math: Make sure image extends to an edge when scaling

Also make sure dimensions don't fall short of request. We do this by always rounding up before capping the size with MIN(). Fixes #212 (GitHub).
hpjansson · Sep 3, 2024 · 32df6a4 · 32df6a4
1 parent 3422917
commit 32df6a4
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Showing 2 changed files with 10 additions and 6 deletions.
diff --git a/chafa/chafa-util.c b/chafa/chafa-util.c
@@ -19,6 +19,7 @@
 
 #include "config.h"
 
+#include <math.h>
 #include "chafa.h"
 #include "internal/chafa-private.h"
 
@@ -124,19 +125,19 @@ chafa_calc_canvas_geometry (gint src_width,
 
         if (dest_width < 1)
         {
-            dest_width = dest_height * (src_aspect / font_ratio) + 0.5;
+            dest_width = ceil (dest_height * (src_aspect / font_ratio));
         }
         else if (dest_height < 1)
         {
-            dest_height = (dest_width / src_aspect) * font_ratio + 0.5;
+            dest_height = ceil ((dest_width / src_aspect) * font_ratio);
         }
         else if (src_aspect > dest_aspect)
         {
-            dest_height = dest_width * (font_ratio / src_aspect) + 0.5;
+            dest_height = ceil (dest_width * (font_ratio / src_aspect));
         }
         else
         {
-            dest_width = dest_height * (src_aspect / font_ratio) + 0.5;
+            dest_width = ceil (dest_height * (src_aspect / font_ratio));
         }
     }
 

diff --git a/chafa/internal/chafa-math-util.c b/chafa/internal/chafa-math-util.c
@@ -18,6 +18,8 @@
  * along with Chafa.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include "config.h"
+
+#include <math.h>
 #include "internal/chafa-private.h"
 #include "internal/chafa-math-util.h"
 
@@ -71,6 +73,7 @@ chafa_tuck_and_align (gint src_width, gint src_height,
         case CHAFA_TUCK_SHRINK_TO_FIT:
             if (src_width <= dest_width && src_height <= dest_height)
             {
+                /* Image fits entirely in dest. Do alignment only, no scaling. */
                 *width_out = src_width;
                 *height_out = src_height;
                 break;
@@ -82,8 +85,8 @@ chafa_tuck_and_align (gint src_width, gint src_height,
             ratio [0] = (gfloat) dest_width / (gfloat) src_width;
             ratio [1] = (gfloat) dest_height / (gfloat) src_height;
 
-            *width_out = src_width * MIN (ratio [0], ratio [1]);
-            *height_out = src_height * MIN (ratio [0], ratio [1]);
+            *width_out = ceilf (src_width * MIN (ratio [0], ratio [1]));
+            *height_out = ceilf (src_height * MIN (ratio [0], ratio [1]));
             break;
 
         default: