Gradients: work in progress

src/util/gradient.h

@@ -0,0 +1,115 @@
+#ifndef GRADIENT_H
+#define GRADIENT_H
+
+#include <glib.h>
+#include <cairo.h>
+
+#include "color.h"
+
+//////////////////////////////////////////////////////////////////////
+// Gradient types read from config options, not associated to any area
+
+typedef enum GradientType {
+	GRADIENT_VERTICAL = 0,
+	GRADIENT_HORIZONTAL,
+	GRADIENT_CENTERED,
+	GRADIENT_LINEAR,
+	GRADIENT_RADIAL
+} GradientType;
+
+typedef struct ColorStop {
+	Color color;
+	// offset in 0-1
+	double offset;
+} ColorStop;
+
+typedef enum Origin {
+	ORIGIN_ELEMENT = 0,
+	ORIGIN_PARENT,
+	ORIGIN_PANEL,
+	ORIGIN_SCREEN,
+	ORIGIN_DESKTOP
+} Origin;
+
+typedef enum SizeVariable {
+	SIZE_WIDTH = 0,
+	SIZE_HEIGHT,
+	SIZE_LEFT,
+	SIZE_RIGHT,
+	SIZE_TOP,
+	SIZE_BOTTOM,
+	SIZE_CENTER,
+	SIZE_RADIUS
+} SizeVariable;
+
+typedef struct Offset {
+	gboolean constant;
+	// if constant == true
+	double constant_value;
+	// else
+	Origin variable_element;
+	SizeVariable variable;
+	double multiplier;
+} Offset;
+
+typedef struct ControlPoint {
+	Origin origin;
+	// Each element is an Offset
+	GList *offsets_x;
+	GList *offsets_y;
+	// Defined only for radial gradients
+	GList *offsets_r;
+} ControlPoint;
+
+typedef struct GradientClass {
+	GradientType type;
+	Color start_color;
+	Color end_color;
+	// Each element is a ColorStop
+	GList *extra_color_stops;
+	ControlPoint from;
+	ControlPoint to;
+} GradientClass;
+
+GradientType gradient_type_from_string(const char *str);
+Origin origin_from_string(const char *str);
+Offset *offset_from_string(const char *str);
+void init_gradient(GradientClass *g, GradientType type);
+void cleanup_gradient(GradientClass *g);
+
+/////////////////////////////////////////
+// Gradient instances associated to Areas
+
+struct Area;
+typedef struct Area Area;
+
+typedef struct OffsetInstance {
+	gboolean constant;
+	// if constant == true
+	double constant_value;
+	// else
+	Area *variable_element;
+	SizeVariable variable;
+	double multiplier;
+} OffsetInstance;
+
+typedef struct ControlPointInstance {
+	Area *origin;
+	// Each element is an OffsetInstance
+	GList *offsets_x;
+	GList *offsets_y;
+	GList *offsets_r;
+} ControlPointInstance;
+
+typedef struct GradientInstance {
+	GradientClass *gradient_class;
+	Area *area;
+	ControlPointInstance from;
+	ControlPointInstance to;
+	cairo_pattern_t *pattern;
+	// Each element is an Area whose geometry is used to compute this gradient
+	// TODO why do we need it?
+	GList *gradient_dependencies;
+} GradientInstance;
+
+#endif // GRADIENT_H