From 38b59b6c312e9bf3220a781f50497fafd3278ce9 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Thu, 21 Jul 2016 16:06:43 +0200
Subject: [PATCH 01/10] WIP: zoom towards cursor rather than centre.

---
 src/interface/window.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/interface/window.c b/src/interface/window.c
index 5e042798d8..e89c141dab 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -374,7 +374,7 @@ static void window_close_surplus(int cap, sint8 avoid_classification)
 /*
  * Changes the maximum amount of windows allowed
  */
-void window_set_window_limit(int value) 
+void window_set_window_limit(int value)
 {
 	int prev = gConfigGeneral.window_limit;
 	int val = clamp(value, WINDOW_LIMIT_MIN, WINDOW_LIMIT_MAX);
@@ -1445,6 +1445,13 @@ void window_rotate_camera(rct_window *w, int direction)
 	reset_all_sprite_quadrant_placements();
 }
 
+void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y)
+{
+	int mouse_x, mouse_y;
+	platform_get_cursor_position(&mouse_x, &mouse_y);
+	get_map_coordinates_from_pos(mouse_x, mouse_y, VIEWPORT_INTERACTION_MASK_NONE, map_x, map_y, NULL, NULL, NULL);
+}
+
 void window_zoom_set(rct_window *w, int zoomLevel)
 {
 	rct_viewport* v = w->viewport;
@@ -1453,12 +1460,15 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 	if (v->zoom == zoomLevel)
 		return;
 
+	sint16 saved_map_x, saved_map_y;
+	window_viewport_get_map_coords_by_cursor(w, &saved_map_x, &saved_map_y);
+
 	// Zoom in
 	while (v->zoom > zoomLevel) {
 		v->zoom--;
 		w->saved_view_x += v->view_width / 4;
 		w->saved_view_y += v->view_height / 4;
-		v->view_width /= 2;
+		v->view_width  /= 2;
 		v->view_height /= 2;
 	}
 
@@ -1467,10 +1477,16 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 		v->zoom++;
 		w->saved_view_x -= v->view_width / 2;
 		w->saved_view_y -= v->view_height / 2;
-		v->view_width *= 2;
+		v->view_width  *= 2;
 		v->view_height *= 2;
 	}
 
+	int dest_x, dest_y;
+	center_2d_coordinates(saved_map_x, saved_map_y, 14, &dest_x, &dest_y, v);
+
+	w->saved_view_x = dest_x;
+	w->saved_view_y = dest_y;
+
 	// HACK: Prevents the redraw from failing when there is
 	// a window on top of the viewport.
 	window_bring_to_front(w);

From a1b8bdfa114386c5c0fbdc07bf6933df7e9e74c0 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Thu, 21 Jul 2016 21:00:29 +0200
Subject: [PATCH 02/10] Make zooming to cursor optional.

This adds a checkbox to the interface settings panel to enable zooming around the cursor.
If disabled, which it is by default, vanilla RCT2 behaviour is retained.
---
 data/language/en-GB.txt       |  2 ++
 src/config.c                  |  2 +-
 src/config.h                  |  1 +
 src/interface/window.c        | 16 +++++++++-----
 src/localisation/string_ids.h |  3 ++-
 src/windows/options.c         | 39 +++++++++++++++++++++--------------
 6 files changed, 41 insertions(+), 22 deletions(-)

diff --git a/data/language/en-GB.txt b/data/language/en-GB.txt
index b92add2344..38c40b2b71 100644
--- a/data/language/en-GB.txt
+++ b/data/language/en-GB.txt
@@ -4214,6 +4214,8 @@ STR_5902    :Show bounding boxes
 STR_5903    :Show paint debug window
 STR_5904    :Reset date
 STR_5905    :{SMALLFONT}{BLACK}A map generation tool that automatically creates a custom landscape
+STR_5906    :Zoom to cursor position
+STR_5907    :{SMALLFONT}{BLACK}When enabled, zooming in will centre around the cursor, as opposed to the screen centre.
 
 #############
 # Scenarios #
diff --git a/src/config.c b/src/config.c
index d5ab291413..e67b39c08a 100644
--- a/src/config.c
+++ b/src/config.c
@@ -227,7 +227,7 @@ config_property_definition _generalDefinitions[] = {
 	{ offsetof(general_configuration, last_save_scenario_directory),    "last_scenario_directory",      CONFIG_VALUE_TYPE_STRING,       { .value_string = NULL },       NULL                    },
 	{ offsetof(general_configuration, last_save_track_directory),       "last_track_directory",         CONFIG_VALUE_TYPE_STRING,       { .value_string = NULL },       NULL                    },
 	{ offsetof(general_configuration, window_limit),					"window_limit",					CONFIG_VALUE_TYPE_UINT8,		WINDOW_LIMIT_MAX,				NULL					},
-	
+	{ offsetof(general_configuration, zoom_to_cursor),					"zoom_to_cursor",				CONFIG_VALUE_TYPE_BOOLEAN,		false,							NULL					},
 };
 
 config_property_definition _interfaceDefinitions[] = {
diff --git a/src/config.h b/src/config.h
index e211374c29..ffc28ba085 100644
--- a/src/config.h
+++ b/src/config.h
@@ -198,6 +198,7 @@ typedef struct general_configuration {
 	utf8string last_save_scenario_directory;
 	utf8string last_save_track_directory;
 	uint8 window_limit;
+	uint8 zoom_to_cursor;
 } general_configuration;
 
 typedef struct interface_configuration {
diff --git a/src/interface/window.c b/src/interface/window.c
index e89c141dab..d4d4b4453f 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -1460,8 +1460,11 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 	if (v->zoom == zoomLevel)
 		return;
 
+	// Zooming to cursor? Remember where we're pointing at the moment.
 	sint16 saved_map_x, saved_map_y;
-	window_viewport_get_map_coords_by_cursor(w, &saved_map_x, &saved_map_y);
+	if (gConfigGeneral.zoom_to_cursor) {
+		window_viewport_get_map_coords_by_cursor(w, &saved_map_x, &saved_map_y);
+	}
 
 	// Zoom in
 	while (v->zoom > zoomLevel) {
@@ -1481,11 +1484,14 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 		v->view_height *= 2;
 	}
 
-	int dest_x, dest_y;
-	center_2d_coordinates(saved_map_x, saved_map_y, 14, &dest_x, &dest_y, v);
+	// Zooming to cursor? Centre around the tile we were hovering over just now.
+	if (gConfigGeneral.zoom_to_cursor) {
+		int dest_x, dest_y;
+		center_2d_coordinates(saved_map_x, saved_map_y, 14, &dest_x, &dest_y, v);
 
-	w->saved_view_x = dest_x;
-	w->saved_view_y = dest_y;
+		w->saved_view_x = dest_x;
+		w->saved_view_y = dest_y;
+	}
 
 	// HACK: Prevents the redraw from failing when there is
 	// a window on top of the viewport.
diff --git a/src/localisation/string_ids.h b/src/localisation/string_ids.h
index db725ab61a..d0613e4dfa 100644
--- a/src/localisation/string_ids.h
+++ b/src/localisation/string_ids.h
@@ -3336,8 +3336,9 @@ enum {
 	STR_DEBUG_PAINT_SHOW_BOUND_BOXES = 5902,
 	STR_DEBUG_DROPDOWN_DEBUG_PAINT = 5903,
 	STR_CHEAT_RESET_DATE = 5904,
-
 	STR_MAP_GENERATOR_TIP = 5905,
+	STR_ZOOM_TO_CURSOR = 5906,
+	STR_ZOOM_TO_CURSOR_TIP = 5907,
 	
 	// Have to include resource strings (from scenarios and objects) for the time being now that language is partially working
 	STR_COUNT = 32768
diff --git a/src/windows/options.c b/src/windows/options.c
index 8d7692b71b..3a341fbb9d 100644
--- a/src/windows/options.c
+++ b/src/windows/options.c
@@ -129,6 +129,7 @@ enum WINDOW_OPTIONS_WIDGET_IDX {
 	WIDX_SCREEN_EDGE_SCROLLING,
 	WIDX_TRAP_CURSOR,
 	WIDX_INVERT_DRAG,
+	WIDX_ZOOM_TO_CURSOR,
 	WIDX_HOTKEY_DROPDOWN,
 	WIDX_THEMES_GROUP,
 	WIDX_THEMES,
@@ -269,27 +270,28 @@ static rct_widget window_options_audio_widgets[] = {
 
 static rct_widget window_options_controls_and_interface_widgets[] = {
 	MAIN_OPTIONS_WIDGETS,
-	{ WWT_GROUPBOX,			1,	5,      304,	53,			129,	STR_CONTROLS_GROUP,						STR_NONE },									// Controls group
+	{ WWT_GROUPBOX,			1,	5,      304,	53,			144,	STR_CONTROLS_GROUP,						STR_NONE },									// Controls group
 	{ WWT_CHECKBOX,			2,	10,		299,	68,			79,		STR_SCREEN_EDGE_SCROLLING,				STR_SCREEN_EDGE_SCROLLING_TIP },			// Edge scrolling
 	{ WWT_CHECKBOX,			2,	10,		299,	83,			94,		STR_TRAP_MOUSE,							STR_TRAP_MOUSE_TIP },						// Trap mouse
 	{ WWT_CHECKBOX,			2,	10,		299,	98,			109,	STR_INVERT_RIGHT_MOUSE_DRAG,			STR_INVERT_RIGHT_MOUSE_DRAG_TIP },			// Invert right mouse dragging
-	{ WWT_DROPDOWN_BUTTON,	1,	26,		185,	113,		124,	STR_HOTKEY,								STR_HOTKEY_TIP },							// Set hotkeys buttons
+	{ WWT_CHECKBOX,			2,	10,		299,	113,		124,	STR_ZOOM_TO_CURSOR,						STR_ZOOM_TO_CURSOR_TIP },			// Zoom to cursor
+	{ WWT_DROPDOWN_BUTTON,	1,	26,		185,	128,		139,	STR_HOTKEY,								STR_HOTKEY_TIP },							// Set hotkeys buttons
 
-	{ WWT_GROUPBOX,			1,	5,      304,	133,		179,	STR_THEMES_GROUP,						STR_NONE },									// Toolbar buttons group
-	{ WWT_DROPDOWN,			1,	155,	299,	147,		158,	STR_NONE,								STR_NONE },									// Themes
-	{ WWT_DROPDOWN_BUTTON,	1,	288,	298,	148,		157,	STR_DROPDOWN_GLYPH,						STR_CURRENT_THEME_TIP },
-	{ WWT_DROPDOWN_BUTTON,	1,	10,		145,	163,		174,	STR_EDIT_THEMES_BUTTON,					STR_EDIT_THEMES_BUTTON_TIP },				// Themes button
+	{ WWT_GROUPBOX,			1,	5,      304,	148,		194,	STR_THEMES_GROUP,						STR_NONE },									// Toolbar buttons group
+	{ WWT_DROPDOWN,			1,	155,	299,	162,		173,	STR_NONE,								STR_NONE },									// Themes
+	{ WWT_DROPDOWN_BUTTON,	1,	288,	298,	163,		172,	STR_DROPDOWN_GLYPH,						STR_CURRENT_THEME_TIP },
+	{ WWT_DROPDOWN_BUTTON,	1,	10,		145,	178,		189,	STR_EDIT_THEMES_BUTTON,					STR_EDIT_THEMES_BUTTON_TIP },				// Themes button
 
-	{ WWT_GROUPBOX,			1,	5,      304,	183,		245,	STR_TOOLBAR_BUTTONS_GROUP,				STR_NONE },									// Toolbar buttons group
-	{ WWT_CHECKBOX,			2,	10,		145,	214,		225,	STR_FINANCES_BUTTON_ON_TOOLBAR,			STR_FINANCES_BUTTON_ON_TOOLBAR_TIP },		// Finances
-	{ WWT_CHECKBOX,			2,	10,		145,	229,		240,	STR_RESEARCH_BUTTON_ON_TOOLBAR,			STR_RESEARCH_BUTTON_ON_TOOLBAR_TIP },		// Research
-	{ WWT_CHECKBOX,			2,	155,	299,	214,		225,	STR_CHEATS_BUTTON_ON_TOOLBAR,			STR_CHEATS_BUTTON_ON_TOOLBAR_TIP },			// Cheats
-	{ WWT_CHECKBOX,			2,	155,	299,	229,		240,	STR_SHOW_RECENT_MESSAGES_ON_TOOLBAR,	STR_SHOW_RECENT_MESSAGES_ON_TOOLBAR_TIP },	// Recent messages
+	{ WWT_GROUPBOX,			1,	5,      304,	198,		260,	STR_TOOLBAR_BUTTONS_GROUP,				STR_NONE },									// Toolbar buttons group
+	{ WWT_CHECKBOX,			2,	10,		145,	229,		240,	STR_FINANCES_BUTTON_ON_TOOLBAR,			STR_FINANCES_BUTTON_ON_TOOLBAR_TIP },		// Finances
+	{ WWT_CHECKBOX,			2,	10,		145,	244,		255,	STR_RESEARCH_BUTTON_ON_TOOLBAR,			STR_RESEARCH_BUTTON_ON_TOOLBAR_TIP },		// Research
+	{ WWT_CHECKBOX,			2,	155,	299,	229,		240,	STR_CHEATS_BUTTON_ON_TOOLBAR,			STR_CHEATS_BUTTON_ON_TOOLBAR_TIP },			// Cheats
+	{ WWT_CHECKBOX,			2,	155,	299,	244,		255,	STR_SHOW_RECENT_MESSAGES_ON_TOOLBAR,	STR_SHOW_RECENT_MESSAGES_ON_TOOLBAR_TIP },	// Recent messages
 
-	{ WWT_CHECKBOX,			2,	10,		299,	254,		265,	STR_SELECT_BY_TRACK_TYPE,				STR_SELECT_BY_TRACK_TYPE_TIP },				// Select by track type
-	{ WWT_DROPDOWN,			2,	155,	299,	269,		280,	STR_NONE,								STR_NONE },									// Scenario select mode
-	{ WWT_DROPDOWN_BUTTON,	2,	288,	298,	270,		279,	STR_DROPDOWN_GLYPH,						STR_SCENARIO_GROUPING_TIP },
-	{ WWT_CHECKBOX,			2,	18,		299,	284,		295,	STR_OPTIONS_SCENARIO_UNLOCKING,			STR_SCENARIO_UNLOCKING_TIP },				// Unlocking of scenarios
+	{ WWT_CHECKBOX,			2,	10,		299,	269,		280,	STR_SELECT_BY_TRACK_TYPE,				STR_SELECT_BY_TRACK_TYPE_TIP },				// Select by track type
+	{ WWT_DROPDOWN,			2,	155,	299,	284,		295,	STR_NONE,								STR_NONE },									// Scenario select mode
+	{ WWT_DROPDOWN_BUTTON,	2,	288,	298,	285,		294,	STR_DROPDOWN_GLYPH,						STR_SCENARIO_GROUPING_TIP },
+	{ WWT_CHECKBOX,			2,	18,		299,	299,		310,	STR_OPTIONS_SCENARIO_UNLOCKING,			STR_SCENARIO_UNLOCKING_TIP },				// Unlocking of scenarios
 	{ WIDGETS_END },
 };
 
@@ -491,6 +493,7 @@ static uint32 window_options_page_enabled_widgets[] = {
 	(1 << WIDX_SCREEN_EDGE_SCROLLING) |
 	(1 << WIDX_TRAP_CURSOR) |
 	(1 << WIDX_INVERT_DRAG) |
+	(1 << WIDX_ZOOM_TO_CURSOR) |
 	(1 << WIDX_HOTKEY_DROPDOWN) |
 	(1 << WIDX_TOOLBAR_SHOW_FINANCES) |
 	(1 << WIDX_TOOLBAR_SHOW_RESEARCH) |
@@ -694,6 +697,11 @@ static void window_options_mouseup(rct_window *w, int widgetIndex)
 			SDL_SetWindowGrab(gWindow, gConfigGeneral.trap_cursor ? SDL_TRUE : SDL_FALSE);
 			window_invalidate(w);
 			break;
+		case WIDX_ZOOM_TO_CURSOR:
+			gConfigGeneral.zoom_to_cursor ^= 1;
+			config_save_default();
+			window_invalidate(w);
+			break;
 		case WIDX_TOOLBAR_SHOW_FINANCES:
 			gConfigInterface.toolbar_show_finances ^= 1;
 			config_save_default();
@@ -1556,6 +1564,7 @@ static void window_options_invalidate(rct_window *w)
 		widget_set_checkbox_value(w, WIDX_SCREEN_EDGE_SCROLLING, gConfigGeneral.edge_scrolling);
 		widget_set_checkbox_value(w, WIDX_TRAP_CURSOR, gConfigGeneral.trap_cursor);
 		widget_set_checkbox_value(w, WIDX_INVERT_DRAG, gConfigGeneral.invert_viewport_drag);
+		widget_set_checkbox_value(w, WIDX_ZOOM_TO_CURSOR, gConfigGeneral.zoom_to_cursor);
 		widget_set_checkbox_value(w, WIDX_TOOLBAR_SHOW_FINANCES, gConfigInterface.toolbar_show_finances);
 		widget_set_checkbox_value(w, WIDX_TOOLBAR_SHOW_RESEARCH, gConfigInterface.toolbar_show_research);
 		widget_set_checkbox_value(w, WIDX_TOOLBAR_SHOW_CHEATS, gConfigInterface.toolbar_show_cheats);

From 17cbdf795e6cd87e13e8792c3c67e3132c561844 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Thu, 21 Jul 2016 21:51:39 +0200
Subject: [PATCH 03/10] Missing header declaration for gcc.

---
 src/interface/window.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/interface/window.h b/src/interface/window.h
index fa7d8a75a8..c97f68c45c 100644
--- a/src/interface/window.h
+++ b/src/interface/window.h
@@ -574,6 +574,7 @@ rct_window *window_get_main();
 void window_scroll_to_viewport(rct_window *w);
 void window_scroll_to_location(rct_window *w, int x, int y, int z);
 void window_rotate_camera(rct_window *w, int direction);
+void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y);
 void window_zoom_set(rct_window *w, int zoomLevel);
 void window_zoom_in(rct_window *w);
 void window_zoom_out(rct_window *w);

From f035bfdecdd3e1d9e90290e72ab9e907e38d7b5c Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Fri, 22 Jul 2016 01:01:24 +0200
Subject: [PATCH 04/10] Try to keep the current tile under the mouse cursor.

This still doesn't work as well as I'd like yet, most notably when zooming out.
---
 src/interface/window.c | 24 +++++++++++++++++++-----
 src/interface/window.h |  1 +
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/interface/window.c b/src/interface/window.c
index d4d4b4453f..25c1eed9dd 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -1452,6 +1452,24 @@ void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint
 	get_map_coordinates_from_pos(mouse_x, mouse_y, VIEWPORT_INTERACTION_MASK_NONE, map_x, map_y, NULL, NULL, NULL);
 }
 
+void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y)
+{
+	// Get viewport coordinates centring around the tile.
+	int dest_x, dest_y;
+	center_2d_coordinates(map_x, map_y, 14, &dest_x, &dest_y, w->viewport);
+
+	// Get mouse position to offset against.
+	int mouse_x, mouse_y;
+	platform_get_cursor_position(&mouse_x, &mouse_y);
+
+	// Rebase mouse position onto centre of window.
+	int rebased_x = (w->width >> 1) - mouse_x,
+		rebased_y = (w->height >> 1) - mouse_y;
+
+	w->saved_view_x = dest_x + rebased_x;
+	w->saved_view_y = dest_y + rebased_y;
+}
+
 void window_zoom_set(rct_window *w, int zoomLevel)
 {
 	rct_viewport* v = w->viewport;
@@ -1486,11 +1504,7 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 
 	// Zooming to cursor? Centre around the tile we were hovering over just now.
 	if (gConfigGeneral.zoom_to_cursor) {
-		int dest_x, dest_y;
-		center_2d_coordinates(saved_map_x, saved_map_y, 14, &dest_x, &dest_y, v);
-
-		w->saved_view_x = dest_x;
-		w->saved_view_y = dest_y;
+		window_viewport_centre_tile_around_cursor(w, saved_map_x, saved_map_y);
 	}
 
 	// HACK: Prevents the redraw from failing when there is
diff --git a/src/interface/window.h b/src/interface/window.h
index c97f68c45c..2774060d88 100644
--- a/src/interface/window.h
+++ b/src/interface/window.h
@@ -575,6 +575,7 @@ void window_scroll_to_viewport(rct_window *w);
 void window_scroll_to_location(rct_window *w, int x, int y, int z);
 void window_rotate_camera(rct_window *w, int direction);
 void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y);
+void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y);
 void window_zoom_set(rct_window *w, int zoomLevel);
 void window_zoom_in(rct_window *w);
 void window_zoom_out(rct_window *w);

From ccdd7bec4fedbb991c79fdf0f8fec2b20934a346 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Fri, 22 Jul 2016 10:47:07 +0200
Subject: [PATCH 05/10] Compensate for zoom level and base height.

---
 src/interface/window.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/interface/window.c b/src/interface/window.c
index 25c1eed9dd..c4ed8cdd92 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -1456,7 +1456,8 @@ void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint
 {
 	// Get viewport coordinates centring around the tile.
 	int dest_x, dest_y;
-	center_2d_coordinates(map_x, map_y, 14, &dest_x, &dest_y, w->viewport);
+	int base_height = map_element_height(map_x, map_y);
+	center_2d_coordinates(map_x, map_y, base_height, &dest_x, &dest_y, w->viewport);
 
 	// Get mouse position to offset against.
 	int mouse_x, mouse_y;
@@ -1466,6 +1467,11 @@ void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint
 	int rebased_x = (w->width >> 1) - mouse_x,
 		rebased_y = (w->height >> 1) - mouse_y;
 
+	// Compensate for zoom level.
+	rebased_x <<= w->viewport->zoom;
+	rebased_y <<= w->viewport->zoom;
+
+	// Apply offset to the viewport.
 	w->saved_view_x = dest_x + rebased_x;
 	w->saved_view_y = dest_y + rebased_y;
 }

From 7c12c48bfd2db209d918845c4b46e70e5d9c2253 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Fri, 22 Jul 2016 10:52:57 +0200
Subject: [PATCH 06/10] Add changelog entry.

[ci skip]
---
 distribution/changelog.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/distribution/changelog.txt b/distribution/changelog.txt
index 22690aad66..0a4e9fff49 100644
--- a/distribution/changelog.txt
+++ b/distribution/changelog.txt
@@ -19,6 +19,7 @@
 - Feature: Add console command to set scenario initial cash.
 - Feature: Objects are scanned from the user directory as well as the RCT2 directory.
 - Feature: Objects directory is scanned recursively.
+- Feature: Optionally zoom in towards the cursor rather than the screen centre.
 - Improve: Performance and reliability of loading objects.
 - Improve: Screenshots are now saved with the name of the park and the current date and time.
 - Improve: More accurate frame rate calculation

From 34bef11f7578b5f4158b9966784f272e033657e0 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Fri, 22 Jul 2016 12:09:38 +0200
Subject: [PATCH 07/10] Compensate mouse position for window scaling.

---
 src/interface/window.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/interface/window.c b/src/interface/window.c
index c4ed8cdd92..716aefb020 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -1449,6 +1449,11 @@ void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint
 {
 	int mouse_x, mouse_y;
 	platform_get_cursor_position(&mouse_x, &mouse_y);
+
+	// Compensate for window scaling.
+	mouse_x = (int) ceilf(mouse_x / gConfigGeneral.window_scale);
+	mouse_y = (int) ceilf(mouse_y / gConfigGeneral.window_scale);
+
 	get_map_coordinates_from_pos(mouse_x, mouse_y, VIEWPORT_INTERACTION_MASK_NONE, map_x, map_y, NULL, NULL, NULL);
 }
 
@@ -1463,6 +1468,10 @@ void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint
 	int mouse_x, mouse_y;
 	platform_get_cursor_position(&mouse_x, &mouse_y);
 
+	// Compensate for window scaling.
+	mouse_x = (int) ceilf(mouse_x / gConfigGeneral.window_scale);
+	mouse_y = (int) ceilf(mouse_y / gConfigGeneral.window_scale);
+
 	// Rebase mouse position onto centre of window.
 	int rebased_x = (w->width >> 1) - mouse_x,
 		rebased_y = (w->height >> 1) - mouse_y;

From 1755fa433fe8dc903556ab987826aea6e85726ee Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Fri, 22 Jul 2016 16:07:14 +0200
Subject: [PATCH 08/10] Enable zoom to cursor by default.

---
 src/config.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/config.c b/src/config.c
index e67b39c08a..c85c76d76d 100644
--- a/src/config.c
+++ b/src/config.c
@@ -227,7 +227,7 @@ config_property_definition _generalDefinitions[] = {
 	{ offsetof(general_configuration, last_save_scenario_directory),    "last_scenario_directory",      CONFIG_VALUE_TYPE_STRING,       { .value_string = NULL },       NULL                    },
 	{ offsetof(general_configuration, last_save_track_directory),       "last_track_directory",         CONFIG_VALUE_TYPE_STRING,       { .value_string = NULL },       NULL                    },
 	{ offsetof(general_configuration, window_limit),					"window_limit",					CONFIG_VALUE_TYPE_UINT8,		WINDOW_LIMIT_MAX,				NULL					},
-	{ offsetof(general_configuration, zoom_to_cursor),					"zoom_to_cursor",				CONFIG_VALUE_TYPE_BOOLEAN,		false,							NULL					},
+	{ offsetof(general_configuration, zoom_to_cursor),					"zoom_to_cursor",				CONFIG_VALUE_TYPE_BOOLEAN,		true,							NULL					},
 };
 
 config_property_definition _interfaceDefinitions[] = {

From 8ac1b79799e966e6b9089ce56109d9f4dc2383c7 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Sat, 30 Jul 2016 21:02:54 +0200
Subject: [PATCH 09/10] Remember and apply cursor position relative to tile.

---
 src/interface/window.c | 34 +++++++++++++++++++++++++++-------
 src/interface/window.h |  4 ++--
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/src/interface/window.c b/src/interface/window.c
index 716aefb020..39267cc5a2 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -1445,7 +1445,7 @@ void window_rotate_camera(rct_window *w, int direction)
 	reset_all_sprite_quadrant_placements();
 }
 
-void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y)
+void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y, sint16 *offset_x, sint16 *offset_y)
 {
 	int mouse_x, mouse_y;
 	platform_get_cursor_position(&mouse_x, &mouse_y);
@@ -1455,9 +1455,29 @@ void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint
 	mouse_y = (int) ceilf(mouse_y / gConfigGeneral.window_scale);
 
 	get_map_coordinates_from_pos(mouse_x, mouse_y, VIEWPORT_INTERACTION_MASK_NONE, map_x, map_y, NULL, NULL, NULL);
+
+	// Get viewport coordinates centring around the tile.
+	int base_height = map_element_height(*map_x, *map_y);
+	int dest_x, dest_y;
+	center_2d_coordinates(*map_x, *map_y, base_height, &dest_x, &dest_y, w->viewport);
+
+	// Rebase mouse position onto centre of window.
+	int rebased_x = (w->width >> 1) - mouse_x,
+		rebased_y = (w->height >> 1) - mouse_y;
+
+	// Compensate for zoom level.
+	rebased_x <<= w->viewport->zoom;
+	rebased_y <<= w->viewport->zoom;
+
+	// Apply offset to the viewport.
+	int new_x = dest_x + rebased_x,
+		new_y = dest_y + rebased_y;
+
+	*offset_x = (w->saved_view_x - new_x) << w->viewport->zoom,
+	*offset_y = (w->saved_view_y - new_y) << w->viewport->zoom;
 }
 
-void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y)
+void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y, sint16 offset_x, sint16 offset_y)
 {
 	// Get viewport coordinates centring around the tile.
 	int dest_x, dest_y;
@@ -1481,8 +1501,8 @@ void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint
 	rebased_y <<= w->viewport->zoom;
 
 	// Apply offset to the viewport.
-	w->saved_view_x = dest_x + rebased_x;
-	w->saved_view_y = dest_y + rebased_y;
+	w->saved_view_x = dest_x + rebased_x + (offset_x >> w->viewport->zoom);
+	w->saved_view_y = dest_y + rebased_y + (offset_y >> w->viewport->zoom);
 }
 
 void window_zoom_set(rct_window *w, int zoomLevel)
@@ -1494,9 +1514,9 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 		return;
 
 	// Zooming to cursor? Remember where we're pointing at the moment.
-	sint16 saved_map_x, saved_map_y;
+	sint16 saved_map_x, saved_map_y, offset_x, offset_y;
 	if (gConfigGeneral.zoom_to_cursor) {
-		window_viewport_get_map_coords_by_cursor(w, &saved_map_x, &saved_map_y);
+		window_viewport_get_map_coords_by_cursor(w, &saved_map_x, &saved_map_y, &offset_x, &offset_y);
 	}
 
 	// Zoom in
@@ -1519,7 +1539,7 @@ void window_zoom_set(rct_window *w, int zoomLevel)
 
 	// Zooming to cursor? Centre around the tile we were hovering over just now.
 	if (gConfigGeneral.zoom_to_cursor) {
-		window_viewport_centre_tile_around_cursor(w, saved_map_x, saved_map_y);
+		window_viewport_centre_tile_around_cursor(w, saved_map_x, saved_map_y, offset_x, offset_y);
 	}
 
 	// HACK: Prevents the redraw from failing when there is
diff --git a/src/interface/window.h b/src/interface/window.h
index 2774060d88..1802060697 100644
--- a/src/interface/window.h
+++ b/src/interface/window.h
@@ -574,8 +574,8 @@ rct_window *window_get_main();
 void window_scroll_to_viewport(rct_window *w);
 void window_scroll_to_location(rct_window *w, int x, int y, int z);
 void window_rotate_camera(rct_window *w, int direction);
-void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y);
-void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y);
+void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y, sint16 *offset_x, sint16 *offset_y);
+void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y, sint16 offset_x, sint16 offset_y);
 void window_zoom_set(rct_window *w, int zoomLevel);
 void window_zoom_in(rct_window *w);
 void window_zoom_out(rct_window *w);

From 29b0b4885ea733535a75c47bdc00cc43370f0c98 Mon Sep 17 00:00:00 2001
From: Aaron van Geffen <aaron@aaronweb.net>
Date: Sat, 30 Jul 2016 21:42:21 +0200
Subject: [PATCH 10/10] Reduce code verbosity.

This introduces the function `platform_get_cursor_position_scaled` as a common means of getting the cursor position compensated for window scaling.
---
 src/interface/window.c  | 43 +++++++++++++----------------------------
 src/platform/platform.h |  1 +
 src/platform/shared.c   |  9 +++++++++
 3 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/src/interface/window.c b/src/interface/window.c
index 39267cc5a2..2fc1a323f7 100644
--- a/src/interface/window.c
+++ b/src/interface/window.c
@@ -1447,13 +1447,11 @@ void window_rotate_camera(rct_window *w, int direction)
 
 void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint16 *map_y, sint16 *offset_x, sint16 *offset_y)
 {
+	// Get mouse position to offset against.
 	int mouse_x, mouse_y;
-	platform_get_cursor_position(&mouse_x, &mouse_y);
-
-	// Compensate for window scaling.
-	mouse_x = (int) ceilf(mouse_x / gConfigGeneral.window_scale);
-	mouse_y = (int) ceilf(mouse_y / gConfigGeneral.window_scale);
+	platform_get_cursor_position_scaled(&mouse_x, &mouse_y);
 
+	// Compute map coordinate by mouse position.
 	get_map_coordinates_from_pos(mouse_x, mouse_y, VIEWPORT_INTERACTION_MASK_NONE, map_x, map_y, NULL, NULL, NULL);
 
 	// Get viewport coordinates centring around the tile.
@@ -1461,20 +1459,13 @@ void window_viewport_get_map_coords_by_cursor(rct_window *w, sint16 *map_x, sint
 	int dest_x, dest_y;
 	center_2d_coordinates(*map_x, *map_y, base_height, &dest_x, &dest_y, w->viewport);
 
-	// Rebase mouse position onto centre of window.
-	int rebased_x = (w->width >> 1) - mouse_x,
-		rebased_y = (w->height >> 1) - mouse_y;
+	// Rebase mouse position onto centre of window, and compensate for zoom level.
+	int rebased_x = ((w->width >> 1) - mouse_x) << w->viewport->zoom,
+		rebased_y = ((w->height >> 1) - mouse_y) << w->viewport->zoom;
 
-	// Compensate for zoom level.
-	rebased_x <<= w->viewport->zoom;
-	rebased_y <<= w->viewport->zoom;
-
-	// Apply offset to the viewport.
-	int new_x = dest_x + rebased_x,
-		new_y = dest_y + rebased_y;
-
-	*offset_x = (w->saved_view_x - new_x) << w->viewport->zoom,
-	*offset_y = (w->saved_view_y - new_y) << w->viewport->zoom;
+	// Compute cursor offset relative to tile.
+	*offset_x = (w->saved_view_x - (dest_x + rebased_x)) << w->viewport->zoom;
+	*offset_y = (w->saved_view_y - (dest_y + rebased_y)) << w->viewport->zoom;
 }
 
 void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint16 map_y, sint16 offset_x, sint16 offset_y)
@@ -1486,19 +1477,11 @@ void window_viewport_centre_tile_around_cursor(rct_window *w, sint16 map_x, sint
 
 	// Get mouse position to offset against.
 	int mouse_x, mouse_y;
-	platform_get_cursor_position(&mouse_x, &mouse_y);
+	platform_get_cursor_position_scaled(&mouse_x, &mouse_y);
 
-	// Compensate for window scaling.
-	mouse_x = (int) ceilf(mouse_x / gConfigGeneral.window_scale);
-	mouse_y = (int) ceilf(mouse_y / gConfigGeneral.window_scale);
-
-	// Rebase mouse position onto centre of window.
-	int rebased_x = (w->width >> 1) - mouse_x,
-		rebased_y = (w->height >> 1) - mouse_y;
-
-	// Compensate for zoom level.
-	rebased_x <<= w->viewport->zoom;
-	rebased_y <<= w->viewport->zoom;
+	// Rebase mouse position onto centre of window, and compensate for zoom level.
+	int rebased_x = ((w->width >> 1) - mouse_x) << w->viewport->zoom,
+		rebased_y = ((w->height >> 1) - mouse_y) << w->viewport->zoom;
 
 	// Apply offset to the viewport.
 	w->saved_view_x = dest_x + rebased_x + (offset_x >> w->viewport->zoom);
diff --git a/src/platform/platform.h b/src/platform/platform.h
index c85e1ec33d..88ad8d3bf9 100644
--- a/src/platform/platform.h
+++ b/src/platform/platform.h
@@ -166,6 +166,7 @@ bool platform_file_delete(const utf8 *path);
 void platform_hide_cursor();
 void platform_show_cursor();
 void platform_get_cursor_position(int *x, int *y);
+void platform_get_cursor_position_scaled(int *x, int *y);
 void platform_set_cursor_position(int x, int y);
 unsigned int platform_get_ticks();
 void platform_resolve_user_data_path();
diff --git a/src/platform/shared.c b/src/platform/shared.c
index 83f28719b4..50eccbf2e0 100644
--- a/src/platform/shared.c
+++ b/src/platform/shared.c
@@ -783,6 +783,15 @@ void platform_get_cursor_position(int *x, int *y)
 	SDL_GetMouseState(x, y);
 }
 
+void platform_get_cursor_position_scaled(int *x, int *y)
+{
+	platform_get_cursor_position(x, y);
+
+	// Compensate for window scaling.
+	*x = (int) ceilf(*x / gConfigGeneral.window_scale);
+	*y = (int) ceilf(*y / gConfigGeneral.window_scale);
+}
+
 void platform_set_cursor_position(int x, int y)
 {
 	SDL_WarpMouseInWindow(NULL, x, y);