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107 lines
4.4 KiB
Rust
107 lines
4.4 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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use app_units::{Au, MAX_AU};
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use euclid::point::Point2D;
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use euclid::rect::Rect;
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use euclid::size::Size2D;
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use std::i32;
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use std::ops::Add;
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// Units for use with euclid::length and euclid::scale_factor.
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/// A normalized "pixel" at the default resolution for the display.
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///
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/// Like the CSS "px" unit, the exact physical size of this unit may vary between devices, but it
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/// should approximate a device-independent reference length. This unit corresponds to Android's
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/// "density-independent pixel" (dip), Mac OS X's "point", and Windows "device-independent pixel."
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///
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/// The relationship between DevicePixel and ScreenPx is defined by the OS. On most low-dpi
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/// screens, one ScreenPx is equal to one DevicePixel. But on high-density screens it can be
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/// some larger number. For example, by default on Apple "retina" displays, one ScreenPx equals
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/// two DevicePixels. On Android "MDPI" displays, one ScreenPx equals 1.5 device pixels.
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///
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/// The ratio between ScreenPx and DevicePixel for a given display be found by calling
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/// `servo::windowing::WindowMethods::hidpi_factor`.
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#[derive(Debug, Copy, Clone)]
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pub enum ScreenPx {}
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/// One CSS "px" in the coordinate system of the "initial viewport":
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/// http://www.w3.org/TR/css-device-adapt/#initial-viewport
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///
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/// ViewportPx is equal to ScreenPx times a "page zoom" factor controlled by the user. This is
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/// the desktop-style "full page" zoom that enlarges content but then reflows the layout viewport
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/// so it still exactly fits the visible area.
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///
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/// At the default zoom level of 100%, one PagePx is equal to one ScreenPx. However, if the
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/// document is zoomed in or out then this scale may be larger or smaller.
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#[derive(RustcEncodable, Debug, Copy, Clone)]
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pub enum ViewportPx {}
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/// One CSS "px" in the root coordinate system for the content document.
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///
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/// PagePx is equal to ViewportPx multiplied by a "viewport zoom" factor controlled by the user.
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/// This is the mobile-style "pinch zoom" that enlarges content without reflowing it. When the
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/// viewport zoom is not equal to 1.0, then the layout viewport is no longer the same physical size
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/// as the viewable area.
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#[derive(RustcEncodable, Debug, Copy, Clone)]
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pub enum PagePx {}
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// In summary, the hierarchy of pixel units and the factors to convert from one to the next:
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//
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// DevicePixel
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// / hidpi_ratio => ScreenPx
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// / desktop_zoom => ViewportPx
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// / pinch_zoom => PagePx
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// An Au is an "App Unit" and represents 1/60th of a CSS pixel. It was
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// originally proposed in 2002 as a standard unit of measure in Gecko.
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// See https://bugzilla.mozilla.org/show_bug.cgi?id=177805 for more info.
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pub static ZERO_POINT: Point2D<Au> = Point2D {
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x: Au(0),
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y: Au(0),
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};
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pub static ZERO_RECT: Rect<Au> = Rect {
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origin: Point2D {
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x: Au(0),
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y: Au(0),
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},
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size: Size2D {
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width: Au(0),
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height: Au(0),
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}
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};
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pub static MAX_RECT: Rect<Au> = Rect {
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origin: Point2D {
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x: Au(i32::MIN / 2),
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y: Au(i32::MIN / 2),
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},
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size: Size2D {
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width: MAX_AU,
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height: MAX_AU,
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}
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};
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/// Returns true if the rect contains the given point. Points on the top or left sides of the rect
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/// are considered inside the rectangle, while points on the right or bottom sides of the rect are
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/// not considered inside the rectangle.
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pub fn rect_contains_point<T: PartialOrd + Add<T, Output=T>>(rect: Rect<T>, point: Point2D<T>) -> bool {
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point.x >= rect.origin.x && point.x < rect.origin.x + rect.size.width &&
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point.y >= rect.origin.y && point.y < rect.origin.y + rect.size.height
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}
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/// A helper function to convert a rect of `f32` pixels to a rect of app units.
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pub fn f32_rect_to_au_rect(rect: Rect<f32>) -> Rect<Au> {
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Rect::new(Point2D::new(Au::from_f32_px(rect.origin.x), Au::from_f32_px(rect.origin.y)),
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Size2D::new(Au::from_f32_px(rect.size.width), Au::from_f32_px(rect.size.height)))
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}
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/// A helper function to convert a rect of `Au` pixels to a rect of f32 units.
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pub fn au_rect_to_f32_rect(rect: Rect<Au>) -> Rect<f32> {
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Rect::new(Point2D::new(rect.origin.x.to_f32_px(), rect.origin.y.to_f32_px()),
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Size2D::new(rect.size.width.to_f32_px(), rect.size.height.to_f32_px()))
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}
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