Android: Improve UI scaling on smaller high-density displays (#7834)

* Android: Improve UI scaling on smaller high-density displays

builtin/mainmenu/tab_settings.lua

@@ -237,9 +237,10 @@ local function formspec(tabview, name, tabdata)
 
 	if core.settings:get("touchscreen_threshold") ~= nil then
 		tab_string = tab_string ..
-			"label[4.3,4.1;" .. fgettext("Touchthreshold (px)") .. "]" ..
-			"dropdown[3.85,4.55;3.85;dd_touchthreshold;0,10,20,30,40,50;" ..
-			((tonumber(core.settings:get("touchscreen_threshold")) / 10) + 1) .. "]"
+			"label[4.3,4.2;" .. fgettext("Touchthreshold: (px)") .. "]" ..
+			"dropdown[4.25,4.65;3.5;dd_touchthreshold;0,10,20,30,40,50;" ..
+			((tonumber(core.settings:get("touchscreen_threshold")) / 10) + 1) ..
+			"]box[4.0,4.5;3.75,1.0;#999999]"
 	end
 
 	if shaders_enabled then

src/client/clientlauncher.cpp

@@ -38,6 +38,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #if USE_SOUND
 	#include "sound_openal.h"
 #endif
+#ifdef __ANDROID__
+	#include "porting.h"
+#endif
 
 /* mainmenumanager.h
  */
@@ -127,7 +130,30 @@ bool ClientLauncher::run(GameParams &game_params, const Settings &cmd_args)
 	skin->setColor(gui::EGDC_3D_SHADOW, video::SColor(255, 0, 0, 0));
 	skin->setColor(gui::EGDC_HIGH_LIGHT, video::SColor(255, 70, 120, 50));
 	skin->setColor(gui::EGDC_HIGH_LIGHT_TEXT, video::SColor(255, 255, 255, 255));
-
+#ifdef __ANDROID__
+	float density = porting::getDisplayDensity();
+	skin->setSize(gui::EGDS_CHECK_BOX_WIDTH, (s32)(17.0f * density));
+	skin->setSize(gui::EGDS_SCROLLBAR_SIZE, (s32)(14.0f * density));
+	skin->setSize(gui::EGDS_WINDOW_BUTTON_WIDTH, (s32)(15.0f * density));
+	if (density > 1.5f) {
+		std::string sprite_path = porting::path_user + "/textures/base/pack/";
+		if (density > 3.5f)
+			sprite_path.append("checkbox_64.png");
+		else if (density > 2.0f)
+			sprite_path.append("checkbox_32.png");
+		else
+			sprite_path.append("checkbox_16.png");
+		// Texture dimensions should be a power of 2
+		gui::IGUISpriteBank *sprites = skin->getSpriteBank();
+		video::IVideoDriver *driver = RenderingEngine::get_video_driver();
+		video::ITexture *sprite_texture = driver->getTexture(sprite_path.c_str());
+		if (sprite_texture) {
+			s32 sprite_id = sprites->addTextureAsSprite(sprite_texture);
+			if (sprite_id != -1)
+				skin->setIcon(gui::EGDI_CHECK_BOX_CHECKED, sprite_id);
+		}
+	}
+#endif
 	g_fontengine = new FontEngine(g_settings, guienv);
 	FATAL_ERROR_IF(g_fontengine == NULL, "Font engine creation failed.");
 

src/gui/guiFormSpecMenu.cpp

@@ -284,12 +284,13 @@ void GUIFormSpecMenu::parseSize(parserData* data, const std::string &element)
 		data->invsize.Y = MYMAX(0, stof(parts[1]));
 
 		lockSize(false);
+#ifndef __ANDROID__
 		if (parts.size() == 3) {
 			if (parts[2] == "true") {
 				lockSize(true,v2u32(800,600));
 			}
 		}
-
+#endif
 		data->explicit_size = true;
 		return;
 	}
@@ -437,10 +438,11 @@ void GUIFormSpecMenu::parseCheckbox(parserData* data, const std::string &element
 			fselected = true;
 
 		std::wstring wlabel = translate_string(utf8_to_wide(unescape_string(label)));
+		s32 spacing = Environment->getSkin()->getSize(gui::EGDS_CHECK_BOX_WIDTH) + 7;
 
 		core::rect<s32> rect = core::rect<s32>(
 				pos.X, pos.Y + ((imgsize.Y / 2) - m_btn_height),
-				pos.X + m_font->getDimension(wlabel.c_str()).Width + 25, // text size + size of checkbox
+				pos.X + m_font->getDimension(wlabel.c_str()).Width + spacing,
 				pos.Y + ((imgsize.Y / 2) + m_btn_height));
 
 		FieldSpec spec(
@@ -2145,8 +2147,19 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 			// the image size can't be less than 0.3 inch
 			// multiplied by gui_scaling, even if this means
 			// the form doesn't fit the screen.
-			double prefer_imgsize = mydata.screensize.Y / 15 *
-				gui_scaling;
+#ifdef __ANDROID__
+			// For mobile devices these magic numbers are
+			// different and forms should always use the
+			// maximum screen space available.
+			double prefer_imgsize = mydata.screensize.Y / 10 * gui_scaling;
+			double fitx_imgsize = mydata.screensize.X /
+				((12.0 / 8.0) * (0.5 + mydata.invsize.X));
+			double fity_imgsize = mydata.screensize.Y /
+				((15.0 / 11.0) * (0.85 + mydata.invsize.Y));
+			use_imgsize = MYMIN(prefer_imgsize,
+					MYMIN(fitx_imgsize, fity_imgsize));
+#else
+			double prefer_imgsize = mydata.screensize.Y / 15 * gui_scaling;
 			double fitx_imgsize = mydata.screensize.X /
 				((5.0 / 4.0) * (0.5 + mydata.invsize.X));
 			double fity_imgsize = mydata.screensize.Y /
@@ -2155,6 +2168,7 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 			double min_imgsize = 0.3 * screen_dpi * gui_scaling;
 			use_imgsize = MYMAX(min_imgsize, MYMIN(prefer_imgsize,
 				MYMIN(fitx_imgsize, fity_imgsize)));
+#endif
 		}
 
 		// Everything else is scaled in proportion to the

src/gui/guiTable.cpp

@@ -78,10 +78,12 @@ GUITable::GUITable(gui::IGUIEnvironment *env,
 	setTabStop(true);
 	setTabOrder(-1);
 	updateAbsolutePosition();
-
+	float density = RenderingEngine::getDisplayDensity();
+#ifdef __ANDROID__
+	density = 1; // dp scaling is applied by the skin
+#endif
 	core::rect<s32> relative_rect = m_scrollbar->getRelativePosition();
-	s32 width = (relative_rect.getWidth()/(2.0/3.0)) *
-			RenderingEngine::getDisplayDensity() *
+	s32 width = (relative_rect.getWidth() / (2.0 / 3.0)) * density *
 			g_settings->getFloat("gui_scaling");
 	m_scrollbar->setRelativePosition(core::rect<s32>(
 			relative_rect.LowerRightCorner.X-width,relative_rect.UpperLeftCorner.Y,