Graphics: Fix aspect ratio of images not being preserved when only a single dimension of the destination rectangle is specified

Fixes #7380

docs/changelog.rst

@@ -55,6 +55,9 @@ Detailed list of changes
 
 - :opt:`paste_actions`: Fix ``replace-newline`` not working with ``confirm`` (:iss:`7374`)
 
+- Graphics: Fix aspect ratio of images not being preserved when only a single
+  dimension of the destination rectangle is specified (:iss:`7380`)
+
 0.34.1 [2024-04-19]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

kitty/graphics.c

@@ -1220,13 +1220,26 @@ grman_update_layers(GraphicsManager *self, unsigned int scrolled_by, float scree
                 }
             }
             r.top = y0 - start_row * dy - dy * (float)ref->cell_y_offset / (float)cell.height;
-            if (ref->num_rows > 0) r.bottom = y0 - (start_row + (int32_t)ref->num_rows) * dy;
-            else r.bottom = r.top - screen_height * (float)ref->src_height / screen_height_px;
-            if (r.top <= screen_bottom || r.bottom >= screen_top) continue;  // not visible
-
             r.left = screen_left + start_column * dx + dx * (float)ref->cell_x_offset / (float) cell.width;
-            if (ref->num_cols > 0) r.right = screen_left + (start_column + (int32_t)ref->num_cols) * dx;
+
-            else r.right = r.left + screen_width * (float)ref->src_width / screen_width_px;
+            int32_t nr = ref->num_rows, nc = ref->num_cols;
+            if (nr) {
+                r.bottom = y0 - (start_row + nr) * dy;
+                if (nc) r.right = screen_left + (start_column + nc) * dx;
+                else {
+                    double height_px = ((r.top - r.bottom) / screen_height) * screen_height_px;
+                    double width_px = height_px * ref->src_width / (double) ref->src_height;
+                    r.right = r.left + (float)((width_px / screen_width_px) * screen_width);
+                }
+            } else {
+                if (nc) r.right = screen_left + (start_column + nc) * dx;
+                else r.right = r.left + screen_width * (float)ref->src_width / screen_width_px;
+                double width_px = ((r.right - r.left) / screen_width) * screen_width_px;
+                double height_px = width_px * ref->src_height / (double)ref->src_width;
+                r.bottom = r.top - (float)((height_px / screen_height_px) * screen_height);
+            }
+
+            if (r.top <= screen_bottom || r.bottom >= screen_top) continue;  // not visible
 
             if (ref->z_index < ((int32_t)INT32_MIN/2))
                 self->num_of_below_refs++;

kitty_tests/graphics.py

@@ -555,17 +555,21 @@ class TestGraphics(BaseTest):
         rect_eq(l0[0]['dest_rect'], -1, 1, -1 + dx, 1 - dy)
         self.ae(l0[0]['group_count'], 1)
         self.ae(s.cursor.x, 1), self.ae(s.cursor.y, 0)
-        iid, (code, idstr) = put_ref(s, num_cols=s.columns, x_off=2, y_off=1, width=3, height=5, cell_x_off=3, cell_y_off=1, z=-1, placement_id=17)
+        src_width, src_height = 3, 5
+        iid, (code, idstr) = put_ref(s, num_cols=s.columns, x_off=2, y_off=1, width=src_width, height=src_height,
+                                     cell_x_off=3, cell_y_off=1, z=-1, placement_id=17)
         self.ae(idstr, f'i={iid},p=17')
         l2 = layers(s)
         self.ae(len(l2), 2)
+        self.ae(l2[1], l0[0])
         rect_eq(l2[0]['src_rect'], 2 / 10, 1 / 20, (2 + 3) / 10, (1 + 5)/20)
-        left, top = -1 + dx + 3 * dx / cw, 1 - 1 * dy / ch
-        rect_eq(l2[0]['dest_rect'], left, top, -1 + (1 + s.columns) * dx, top - dy * 5 / ch)
-        rect_eq(l2[1]['src_rect'], 0, 0, 1, 1)
-        rect_eq(l2[1]['dest_rect'], -1, 1, -1 + dx, 1 - dy)
         self.ae(l2[0]['group_count'], 2)
-        self.ae(l2[1]['group_count'], 1)
+        left, top = -1 + dx + 3 * dx / cw, 1 - 1 * dy / ch
+        right = -1 + (1 + s.columns) * dx
+        width_px = ((right - left) / 2) * (cw * s.columns)
+        height_px = width_px * (src_height / src_width)
+        bottom = top - (height_px / (ch * s.lines)) * 2
+        rect_eq(l2[0]['dest_rect'], left, top, right, bottom)
         self.ae(s.cursor.x, 0), self.ae(s.cursor.y, 1)
         self.ae(put_image(s, 10, 20, cursor_movement=1)[1], 'OK')
         self.ae(s.cursor.x, 0), self.ae(s.cursor.y, 1)