cairo rendering

1 files changed, 54 insertions, 0 deletions

diff --git a/render.c b/render.c
new file mode 100644
index 0000000..5c650f2
--- /dev/null
+++ b/render.c
@@ -0,0 +1,54 @@
+#include <cairo.h>
+
+static int pad = 10;
+
+static void render_color_bar(cairo_t *cr, int x, int y, int w, int h,
+                             double r, double g, double b, const char *name)
+{
+    cairo_font_extents_t ext;
+    cairo_pattern_t *gr;
+
+    gr = cairo_pattern_create_linear(x, y+h/2, w, y+h/2);
+    cairo_pattern_add_color_stop_rgb(gr, 0, 0, 0, 0);
+    cairo_pattern_add_color_stop_rgb(gr, 1, r, g, b);
+    cairo_rectangle (cr, x, y, w, h);
+    cairo_set_source (cr, gr);
+    cairo_fill (cr);
+    cairo_pattern_destroy(gr);
+
+    cairo_set_source_rgb(cr, r, g, b);
+    cairo_select_font_face(cr, "mono",
+                           CAIRO_FONT_SLANT_NORMAL,
+                           CAIRO_FONT_WEIGHT_NORMAL);
+    cairo_set_font_size(cr, h - 2*pad);
+    cairo_font_extents (cr, &ext);
+    cairo_move_to(cr, x + pad, y + pad + ext.ascent);
+    cairo_show_text(cr, name);
+}
+
+void render_test(cairo_t *cr, int width, int height)
+{
+    int bar = 100;
+
+    while (6 * bar + 2 * pad > height &&
+           bar > 4 * pad)
+        bar -= 10;
+
+    cairo_set_source_rgb(cr, 0, 0, 0);
+    cairo_rectangle (cr, 0, 0, width, height);
+    cairo_fill (cr);
+
+    cairo_set_line_width (cr, 1);
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_rectangle (cr, pad - 0.5, pad - 0.5, width - 2*pad + 1, 6*bar + 1);
+    cairo_stroke (cr);
+
+    render_color_bar(cr, pad, bar * 0 + pad, width - 2*pad, bar, 1, 0, 0, "red");
+    render_color_bar(cr, pad, bar * 1 + pad, width - 2*pad, bar, 1, 1, 0, "yellow");
+    render_color_bar(cr, pad, bar * 2 + pad, width - 2*pad, bar, 0, 1, 0, "green");
+    render_color_bar(cr, pad, bar * 3 + pad, width - 2*pad, bar, 0, 1, 1, "cyan");
+    render_color_bar(cr, pad, bar * 4 + pad, width - 2*pad, bar, 0, 0, 1, "blue");
+    render_color_bar(cr, pad, bar * 5 + pad, width - 2*pad, bar, 1, 0, 1, "magenta");
+}
+
+