Add screenshot functionality.

Cargo.lock

@@ -504,6 +504,7 @@ version = "0.1.0"
 dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "gl 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "image 0.21.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jemallocator 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "nfd 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "pathfinder_geometry 0.3.0",

demo/common/Cargo.toml

@@ -13,6 +13,11 @@ rayon = "1.0"
 sdl2 = "0.32"
 usvg = "0.4"
 
+[dependencies.image]
+version = "0.21"
+default-features = false
+features = ["png_codec"]
+
 [dependencies.pathfinder_geometry]
 path = "../../geometry"
 

demo/common/src/lib.rs

@@ -12,7 +12,8 @@
 
 use crate::ui::{DemoUI, UIAction, UIEvent};
 use clap::{App, Arg};
-use gl::types::GLsizei;
+use gl::types::{GLsizei, GLvoid};
+use image::ColorType;
 use jemallocator;
 use pathfinder_geometry::basic::point::{Point2DF32, Point2DI32, Point3DF32};
 use pathfinder_geometry::basic::rect::RectF32;
@@ -89,6 +90,7 @@ pub struct DemoApp {
     camera: Camera,
     frame_counter: u32,
     events: Vec<Event>,
+    pending_screenshot_path: Option<PathBuf>,
     exit: bool,
     mouselook_enabled: bool,
     dirty: bool,
@@ -164,6 +166,7 @@ impl DemoApp {
 
             camera,
             frame_counter: 0,
+            pending_screenshot_path: None,
             events: vec![],
             exit: false,
             mouselook_enabled: false,
@@ -342,6 +345,10 @@ impl DemoApp {
         self.draw_environment(&render_transform);
         self.render_vector_scene(&built_scene);
 
+        if self.pending_screenshot_path.is_some() {
+            self.take_screenshot();
+        }
+
         let rendering_time = self.renderer.shift_timer_query();
         self.renderer.debug_ui.add_sample(tile_time, rendering_time);
         self.renderer.debug_ui.draw();
@@ -499,6 +506,11 @@ impl DemoApp {
                 self.dirty = true;
             }
 
+            UIAction::TakeScreenshot(ref path) => {
+                self.pending_screenshot_path = Some((*path).clone());
+                self.dirty = true;
+            }
+
             UIAction::ZoomIn => {
                 if let Camera::TwoD(ref mut transform) = self.camera {
                     let scale = Point2DF32::splat(1.0 + CAMERA_ZOOM_AMOUNT_2D);
@@ -531,6 +543,17 @@ impl DemoApp {
         }
     }
 
+    fn take_screenshot(&mut self) {
+        let screenshot_path = self.pending_screenshot_path.take().unwrap();
+        let (drawable_width, drawable_height) = self.window.drawable_size();
+        let pixels = self.device.readback_pixels(drawable_width, drawable_height);
+        image::save_buffer(screenshot_path,
+                           &pixels,
+                           drawable_width,
+                           drawable_height,
+                           ColorType::RGBA(8)).unwrap();
+    }
+
     fn background_color(&self) -> ColorU {
         if self.ui.dark_background_enabled { DARK_BG_COLOR } else { LIGHT_BG_COLOR }
     }
@@ -817,6 +840,29 @@ impl DemoDevice {
             gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT | gl::STENCIL_BUFFER_BIT);
         }
     }
+
+    fn readback_pixels(&self, width: u32, height: u32) -> Vec<u8> {
+        let mut pixels = vec![0; width as usize * height as usize * 4];
+        unsafe {
+            gl::BindFramebuffer(gl::FRAMEBUFFER, 0);
+            gl::ReadPixels(0, 0,
+                           width as GLsizei, height as GLsizei,
+                           gl::RGBA,
+                           gl::UNSIGNED_BYTE,
+                           pixels.as_mut_ptr() as *mut GLvoid);
+        }
+
+        // Flip right-side-up.
+        let stride = width as usize * 4;
+        for y in 0..(height as usize / 2) {
+            let (index_a, index_b) = (y * stride, (height as usize - y - 1) * stride);
+            for offset in 0..stride {
+                pixels.swap(index_a + offset, index_b + offset);
+            }
+        }
+
+        pixels
+    }
 }
 
 struct GroundProgram {

demo/common/src/ui.rs

@@ -30,19 +30,23 @@ const SLIDER_KNOB_HEIGHT: i32 = 48;
 const EFFECTS_PANEL_WIDTH: i32 = 550;
 const EFFECTS_PANEL_HEIGHT: i32 = BUTTON_HEIGHT * 3 + PADDING * 4;
 
-const BACKGROUND_SWITCH_X: i32 = PADDING + (BUTTON_WIDTH + PADDING) * 2 + PADDING + SWITCH_SIZE;
+const OPEN_BUTTON_X:       i32 = PADDING + (BUTTON_WIDTH + PADDING) * 1;
+const SCREENSHOT_BUTTON_X: i32 = PADDING + (BUTTON_WIDTH + PADDING) * 2;
+const THREE_D_SWITCH_X:    i32 = PADDING + (BUTTON_WIDTH + PADDING) * 3;
+const BACKGROUND_SWITCH_X: i32 = PADDING + (BUTTON_WIDTH + PADDING) * 3 + PADDING + SWITCH_SIZE;
 
-const ROTATE_PANEL_X: i32 = PADDING + (BUTTON_WIDTH + PADDING) * 2 + (PADDING + SWITCH_SIZE) * 2;
+const ROTATE_PANEL_X: i32 = PADDING + (BUTTON_WIDTH + PADDING) * 3 + (PADDING + SWITCH_SIZE) * 2;
 const ROTATE_PANEL_WIDTH: i32 = SLIDER_WIDTH + PADDING * 2;
 const ROTATE_PANEL_HEIGHT: i32 = PADDING * 2 + SLIDER_HEIGHT;
 
-static EFFECTS_PNG_NAME: &'static str = "demo-effects";
+static EFFECTS_PNG_NAME:    &'static str = "demo-effects";
-static OPEN_PNG_NAME: &'static str = "demo-open";
+static OPEN_PNG_NAME:       &'static str = "demo-open";
-static ROTATE_PNG_NAME: &'static str = "demo-rotate";
+static ROTATE_PNG_NAME:     &'static str = "demo-rotate";
-static ZOOM_IN_PNG_NAME: &'static str = "demo-zoom-in";
+static ZOOM_IN_PNG_NAME:    &'static str = "demo-zoom-in";
-static ZOOM_OUT_PNG_NAME: &'static str = "demo-zoom-out";
+static ZOOM_OUT_PNG_NAME:   &'static str = "demo-zoom-out";
-static BG_LIGHT_PNG_NAME: &'static str = "demo-bg-light";
+static BG_LIGHT_PNG_NAME:   &'static str = "demo-bg-light";
-static BG_DARK_PNG_NAME: &'static str = "demo-bg-dark";
+static BG_DARK_PNG_NAME:    &'static str = "demo-bg-dark";
+static SCREENSHOT_PNG_NAME: &'static str = "demo-screenshot";
 
 pub struct DemoUI {
     effects_texture: Texture,
@@ -52,6 +56,7 @@ pub struct DemoUI {
     zoom_out_texture: Texture,
     bg_light_texture: Texture,
     bg_dark_texture: Texture,
+    screenshot_texture: Texture,
 
     effects_panel_visible: bool,
     rotate_panel_visible: bool,
@@ -73,6 +78,7 @@ impl DemoUI {
         let zoom_out_texture = device.create_texture_from_png(ZOOM_OUT_PNG_NAME);
         let bg_light_texture = device.create_texture_from_png(BG_LIGHT_PNG_NAME);
         let bg_dark_texture = device.create_texture_from_png(BG_DARK_PNG_NAME);
+        let screenshot_texture = device.create_texture_from_png(SCREENSHOT_PNG_NAME);
 
         DemoUI {
             effects_texture,
@@ -82,6 +88,7 @@ impl DemoUI {
             zoom_out_texture,
             bg_light_texture,
             bg_dark_texture,
+            screenshot_texture,
             three_d_enabled: options.three_d,
             dark_background_enabled: true,
             effects_panel_visible: false,
@@ -107,27 +114,36 @@ impl DemoUI {
         }
 
         // Draw open button.
-        let open_button_x = PADDING + BUTTON_WIDTH + PADDING;
+        let lower_button_y = bottom - BUTTON_HEIGHT;
-        let open_button_y = bottom - BUTTON_HEIGHT;
+        let open_button_position = Point2DI32::new(OPEN_BUTTON_X, lower_button_y);
-        let open_button_position = Point2DI32::new(open_button_x, open_button_y);
         if self.draw_button(debug_ui, event, open_button_position, &self.open_texture) {
             if let Ok(Response::Okay(file)) = nfd::open_file_dialog(Some("svg"), None) {
                 *action = UIAction::OpenFile(PathBuf::from(file));
             }
         }
 
+        // Draw screenshot button.
+        let screenshot_button_position = Point2DI32::new(SCREENSHOT_BUTTON_X, lower_button_y);
+        if self.draw_button(debug_ui,
+                            event,
+                            screenshot_button_position,
+                            &self.screenshot_texture) {
+            if let Ok(Response::Okay(file)) = nfd::open_save_dialog(Some("png"), None) {
+                *action = UIAction::TakeScreenshot(PathBuf::from(file));
+            }
+        }
+
         // Draw 3D switch.
-        let threed_switch_x = PADDING + (BUTTON_WIDTH + PADDING) * 2;
+        let three_d_switch_origin = Point2DI32::new(THREE_D_SWITCH_X, lower_button_y);
-        let threed_switch_origin = Point2DI32::new(threed_switch_x, open_button_y);
         self.three_d_enabled = self.draw_text_switch(debug_ui,
                                                      event,
-                                                     threed_switch_origin,
+                                                     three_d_switch_origin,
                                                      "2D",
                                                      "3D",
                                                      self.three_d_enabled);
 
         // Draw background switch.
-        let background_switch_origin = Point2DI32::new(BACKGROUND_SWITCH_X, open_button_y);
+        let background_switch_origin = Point2DI32::new(BACKGROUND_SWITCH_X, lower_button_y);
         self.dark_background_enabled = self.draw_image_switch(debug_ui,
                                                               event,
                                                               background_switch_origin,
@@ -354,6 +370,7 @@ impl DemoUI {
 pub enum UIAction {
     None,
     OpenFile(PathBuf),
+    TakeScreenshot(PathBuf),
     ZoomIn,
     ZoomOut,
     Rotate(f32),