draw: Rename set_clip to override_clip to make usage clear

Also fixed a couple incorrect usages.

src/display.cpp

@@ -790,7 +790,7 @@ surface display::screenshot(bool map_screenshot)
 	       << " texture for map screenshot" << std::endl;
 	texture output_texture(area.w, area.h, SDL_TEXTUREACCESS_TARGET);
 	auto target_setter = draw::set_render_target(output_texture);
-	auto clipper = draw::set_clip(area);
+	auto clipper = draw::override_clip(area);
 
 	map_screenshot_ = true;
 
@@ -1264,7 +1264,7 @@ void display::drawing_buffer_commit()
 	// std::list::sort() is a stable sort
 	drawing_buffer_.sort();
 
-	auto clipper = draw::set_clip(map_area());
+	auto clipper = draw::reduce_clip(map_area());
 
 	/*
 	 * Info regarding the rendering algorithm.
@@ -2566,19 +2566,18 @@ void display::render()
 
 bool display::expose(const SDL_Rect& region)
 {
-	if (region == sdl::empty_rect) { return false; } // TODO temp
-	//DBG_DP << "display::expose " << region << endl;
-	//invalidate_locations_in_rect(region);
+	// Note: clipping region is set by draw_manager,
+	// and will be contained by <region>.
+
+	// Blit from the pre-rendered front buffer.
 	// TODO: draw_manager - API to get src region in output space
 	rect src_region = region;
 	src_region *= video().get_pixel_scale();
 	//DBG_DP << "  src region " << src_region << endl;
-	//draw::blit(front_, region);
 	draw::blit(front_, region, src_region);
-	//draw();
+
+	// Render halos.
 	// TODO: draw_manager - halo render region not rely on clip?
-	// TODO: draw_manager - can we rely on clip already being set?
-	auto clipper = draw::set_clip(region);
 	halo_man_.render();
 
 	// These all check for clip region overlap before drawing
@@ -2679,7 +2678,7 @@ rect display::get_clip_rect() const
 void display::draw_invalidated() {
 //	log_scope("display::draw_invalidated");
 	SDL_Rect clip_rect = get_clip_rect();
-	auto clipper = draw::set_clip(clip_rect);
+	auto clipper = draw::reduce_clip(clip_rect);
 	DBG_DP << "drawing " << invalidated_.size() << " invalidated hexes"
 		<< " with clip " << clip_rect << endl;
 	for (const map_location& loc : invalidated_) {

src/draw.cpp

@@ -473,7 +473,7 @@ draw::clip_setter::~clip_setter()
 	}
 }
 
-draw::clip_setter draw::set_clip(const SDL_Rect& clip)
+draw::clip_setter draw::override_clip(const SDL_Rect& clip)
 {
 	return draw::clip_setter(clip);
 }

src/draw.hpp

@@ -296,8 +296,8 @@ void tiled_highres(const texture& tex,
 /** A class to manage automatic restoration of the clipping region.
  *
  * This can be constructed on its own, or one of the utility functions
- * set_clip() and reduce_clip() can be used. Constructing a clip_setter
- * or using set_clip() will completely override the current clipping area.
+ * override_clip() and reduce_clip() can be used. Constructing a clip_setter
+ * or using override_clip() will completely override the current clipping area.
  * To intersect with the current clipping area in stead, use reduce_clip().
  */
 class clip_setter
@@ -311,7 +311,7 @@ private:
 };
 
 /**
- * Set the clipping area. All draw calls will be clipped to this region.
+ * Override the clipping area. All draw calls will be clipped to this region.
  *
  * The clipping area is specified in draw-space coordinates.
  *
@@ -323,13 +323,13 @@ private:
  *                      the clipping region will be restored to whatever
  *                      it was before this call.
  */
-clip_setter set_clip(const SDL_Rect& clip);
+clip_setter override_clip(const SDL_Rect& clip);
 
 /**
  * Set the clipping area to the intersection of the current clipping
  * area and the given rectangle.
  *
- * Otherwise acts as set_clip().
+ * Otherwise acts as override_clip().
  */
 clip_setter reduce_clip(const SDL_Rect& clip);
 

src/draw_manager.cpp

@@ -204,7 +204,7 @@ next:
 		}
 		DBG_DM << "drawing " << r << endl;
 		//PLAIN_LOG << "+";
-		auto clipper = draw::set_clip(r);
+		auto clipper = draw::override_clip(r);
 		for (auto tld : top_level_drawables_) {
 			rect i = r.intersect(tld->screen_location());
 			if (i.empty()) {

src/widgets/menu_style.cpp

@@ -153,7 +153,7 @@ void menu::imgsel_style::draw_row(menu& menu_ref, const std::size_t row_index, c
 			// draw border
 			texture image;
 			SDL_Rect area;
-			auto clipper = draw::set_clip(rect);
+			auto clipper = draw::reduce_clip(rect);
 			area.x = rect.x;
 			area.y = rect.y;
 

src/widgets/textbox.cpp

@@ -209,7 +209,7 @@ void textbox::draw_contents()
 			const int endx = char_x_[end];
 			const int endy = char_y_[end];
 
-			auto clipper = draw::set_clip(loc);
+			auto clipper = draw::reduce_clip(loc);
 
 			while(starty <= endy) {
 				const std::size_t right = starty == endy ? endx : text_image_.w();