Add a global gesture to take a screenshot

doc/MANUAL.md

@@ -71,6 +71,8 @@ Hold the next/previous page icon to go the next/previous chapter.
 
 # Home & Reader
 
+Tap two diagonally opposite corners to take a screenshot.
+
 ## Menus
 
 You can select a menu entry *without closing the menu* by holding it.

src/app.rs

@@ -25,7 +25,7 @@ use crate::settings::{Settings, SETTINGS_PATH};
 use crate::frontlight::{Frontlight, StandardFrontlight, NaturalFrontlight, PremixedFrontlight};
 use crate::lightsensor::{LightSensor, KoboLightSensor};
 use crate::battery::{Battery, KoboBattery};
-use crate::geom::Rectangle;
+use crate::geom::{Rectangle, Edge};
 use crate::view::home::Home;
 use crate::view::reader::Reader;
 use crate::view::confirmation::Confirmation;
@@ -564,7 +564,17 @@ pub fn run() -> Result<(), Error> {
  power_off(&mut history, &mut updating, &mut context);
  exit_status = ExitStatus::PowerOff;
  break;
- }
+ },
+ GestureEvent::MultiTap(points) => {
+ let mut rect = context.fb.rect();
+ let w = rect.width() as i32;
+ let h = rect.height() as i32;
+ let m = w.min(h);
+ rect.shrink(&Edge::uniform(m / 12));
+ if (points[0].dist2(points[1]) >= rect.diag2()) {
+ tx.send(Event::Select(EntryId::TakeScreenshot)).unwrap();
+ }
+ },
  _ => {
  handle_event(view.as_mut(), &evt, &tx, &mut bus, &mut context);
  },

src/geom.rs

@@ -453,6 +453,10 @@ impl Rectangle {
  }
  }
 
+ pub fn diag2(&self) -> u32 {
+ self.min.dist2(self.max)
+ }
+
  pub fn includes(&self, pt: Point) -> bool {
  self.min.x <= pt.x && pt.x < self.max.x &&
  self.min.y <= pt.y && pt.y < self.max.y