Refactored handling of window/renderer size getters

* Removed display::screen_area(), display::w(), and display::h().
* Moved the global screen_area() function into the CVideo class.
* Renamed CVideo::getx() and gety() to get_width() and get_height()
* Made those two functions return the result of screen_area() instead of the other way around.
* Added preliminary support for high-DPI rendering to screen_area()

Note on the last point: When I fixed bug #1772 (aa8f6c7e7 right now but will probably change with rebasing)
I noted that SDL_GetWindowSize and SDL_GetRendererOutputSize returned the same results for me (even with
Window's automatic scaling for non-high-DPI-enabled apps disabled) but that the SDL documentation stated the
former returned screen coordinates and the latter pixels. In that same commit I changed the dimension functions
to use SDL_GetWindowSize. I've now reversed that decision and gone back to using SDL_GetRendererOutputSize so
I can guarantee output in pixels. If use_pixels is false, the code will return coordinates in 96 DPI, so I need
to have pixel measurements for the calculations.

Again, though, I do not know if SDL_GetWindowSize returns a different value that pixel size (which it's said
to do) on macOS or iOS. I'll need to do some testing. It's possible on those platforms I won't need the 96 DPI
measurements, but it's also possible it will be needed on on platforms, since all of our code relies on pixel
measurements.

src/display.cpp

@@ -145,7 +145,7 @@ display::display(const display_context * dc, std::weak_ptr<wb::manager> wb, repo
 	, xpos_(0)
 	, ypos_(0)
 	, view_locked_(false)
-	, theme_(theme_cfg, screen_.screen_area())
+	, theme_(theme_cfg, video().screen_area())
 	, zoom_index_(0)
 	, fake_unit_man_(new fake_unit_manager(*this))
 	, builder_(new terrain_builder(level, (dc_ ? &dc_->map() : nullptr), theme_.border().tile_image, theme_.border().show_border))
@@ -241,9 +241,7 @@ display::~display()
 }
 
 void display::set_theme(config theme_cfg) {
-	theme_ = theme(theme_cfg, screen_.screen_area());
-	builder_->set_draw_border(theme_.border().show_border);
-	menu_buttons_.clear();
+	theme_ = theme(theme_cfg, video_.screen_area());	menu_buttons_.clear();
 	action_buttons_.clear();
 	create_buttons();
 }
@@ -795,7 +793,7 @@ void display::layout_buttons()
 	for(const auto& menu : theme_.menus()) {
 		std::shared_ptr<gui::button> b = find_menu_button(menu.get_id());
 		if(b) {
-			const SDL_Rect& loc = menu.location(screen_.screen_area());
+			const SDL_Rect& loc = menu.location(video_.screen_area());
 			b->set_location(loc);
 			b->set_measurements(0,0);
 			b->set_label(menu.title());
@@ -807,7 +805,7 @@ void display::layout_buttons()
 	for(const auto& action : theme_.actions()) {
 		std::shared_ptr<gui::button> b = find_action_button(action.get_id());
 		if(b) {
-			const SDL_Rect& loc = action.location(screen_.screen_area());
+			const SDL_Rect& loc = action.location(video_.screen_area());
 			b->set_location(loc);
 			b->set_measurements(0,0);
 			b->set_label(action.title());
@@ -1942,7 +1940,7 @@ void display::refresh_report(const std::string& report_name, const config * new_
 		new_cfg = &generated_cfg;
 
 	SDL_Rect &rect = reportRects_[report_name];
-	const SDL_Rect &new_rect = item->location(screen_.screen_area());
+	const SDL_Rect &new_rect = item->location(video_.screen_area());
 	surface &surf = reportSurfaces_[report_name];
 	config &report = reports_[report_name];
 
@@ -2260,7 +2258,7 @@ void display::redraw_everything()
 
 	tooltips::clear_tooltips();
 
-	theme_.set_resolution(screen_area());
+	theme_.set_resolution(video_.screen_area());
 
 	if(!menu_buttons_.empty() || !action_buttons_.empty()) {
 		create_buttons();

src/display.hpp

@@ -276,18 +276,6 @@ public:
 	 * Between mapx and x is the sidebar region.
 	 */
 
-	/** Screen width */
-	int w() const
-	{
-		return video_.get_width();
-	}
-
-	/** Screen height */
-	int h() const
-	{
-		return video_.get_hright();
-	}
-
 	const SDL_Rect& minimap_area() const
 	{
 		return theme_.mini_map_location(video_.screen_area());
@@ -303,11 +291,6 @@ public:
 		return theme_.unit_image_location(video_.screen_area());
 	}
 
-	SDL_Rect screen_area() const
-	{
-		return {0, 0, w(), h()};
-	}
-
 	/** Returns the maximum area used for the map regardless to resolution and view size */
 	const SDL_Rect& max_map_area() const;
 

src/floating_label.cpp

@@ -20,6 +20,7 @@
 #include "sdl/render_utils.hpp"
 #include "sdl/surface.hpp"
 #include "utils/general.hpp"
+#include "video.hpp"
 
 #include <boost/algorithm/string.hpp>
 
@@ -60,7 +61,7 @@ floating_label::floating_label(const std::string& text)
 	, border_(0)
 	, alpha_change_(0)
 	, current_alpha_(255)
-	, clip_rect_(screen_area())
+	, clip_rect_(CVideo::get_singleton().screen_area())
 	, align_(CENTER_ALIGN)
 	, scroll_(ANCHOR_LABEL_SCREEN)
 	, visible_(true)

src/show_dialog.cpp

@@ -321,7 +321,7 @@ void dialog_frame::draw_background()
 
 SDL_Rect dialog_frame::draw_title(CVideo* video)
 {
-	SDL_Rect rect = CVideo::get_singleton().screen_area();
+	SDL_Rect rect = video->screen_area();
 	return font::draw_text(video, rect, font::SIZE_TITLE, font::TITLE_COLOR,
 	                       title_, dim_.title.x, dim_.title.y, false, TTF_STYLE_NORMAL);
 }