added Image::draw_image_partial

src/image.rs

@@ -1,4 +1,5 @@
 use crate::vec2::Vec2;
+use crate::Rect;
 use std::fs;
 use std::fs::File;
 
@@ -53,9 +54,22 @@ impl Image {
     }
 
     pub fn draw_image(&mut self, pos: Vec2<i32>, image: &Image) {
+        self.draw_image_partial(
+            pos,
+            image,
+            Rect {
+                pos: Vec2::zero(),
+                size: image.size,
+            },
+        );
+    }
+
+    pub fn draw_image_partial(&mut self, pos: Vec2<i32>, image: &Image, src_rect: Rect<i32>) {
         //todo: write proper implementation later
-        for y in 0..image.size.y {
-            for x in 0..image.size.x {
+        for y in 0..src_rect.size.y {
+            for x in 0..src_rect.size.x {
+                let x = x + src_rect.pos.x;
+                let y = y + src_rect.pos.y;
                 //todo: implement better(very stupid to do per pixel)
                 if x + pos.x >= 0
                     && y + pos.y >= 0