libcamera: converter: Add dw100 vertex map class

Using a custom vertex map the dw100 dewarper is capable of doing
complex and useful transformations on the image data. This class
implements a pipeline featuring:
- Arbitrary ScalerCrop
- Full transform support (Flip, 90deg rotations)
- Arbitrary move, scale, rotate

ScalerCrop and Transform is implemented to provide a interface that is
standardized libcamera wide. The rest is implemented on top for more
flexible dw100 specific features.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/converter/converter_dw100_vertexmap.h

@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2025, Ideas on Board Oy
+ *
+ * DW100 vertex map interface
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <cmath>
+#include <stdint.h>
+#include <vector>
+
+#include <libcamera/base/span.h>
+
+#include <libcamera/geometry.h>
+#include <libcamera/transform.h>
+
+namespace libcamera {
+
+class Dw100VertexMap
+{
+public:
+	enum ScaleMode {
+		Fill = 0,
+		Crop = 1,
+	};
+
+	void applyLimits();
+	void setInputSize(const Size &size)
+	{
+		inputSize_ = size;
+		scalerCrop_ = Rectangle(size);
+	}
+
+	void setSensorCrop(const Rectangle &rect) { sensorCrop_ = rect; }
+
+	void setScalerCrop(const Rectangle &rect) { scalerCrop_ = rect; }
+	const Rectangle &effectiveScalerCrop() const { return effectiveScalerCrop_; }
+
+	void setOutputSize(const Size &size) { outputSize_ = size; }
+	const Size &outputSize() const { return outputSize_; }
+
+	void setTransform(const Transform &transform) { transform_ = transform; }
+	const Transform &transform() const { return transform_; }
+
+	void setScale(const float scale) { scale_ = scale; }
+	float effectiveScale() const { return (effectiveScaleX_ + effectiveScaleY_) * 0.5; }
+
+	void setRotation(const float rotation) { rotation_ = rotation; }
+	float rotation() const { return rotation_; }
+
+	void setOffset(const Point &offset) { offset_ = offset; }
+	const Point &effectiveOffset() const { return effectiveOffset_; }
+
+	void setMode(const ScaleMode mode) { mode_ = mode; }
+	ScaleMode mode() const { return mode_; }
+
+	std::vector<uint32_t> getVertexMap();
+
+private:
+	Rectangle scalerCrop_;
+	Rectangle sensorCrop_;
+	Transform transform_ = Transform::Identity;
+	Size inputSize_;
+	Size outputSize_;
+	Point offset_;
+	double scale_ = 1.0;
+	double rotation_ = 0.0;
+	ScaleMode mode_ = Fill;
+	double effectiveScaleX_;
+	double effectiveScaleY_;
+	Point effectiveOffset_;
+	Rectangle effectiveScalerCrop_;
+};
+
+} /* namespace libcamera */

include/libcamera/internal/converter/meson.build

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: CC0-1.0
 
 libcamera_internal_headers += files([
+    'converter_dw100_vertexmap.h',
     'converter_v4l2_m2m.h',
 ])