Return early if blit got zero width or height (#161)

Author: tuupola

CHANGELOG.md

@@ -8,7 +8,7 @@ All notable changes to this project will be documented in this file, in reverse
 - Wrong image guard in `image.h`  ([#113](https://github.com/tuupola/hagl/pull/113)).
 - Filled polygon rendered incorrectly with negative x coordinates ([#122](https://github.com/tuupola/hagl/pull/122)).
 - Polygon and rectangle output did not match ([#123](https://github.com/tuupola/hagl/pull/123), [#124](https://github.com/tuupola/hagl/pull/124)).
-- Horizontal and vertical line parameters are now sorted ([#125](https://github.com/tuupola/hagl/pull/125)).
+- Horizontal and vertical line parameters are now sorted ([#125](https://github.com/tuupola/hagl/pull/125), [#121](https://github.com/tuupola/hagl/issues/121)).
 - Filled circle with radius of one did not produce correct output ([#145](https://github.com/tuupola/hagl/pull/145), [#144](https://github.com/tuupola/hagl/issues/144)).
 - Circle with zero radius did not produce a single pixel ([#146](https://github.com/tuupola/hagl/pull/146), [#140](https://github.com/tuupola/hagl/issues/140)).
 - Surface callbacks received pointer-to-pointer instead of pointer-to-struct ([#147](https://github.com/tuupola/hagl/pull/147)).

include/hagl/blit.h

@@ -71,7 +71,7 @@ static void inline hagl_blit(
     void const *surface, int16_t x0, int16_t y0, hagl_bitmap_t *source
 ) {
     hagl_blit_xy(surface, x0, y0, source);
-};
+}
 
 /**
  * Blit and scale a bitmap to a surface
@@ -111,7 +111,7 @@ static void inline hagl_blit_xyxy(
     uint16_t max_x = (x0 > x1) ? x0 : x1;
     uint16_t max_y = (y0 > y1) ? y0 : y1;
     hagl_blit_xywh(surface, min_x, min_y, max_x - min_x + 1, max_y - min_y + 1, source);
-};
+}
 
 #ifdef __cplusplus
 }

src/hagl_blit.c

@@ -72,14 +72,18 @@ void hagl_blit_xy(void const *_surface, int16_t x0, int16_t y0, hagl_bitmap_t *s
             }
         }
     }
-};
+}
 
 void hagl_blit_xywh(
     void const *_surface, uint16_t x0, uint16_t y0, uint16_t w, uint16_t h,
     hagl_bitmap_t *source
 ) {
     const hagl_surface_t *surface = _surface;
 
+    if (0 == w || 0 == h) {
+        return;
+    }
+
     if (surface->scale_blit) {
         surface->scale_blit((void *)_surface, x0, y0, w, h, source);
     } else {
@@ -97,4 +101,4 @@ void hagl_blit_xywh(
             }
         }
     }
-};
+}