Minor refactor to pass draw regions in display::expose()

src/display.cpp

@@ -1458,15 +1458,26 @@ void display::draw_label(const theme::label& label)
 	}
 }
 
-void display::draw_all_panels()
+bool display::draw_all_panels(const rect& region)
 {
+	bool drew = false;
+	const rect game_canvas = video::game_canvas();
+
 	for(const auto& panel : theme_.panels()) {
-		draw_panel(panel);
+		if(region.overlaps(panel.location(game_canvas))) {
+			draw_panel(panel);
+			drew = true;
+		}
 	}
 
 	for(const auto& label : theme_.labels()) {
-		draw_label(label);
+		if(region.overlaps(label.location(game_canvas))) {
+			draw_label(label);
+			drew = true;
+		}
 	}
+
+	return drew;
 }
 
 void display::draw_text_in_hex(const map_location& loc,
@@ -2574,28 +2585,30 @@ void display::render()
 
 bool display::expose(const SDL_Rect& region)
 {
-	// Note: clipping region is set by draw_manager,
-	// and will be contained by <region>.
-
 	if(prevent_draw_) {
 		DBG_DP << "draw prevented";
 		return false;
 	}
 
+	rect clipped_region = draw::get_clip().intersect(region);
+
 	// Blit from the pre-rendered front buffer.
-	front_.set_src(region);
-	draw::blit(front_, region);
-	front_.clear_src();
+	if(clipped_region.overlaps(map_outside_area())) {
+		front_.set_src(clipped_region);
+		draw::blit(front_, clipped_region);
+		front_.clear_src();
+	}
 
 	// Render halos.
-	// TODO: draw_manager - halo render region not rely on clip?
-	halo_man_.render();
+	halo_man_.render(clipped_region);
 
-	// These all check for clip region overlap before drawing
-	draw_all_panels();
-	draw_reports();
-	draw_minimap();
-	draw_buttons();
+	// Render UI elements.
+	draw_all_panels(clipped_region);
+	draw_reports(clipped_region);
+	if(clipped_region.overlaps(minimap_area())) {
+		draw_minimap();
+	}
+	//draw_buttons();
 
 	// TODO: draw_manager - hmm... buttons redraw over tooltips, because they are TLDs
 	font::draw_floating_labels();
@@ -2607,7 +2620,9 @@ bool display::expose(const SDL_Rect& region)
 
 	DBG_DP << "display::expose " << region;
 
-	return true; // TODO: draw_manager - maybe don't flip yeah?
+	// The display covers the entire screen.
+	// We will always be drawing something.
+	return true;
 }
 
 rect display::screen_location()
@@ -3141,17 +3156,18 @@ void display::draw_report(const std::string& report_name, bool tooltip_test)
 	}
 }
 
-// TODO: draw_manager - pass in bounds in stead of using clip region
-// TODO: draw_manager - return whether anything was drawn
-void display::draw_reports()
+bool display::draw_reports(const rect& region)
 {
+	bool drew = false;
 	for(const auto& it : reports_) {
 		const std::string& name = it.first;
 		const rect& loc = reportLocations_[name];
-		if(loc.overlaps(draw::get_clip())) {
+		if(loc.overlaps(region)) {
 			draw_report(name);
+			drew = true;
 		}
 	}
+	return drew;
 }
 
 void display::invalidate_all()

src/display.hpp

@@ -413,8 +413,9 @@ public:
 	 */
 	void draw_report(const std::string& report_name, bool test_run = false);
 
-	/** Draw all reports. This will respect the clipping region, if set. */
-	void draw_reports();
+	/** Draw all reports in the given region.
+	  * Returns true if something was drawn, false otherwise. */
+	bool draw_reports(const rect& region);
 
 	void draw_minimap_units();
 
@@ -1086,8 +1087,10 @@ protected:
 	/** Clears the drawing buffer. */
 	void drawing_buffer_clear();
 
-	/** redraw all panels associated with the map display */
-	void draw_all_panels();
+	/** Redraws all panels intersecting the given region.
+	  * Returns true if something was drawn, false otherwise. */
+	bool draw_all_panels(const rect& region);
+
 private:
 	void draw_panel(const theme::panel& panel);
 	void draw_label(const theme::label& label);

src/halo.cpp

@@ -146,7 +146,9 @@ class halo_impl
 	void remove(int handle);
 
 	void update();
-	void render();
+
+	/** Render all halos overlapping the given region */
+	void render(const rect&);
 
 }; //end halo_impl
 
@@ -404,17 +406,14 @@ void halo_impl::update()
 	}
 }
 
-void halo_impl::render()
+void halo_impl::render(const rect& region)
 {
 	if(haloes.empty()) {
 		return;
 	}
 
-	// TODO: draw_manager - pass in rect in stead of assuming clip makes sense
-	rect clip = draw::get_clip();
-
 	for(auto& [id, effect] : haloes) {
-		if(clip.overlaps(effect.get_draw_location())) {
+		if(region.overlaps(effect.get_draw_location())) {
 			DBG_HL << "drawing intersected halo " << id;
 			effect.render();
 		}
@@ -456,9 +455,9 @@ void manager::update()
 	impl_->update();
 }
 
-void manager::render()
+void manager::render(const rect& r)
 {
-	impl_->render();
+	impl_->render(r);
 }
 
 // end halo::manager implementation

src/halo.hpp

@@ -16,6 +16,7 @@
 #pragma once
 
 class display;
+struct rect;
 
 #include "map/location.hpp"
 
@@ -62,8 +63,8 @@ public:
 	  * regions now requiring redraw. */
 	void update();
 
-	/** Render halos. */
-	void render();
+	/** Render halos in region. */
+	void render(const rect& r);
 
 private:
 	std::shared_ptr<halo_impl> impl_;