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Merge pull request #2330 from Gigas002/viewer_content_fit
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Implement content_fit for viewer widget
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@hecrj
hecrj authored Jun 17, 2024
2 parents 6c1027a + c95e296 commit 368b15f
Showing 1 changed file with 80 additions and 76 deletions.
156 changes: 80 additions & 76 deletions widget/src/image/viewer.rs
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
//! Zoom and pan on an image.
use crate::core::event::{self, Event};
use crate::core::image;
use crate::core::image::{self, FilterMethod};
use crate::core::layout;
use crate::core::mouse;
use crate::core::renderer;
use crate::core::widget::tree::{self, Tree};
use crate::core::{
Clipboard, Element, Layout, Length, Pixels, Point, Radians, Rectangle,
Shell, Size, Vector, Widget,
Clipboard, ContentFit, Element, Layout, Length, Pixels, Point, Radians,
Rectangle, Shell, Size, Vector, Widget,
};

/// A frame that displays an image with the ability to zoom in/out and pan.
Expand All @@ -20,30 +20,38 @@ pub struct Viewer<Handle> {
max_scale: f32,
scale_step: f32,
handle: Handle,
filter_method: image::FilterMethod,
filter_method: FilterMethod,
content_fit: ContentFit,
}

impl<Handle> Viewer<Handle> {
/// Creates a new [`Viewer`] with the given [`State`].
pub fn new(handle: Handle) -> Self {
pub fn new<T: Into<Handle>>(handle: T) -> Self {
Viewer {
handle,
handle: handle.into(),
padding: 0.0,
width: Length::Shrink,
height: Length::Shrink,
min_scale: 0.25,
max_scale: 10.0,
scale_step: 0.10,
filter_method: image::FilterMethod::default(),
filter_method: FilterMethod::default(),
content_fit: ContentFit::default(),
}
}

/// Sets the [`image::FilterMethod`] of the [`Viewer`].
/// Sets the [`FilterMethod`] of the [`Viewer`].
pub fn filter_method(mut self, filter_method: image::FilterMethod) -> Self {
self.filter_method = filter_method;
self
}

/// Sets the [`ContentFit`] of the [`Viewer`].
pub fn content_fit(mut self, content_fit: ContentFit) -> Self {
self.content_fit = content_fit;
self
}

/// Sets the padding of the [`Viewer`].
pub fn padding(mut self, padding: impl Into<Pixels>) -> Self {
self.padding = padding.into().0;
Expand Down Expand Up @@ -115,36 +123,30 @@ where
renderer: &Renderer,
limits: &layout::Limits,
) -> layout::Node {
let Size { width, height } = renderer.measure_image(&self.handle);

let mut size = limits.resolve(
self.width,
self.height,
Size::new(width as f32, height as f32),
);

let expansion_size = if height > width {
self.width
} else {
self.height
// The raw w/h of the underlying image
let image_size = renderer.measure_image(&self.handle);
let image_size =
Size::new(image_size.width as f32, image_size.height as f32);

// The size to be available to the widget prior to `Shrink`ing
let raw_size = limits.resolve(self.width, self.height, image_size);

// The uncropped size of the image when fit to the bounds above
let full_size = self.content_fit.fit(image_size, raw_size);

// Shrink the widget to fit the resized image, if requested
let final_size = Size {
width: match self.width {
Length::Shrink => f32::min(raw_size.width, full_size.width),
_ => raw_size.width,
},
height: match self.height {
Length::Shrink => f32::min(raw_size.height, full_size.height),
_ => raw_size.height,
},
};

// Only calculate viewport sizes if the images are constrained to a limited space.
// If they are Fill|Portion let them expand within their allotted space.
match expansion_size {
Length::Shrink | Length::Fixed(_) => {
let aspect_ratio = width as f32 / height as f32;
let viewport_aspect_ratio = size.width / size.height;
if viewport_aspect_ratio > aspect_ratio {
size.width = width as f32 * size.height / height as f32;
} else {
size.height = height as f32 * size.width / width as f32;
}
}
Length::Fill | Length::FillPortion(_) => {}
}

layout::Node::new(size)
layout::Node::new(final_size)
}

fn on_event(
Expand Down Expand Up @@ -182,11 +184,12 @@ where
})
.clamp(self.min_scale, self.max_scale);

let image_size = image_size(
let scaled_size = scaled_image_size(
renderer,
&self.handle,
state,
bounds.size(),
self.content_fit,
);

let factor = state.scale / previous_scale - 1.0;
Expand All @@ -198,12 +201,12 @@ where
+ state.current_offset * factor;

state.current_offset = Vector::new(
if image_size.width > bounds.width {
if scaled_size.width > bounds.width {
state.current_offset.x + adjustment.x
} else {
0.0
},
if image_size.height > bounds.height {
if scaled_size.height > bounds.height {
state.current_offset.y + adjustment.y
} else {
0.0
Expand Down Expand Up @@ -242,32 +245,32 @@ where
let state = tree.state.downcast_mut::<State>();

if let Some(origin) = state.cursor_grabbed_at {
let image_size = image_size(
let scaled_size = scaled_image_size(
renderer,
&self.handle,
state,
bounds.size(),
self.content_fit,
);

let hidden_width = (image_size.width - bounds.width / 2.0)
let hidden_width = (scaled_size.width - bounds.width / 2.0)
.max(0.0)
.round();

let hidden_height = (image_size.height
let hidden_height = (scaled_size.height
- bounds.height / 2.0)
.max(0.0)
.round();

let delta = position - origin;

let x = if bounds.width < image_size.width {
let x = if bounds.width < scaled_size.width {
(state.starting_offset.x - delta.x)
.clamp(-hidden_width, hidden_width)
} else {
0.0
};

let y = if bounds.height < image_size.height {
let y = if bounds.height < scaled_size.height {
(state.starting_offset.y - delta.y)
.clamp(-hidden_height, hidden_height)
} else {
Expand Down Expand Up @@ -319,33 +322,43 @@ where
let state = tree.state.downcast_ref::<State>();
let bounds = layout.bounds();

let image_size =
image_size(renderer, &self.handle, state, bounds.size());
let final_size = scaled_image_size(
renderer,
&self.handle,
state,
bounds.size(),
self.content_fit,
);

let translation = {
let image_top_left = Vector::new(
bounds.width / 2.0 - image_size.width / 2.0,
bounds.height / 2.0 - image_size.height / 2.0,
);
let diff_w = bounds.width - final_size.width;
let diff_h = bounds.height - final_size.height;

image_top_left - state.offset(bounds, image_size)
let image_top_left = match self.content_fit {
ContentFit::None => {
Vector::new(diff_w.max(0.0) / 2.0, diff_h.max(0.0) / 2.0)
}
_ => Vector::new(diff_w / 2.0, diff_h / 2.0),
};

image_top_left - state.offset(bounds, final_size)
};

renderer.with_layer(bounds, |renderer| {
let drawing_bounds = Rectangle::new(bounds.position(), final_size);

let render = |renderer: &mut Renderer| {
renderer.with_translation(translation, |renderer| {
renderer.draw_image(
self.handle.clone(),
self.filter_method,
Rectangle {
x: bounds.x,
y: bounds.y,
..Rectangle::with_size(image_size)
},
drawing_bounds,
Radians(0.0),
1.0,
);
});
});
};

renderer.with_layer(bounds, render);
}
}

Expand Down Expand Up @@ -411,32 +424,23 @@ where
/// Returns the bounds of the underlying image, given the bounds of
/// the [`Viewer`]. Scaling will be applied and original aspect ratio
/// will be respected.
pub fn image_size<Renderer>(
pub fn scaled_image_size<Renderer>(
renderer: &Renderer,
handle: &<Renderer as image::Renderer>::Handle,
state: &State,
bounds: Size,
content_fit: ContentFit,
) -> Size
where
Renderer: image::Renderer,
{
let Size { width, height } = renderer.measure_image(handle);
let image_size = Size::new(width as f32, height as f32);

let (width, height) = {
let dimensions = (width as f32, height as f32);

let width_ratio = bounds.width / dimensions.0;
let height_ratio = bounds.height / dimensions.1;

let ratio = width_ratio.min(height_ratio);
let scale = state.scale;

if ratio < 1.0 {
(dimensions.0 * ratio * scale, dimensions.1 * ratio * scale)
} else {
(dimensions.0 * scale, dimensions.1 * scale)
}
};
let adjusted_fit = content_fit.fit(image_size, bounds);

Size::new(width, height)
Size::new(
adjusted_fit.width * state.scale,
adjusted_fit.height * state.scale,
)
}

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