Work on gradients: linear and radial

- Color space is wrong
- No proper error handling

src/hvif-cairo.c

@@ -1,6 +1,7 @@
 #include "hvif-light.h"
 
 #include <stdint.h>
+#include <stdlib.h>
 #include <assert.h>
 #include <cairo.h>
 
@@ -14,6 +15,26 @@
  *  3. Put everything together
  */
 
+/* TODO: Gradients
+ *  - Check the various forms
+ *  - How is the gradient oriented in the picture
+ *  - Apply transformation matrix
+ *  - Color space
+ */
+
+void
+cairo_matrix_init_from_matrix(cairo_matrix_t* matrix, const hvif_matrix* hvif_matrix)
+{
+	cairo_matrix_init(matrix,
+		hvif_matrix->xx,
+		hvif_matrix->yx,
+		hvif_matrix->xy,
+		hvif_matrix->yy,
+		hvif_matrix->x0,
+		hvif_matrix->y0
+	);
+}
+
 void
 create_path(cairo_t* cr, hvif_path* path)
 {
@@ -23,26 +44,93 @@ create_path(cairo_t* cr, hvif_path* path)
 		hvif_point p = path->points[3 * i];
 		hvif_point cp1 = path->points[3 * i + 1];
 		hvif_point cp2 = path->points[3 * i + 2];
-		cairo_curve_to(cr, cp1.x, cp1.y, cp2.x, cp2.y, p.x, p.y);
+		uint8_t command = path_command_at(path, i);
+		if (command == PATH_COMMAND_CURVE)
+			cairo_curve_to(cr, cp1.x, cp1.y, cp2.x, cp2.y, p.x, p.y);
+		else
+			cairo_line_to(cr, p.x, p.y);
 	}
 
 	if (path->closed)
 		cairo_close_path(cr);
 }
 
+void
+create_style(cairo_t* cr, hvif_style* style)
+{
+	assert(style->num_stops > 0);
+	cairo_pattern_t *pat;
+
+	switch (style->gradient_type) {
+		case GRADIENT_LINEAR:
+			printf("GRADIENT_LINEAR\n");
+			pat = cairo_pattern_create_linear(-64, 32, 64, 32);
+			break;
+		case GRADIENT_CIRCULAR:
+			printf("GRADIENT_CIRCULAR\n");
+			pat = cairo_pattern_create_radial(0, 0, 0, 0, 0, 64);
+			break;
+		case GRADIENT_DIAMOND:
+			printf("GRADIENT_DIAMOND\n");
+			assert(false);
+			break;
+		case GRADIENT_CONIC:
+			printf("GRADIENT_CONIC\n");
+			assert(false);
+			break;
+		case GRADIENT_XY:
+			printf("GRADIENT_XY\n");
+			assert(false);
+			break;
+		case GRADIENT_SQRT_XY:
+			printf("GRADIENT_SQRT_XY\n");
+			assert(false);
+			break;
+	}
+
+	for (unsigned i = 0; i < style->num_stops; ++i) {
+		printf("stop %f\n", style->offsets[i]);
+		hvif_color c = style->colors[i];
+		cairo_pattern_add_color_stop_rgba(pat, style->offsets[i],
+			COLOR_GET_RED(c) / 255.0,
+			COLOR_GET_GREEN(c) / 255.0,
+			COLOR_GET_BLUE(c) / 255.0,
+			COLOR_GET_ALPHA(c) / 255.0);
+	}
+
+	cairo_matrix_t transformation;
+	cairo_matrix_init_from_matrix(&transformation, &style->transformation);
+	if (cairo_matrix_invert(&transformation) != CAIRO_STATUS_SUCCESS) {
+		printf("could not invert style transformation\n");
+		exit(1);
+	}
+	cairo_pattern_set_matrix(pat, &transformation);
+
+	cairo_rectangle(cr, 0, 0, 64, 64);
+	cairo_set_source(cr, pat);
+	cairo_fill(cr);
+	cairo_pattern_destroy(pat);
+}
+
 bool
 hvif_render_image(const char* filename, hvif_image* image)
 {
 	cairo_surface_t* surface =
-		cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 254, 254);
+		/* cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 254, 254); */
+		cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 65, 64);
 	cairo_t* cr = cairo_create(surface);
-	cairo_scale(cr, 4.0, 4.0);
+	/* cairo_scale(cr, 4.0, 4.0); */
+	cairo_scale(cr, 1.0, 1.0);
 
 	cairo_set_line_width(cr, 0.2);
 
 	double r = 0;
 	double delta = 1.0 / image->num_shapes;
 
+	printf("styles %u\n", image->num_styles);
+	create_style(cr, &image->styles[0]);
+
+/*
 	for (unsigned i = 0; i < image->num_shapes; ++i) {
 		cairo_set_source_rgb(cr, r, 0, 0);
 		r = r + delta;
@@ -57,6 +145,7 @@ hvif_render_image(const char* filename, hvif_image* image)
 			cairo_stroke(cr);
 		}
 	}
+	*/
 
 	cairo_destroy(cr);
 

src/hvif-light.c

@@ -101,20 +101,18 @@ typedef enum hvif_line_cap
 typedef struct hvif_matrix hvif_matrix;
 struct hvif_matrix
 {
-	double v1;
-	double v2;
-	double v3;
-	double v4;
-	double v5;
-	double v6;
+	double xx;
+	double yx;
+	double xy;
+	double yy;
+	double x0;
+	double y0;
 };
 
-/* TODO: This is most likely wrong */
 #define MATRIX_ID \
-	(hvif_matrix) { 1.0, 0.0, 0.0, 0.0, 1.0, 0.0 }
-/* TODO: This is most likely wrong */
+	(hvif_matrix) { 1.0, 0.0, 0.0, 1.0, 0.0, 0.0 }
 #define MATRIX_TRANSLATION(P) \
-	(hvif_matrix) { P.x, 0.0, 0.0, 0.0, P.y, 0.0 }
+	(hvif_matrix) { 1.0, 0.0, 0.0, 1.0, P.x, P.y }
 
 typedef struct hvif_point hvif_point;
 struct hvif_point
@@ -211,20 +209,29 @@ struct hvif_image
 	hvif_shape* shapes;
 };
 
+inline uint8_t
+path_command_at(hvif_path* path, uint8_t index)
+{
+	uint8_t byte = path->commands[index / 4];
+	uint8_t byte_idx = index % 4;
+	return (byte >> (2 * byte_idx)) & 0x03;
+}
+
 #ifndef INTERNAL_DATASTRUCTURES
+
 #define hvif_decode(V, BUFFER) \
 	V = _Generic((V), uint32_t \
 							 : hvif_decode_uint32, float \
 							 : hvif_decode_float, hvif_matrix \
 							 : hvif_decode_hvif_matrix)(BUFFER)
 static inline uint32_t
-hvif_decode_uint32(char buffer[static 1])
+hvif_decode_uint32(uint8_t buffer[static 1])
 {
 	return (buffer[0] << 0) | (buffer[1] << 8) | (buffer[2] << 16) |
 		(buffer[3] << 24);
 }
 static inline float
-hvif_decode_float(char buffer[static 1])
+hvif_decode_float(uint8_t buffer[static 1])
 {
 	int shortValue = (buffer[0] << 16) | (buffer[1] << 8) | buffer[2];
 	int sign = (shortValue & 0x800000) >> 23;
@@ -234,12 +241,13 @@ hvif_decode_float(char buffer[static 1])
 	if (shortValue == 0)
 		return 0.0;
 	else {
+		/* TODO: float might not be IEEE 754 compatible */
 		uint32_t value = (sign << 31) | ((exponent + 127) << 23) | mantissa;
-		return (float)value;
+		return *((float*)&value);
 	}
 }
 static inline hvif_matrix
-hvif_decode_hvif_matrix(char buffer[static 1])
+hvif_decode_hvif_matrix(uint8_t buffer[static 1])
 {
 	return (hvif_matrix){
 		hvif_decode_float(buffer),      hvif_decode_float(&buffer[3]),
@@ -248,16 +256,8 @@ hvif_decode_hvif_matrix(char buffer[static 1])
 	};
 }
 
-uint8_t
-path_command_at(hvif_path* path, uint8_t index)
-{
-	uint8_t byte = path->commands[index / 4];
-	uint8_t byte_idx = index % 4;
-	return (byte >> (2 * byte_idx)) & 0x03;
-}
-
 hvif_color
-decode_color(char* buffer, bool gray, bool alpha)
+decode_color(uint8_t* buffer, bool gray, bool alpha)
 {
 	/* On disk a color is:
 	 	   red, green, blue, alpha
@@ -286,7 +286,7 @@ decode_color(char* buffer, bool gray, bool alpha)
 }
 
 hvif_status
-read_color_style(hvif_style* style, char* buffer, bool gray, bool alpha)
+read_color_style(hvif_style* style, uint8_t* buffer, bool gray, bool alpha)
 {
 #ifdef DEBUG
 	printf("%s: start.\n", __func__);
@@ -303,7 +303,7 @@ read_color_style(hvif_style* style, char* buffer, bool gray, bool alpha)
 }
 
 hvif_status
-read_gradient_style(hvif_style* style, FILE* file, char* style_buffer)
+read_gradient_style(hvif_style* style, FILE* file, uint8_t* style_buffer)
 {
 #ifdef DEBUG
 	printf("%s: start.\n", __func__);
@@ -328,7 +328,7 @@ read_gradient_style(hvif_style* style, FILE* file, char* style_buffer)
 		printf("%s: read transfomation matrix.\n", __func__);
 #endif
 		/* The transformation matrix is 6 hvif-floats: 18 bytes */
-		char buffer[18];
+		uint8_t buffer[18];
 		if (fread(buffer, 1, 18, file) != 18) { return ERROR_EOF; }
 		hvif_decode(transformation, buffer);
 	} else {
@@ -345,7 +345,7 @@ read_gradient_style(hvif_style* style, FILE* file, char* style_buffer)
 #ifdef DEBUG
 	printf("%s: read %u stops.\n", __func__, gradient_stops);
 #endif
-	char buffer[4];
+	uint8_t buffer[4];
 	for (unsigned i = 0; i < gradient_stops; ++i) {
 		if (fread(buffer, 1, 1, file) != 1) { return ERROR_EOF; }
 		float offset = buffer[0] / 255.0;
@@ -379,7 +379,7 @@ read_style(FILE* file, hvif_style* style)
 {
 	uint8_t type;
 	if (fread(&type, 1, 1, file) != 1) { return ERROR_EOF; }
-	char buffer[4];
+	uint8_t buffer[4];
 	switch (type) {
 		case STYLE_TYPE_SOLID_COLOR:
 			if (fread(buffer, 1, 4, file) != 4) { return ERROR_EOF; }
@@ -565,7 +565,7 @@ read_transformer(FILE* file, hvif_transformer* transformer)
 	switch (byte) {
 		case TRANSFORMER_TYPE_AFFINE:
 			transformer->transformer_type = byte;
-			char buffer[18];
+			uint8_t buffer[18];
 			hvif_matrix matrix;
 			if (fread(buffer, 1, 18, file) != 18) return ERROR_EOF;
 			hvif_decode(matrix, buffer);
@@ -645,7 +645,7 @@ read_shape(FILE* file, hvif_image const* const image, hvif_shape* shape)
 
 	hvif_matrix transformation;
 	if (shape_flags & SHAPE_FLAG_TRANSFORM) {
-		char buffer[18];
+		uint8_t buffer[18];
 		if (fread(buffer, 1, 18, file) != 18) { return ERROR_EOF; }
 		hvif_decode(transformation, buffer);
 	} else if (shape_flags & SHAPE_FLAG_TRANSLATION) {
@@ -700,7 +700,7 @@ hvif_from_file(FILE* file)
 #ifdef DEBUG
 	printf("%s: checking magic number.\n", __func__);
 #endif
-	char magic_buffer[4];
+	uint8_t magic_buffer[4];
 	if (fread(magic_buffer, 1, 4, file) != 4) return ERROR_RESULT(ERROR_EOF);
 	uint32_t read_magic;
 	hvif_decode(read_magic, magic_buffer);