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// Copyright 2020 The Druid Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use crate::{Affine, Data, Size};
// These are based on https://api.flutter.dev/flutter/painting/BoxFit.html
/// Strategies for inscribing a rectangle inside another rectangle.
#[derive(Default, Clone, Data, Copy, PartialEq, Eq)]
pub enum FillStrat {
/// As large as possible without changing aspect ratio of image and all of image shown
#[default]
Contain,
/// As large as possible with no dead space so that some of the image may be clipped
Cover,
/// Fill the widget with no dead space, aspect ratio of widget is used
Fill,
/// Fill the height with the images aspect ratio, some of the image may be clipped
FitHeight,
/// Fill the width with the images aspect ratio, some of the image may be clipped
FitWidth,
/// Do not scale
None,
/// Scale down to fit but do not scale up
ScaleDown,
}
impl FillStrat {
/// Calculate an origin and scale for an image with a given `FillStrat`.
///
/// This takes some properties of a widget and a fill strategy and returns an affine matrix
/// used to position and scale the image in the widget.
pub fn affine_to_fill(self, parent: Size, fit_box: Size) -> Affine {
let raw_scalex = parent.width / fit_box.width;
let raw_scaley = parent.height / fit_box.height;
let (scalex, scaley) = match self {
FillStrat::Contain => {
let scale = raw_scalex.min(raw_scaley);
(scale, scale)
}
FillStrat::Cover => {
let scale = raw_scalex.max(raw_scaley);
(scale, scale)
}
FillStrat::Fill => (raw_scalex, raw_scaley),
FillStrat::FitHeight => (raw_scaley, raw_scaley),
FillStrat::FitWidth => (raw_scalex, raw_scalex),
FillStrat::ScaleDown => {
let scale = raw_scalex.min(raw_scaley).min(1.0);
(scale, scale)
}
FillStrat::None => (1.0, 1.0),
};
let origin_x = (parent.width - (fit_box.width * scalex)) / 2.0;
let origin_y = (parent.height - (fit_box.height * scaley)) / 2.0;
Affine::new([scalex, 0., 0., scaley, origin_x, origin_y])
}
}