Add VirtualWidget, add SequentialLayout

include/app.hpp

@@ -322,7 +322,7 @@ struct MomentarySwitch : virtual Switch {
 // IO widgets
 ////////////////////
 
-struct LedDisplay : Widget {
+struct LedDisplay : VirtualWidget {
 	void draw(NVGcontext *vg) override;
 };
 
@@ -484,7 +484,7 @@ struct Toolbar : OpaqueWidget {
 	void draw(NVGcontext *vg) override;
 };
 
-struct PluginManagerWidget : Widget {
+struct PluginManagerWidget : VirtualWidget {
 	Widget *loginWidget;
 	Widget *manageWidget;
 	Widget *downloadWidget;

include/ui.hpp

@@ -5,15 +5,39 @@
 
 namespace rack {
 
+////////////////////
+// Layouts
+////////////////////
+
+/** Positions children in a row/column based on their widths/heights */
+struct SequentialLayout : virtual Widget {
+	enum Orientation {
+		HORIZONTAL_ORIENTATION,
+		VERTICAL_ORIENTATION,
+	};
+	Orientation orientation = HORIZONTAL_ORIENTATION;
+	enum Alignment {
+		LEFT_ALIGNMENT,
+		CENTER_ALIGNMENT,
+		RIGHT_ALIGNMENT,
+	};
+	Alignment alignment = LEFT_ALIGNMENT;
+	float margin = 0.0;
+	void step() override;
+};
+
+////////////////////
+// Blendish UI elements
+////////////////////
 
-struct Label : Widget {
+struct Label : VirtualWidget {
 	std::string text;
-	enum Align {
-		LEFT_ALIGN,
-		CENTER_ALIGN,
-		RIGHT_ALIGN
+	enum Alignment {
+		LEFT_ALIGNMENT,
+		CENTER_ALIGNMENT,
+		RIGHT_ALIGNMENT,
 	};
-	Align align = LEFT_ALIGN;
+	Alignment alignment = LEFT_ALIGNMENT;
 	Label() {
 		box.size.y = BND_WIDGET_HEIGHT;
 	}
@@ -200,7 +224,7 @@ struct ProgressBar : QuantityWidget {
 	void draw(NVGcontext *vg) override;
 };
 
-struct Tooltip : Widget {
+struct Tooltip : VirtualWidget {
 	void step() override;
 	void draw(NVGcontext *vg) override;
 };

include/widgets.hpp

@@ -44,7 +44,9 @@ struct SVG {
 // Base widget
 ////////////////////
 
-/** A node in the 2D scene graph */
+/** A node in the 2D scene graph
+Never inherit from Widget directly. Instead, inherit from VirtualWidget declared below.
+*/
 struct Widget {
 	/** Stores position and size */
 	Rect box = Rect(Vec(), Vec(INFINITY, INFINITY));
@@ -152,7 +154,11 @@ struct Widget {
 	}
 };
 
-struct TransformWidget : Widget {
+/** Instead of inheriting from Widget directly, inherit from VirtualWidget to guarantee that only one copy of Widget's member variables are used by each instance of the Widget hierarchy.
+*/
+struct VirtualWidget : virtual Widget {};
+
+struct TransformWidget : VirtualWidget {
 	/** The transformation matrix */
 	float transform[6];
 	TransformWidget();
@@ -164,7 +170,7 @@ struct TransformWidget : Widget {
 	void draw(NVGcontext *vg) override;
 };
 
-struct ZoomWidget : Widget {
+struct ZoomWidget : VirtualWidget {
 	float zoom = 1.0;
 	Vec getRelativeOffset(Vec v, Widget *relative) override;
 	Rect getViewport(Rect r) override;
@@ -183,7 +189,7 @@ struct ZoomWidget : Widget {
 ////////////////////
 
 /** Widget that does not respond to events */
-struct TransparentWidget : virtual Widget {
+struct TransparentWidget : VirtualWidget {
 	void onMouseDown(EventMouseDown &e) override {}
 	void onMouseUp(EventMouseUp &e) override {}
 	void onMouseMove(EventMouseMove &e) override {}
@@ -191,7 +197,7 @@ struct TransparentWidget : virtual Widget {
 };
 
 /** Widget that automatically responds to all mouse events but gives a chance for children to respond instead */
-struct OpaqueWidget : virtual Widget {
+struct OpaqueWidget : VirtualWidget {
 	void onMouseDown(EventMouseDown &e) override {
 		Widget::onMouseDown(e);
 		if (!e.target)
@@ -216,7 +222,7 @@ struct OpaqueWidget : virtual Widget {
 	}
 };
 
-struct SpriteWidget : virtual Widget {
+struct SpriteWidget : VirtualWidget {
 	Vec spriteOffset;
 	Vec spriteSize;
 	std::shared_ptr<Image> spriteImage;
@@ -224,7 +230,7 @@ struct SpriteWidget : virtual Widget {
 	void draw(NVGcontext *vg) override;
 };
 
-struct SVGWidget : virtual Widget {
+struct SVGWidget : VirtualWidget {
 	std::shared_ptr<SVG> svg;
 	/** Sets the box size to the svg image size */
 	void wrap();
@@ -237,7 +243,7 @@ struct SVGWidget : virtual Widget {
 When `dirty` is true, its children will be re-rendered on the next call to step() override.
 Events are not passed to the underlying scene.
 */
-struct FramebufferWidget : virtual Widget {
+struct FramebufferWidget : VirtualWidget {
 	/** Set this to true to re-render the children to the framebuffer the next time it is drawn */
 	bool dirty = true;
 	/** A margin in pixels around the children in the framebuffer
@@ -258,7 +264,7 @@ struct FramebufferWidget : virtual Widget {
 };
 
 /** A Widget representing a float value */
-struct QuantityWidget : virtual Widget {
+struct QuantityWidget : VirtualWidget {
 	float value = 0.0;
 	float minValue = 0.0;
 	float maxValue = 1.0;

src/app/ModuleBrowser.cpp

@@ -95,7 +95,7 @@ struct ModelItem : BrowserListItem {
 		nameLabel = Widget::create<Label>(Vec(0, 0));
 		addChild(nameLabel);
 		manufacturerLabel = Widget::create<Label>(Vec(0, 0));
-		manufacturerLabel->align = Label::RIGHT_ALIGN;
+		manufacturerLabel->alignment = Label::RIGHT_ALIGNMENT;
 		addChild(manufacturerLabel);
 		tagsLabel = Widget::create<Label>(Vec(26, BND_WIDGET_HEIGHT));
 		addChild(tagsLabel);

src/ui/Label.cpp

@@ -7,10 +7,10 @@ namespace rack {
 
 void Label::draw(NVGcontext *vg) {
 	float x = 0.0;
-	if (align == RIGHT_ALIGN) {
+	if (alignment == RIGHT_ALIGNMENT) {
 		x = box.size.x - bndLabelWidth(vg, -1, text.c_str());
 	}
-	else if (align == CENTER_ALIGN) {
+	else if (alignment == CENTER_ALIGNMENT) {
 		x = (box.size.x - bndLabelWidth(vg, -1, text.c_str())) / 2.0;
 	}
 

src/ui/layouts.cpp

@@ -0,0 +1,39 @@
+#include "ui.hpp"
+
+
+namespace rack {
+
+
+void SequentialLayout::step() {
+	Widget::step();
+
+	float offset = 0.0;
+	for (Widget *child : children) {
+		if (!child->visible)
+			continue;
+		// Set position
+		(orientation == HORIZONTAL_ORIENTATION ? child->box.pos.x : child->box.pos.y) = offset;
+		// Increment by size
+		offset += (orientation == HORIZONTAL_ORIENTATION ? child->box.size.x : child->box.size.y);
+		offset += margin;
+	}
+
+	// We're done if left aligned
+	if (alignment == LEFT_ALIGNMENT)
+		return;
+
+	// Adjust positions based on width of the layout itself
+	offset -= margin;
+	if (alignment == RIGHT_ALIGNMENT)
+		offset -= (orientation == HORIZONTAL_ORIENTATION ? box.size.x : box.size.y);
+	else if (alignment == CENTER_ALIGNMENT)
+		offset -= (orientation == HORIZONTAL_ORIENTATION ? box.size.x : box.size.y) / 2.0;
+	for (Widget *child : children) {
+		if (!child->visible)
+			continue;
+		(orientation == HORIZONTAL_ORIENTATION ? child->box.pos.x : child->box.pos.y) += offset;
+	}
+}
+
+
+} // namespace rack