graph: factor out cairo text drawing helpers
Signed-off-by: Stephen M. Cameron <stephenmcameron@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/cairo_text_helpers.c b/cairo_text_helpers.c
new file mode 100644
index 0000000..89b9aa2
--- /dev/null
+++ b/cairo_text_helpers.c
@@ -0,0 +1,85 @@
+#include <cairo.h>
+#include <gtk/gtk.h>
+#include <math.h>
+
+static void draw_aligned_text(cairo_t *cr, const char *font, double x, double y,
+ double fontsize, const char *text, int alignment)
+{
+#define CENTERED 0
+#define LEFT_JUSTIFIED 1
+#define RIGHT_JUSTIFIED 2
+
+ double factor, direction;
+ cairo_text_extents_t extents;
+
+ switch(alignment) {
+ case CENTERED:
+ direction = -1.0;
+ factor = 0.5;
+ break;
+ case RIGHT_JUSTIFIED:
+ direction = -1.0;
+ factor = 1.0;
+ break;
+ case LEFT_JUSTIFIED:
+ default:
+ direction = 1.0;
+ factor = 1.0;
+ break;
+ }
+ cairo_select_font_face(cr, font, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
+
+ cairo_set_font_size(cr, fontsize);
+ cairo_text_extents(cr, text, &extents);
+ x = x + direction * (factor * extents.width + extents.x_bearing);
+ y = y - (extents.height / 2 + extents.y_bearing);
+
+ cairo_move_to(cr, x, y);
+ cairo_show_text(cr, text);
+}
+
+void draw_centered_text(cairo_t *cr, const char *font, double x, double y,
+ double fontsize, const char *text)
+{
+ draw_aligned_text(cr, font, x, y, fontsize, text, CENTERED);
+}
+
+void draw_right_justified_text(cairo_t *cr, const char *font,
+ double x, double y,
+ double fontsize, const char *text)
+{
+ draw_aligned_text(cr, font, x, y, fontsize, text, RIGHT_JUSTIFIED);
+}
+
+void draw_left_justified_text(cairo_t *cr, const char *font,
+ double x, double y,
+ double fontsize, const char *text)
+{
+ draw_aligned_text(cr, font, x, y, fontsize, text, LEFT_JUSTIFIED);
+}
+
+void draw_vertical_centered_text(cairo_t *cr, const char * font, double x,
+ double y, double fontsize,
+ const char *text)
+{
+ double sx, sy;
+ cairo_text_extents_t extents;
+
+ cairo_select_font_face(cr, font, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
+
+ cairo_set_font_size(cr, fontsize);
+ cairo_text_extents(cr, text, &extents);
+ sx = x;
+ sy = y;
+ y = y + (extents.width / 2.0 + extents.x_bearing);
+ x = x - (extents.height / 2.0 + extents.y_bearing);
+
+ cairo_move_to(cr, x, y);
+ cairo_save(cr);
+ cairo_translate(cr, -sx, -sy);
+ cairo_rotate(cr, -90.0 * M_PI / 180.0);
+ cairo_translate(cr, sx, sy);
+ cairo_show_text(cr, text);
+ cairo_restore(cr);
+}
+