 			globalContainer->setSize(static_cast<float>(viewport.getWidth()), static_cast<float>(viewport.getHeight()));

GUI_Manager.h

@@ -105,6 +105,7 @@ class GUI_Manager {
 		GUIAPI void display();
 	#endif // GUI_BACKEND_RENDERING
 		GUIAPI Geometry::Rect getScreenRect()const;
+		GUIAPI void setScreenSize(const Geometry::Vec2& size);
 
 		//! Associate a window (e.g. X11 or SDL) to the GUI manager
 		void setWindow(Util::UI::Window * newWindow) {