no margins

1 files changed, 17 insertions, 13 deletions

diff --git a/src/render/composite.rs b/src/render/composite.rs
index 99950f1..ea9cc29 100644
--- a/src/render/composite.rs
+++ b/src/render/composite.rs
@@ -7,21 +7,25 @@ pub const CHUNK_SIZE: usize = 16;
 pub fn image_buffer_blit(
     target: &mut ImageBuffer<Rgba<u8>, Vec<u8>>,
     source: &ImageBuffer<Rgba<u8>, Vec<u8>>,
-    offset: (u32, u32),
+    offset: (isize, isize),
 ) {
     for (x, y, source_pixel) in source.enumerate_pixels() {
-        let target_pixel = target.get_pixel_mut(x + offset.0, y + offset.1);
-        let sa = source_pixel.0[3] as u16;
-        let new_pixel = Rgba::from([
-            ((target_pixel.0[0] as u16 * (255 - sa)) / 255 + (source_pixel.0[0] as u16 * sa) / 255)
-                as u8,
-            ((target_pixel.0[1] as u16 * (255 - sa)) / 255 + (source_pixel.0[1] as u16 * sa) / 255)
-                as u8,
-            ((target_pixel.0[2] as u16 * (255 - sa)) / 255 + (source_pixel.0[2] as u16 * sa) / 255)
-                as u8,
-            255 - (((255 - target_pixel.0[3] as u16) * (255 - sa)) / 255) as u8,
-        ]);
-        *target_pixel = new_pixel;
+        let tx = x as isize + offset.0;
+        let ty = y as isize + offset.1;
+        if tx >= 0 && tx < target.width() as isize && ty >= 0 && ty < target.height() as isize {
+            let target_pixel = target.get_pixel_mut(tx as u32, ty as u32);
+            let sa = source_pixel.0[3] as u16;
+            let new_pixel = Rgba::from([
+                ((target_pixel.0[0] as u16 * (255 - sa)) / 255
+                    + (source_pixel.0[0] as u16 * sa) / 255) as u8,
+                ((target_pixel.0[1] as u16 * (255 - sa)) / 255
+                    + (source_pixel.0[1] as u16 * sa) / 255) as u8,
+                ((target_pixel.0[2] as u16 * (255 - sa)) / 255
+                    + (source_pixel.0[2] as u16 * sa) / 255) as u8,
+                255 - (((255 - target_pixel.0[3] as u16) * (255 - sa)) / 255) as u8,
+            ]);
+            *target_pixel = new_pixel;
+        }
     }
 }