Merge pull request #58 from gabm/fix-coordinate-remapping

fix coordinate remapping

.vscode/launch.json

@@ -21,7 +21,8 @@
             },
             "args": [
                 "--filename",
-                "/home/gabm/Pictures/Screenshots/satty-20240109-22:19:08.png",
+                "/home/gabm/Pictures/Screenshots/satty-20240219-14:19:29.png",
+                //"/home/gabm/Pictures/Screenshots/satty-20240109-22:19:08.png",
                 //"/home/gabm/Pictures/Wallpaper/torres_1.jpg"
                 "--output-filename",
                 "/tmp/out.png"

src/femtovg_area/imp.rs

@@ -38,6 +38,7 @@ pub struct FemtoVgAreaMut {
     active_tool: Rc<RefCell<dyn Tool>>,
     crop_tool: Rc<RefCell<CropTool>>,
     scale_factor: f32,
+    offset: Vec2D,
     drawables: Vec<Box<dyn Drawable>>,
     redo_stack: Vec<Box<dyn Drawable>>,
 }
@@ -86,7 +87,7 @@ impl GLAreaImpl for FemtoVGArea {
         self.inner()
             .as_mut()
             .expect("Did you call init before using FemtoVgArea?")
-            .update_scale_factor(canvas);
+            .update_transformation(canvas);
     }
     fn render(&self, _context: &gtk::gdk::GLContext) -> bool {
         self.ensure_canvas();
@@ -147,6 +148,7 @@ impl FemtoVGArea {
             active_tool,
             crop_tool,
             scale_factor: 1.0,
+            offset: Vec2D::zero(),
             drawables: Vec::new(),
             redo_stack: Vec::new(),
         });
@@ -299,13 +301,8 @@ impl FemtoVgAreaMut {
 
         // setup transform to image coordinates
         let mut transform = Transform2D::identity();
-        let offset_x =
-            canvas.width() as f32 - self.background_image.width() as f32 * self.scale_factor;
-        let offset_y =
-            canvas.height() as f32 - self.background_image.height() as f32 * self.scale_factor;
-
         transform.scale(self.scale_factor, self.scale_factor);
-        transform.translate(offset_x / 2.0, offset_y / 2.0);
+        transform.translate(self.offset.x, self.offset.y);
 
         canvas.reset_transform();
         canvas.set_transform(&transform);
@@ -440,7 +437,11 @@ impl FemtoVgAreaMut {
         Ok(background_image_id)
     }
 
-    pub fn update_scale_factor(&mut self, canvas: &mut femtovg::Canvas<femtovg::renderer::OpenGl>) {
+    pub fn update_transformation(
+        &mut self,
+        canvas: &mut femtovg::Canvas<femtovg::renderer::OpenGl>,
+    ) {
+        // calculate scale
         let image_width = self.background_image.width() as f32;
         let image_height = self.background_image.height() as f32;
         let aspect_ratio = image_width / image_height;
@@ -453,9 +454,26 @@ impl FemtoVgAreaMut {
         } else {
             canvas_height * aspect_ratio / image_width
         };
+
+        // calculate offset
+        self.offset = Vec2D::new(
+            (canvas.width() as f32 - self.background_image.width() as f32 * self.scale_factor)
+                / 2.0,
+            (canvas.height() as f32 - self.background_image.height() as f32 * self.scale_factor)
+                / 2.0,
+        );
     }
 
-    pub fn get_scale_factor(&self) -> f32 {
-        self.scale_factor
+    pub fn abs_canvas_to_image_coordinates(&self, input: Vec2D, dpi_scale_factor: f32) -> Vec2D {
+        Vec2D::new(
+            (input.x * dpi_scale_factor - self.offset.x) / self.scale_factor,
+            (input.y * dpi_scale_factor - self.offset.y) / self.scale_factor,
+        )
+    }
+    pub fn rel_canvas_to_image_coordinates(&self, input: Vec2D, dpi_scale_factor: f32) -> Vec2D {
+        Vec2D::new(
+            input.x * dpi_scale_factor / self.scale_factor,
+            input.y * dpi_scale_factor / self.scale_factor,
+        )
     }
 }

src/femtovg_area/mod.rs

@@ -10,6 +10,7 @@ use relm4::{
 };
 
 use crate::{
+    math::Vec2D,
     sketch_board::{Action, SketchBoardInput},
     tools::{CropTool, Drawable, Tool},
 };
@@ -59,16 +60,20 @@ impl FemtoVGArea {
         self.imp().request_render(action);
     }
 
-    pub fn get_scale_factor(&self) -> f32 {
-        let renderer_scale_factor = self
-            .imp()
+    pub fn abs_canvas_to_image_coordinates(&self, input: Vec2D) -> Vec2D {
+        self.imp()
             .inner()
             .as_mut()
             .expect("Did you call init before using FemtoVgArea?")
-            .get_scale_factor();
-        let dpi_scale_factor = self.scale_factor() as f32;
+            .abs_canvas_to_image_coordinates(input, self.scale_factor() as f32)
+    }
 
-        renderer_scale_factor / dpi_scale_factor
+    pub fn rel_canvas_to_image_coordinates(&self, input: Vec2D) -> Vec2D {
+        self.imp()
+            .inner()
+            .as_mut()
+            .expect("Did you call init before using FemtoVgArea?")
+            .rel_canvas_to_image_coordinates(input, self.scale_factor() as f32)
     }
     pub fn init(
         &mut self,

src/sketch_board.rs

@@ -70,7 +70,7 @@ pub enum TextEventMsg {
     Commit(String),
 }
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub enum MouseEventType {
     BeginDrag,
     EndDrag,
@@ -122,14 +122,16 @@ impl From<u32> for MouseButton {
 }
 
 impl InputEvent {
-    fn screen2image(p: &mut Vec2D, scale: f32) {
-        p.x /= scale;
-        p.y /= scale;
-    }
-
-    fn remap_event_coordinates(&mut self, scale: f32) {
+    fn remap_event_coordinates(&mut self, renderer: &FemtoVGArea) {
         if let InputEvent::Mouse(me) = self {
-            Self::screen2image(&mut me.pos, scale)
+            match me.type_ {
+                MouseEventType::BeginDrag | MouseEventType::Click => {
+                    me.pos = renderer.abs_canvas_to_image_coordinates(me.pos)
+                }
+                MouseEventType::EndDrag | MouseEventType::UpdateDrag => {
+                    me.pos = renderer.rel_canvas_to_image_coordinates(me.pos)
+                }
+            }
         };
     }
 }
@@ -440,7 +442,7 @@ impl Component for SketchBoard {
                             .handle_event(ToolEvent::Input(ie))
                     }
                 } else {
-                    ie.remap_event_coordinates(self.renderer.get_scale_factor());
+                    ie.remap_event_coordinates(&self.renderer);
                     self.active_tool
                         .borrow_mut()
                         .handle_event(ToolEvent::Input(ie))