core/colorquant: add imageRect option for cropping image

changelog/next.md

@@ -29,6 +29,7 @@ set shell id.
 - Added generic WindowManager interface implementing ext-workspace.
 - Added ext-background-effect window blur support.
 - Added per-corner radius support to Region.
+- Added ColorQuantizer region selection.
 
 ## Other Changes
 

src/core/colorquantizer.cpp

@@ -13,6 +13,7 @@
 #include <qnumeric.h>
 #include <qobject.h>
 #include <qqmllist.h>
+#include <qrect.h>
 #include <qrgb.h>
 #include <qthreadpool.h>
 #include <qtmetamacros.h>
@@ -24,9 +25,15 @@ namespace {
 QS_LOGGING_CATEGORY(logColorQuantizer, "quickshell.colorquantizer", QtWarningMsg);
 }
 
-ColorQuantizerOperation::ColorQuantizerOperation(QUrl* source, qreal depth, qreal rescaleSize)
+ColorQuantizerOperation::ColorQuantizerOperation(
+    QUrl* source,
+    qreal depth,
+    QRect imageRect,
+    qreal rescaleSize
+)
     : source(source)
     , maxDepth(depth)
+    , imageRect(imageRect)
     , rescaleSize(rescaleSize) {
 	this->setAutoDelete(false);
 }
@@ -37,6 +44,11 @@ void ColorQuantizerOperation::quantizeImage(const QAtomicInteger<bool>& shouldCa
 	this->colors.clear();
 
 	auto image = QImage(this->source->toLocalFile());
+
+	if (this->imageRect.isValid()) {
+		image = image.copy(this->imageRect);
+	}
+
 	if ((image.width() > this->rescaleSize || image.height() > this->rescaleSize)
 	    && this->rescaleSize > 0)
 	{
@@ -198,16 +210,27 @@ void ColorQuantizer::setDepth(qreal depth) {
 		this->mDepth = depth;
 		emit this->depthChanged();
 
-		if (this->componentCompleted) this->quantizeAsync();
+		if (this->componentCompleted && !this->mSource.isEmpty()) this->quantizeAsync();
+	}
+}
+
+void ColorQuantizer::setImageRect(QRect imageRect) {
+	if (this->mImageRect != imageRect) {
+		this->mImageRect = imageRect;
+		emit this->imageRectChanged();
+
+		if (this->componentCompleted && !this->mSource.isEmpty()) this->quantizeAsync();
 	}
 }
 
+void ColorQuantizer::resetImageRect() { this->setImageRect(QRect()); }
+
 void ColorQuantizer::setRescaleSize(int rescaleSize) {
 	if (this->mRescaleSize != rescaleSize) {
 		this->mRescaleSize = rescaleSize;
 		emit this->rescaleSizeChanged();
 
-		if (this->componentCompleted) this->quantizeAsync();
+		if (this->componentCompleted && !this->mSource.isEmpty()) this->quantizeAsync();
 	}
 }
 
@@ -221,8 +244,13 @@ void ColorQuantizer::quantizeAsync() {
 	if (this->liveOperation) this->cancelAsync();
 
 	qCDebug(logColorQuantizer) << "Starting color quantization asynchronously";
-	this->liveOperation =
-	    new ColorQuantizerOperation(&this->mSource, this->mDepth, this->mRescaleSize);
+
+	this->liveOperation = new ColorQuantizerOperation(
+	    &this->mSource,
+	    this->mDepth,
+	    this->mImageRect,
+	    this->mRescaleSize
+	);
 
 	QObject::connect(
 	    this->liveOperation,

src/core/colorquantizer.hpp

@@ -5,6 +5,7 @@
 #include <qproperty.h>
 #include <qqmlintegration.h>
 #include <qqmlparserstatus.h>
+#include <qrect.h>
 #include <qrunnable.h>
 #include <qtmetamacros.h>
 #include <qtypes.h>
@@ -16,7 +17,7 @@ class ColorQuantizerOperation
 	Q_OBJECT;
 
 public:
-	explicit ColorQuantizerOperation(QUrl* source, qreal depth, qreal rescaleSize);
+	explicit ColorQuantizerOperation(QUrl* source, qreal depth, QRect imageRect, qreal rescaleSize);
 
 	void run() override;
 	void tryCancel();
@@ -44,6 +45,7 @@ private slots:
 	QList<QColor> colors;
 	QUrl* source;
 	qreal maxDepth;
+	QRect imageRect;
 	qreal rescaleSize;
 };
 
@@ -78,6 +80,13 @@ class ColorQuantizer
 	/// binary split of the color space
 	Q_PROPERTY(qreal depth READ depth WRITE setDepth NOTIFY depthChanged);
 
+	// clang-format off
+	/// Rectangle that the source image is cropped to.
+	///
+	/// Can be set to `undefined` to reset.
+	Q_PROPERTY(QRect imageRect READ imageRect WRITE setImageRect RESET resetImageRect NOTIFY imageRectChanged);
+	// clang-format on
+
 	/// The size to rescale the image to, when rescaleSize is 0 then no scaling will be done.
 	/// > [!NOTE] Results from color quantization doesn't suffer much when rescaling, it's
 	/// > reccommended to rescale, otherwise the quantization process will take much longer.
@@ -97,13 +106,18 @@ class ColorQuantizer
 	[[nodiscard]] qreal depth() const { return this->mDepth; }
 	void setDepth(qreal depth);
 
+	[[nodiscard]] QRect imageRect() const { return this->mImageRect; }
+	void setImageRect(QRect imageRect);
+	void resetImageRect();
+
 	[[nodiscard]] qreal rescaleSize() const { return this->mRescaleSize; }
 	void setRescaleSize(int rescaleSize);
 
 signals:
 	void colorsChanged();
 	void sourceChanged();
 	void depthChanged();
+	void imageRectChanged();
 	void rescaleSizeChanged();
 
 public slots:
@@ -117,6 +131,7 @@ public slots:
 	ColorQuantizerOperation* liveOperation = nullptr;
 	QUrl mSource;
 	qreal mDepth = 0;
+	QRect mImageRect;
 	qreal mRescaleSize = 0;
 
 	Q_OBJECT_BINDABLE_PROPERTY(