Add a pen which paints glow effects

cyberpunk-splash/src/main.rs

@@ -143,6 +143,15 @@ impl SplashPrivate {
     }
 
     fn redraw_background(&self) {
+        let pen = GlowPen::new(
+            *self.width.borrow(),
+            *self.height.borrow(),
+            2.,
+            8.,
+            8.,
+            (0.7, 0., 1.),
+        );
+
         let background =
             ImageSurface::create(Format::Rgb24, *self.width.borrow(), *self.height.borrow())
                 .unwrap();
@@ -175,11 +184,8 @@ impl SplashPrivate {
                 invert: false,
             };
 
-            context.set_line_cap(LineCap::Round);
+            title_cutout.draw(&pen);
-            context.set_source_rgb(0.7, 0., 1.);
+            pen.stroke();
-            context.set_line_width(2.);
-            title_cutout.draw(&context);
-            let _ = context.stroke();
         }
 
         {
@@ -200,7 +206,6 @@ impl SplashPrivate {
         }
 
         {
-            context.set_source_rgb(0.7, 0., 1.);
             AsymLine {
                 orientation: gtk::Orientation::Horizontal,
                 start_x: 100.,
@@ -210,8 +215,8 @@ impl SplashPrivate {
                 total_length: 650.,
                 invert: true,
             }
-            .draw(&context);
+            .draw(&pen);
-            let _ = context.stroke();
+            pen.stroke();
         }
 
         {
@@ -225,10 +230,14 @@ impl SplashPrivate {
                 total_length: 650.,
                 invert: false,
             }
-            .draw(&context);
+            .draw(&pen);
-            let _ = context.stroke();
+            pen.stroke();
         }
 
+        let tracery = pen.finish();
+        let _ = context.set_source(tracery);
+        let _ = context.paint();
+
         let background = context.pop_group().unwrap();
 
         *self.background.borrow_mut() = background;
@@ -394,7 +403,7 @@ struct AsymLineCutout {
 }
 
 impl AsymLineCutout {
-    fn draw(&self, context: &Context) {
+    fn draw(&self, pen: &impl Pen) {
         let dodge = if self.invert {
             self.height
         } else {
@@ -402,17 +411,17 @@ impl AsymLineCutout {
         };
         match self.orientation {
             gtk::Orientation::Horizontal => {
-                context.move_to(self.start_x, self.start_y);
+                pen.move_to(self.start_x, self.start_y);
-                context.line_to(self.start_x + self.start_length, self.start_y);
+                pen.line_to(self.start_x + self.start_length, self.start_y);
-                context.line_to(
+                pen.line_to(
                     self.start_x + self.start_length + self.height,
                     self.start_y + dodge,
                 );
-                context.line_to(
+                pen.line_to(
                     self.start_x + self.start_length + self.height + self.cutout_length,
                     self.start_y + dodge,
                 );
-                context.line_to(
+                pen.line_to(
                     self.start_x
                         + self.start_length
                         + self.height
@@ -420,20 +429,20 @@ impl AsymLineCutout {
                         + (self.height / 2.),
                     self.start_y + dodge / 2.,
                 );
-                context.line_to(self.total_length, self.start_y + dodge / 2.);
+                pen.line_to(self.total_length, self.start_y + dodge / 2.);
             }
             gtk::Orientation::Vertical => {
-                context.move_to(self.start_x, self.start_y);
+                pen.move_to(self.start_x, self.start_y);
-                context.line_to(self.start_x, self.start_y + self.start_length);
+                pen.line_to(self.start_x, self.start_y + self.start_length);
-                context.line_to(
+                pen.line_to(
                     self.start_x + dodge,
                     self.start_y + self.start_length + self.height,
                 );
-                context.line_to(
+                pen.line_to(
                     self.start_x + dodge,
                     self.start_y + self.start_length + self.height + self.cutout_length,
                 );
-                context.line_to(
+                pen.line_to(
                     self.start_x + dodge / 2.,
                     self.start_y
                         + self.start_length
@@ -441,7 +450,7 @@ impl AsymLineCutout {
                         + self.cutout_length
                         + (self.height / 2.),
                 );
-                context.line_to(self.start_x + dodge / 2., self.total_length);
+                pen.line_to(self.start_x + dodge / 2., self.total_length);
             }
             _ => panic!("unknown orientation"),
         }
@@ -459,7 +468,7 @@ struct AsymLine {
 }
 
 impl AsymLine {
-    fn draw(&self, context: &Context) {
+    fn draw(&self, pen: &impl Pen) {
         let dodge = if self.invert {
             self.height
         } else {
@@ -467,13 +476,13 @@ impl AsymLine {
         };
         match self.orientation {
             gtk::Orientation::Horizontal => {
-                context.move_to(self.start_x, self.start_y);
+                pen.move_to(self.start_x, self.start_y);
-                context.line_to(self.start_x + self.start_length, self.start_y);
+                pen.line_to(self.start_x + self.start_length, self.start_y);
-                context.line_to(
+                pen.line_to(
                     self.start_x + self.start_length + self.height,
                     self.start_y + dodge,
                 );
-                context.line_to(self.start_x + self.total_length, self.start_y + dodge);
+                pen.line_to(self.start_x + self.total_length, self.start_y + dodge);
             }
             gtk::Orientation::Vertical => {}
             _ => panic!("unknown orientation"),
@@ -551,6 +560,80 @@ impl SlashMeter {
     }
 }
 
+trait Pen {
+    fn move_to(&self, x: f64, y: f64);
+    fn line_to(&self, x: f64, y: f64);
+    fn stroke(&self);
+
+    fn finish(self) -> Pattern;
+}
+
+struct GlowPen {
+    blur_context: Context,
+    draw_context: Context,
+
+    line_width: f64,
+    blur_line_width: f64,
+    blur_size: f64,
+}
+
+impl GlowPen {
+    fn new(
+        width: i32,
+        height: i32,
+        line_width: f64,
+        blur_line_width: f64,
+        blur_size: f64,
+        color: (f64, f64, f64),
+    ) -> Self {
+        let blur_context =
+            Context::new(ImageSurface::create(Format::Rgb24, width, height).unwrap()).unwrap();
+        blur_context.set_line_width(blur_line_width);
+        blur_context.set_source_rgba(color.0, color.1, color.2, 0.5);
+        blur_context.push_group();
+        blur_context.set_line_cap(LineCap::Round);
+
+        let draw_context =
+            Context::new(ImageSurface::create(Format::Rgb24, width, height).unwrap()).unwrap();
+        draw_context.set_line_width(line_width);
+        draw_context.set_source_rgb(color.0, color.1, color.2);
+        draw_context.push_group();
+        draw_context.set_line_cap(LineCap::Round);
+
+        Self {
+            blur_context,
+            draw_context,
+            line_width,
+            blur_line_width,
+            blur_size,
+        }
+    }
+}
+
+impl Pen for GlowPen {
+    fn move_to(&self, x: f64, y: f64) {
+        self.blur_context.move_to(x, y);
+        self.draw_context.move_to(x, y);
+    }
+
+    fn line_to(&self, x: f64, y: f64) {
+        self.blur_context.line_to(x, y);
+        self.draw_context.line_to(x, y);
+    }
+
+    fn stroke(&self) {
+        self.blur_context.stroke();
+        self.draw_context.stroke();
+    }
+
+    fn finish(self) -> Pattern {
+        let foreground = self.draw_context.pop_group().unwrap();
+        self.blur_context.set_source(foreground).unwrap();
+        self.blur_context.paint().unwrap();
+        self.blur_context.pop_group().unwrap()
+    }
+}
+
 fn main() {
     let app = gtk::Application::builder()
         .application_id("com.luminescent-dreams.cyberpunk-splash")