Permit scrollbars to be styled

doc/lua_api.md

@@ -3424,7 +3424,8 @@ Elements
       units the thumb spans out of the range of the scrollbar values.
     * Example: If a scrollbar has a `min` of 1 and a `max` of 100, a thumbsize of 10
       would span a tenth of the scrollbar space.
-    * If this is set to zero or less, the value will be reset to `1`.
+    * If set to less than zero, the value will be reset to `1`.
+    * If set to zero, the thumb size will be the same as the thickness of the scrollbar (i.e. the thumb will always be a square).
 * `arrows=<show/hide/default>`
     * Whether to show the arrow buttons on the scrollbar. `default` hides the arrows
       when the scrollbar gets too small, but shows them otherwise.
@@ -3634,6 +3635,23 @@ Some types may inherit styles from parent types.
 * textlist
 * vertlabel, inherits from label
 
+### Pseudo-Elements
+
+Certain elements, like scrollbars, can create implicit pseudo-elements of different types.
+These pseudo-elements may be styled either with the appropriate `style_type` rule or with
+an ordinary `style` rule. In the latter case, the pseudo-element's name is its parent's
+name suffixed with `.` and the pseudo-element's identifier (e.g. `myscrollbar.up`). If
+a pseudo-element is of a type that creates its own pseudo-elements, those pseudo-elements
+are named in the same way, e.g. `mytextarea.scrollbar.up`.
+
+Current pseudo-elements (by parent type):
+
+* scrollbar
+    * `.up` (image_button): The up (or right) arrow button of the scrollbar, if arrows are enabled.
+    * `.down` (image_button): The down (or left) arrow button of the scrollbar, if arrows are enabled.
+* textarea, hypertext, textlist, table
+    * `.scrollbar` (scrollbar): The implicit scrollbar created when the contents of the element
+      overflow its bounds.
 
 ### Valid Properties
 
@@ -3730,6 +3748,19 @@ Some types may inherit styles from parent types.
     * sound - a sound to be played when triggered.
 * scrollbar
     * noclip - boolean, set to true to allow the element to exceed formspec bounds.
+    * border - boolean, set to false to hide the default track and thumb. Defaults to true.
+    * bgcolor - color, sets the scrollbar's tint.
+    * bgimg - The background image of the scrollbar's track.
+    * bgimg_middle - Makes the bgimg render in 9-sliced mode and defines the middle rect.
+    * fgimg - The image of the scrollbar's thumb. Note: If `fgimg_middle` is not specified, this
+      will implicitly behave as if `thumbsize=0` were set.
+    * fgimg_middle - Makes the fgimg render in 9-sliced mode and defines the middle rect.
+        * Note that if this is not specified, the scrollbar thumb will not be stretched
+          to reflect the size of the scrollbar's range, equivalently to the `thumbsize=0`
+          scrollbar option.
+    * padding - rect. The space, in pixels, with which to pad the scrollbar's track background.
+    * size - integer, sets the thickness (in pixels) of implicit scrollbars (those attached to
+      `hypertext[]` or `textarea[]` elements).
 * tabheader
     * noclip - boolean, set to true to allow the element to exceed formspec bounds.
     * sound - a sound to be played when a different tab is selected.

src/gui/guiEditBoxWithScrollbar.cpp

@@ -79,9 +79,11 @@ void GUIEditBoxWithScrollBar::createVScrollBar()
 
 	core::rect<s32> scrollbarrect = RelativeRect;
 	scrollbarrect.UpperLeftCorner.X += RelativeRect.getWidth() - VScrollBarWidth;
-	VScrollBar = new GUIScrollBar(Environment, getParent(), -1,
+	m_vscrollbar = new GUIScrollBar(Environment, getParent(), -1,
 			scrollbarrect, false, true, m_tsrc);
 
+	VScrollBar = m_vscrollbar;
+
 	VScrollBar->setVisible(false);
 	VScrollBar->setSmallStep(3 * fontHeight);
 	VScrollBar->setLargeStep(10 * fontHeight);
@@ -93,3 +95,18 @@ void GUIEditBoxWithScrollBar::setBackgroundColor(const video::SColor &bg_color)
 	m_bg_color = bg_color;
 	m_bg_color_used = true;
 }
+
+void GUIEditBoxWithScrollBar::setScrollbarStyle(
+		const std::array<StyleSpec, StyleSpec::NUM_STATES>& styles,
+		const std::array<StyleSpec, StyleSpec::NUM_STATES>& up_arrow_styles,
+		const std::array<StyleSpec, StyleSpec::NUM_STATES>& down_arrow_styles)
+{
+	if (styles[StyleSpec::STATE_DEFAULT].isNotDefault(StyleSpec::SIZE)) {
+		VScrollBarWidth = styles[StyleSpec::STATE_DEFAULT].getIntArray(StyleSpec::SIZE, {0, 0, 0, 0})[0];
+
+		core::rect<s32> scrollbarrect = RelativeRect;
+		scrollbarrect.UpperLeftCorner.X += RelativeRect.getWidth() - VScrollBarWidth;
+		VScrollBar->setRelativePosition(scrollbarrect);
+	}
+	m_vscrollbar->setStyles(styles, up_arrow_styles, down_arrow_styles);
+}

src/gui/guiEditBoxWithScrollbar.h

@@ -6,6 +6,8 @@
 #define GUIEDITBOXWITHSCROLLBAR_HEADER
 
 #include "CGUIEditBox.h"
+#include "StyleSpec.h"
+#include "guiScrollBar.h"
 
 class ISimpleTextureSource;
 
@@ -27,10 +29,16 @@ class GUIEditBoxWithScrollBar : public gui::CGUIEditBox
 	//! Change the background color
 	void setBackgroundColor(const video::SColor &bg_color);
 
+	void setScrollbarStyle(const std::array<StyleSpec, StyleSpec::NUM_STATES>& styles,
+			const std::array<StyleSpec, StyleSpec::NUM_STATES>& up_arrow_styles,
+			const std::array<StyleSpec, StyleSpec::NUM_STATES>& down_arrow_styles);
+
 protected:
 	//! create a Vertical ScrollBar
 	void createVScrollBar();
 
+	GUIScrollBar* m_vscrollbar;
+
 	bool m_bg_color_used;
 	video::SColor m_bg_color;
 

src/gui/guiFormSpecMenu.cpp

@@ -683,8 +683,14 @@ void GUIFormSpecMenu::parseScrollBar(parserData* data, const std::string &elemen
 	GUIScrollBar *e = new GUIScrollBar(Environment, data->current_parent,
 			spec.fid, rect, is_horizontal, true, m_tsrc);
 
-	auto style = getDefaultStyleForElement("scrollbar", name);
-	e->setNotClipped(style.getBool(StyleSpec::NOCLIP, false));
+	auto style = getStyleForElement("scrollbar", name);
+	// FIXME: There's no way to access the GUIFormSpecMenu instance from the element class,
+	// so we are compelled to look up styling information for the arrow buttons here
+	// and pass it down.
+	auto up_arrow_style = getStyleForElement("button", name + ".up");
+	auto down_arrow_style = getStyleForElement("button", name + ".down");
+	e->setNotClipped(style[StyleSpec::STATE_DEFAULT].getBool(StyleSpec::NOCLIP, false));
+	e->setStyles(style, up_arrow_style, down_arrow_style);
 	e->setArrowsVisible(data->scrollbar_options.arrow_visiblity);
 
 	s32 max = data->scrollbar_options.max;
@@ -702,7 +708,10 @@ void GUIFormSpecMenu::parseScrollBar(parserData* data, const std::string &elemen
 
 	s32 scrollbar_size = is_horizontal ? dim.X : dim.Y;
 
-	e->setPageSize(scrollbar_size * (max - min + 1) / data->scrollbar_options.thumb_size);
+	if (data->scrollbar_options.thumb_size == 0)
+		e->setPageSize(S32_MAX);
+	else
+		e->setPageSize(scrollbar_size * (max - min + 1) / data->scrollbar_options.thumb_size);
 
 	if (spec.fname == m_focused_element) {
 		Environment->setFocus(e);
@@ -747,7 +756,7 @@ void GUIFormSpecMenu::parseScrollBarOptions(parserData* data, const std::string
 			continue;
 		} else if (options[0] == "thumbsize") {
 			int value = stoi(options[1]);
-			data->scrollbar_options.thumb_size = value <= 0 ? 1 : value;
+			data->scrollbar_options.thumb_size = value < 0 ? 1 : value;
 			continue;
 		} else if (options[0] == "arrows") {
 			auto value = trim(options[1]);
@@ -1234,6 +1243,11 @@ void GUIFormSpecMenu::parseTable(parserData* data, const std::string &element)
 	GUITable *e = new GUITable(Environment, data->current_parent, spec.fid,
 			rect, m_tsrc);
 
+	auto scrollbar_style = getStyleForElement("scrollbar", spec.fname + ".scrollbar");
+	auto up_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.up");
+	auto down_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.down");
+	e->setScrollbarStyle(scrollbar_style, up_arrow_styles, down_arrow_styles);
+
 	// Apply styling before calculating the cell sizes
 	auto style = getDefaultStyleForElement("table", name);
 	e->setNotClipped(style.getBool(StyleSpec::NOCLIP, false));
@@ -1311,6 +1325,11 @@ void GUIFormSpecMenu::parseTextList(parserData* data, const std::string &element
 	GUITable *e = new GUITable(Environment, data->current_parent, spec.fid,
 			rect, m_tsrc);
 
+	auto scrollbar_style = getStyleForElement("scrollbar", spec.fname + ".scrollbar");
+	auto up_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.up");
+	auto down_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.down");
+	e->setScrollbarStyle(scrollbar_style, up_arrow_styles, down_arrow_styles);
+
 	if (spec.fname == m_focused_element) {
 		Environment->setFocus(e);
 	}
@@ -1535,8 +1554,13 @@ void GUIFormSpecMenu::createTextField(parserData *data, FieldSpec &spec,
 
 	gui::IGUIEditBox *e = nullptr;
 	if (is_multiline) {
-		e = new GUIEditBoxWithScrollBar(spec.fdefault.c_str(), true, Environment,
+		auto textarea = new GUIEditBoxWithScrollBar(spec.fdefault.c_str(), true, Environment,
 				data->current_parent, spec.fid, rect, m_tsrc, is_editable, true);
+		auto scrollbar_style = getStyleForElement("scrollbar", spec.fname + ".scrollbar");
+		auto up_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.up");
+		auto down_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.down");
+		textarea->setScrollbarStyle(scrollbar_style, up_arrow_styles, down_arrow_styles);
+		e = textarea;
 	} else if (is_editable) {
 		e = Environment->addEditBox(spec.fdefault.c_str(), rect, true,
 				data->current_parent, spec.fid);
@@ -1760,6 +1784,11 @@ void GUIFormSpecMenu::parseHyperText(parserData *data, const std::string &elemen
 			data->current_parent, spec.fid, rect, m_client, m_tsrc);
 	e->drop();
 
+	auto scrollbar_style = getStyleForElement("scrollbar", spec.fname + ".scrollbar");
+	auto up_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.up");
+	auto down_arrow_styles = getStyleForElement("button", spec.fname + ".scrollbar.down");
+	e->setScrollbarStyle(scrollbar_style, up_arrow_styles, down_arrow_styles);
+
 	m_fields.push_back(spec);
 }
 

src/gui/guiHyperText.cpp

@@ -1176,3 +1176,19 @@ void GUIHyperText::draw()
 	// draw children
 	IGUIElement::draw();
 }
+
+void GUIHyperText::setScrollbarStyle(
+		const std::array<StyleSpec, StyleSpec::NUM_STATES>& styles,
+		const std::array<StyleSpec, StyleSpec::NUM_STATES>& up_arrow_styles,
+		const std::array<StyleSpec, StyleSpec::NUM_STATES>& down_arrow_styles)
+{
+	if (styles[StyleSpec::STATE_DEFAULT].isNotDefault(StyleSpec::SIZE)) {
+		m_scrollbar_width = styles[StyleSpec::STATE_DEFAULT].getIntArray(StyleSpec::SIZE, {0, 0, 0, 0})[0];
+
+		core::rect<s32> rect = core::rect<s32>(
+				RelativeRect.getWidth() - m_scrollbar_width, 0,
+				RelativeRect.getWidth(), RelativeRect.getHeight());
+		m_vscrollbar->setRelativePosition(rect);
+	}
+	m_vscrollbar->setStyles(styles, up_arrow_styles, down_arrow_styles);
+}

src/gui/guiHyperText.h

@@ -11,6 +11,7 @@
 #include <IGUIElement.h>
 #include <IGUIEnvironment.h>
 #include "irr_v3d.h"
+#include "StyleSpec.h"
 
 
 class ISimpleTextureSource;
@@ -201,14 +202,18 @@ class GUIHyperText : public gui::IGUIElement
 
 	bool OnEvent(const SEvent &event);
 
+	void setScrollbarStyle(const std::array<StyleSpec, StyleSpec::NUM_STATES>& styles,
+			const std::array<StyleSpec, StyleSpec::NUM_STATES>& up_arrow_styles,
+			const std::array<StyleSpec, StyleSpec::NUM_STATES>& down_arrow_styles);
+
 protected:
 	// GUI members
 	ISimpleTextureSource *m_tsrc;
 	GUIScrollBar *m_vscrollbar;
 	TextDrawer m_drawer;
 
 	// Positioning
-	u32 m_scrollbar_width;
+	u32 m_scrollbar_width = 0;
 	core::rect<s32> m_display_text_rect;
 	core::position2d<s32> m_text_scrollpos;