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84 lines
3 KiB
Rust
84 lines
3 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 https://mozilla.org/MPL/2.0/. */
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#[macro_use]
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extern crate malloc_size_of_derive;
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use app_units::{Au, MAX_AU, MIN_AU};
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use euclid::{
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default::{Point2D, Rect, Size2D},
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Length,
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};
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use std::f32;
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use webrender_api::units::{FramebufferPixel, LayoutPoint, LayoutRect, LayoutSize};
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// Units for use with euclid::length and euclid::scale_factor.
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pub type FramebufferUintLength = Length<u32, FramebufferPixel>;
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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 DeviceIndependentPixel is defined by the OS. On most low-dpi
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/// screens, one DeviceIndependentPixel 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 DeviceIndependentPixel equals
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/// two DevicePixels. On Android "MDPI" displays, one DeviceIndependentPixel equals 1.5 device pixels.
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///
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/// The ratio between DeviceIndependentPixel and DevicePixel for a given display be found by calling
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/// `servo::windowing::WindowMethods::hidpi_factor`.
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#[derive(Clone, Copy, Debug, MallocSizeOf)]
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pub enum DeviceIndependentPixel {}
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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 trait MaxRect {
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fn max_rect() -> Self;
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}
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impl MaxRect for Rect<Au> {
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#[inline]
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fn max_rect() -> Rect<Au> {
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Rect::new(
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Point2D::new(MIN_AU / 2, MIN_AU / 2),
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Size2D::new(MAX_AU, MAX_AU),
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)
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}
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}
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impl MaxRect for LayoutRect {
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#[inline]
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fn max_rect() -> LayoutRect {
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LayoutRect::new(
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LayoutPoint::new(f32::MIN / 2.0, f32::MIN / 2.0),
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LayoutSize::new(f32::MAX, f32::MAX),
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)
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}
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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(
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Point2D::new(
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Au::from_f32_px(rect.origin.x),
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Au::from_f32_px(rect.origin.y),
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),
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Size2D::new(
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Au::from_f32_px(rect.size.width),
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Au::from_f32_px(rect.size.height),
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),
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)
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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(
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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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}
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