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include/mupdf/fitz/shade.h

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+#ifndef MUPDF_FITZ_SHADE_H
+#define MUPDF_FITZ_SHADE_H
+
+#include "mupdf/fitz/system.h"
+#include "mupdf/fitz/context.h"
+#include "mupdf/fitz/geometry.h"
+#include "mupdf/fitz/store.h"
+#include "mupdf/fitz/colorspace.h"
+#include "mupdf/fitz/pixmap.h"
+#include "mupdf/fitz/compressed-buffer.h"
+
+/*
+ * The shading code uses gouraud shaded triangle meshes.
+ */
+
+enum
+{
+	FZ_FUNCTION_BASED = 1,
+	FZ_LINEAR = 2,
+	FZ_RADIAL = 3,
+	FZ_MESH_TYPE4 = 4,
+	FZ_MESH_TYPE5 = 5,
+	FZ_MESH_TYPE6 = 6,
+	FZ_MESH_TYPE7 = 7
+};
+
+/*
+	Structure is public to allow derived classes. Do not
+	access the members directly.
+*/
+typedef struct fz_shade_s
+{
+	fz_storable storable;
+
+	fz_rect bbox;		/* can be fz_infinite_rect */
+	fz_colorspace *colorspace;
+
+	fz_matrix matrix;	/* matrix from pattern dict */
+	int use_background;	/* background color for fills but not 'sh' */
+	float background[FZ_MAX_COLORS];
+
+	/* Just to be confusing, PDF Shadings of Type 1 (Function Based
+	 * Shadings), do NOT use_function, but all the others do. This
+	 * is because Type 1 shadings take 2 inputs, whereas all the
+	 * others (when used with a function take 1 input. The type 1
+	 * data is in the 'f' field of the union below. */
+	int use_function;
+	float function[256][FZ_MAX_COLORS + 1];
+
+	int type; /* function, linear, radial, mesh */
+	union
+	{
+		struct
+		{
+			int extend[2];
+			float coords[2][3]; /* (x,y,r) twice */
+		} l_or_r;
+		struct
+		{
+			int vprow;
+			int bpflag;
+			int bpcoord;
+			int bpcomp;
+			float x0, x1;
+			float y0, y1;
+			float c0[FZ_MAX_COLORS];
+			float c1[FZ_MAX_COLORS];
+		} m;
+		struct
+		{
+			fz_matrix matrix;
+			int xdivs;
+			int ydivs;
+			float domain[2][2];
+			float *fn_vals;
+		} f;
+	} u;
+
+	fz_compressed_buffer *buffer;
+} fz_shade;
+
+/*
+	fz_keep_shade: Add a reference to a fz_shade.
+
+	shade: The reference to keep.
+
+	Returns shade.
+*/
+fz_shade *fz_keep_shade(fz_context *ctx, fz_shade *shade);
+
+/*
+	fz_drop_shade: Drop a reference to a fz_shade.
+
+	shade: The reference to drop. If this is the last
+	reference, shade will be destroyed.
+*/
+void fz_drop_shade(fz_context *ctx, fz_shade *shade);
+
+/*
+	fz_drop_shade_imp: Internal function to destroy a
+	shade. Only exposed for use with the fz_store.
+
+	shade: The reference to destroy.
+*/
+void fz_drop_shade_imp(fz_context *ctx, fz_storable *shade);
+
+/*
+	fz_bound_shade: Bound a given shading.
+
+	shade: The shade to bound.
+
+	ctm: The transform to apply to the shade before bounding.
+
+	r: Pointer to storage to put the bounds in.
+
+	Returns r, updated to contain the bounds for the shading.
+*/
+fz_rect *fz_bound_shade(fz_context *ctx, fz_shade *shade, const fz_matrix *ctm, fz_rect *r);
+
+/*
+	fz_paint_shade: Render a shade to a given pixmap.
+
+	shade: The shade to paint.
+
+	override_cs: NULL, or colorspace to override the shades
+	inbuilt colorspace.
+
+	ctm: The transform to apply.
+
+	dest: The pixmap to render into.
+
+	color_params: The color rendering settings
+
+	bbox: Pointer to a bounding box to limit the rendering
+	of the shade.
+
+	op: NULL, or pointer to overprint bitmap.
+*/
+void fz_paint_shade(fz_context *ctx, fz_shade *shade, fz_colorspace *override_cs, const fz_matrix *ctm, fz_pixmap *dest, const fz_color_params *color_params, const fz_irect *bbox, const fz_overprint *op);
+
+/*
+ *	Handy routine for processing mesh based shades
+ */
+typedef struct fz_vertex_s fz_vertex;
+
+struct fz_vertex_s
+{
+	fz_point p;
+	float c[FZ_MAX_COLORS];
+};
+
+/*
+	fz_shade_prepare_fn: Callback function type for use with
+	fz_process_shade.
+
+	arg: Opaque pointer from fz_process_shade caller.
+
+	v: Pointer to a fz_vertex structure to populate.
+
+	c: Pointer to an array of floats used to populate v.
+*/
+typedef void (fz_shade_prepare_fn)(fz_context *ctx, void *arg, fz_vertex *v, const float *c);
+
+/*
+	fz_shade_process_fn: Callback function type for use with
+	fz_process_shade.
+
+	arg: Opaque pointer from fz_process_shade caller.
+
+	av, bv, cv: Pointers to a fz_vertex structure describing
+	the corner locations and colors of a triangle to be
+	filled.
+*/
+typedef void (fz_shade_process_fn)(fz_context *ctx, void *arg, fz_vertex *av, fz_vertex *bv, fz_vertex *cv);
+
+/*
+	fz_process_shade: Process a shade, using supplied callback
+	functions. This decomposes the shading to a mesh (even ones
+	that are not natively meshes, such as linear or radial
+	shadings), and processes triangles from those meshes.
+
+	shade: The shade to process.
+
+	ctm: The transform to use
+
+	prepare: Callback function to 'prepare' each vertex.
+	This function is passed an array of floats, and populates
+	a fz_vertex structure.
+
+	process: This function is passed 3 pointers to vertex
+	structures, and actually performs the processing (typically
+	filling the area between the vertexes).
+
+	process_arg: An opaque argument passed through from caller
+	to callback functions.
+*/
+void fz_process_shade(fz_context *ctx, fz_shade *shade, const fz_matrix *ctm,
+			fz_shade_prepare_fn *prepare,
+			fz_shade_process_fn *process,
+			void *process_arg);
+
+#endif