core/colorquant: add ColorQuantizer

src/core/colorquantizer.hpp

@@ -0,0 +1,128 @@
+#pragma once
+
+#include <qlist.h>
+#include <qobject.h>
+#include <qproperty.h>
+#include <qqmlintegration.h>
+#include <qqmlparserstatus.h>
+#include <qrunnable.h>
+#include <qtmetamacros.h>
+#include <qtypes.h>
+#include <qurl.h>
+
+class ColorQuantizerOperation
+    : public QObject
+    , public QRunnable {
+	Q_OBJECT;
+
+public:
+	explicit ColorQuantizerOperation(QUrl* source, qreal depth, qreal rescaleSize);
+
+	void run() override;
+	void tryCancel();
+
+signals:
+	void done(QList<QColor> colors);
+
+private slots:
+	void finished();
+
+private:
+	static char findBiggestColorRange(const QList<QColor>& rgbValues);
+
+	void quantizeImage(const QAtomicInteger<bool>& shouldCancel = false);
+
+	QList<QColor> quantization(
+	    QList<QColor>& rgbValues,
+	    qreal depth,
+	    const QAtomicInteger<bool>& shouldCancel = false
+	);
+
+	void finishRun();
+
+	QAtomicInteger<bool> shouldCancel = false;
+	QList<QColor> colors;
+	QUrl* source;
+	qreal maxDepth;
+	qreal rescaleSize;
+};
+
+///! Color Quantization Utility
+/// A color quantization utility used for getting prevalent colors in an image, by
+/// averaging out the image's color data recursively.
+///
+/// #### Example
+/// ```qml
+/// ColorQuantizer {
+///   id: colorQuantizer
+///   source: Qt.resolvedUrl("./yourImage.png")
+///   depth: 3 // Will produce 8 colors (2³)
+///   rescaleSize: 64 // Rescale to 64x64 for faster processing
+/// }
+/// ```
+class ColorQuantizer
+    : public QObject
+    , public QQmlParserStatus {
+	Q_OBJECT;
+	QML_ELEMENT;
+	Q_INTERFACES(QQmlParserStatus);
+	/// Access the colors resulting from the color quantization performed.
+	/// > [!NOTE] The amount of colors returned from the quantization is determined by
+	/// > the property depth, specifically 2ⁿ where n is the depth.
+	Q_PROPERTY(QList<QColor> colors READ default NOTIFY colorsChanged BINDABLE bindableColors);
+
+	/// Path to the image you'd like to run the color quantization on.
+	Q_PROPERTY(QUrl source READ source WRITE setSource NOTIFY sourceChanged);
+
+	/// Max depth for the color quantization. Each level of depth represents another
+	/// binary split of the color space
+	Q_PROPERTY(qreal depth READ depth WRITE setDepth NOTIFY depthChanged);
+
+	/// 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.
+	Q_PROPERTY(qreal rescaleSize READ rescaleSize WRITE setRescaleSize NOTIFY rescaleSizeChanged);
+
+public:
+	explicit ColorQuantizer(QObject* parent = nullptr): QObject(parent) {}
+
+	void componentComplete() override;
+	void classBegin() override {}
+
+	[[nodiscard]] QBindable<QList<QColor>> bindableColors() { return &this->bColors; }
+
+	[[nodiscard]] QUrl source() const { return mSource; }
+	void setSource(const QUrl& source);
+
+	[[nodiscard]] qreal depth() const { return mDepth; }
+	void setDepth(qreal depth);
+
+	[[nodiscard]] qreal rescaleSize() const { return mRescaleSize; }
+	void setRescaleSize(int rescaleSize);
+
+signals:
+	void colorsChanged();
+	void sourceChanged();
+	void depthChanged();
+	void rescaleSizeChanged();
+
+public slots:
+	void operationFinished(const QList<QColor>& result);
+
+private:
+	void quantizeAsync();
+	void cancelAsync();
+
+	bool componentCompleted = false;
+	ColorQuantizerOperation* liveOperation = nullptr;
+	QUrl mSource;
+	qreal mDepth = 0;
+	qreal mRescaleSize = 0;
+
+	Q_OBJECT_BINDABLE_PROPERTY(
+	    ColorQuantizer,
+	    QList<QColor>,
+	    bColors,
+	    &ColorQuantizer::colorsChanged
+	);
+};