6 files changed, 16 insertions, 14 deletions
diff --git a/src/font.c b/src/font.c
index c351857..fb54604 100644
--- a/src/font.c
+++ b/src/font.c
@@ -65,19 +65,19 @@ font_find(const char *name)
 }
 
 int
-font_get_width(struct font *font)
+font_get_width(const struct font *font)
 {
 	return font->desc.width;
 }
 
 int
-font_get_height(struct font *font)
+font_get_height(const struct font *font)
 {
 	return font->desc.height;
 }
 
 void
-font_render(struct font *font, png_const_colorp fg, png_const_colorp bg,
+font_render(const struct font *font, png_const_colorp fg, png_const_colorp bg,
 		unsigned char ch, png_bytepp rows, int row, int col)
 {
 	size_t        y;
diff --git a/src/font.h b/src/font.h
index f82f2a0..27cc08e 100644
--- a/src/font.h
+++ b/src/font.h
@@ -30,13 +30,13 @@ struct font *
 font_find(const char *name) __attribute__((pure));
 
 int
-font_get_width(struct font *font) __attribute__((pure));
+font_get_width(const struct font *font) __attribute__((pure));
 
 int
-font_get_height(struct font *font) __attribute__((pure));
+font_get_height(const struct font *font) __attribute__((pure));
 
 void
-font_render(struct font *font, png_const_colorp fg, png_const_colorp bg,
+font_render(const struct font *font, png_const_colorp fg, png_const_colorp bg,
 		unsigned char ch, png_bytepp rows, int row, int col);
 
 #endif  /* FONT_H_ */
diff --git a/src/image.c b/src/image.c
index 3c5d98f..e55f955 100644
--- a/src/image.c
+++ b/src/image.c
@@ -76,7 +76,8 @@ image_new(const char *file_name)
 }
 
 void
-image_render(struct image *image, struct text *text, struct font *font)
+image_render(struct image *image, const struct text *text,
+		const struct font *font)
 {
 	size_t     width;
 	size_t     height;
diff --git a/src/image.h b/src/image.h
index b303c23..ece53f7 100644
--- a/src/image.h
+++ b/src/image.h
@@ -38,7 +38,8 @@ struct image *
 image_new(const char *file_name);
 
 void
-image_render(struct image *image, struct text *text, struct font *font);
+image_render(struct image *image, const struct text *text,
+		const struct font *font);
 
 struct image *
 image_destroy(struct image **image);
diff --git a/src/text.c b/src/text.c
index fedbd3f..995d10e 100644
--- a/src/text.c
+++ b/src/text.c
@@ -105,13 +105,13 @@ text_new(FILE *stream)
 }
 
 size_t
-text_get_width(struct text *text)
+text_get_width(const struct text *text)
 {
 	return text->width;
 }
 
 size_t
-text_get_height(struct text *text)
+text_get_height(const struct text *text)
 {
 	return text->height;
 }
@@ -129,7 +129,7 @@ text_set_height(struct text *text, size_t height)
 }
 
 void
-text_render(struct text *text, struct font *font, png_bytepp rows)
+text_render(const struct text *text, const struct font *font, png_bytepp rows)
 {
 	unsigned char *string_start;
 	unsigned char *string;
diff --git a/src/text.h b/src/text.h
index 8ee0245..a76e14e 100644
--- a/src/text.h
+++ b/src/text.h
@@ -34,10 +34,10 @@ struct text *
 text_new(FILE *stream);
 
 size_t
-text_get_width(struct text *text) __attribute__((pure));
+text_get_width(const struct text *text) __attribute__((pure));
 
 size_t
-text_get_height(struct text *text) __attribute__((pure));
+text_get_height(const struct text *text) __attribute__((pure));
 
 size_t
 text_set_width(struct text *text, size_t width);
@@ -46,7 +46,7 @@ size_t
 text_set_height(struct text *text, size_t height);
 
 void
-text_render(struct text *text, struct font *font, png_bytepp rows);
+text_render(const struct text *text, const struct font *font, png_bytepp rows);
 
 struct text *
 text_destroy(struct text **text_p);