[drag-and-drop] Add ability to translate layers and PaintCmd:s

egui/src/layers.rs

@@ -1,6 +1,6 @@
 use ahash::AHashMap;
 
-use crate::{math::Rect, paint::PaintCmd, Id};
+use crate::{math::Rect, paint::PaintCmd, Id, *};
 
 /// Different layer categories
 #[derive(Clone, Copy, Debug, Hash, Eq, PartialEq, Ord, PartialOrd)]
@@ -105,6 +105,14 @@ impl PaintList {
         assert!(idx.0 < self.0.len());
         self.0[idx.0] = (clip_rect, cmd);
     }
+
+    /// Translate each paint-command and clip rectangle by this much, in-place
+    pub fn translate(&mut self, delta: Vec2) {
+        for (clip_rect, cmd) in &mut self.0 {
+            *clip_rect = clip_rect.translate(delta);
+            cmd.translate(delta);
+        }
+    }
 }
 
 #[derive(Clone, Default)]

egui/src/paint/command.rs

@@ -3,6 +3,7 @@ use {
     crate::{
         align::{anchor_rect, Align},
         math::{Pos2, Rect},
+        *,
     },
 };
 
@@ -152,6 +153,35 @@ impl PaintCmd {
             super::TextureId::Egui
         }
     }
+
+    /// Translate location by this much, in-place
+    pub fn translate(&mut self, delta: Vec2) {
+        match self {
+            PaintCmd::Noop => {}
+            PaintCmd::Circle { center, .. } => {
+                *center += delta;
+            }
+            PaintCmd::LineSegment { points, .. } => {
+                for p in points {
+                    *p += delta;
+                }
+            }
+            PaintCmd::Path { points, .. } => {
+                for p in points {
+                    *p += delta;
+                }
+            }
+            PaintCmd::Rect { rect, .. } => {
+                *rect = rect.translate(delta);
+            }
+            PaintCmd::Text { pos, .. } => {
+                *pos += delta;
+            }
+            PaintCmd::Triangles(triangles) => {
+                triangles.translate(delta);
+            }
+        }
+    }
 }
 
 #[derive(Clone, Copy, Debug, Default, PartialEq)]

egui/src/paint/tessellator.rs

@@ -243,6 +243,13 @@ impl Triangles {
         }
         output
     }
+
+    /// Translate location by this much, in-place
+    pub fn translate(&mut self, delta: Vec2) {
+        for v in &mut self.vertices {
+            v.pos += delta;
+        }
+    }
 }
 
 // ----------------------------------------------------------------------------
@@ -697,7 +704,7 @@ fn tessellate_paint_command(
             if triangles.is_valid() {
                 out.append(triangles);
             } else {
-                debug_assert!(false, "Ivalid Triangles in PaintCmd::Traingles");
+                debug_assert!(false, "Invalid Triangles in PaintCmd::Triangles");
             }
         }
         PaintCmd::LineSegment { points, stroke } => {