widgets: add ClippingRectangle

src/widgets/CMakeLists.txt

@@ -1,10 +1,28 @@
-qt_add_library(quickshell-widgets STATIC)
+qt_add_library(quickshell-widgets STATIC
+	cliprect.cpp
+)
 
 qt_add_qml_module(quickshell-widgets
 	URI Quickshell.Widgets
 	VERSION 0.1
 	QML_FILES
 		IconImage.qml
+		ClippingRectangle.qml
+)
+
+qt6_add_shaders(quickshell-widgets "widgets-cliprect"
+	NOHLSL NOMSL BATCHABLE PRECOMPILE OPTIMIZED QUIET
+	PREFIX "/Quickshell/Widgets"
+	FILES shaders/cliprect.frag
+	OUTPUTS shaders/cliprect.frag.qsb
+)
+
+qt6_add_shaders(quickshell-widgets "widgets-cliprect-ub"
+	NOHLSL NOMSL BATCHABLE PRECOMPILE OPTIMIZED QUIET
+	PREFIX "/Quickshell/Widgets"
+	FILES shaders/cliprect.frag
+	OUTPUTS shaders/cliprect-ub.frag.qsb
+	DEFINES CONTENT_UNDER_BORDER
 )
 
 install_qml_module(quickshell-widgets)

src/widgets/ClippingRectangle.qml

@@ -0,0 +1,82 @@
+import QtQuick
+
+///! Rectangle capable of clipping content inside its border.
+/// > [!WARNING] This type requires at least Qt 6.7.
+///
+/// This is a specialized version of @@QtQuick.Rectangle that clips content
+/// inside of its border, including rounded rectangles. It costs more than
+/// @@QtQuick.Rectangle, so it should not be used unless you need to clip
+/// items inside of it to the border.
+Item {
+	id: root
+
+	/// If content should be displayed underneath the border.
+	///
+	/// Defaults to false, does nothing if the border is opaque.
+	property bool contentUnderBorder: false;
+	/// If the content item should be resized to fit inside the border.
+	///
+	/// Defaults to `!contentUnderBorder`. Most useful when combined with
+	/// `anchors.fill: parent` on an item passed to the ClippingRectangle.
+	property bool contentInsideBorder: !root.contentUnderBorder;
+	/// If the rectangle should be antialiased.
+	///
+	/// Defaults to true if any corner has a non-zero radius, otherwise false.
+	property /*bool*/alias antialiasing: rectangle.antialiasing;
+	/// The background color of the rectangle, which goes under its content.
+	property /*color*/alias color: shader.backgroundColor;
+	/// See @@QtQuick.Rectangle.border.
+	property clippingRectangleBorder border;
+	/// Radius of all corners. Defaults to 0.
+	property /*real*/alias radius: rectangle.radius
+	/// Radius of the top left corner. Defaults to @@radius.
+	property /*real*/alias topLeftRadius: rectangle.topLeftRadius
+	/// Radius of the top right corner. Defaults to @@radius.
+	property /*real*/alias topRightRadius: rectangle.topRightRadius
+	/// Radius of the bottom left corner. Defaults to @@radius.
+	property /*real*/alias bottomLeftRadius: rectangle.bottomLeftRadius
+	/// Radius of the bottom right corner. Defaults to @@radius.
+	property /*real*/alias borromRightRadius: rectangle.bottomRightRadius
+
+	/// Visual children of the ClippingRectangle's @@contentItem. (`list<Item>`).
+	///
+	/// See @@QtQuick.Item.children for details.
+	default property alias children: contentItem.children;
+	/// The item containing the rectangle's content.
+	/// There is usually no reason to use this directly.
+	readonly property alias contentItem: contentItem;
+
+	Rectangle {
+		id: rectangle
+		anchors.fill: root
+		color: "#ffff0000"
+		border.color: "#ff00ff00"
+		border.pixelAligned: root.border.pixelAligned
+		border.width: root.border.width
+		layer.enabled: true
+		visible: false
+	}
+
+	Item {
+		id: contentItemContainer
+		anchors.fill: root
+		layer.enabled: true
+		visible: false
+
+		Item {
+			id: contentItem
+			anchors.fill: parent
+			anchors.margins: root.contentInsideBorder ? root.border.width : 0
+		}
+	}
+
+	ShaderEffect {
+		id: shader
+		anchors.fill: root
+		fragmentShader: `qrc:/Quickshell/Widgets/shaders/cliprect${root.contentUnderBorder ? "-ub" : ""}.frag.qsb`
+		property Rectangle rect: rectangle;
+		property color backgroundColor;
+		property color borderColor: root.border.color;
+		property Item content: contentItemContainer;
+	}
+}

src/widgets/cliprect.cpp

@@ -0,0 +1 @@
+#include "cliprect.hpp" // NOLINT

src/widgets/cliprect.hpp

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <qcolor.h>
+#include <qmetaobject.h>
+#include <qnamespace.h>
+#include <qqmlintegration.h>
+#include <qtmetamacros.h>
+
+class ClippingRectangleBorder {
+	Q_GADGET;
+	Q_PROPERTY(QColor color MEMBER color);
+	Q_PROPERTY(bool pixelAligned MEMBER pixelAligned);
+	Q_PROPERTY(int width MEMBER width);
+	QML_VALUE_TYPE(clippingRectangleBorder);
+
+public:
+	QColor color = Qt::black;
+	bool pixelAligned = true;
+	int width = 0;
+};

src/widgets/module.md

@@ -2,5 +2,6 @@ name = "Quickshell.Widgets"
 description = "Bundled widgets"
 qml_files = [
 	"IconImage.qml",
+	"ClippingRectangle.qml",
 ]
 -----

src/widgets/shaders/cliprect.frag

@@ -0,0 +1,40 @@
+#version 440
+layout(location = 0) in vec2 qt_TexCoord0;
+layout(location = 0) out vec4 fragColor;
+
+layout(std140, binding = 0) uniform buf {
+	mat4 qt_Matrix;
+	float qt_Opacity;
+	vec4 backgroundColor;
+	vec4 borderColor;
+};
+
+layout(binding = 1) uniform sampler2D rect;
+layout(binding = 2) uniform sampler2D content;
+
+vec4 overlay(vec4 base, vec4 overlay) {
+	if (overlay.a == 0.0) return base;
+
+	float baseMul = 1.0 - overlay.a;
+	float newAlpha = overlay.a + base.a * baseMul;
+	vec3 rgb = (overlay.rgb * overlay.a + base.rgb * base.a * baseMul) / newAlpha;
+	return vec4(rgb, newAlpha);
+}
+
+void main() {
+	vec4 contentColor = texture(content, qt_TexCoord0.xy);
+	vec4 rectColor = texture(rect, qt_TexCoord0.xy);
+
+#ifdef CONTENT_UNDER_BORDER
+	float contentAlpha = rectColor.a;
+#else
+	float contentAlpha = rectColor.r;
+#endif
+
+	float borderAlpha = rectColor.g;
+
+	vec4 innerColor = overlay(backgroundColor, contentColor) * contentAlpha;
+	vec4 borderColor = borderColor * borderAlpha;
+
+	fragColor = (innerColor * (1.0 - borderColor.a) + borderColor) * qt_Opacity;
+}