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// Copyright 2006 The Android Open Source Project
// Copyright 2020 Yevhenii Reizner
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use crate::*;
use tiny_skia_path::{PathStroker, Scalar, SCALAR_MAX};
use crate::geom::ScreenIntRect;
use crate::mask::SubMaskRef;
use crate::pipeline::{RasterPipelineBlitter, RasterPipelineBuilder};
use crate::pixmap::SubPixmapMut;
use crate::scan;
use crate::geom::IntSizeExt;
#[cfg(all(not(feature = "std"), feature = "no-std-float"))]
use tiny_skia_path::NoStdFloat;
/// A path filling rule.
#[derive(Copy, Clone, PartialEq, Debug)]
pub enum FillRule {
/// Specifies that "inside" is computed by a non-zero sum of signed edge crossings.
Winding,
/// Specifies that "inside" is computed by an odd number of edge crossings.
EvenOdd,
}
impl Default for FillRule {
fn default() -> Self {
FillRule::Winding
}
}
/// Controls how a shape should be painted.
#[derive(Clone, PartialEq, Debug)]
pub struct Paint<'a> {
/// A paint shader.
///
/// Default: black color
pub shader: Shader<'a>,
/// Paint blending mode.
///
/// Default: SourceOver
pub blend_mode: BlendMode,
/// Enables anti-aliased painting.
///
/// Default: true
pub anti_alias: bool,
/// Forces the high quality/precision rendering pipeline.
///
/// `tiny-skia`, just like Skia, has two rendering pipelines:
/// one uses `f32` and another one uses `u16`. `u16` one is usually way faster,
/// but less precise. Which can lead to slight differences.
///
/// By default, `tiny-skia` will choose the pipeline automatically,
/// depending on a blending mode and other parameters.
/// But you can force the high quality one using this flag.
///
/// This feature is especially useful during testing.
///
/// Unlike high quality pipeline, the low quality one doesn't support all
/// rendering stages, therefore we cannot force it like hq one.
///
/// Default: false
pub force_hq_pipeline: bool,
}
impl Default for Paint<'_> {
fn default() -> Self {
Paint {
shader: Shader::SolidColor(Color::BLACK),
blend_mode: BlendMode::default(),
anti_alias: true,
force_hq_pipeline: false,
}
}
}
impl<'a> Paint<'a> {
/// Sets a paint source to a solid color.
pub fn set_color(&mut self, color: Color) {
self.shader = Shader::SolidColor(color);
}
/// Sets a paint source to a solid color.
///
/// `self.shader = Shader::SolidColor(Color::from_rgba8(50, 127, 150, 200));` shorthand.
pub fn set_color_rgba8(&mut self, r: u8, g: u8, b: u8, a: u8) {
self.set_color(Color::from_rgba8(r, g, b, a))
}
/// Checks that the paint source is a solid color.
pub fn is_solid_color(&self) -> bool {
matches!(self.shader, Shader::SolidColor(_))
}
}
impl Pixmap {
/// Draws a filled rectangle onto the pixmap.
///
/// See [`PixmapMut::fill_rect`](struct.PixmapMut.html#method.fill_rect) for details.
pub fn fill_rect(
&mut self,
rect: Rect,
paint: &Paint,
transform: Transform,
mask: Option<&Mask>,
) {
self.as_mut().fill_rect(rect, paint, transform, mask);
}
/// Draws a filled path onto the pixmap.
///
/// See [`PixmapMut::fill_path`](struct.PixmapMut.html#method.fill_path) for details.
pub fn fill_path(
&mut self,
path: &Path,
paint: &Paint,
fill_rule: FillRule,
transform: Transform,
mask: Option<&Mask>,
) {
self.as_mut()
.fill_path(path, paint, fill_rule, transform, mask);
}
/// Strokes a path.
///
/// See [`PixmapMut::stroke_path`](struct.PixmapMut.html#method.stroke_path) for details.
pub fn stroke_path(
&mut self,
path: &Path,
paint: &Paint,
stroke: &Stroke,
transform: Transform,
mask: Option<&Mask>,
) {
self.as_mut()
.stroke_path(path, paint, stroke, transform, mask);
}
/// Draws a `Pixmap` on top of the current `Pixmap`.
///
/// See [`PixmapMut::draw_pixmap`](struct.PixmapMut.html#method.draw_pixmap) for details.
pub fn draw_pixmap(
&mut self,
x: i32,
y: i32,
pixmap: PixmapRef,
paint: &PixmapPaint,
transform: Transform,
mask: Option<&Mask>,
) {
self.as_mut()
.draw_pixmap(x, y, pixmap, paint, transform, mask);
}
/// Applies a masks.
///
/// See [`PixmapMut::apply_mask`](struct.PixmapMut.html#method.apply_mask) for details.
pub fn apply_mask(&mut self, mask: &Mask) {
self.as_mut().apply_mask(mask);
}
}
impl PixmapMut<'_> {
// TODO: accept NonZeroRect?
/// Draws a filled rectangle onto the pixmap.
///
/// This function is usually slower than filling a rectangular path,
/// but it produces better results. Mainly it doesn't suffer from weird
/// clipping of horizontal/vertical edges.
///
/// Used mainly to render a pixmap onto a pixmap.
///
/// Returns `None` when there is nothing to fill or in case of a numeric overflow.
pub fn fill_rect(
&mut self,
rect: Rect,
paint: &Paint,
transform: Transform,
mask: Option<&Mask>,
) {
// TODO: we probably can use tiler for rect too
if transform.is_identity() && !DrawTiler::required(self.width(), self.height()) {
// TODO: ignore rects outside the pixmap
let clip = self.size().to_screen_int_rect(0, 0);
let mask = mask.map(|mask| mask.as_submask());
let mut subpix = self.as_subpixmap();
let mut blitter = match RasterPipelineBlitter::new(paint, mask, &mut subpix) {
Some(v) => v,
None => return, // nothing to do, all good
};
if paint.anti_alias {
scan::fill_rect_aa(&rect, &clip, &mut blitter);
} else {
scan::fill_rect(&rect, &clip, &mut blitter);
}
} else {
let path = PathBuilder::from_rect(rect);
self.fill_path(&path, paint, FillRule::Winding, transform, mask);
}
}
/// Draws a filled path onto the pixmap.
pub fn fill_path(
&mut self,
path: &Path,
paint: &Paint,
fill_rule: FillRule,
transform: Transform,
mask: Option<&Mask>,
) {
if transform.is_identity() {
// This is sort of similar to SkDraw::drawPath
// Skip empty paths and horizontal/vertical lines.
let path_bounds = path.bounds();
if path_bounds.width().is_nearly_zero() || path_bounds.height().is_nearly_zero() {
log::warn!("empty paths and horizontal/vertical lines cannot be filled");
return;
}
if is_too_big_for_math(path) {
log::warn!("path coordinates are too big");
return;
}
// TODO: ignore paths outside the pixmap
if let Some(tiler) = DrawTiler::new(self.width(), self.height()) {
let mut path = path.clone(); // TODO: avoid cloning
let mut paint = paint.clone();
for tile in tiler {
let ts = Transform::from_translate(-(tile.x() as f32), -(tile.y() as f32));
path = match path.transform(ts) {
Some(v) => v,
None => {
log::warn!("path transformation failed");
return;
}
};
paint.shader.transform(ts);
let clip_rect = tile.size().to_screen_int_rect(0, 0);
let mut subpix = match self.subpixmap(tile.to_int_rect()) {
Some(v) => v,
None => continue, // technically unreachable
};
let submask = mask.and_then(|mask| mask.submask(tile.to_int_rect()));
let mut blitter = match RasterPipelineBlitter::new(&paint, submask, &mut subpix)
{
Some(v) => v,
None => continue, // nothing to do, all good
};
// We're ignoring "errors" here, because `fill_path` will return `None`
// when rendering a tile that doesn't have a path on it.
// Which is not an error in this case.
if paint.anti_alias {
scan::path_aa::fill_path(&path, fill_rule, &clip_rect, &mut blitter);
} else {
scan::path::fill_path(&path, fill_rule, &clip_rect, &mut blitter);
}
let ts = Transform::from_translate(tile.x() as f32, tile.y() as f32);
path = match path.transform(ts) {
Some(v) => v,
None => return, // technically unreachable
};
paint.shader.transform(ts);
}
} else {
let clip_rect = self.size().to_screen_int_rect(0, 0);
let submask = mask.map(|mask| mask.as_submask());
let mut subpix = self.as_subpixmap();
let mut blitter = match RasterPipelineBlitter::new(paint, submask, &mut subpix) {
Some(v) => v,
None => return, // nothing to do, all good
};
if paint.anti_alias {
scan::path_aa::fill_path(path, fill_rule, &clip_rect, &mut blitter);
} else {
scan::path::fill_path(path, fill_rule, &clip_rect, &mut blitter);
}
}
} else {
let path = match path.clone().transform(transform) {
Some(v) => v,
None => {
log::warn!("path transformation failed");
return;
}
};
let mut paint = paint.clone();
paint.shader.transform(transform);
self.fill_path(&path, &paint, fill_rule, Transform::identity(), mask)
}
}
/// Strokes a path.
///
/// Stroking is implemented using two separate algorithms:
///
/// 1. If a stroke width is wider than 1px (after applying the transformation),
/// a path will be converted into a stroked path and then filled using `fill_path`.
/// Which means that we have to allocate a separate `Path`, that can be 2-3x larger
/// then the original path.
/// 2. If a stroke width is thinner than 1px (after applying the transformation),
/// we will use hairline stroking, which doesn't involve a separate path allocation.
///
/// Also, if a `stroke` has a dash array, then path will be converted into
/// a dashed path first and then stroked. Which means a yet another allocation.
pub fn stroke_path(
&mut self,
path: &Path,
paint: &Paint,
stroke: &Stroke,
transform: Transform,
mask: Option<&Mask>,
) {
if stroke.width < 0.0 {
log::warn!("negative stroke width isn't allowed");
return;
}
let res_scale = PathStroker::compute_resolution_scale(&transform);
let dash_path;
let path = if let Some(ref dash) = stroke.dash {
dash_path = match path.dash(dash, res_scale) {
Some(v) => v,
None => {
log::warn!("path dashing failed");
return;
}
};
&dash_path
} else {
path
};
if let Some(coverage) = treat_as_hairline(paint, stroke, transform) {
let mut paint = paint.clone();
if coverage == 1.0 {
// No changes to the `paint`.
} else if paint.blend_mode.should_pre_scale_coverage() {
// This is the old technique, which we preserve for now so
// we don't change previous results (testing)
// the new way seems fine, its just (a tiny bit) different.
let scale = (coverage * 256.0) as i32;
let new_alpha = (255 * scale) >> 8;
paint.shader.apply_opacity(new_alpha as f32 / 255.0);
}
if let Some(tiler) = DrawTiler::new(self.width(), self.height()) {
let mut path = path.clone(); // TODO: avoid cloning
let mut paint = paint.clone();
if !transform.is_identity() {
paint.shader.transform(transform);
path = match path.transform(transform) {
Some(v) => v,
None => {
log::warn!("path transformation failed");
return;
}
};
}
for tile in tiler {
let ts = Transform::from_translate(-(tile.x() as f32), -(tile.y() as f32));
path = match path.transform(ts) {
Some(v) => v,
None => {
log::warn!("path transformation failed");
return;
}
};
paint.shader.transform(ts);
let mut subpix = match self.subpixmap(tile.to_int_rect()) {
Some(v) => v,
None => continue, // technically unreachable
};
let submask = mask.and_then(|mask| mask.submask(tile.to_int_rect()));
// We're ignoring "errors" here, because `stroke_hairline` will return `None`
// when rendering a tile that doesn't have a path on it.
// Which is not an error in this case.
Self::stroke_hairline(&path, &paint, stroke.line_cap, submask, &mut subpix);
let ts = Transform::from_translate(tile.x() as f32, tile.y() as f32);
path = match path.transform(ts) {
Some(v) => v,
None => return,
};
paint.shader.transform(ts);
}
} else {
let subpix = &mut self.as_subpixmap();
let submask = mask.map(|mask| mask.as_submask());
if !transform.is_identity() {
paint.shader.transform(transform);
// TODO: avoid clone
let path = match path.clone().transform(transform) {
Some(v) => v,
None => {
log::warn!("path transformation failed");
return;
}
};
Self::stroke_hairline(&path, &paint, stroke.line_cap, submask, subpix);
} else {
Self::stroke_hairline(path, &paint, stroke.line_cap, submask, subpix);
}
}
} else {
let path = match path.stroke(stroke, res_scale) {
Some(v) => v,
None => {
log::warn!("path stroking failed");
return;
}
};
self.fill_path(&path, paint, FillRule::Winding, transform, mask);
}
}
/// A stroking for paths with subpixel/hairline width.
fn stroke_hairline(
path: &Path,
paint: &Paint,
line_cap: LineCap,
mask: Option<SubMaskRef>,
pixmap: &mut SubPixmapMut,
) {
let clip = pixmap.size.to_screen_int_rect(0, 0);
let mut blitter = match RasterPipelineBlitter::new(paint, mask, pixmap) {
Some(v) => v,
None => return, // nothing to do, all good
};
if paint.anti_alias {
scan::hairline_aa::stroke_path(path, line_cap, &clip, &mut blitter);
} else {
scan::hairline::stroke_path(path, line_cap, &clip, &mut blitter);
}
}
/// Draws a `Pixmap` on top of the current `Pixmap`.
///
/// The same as filling a rectangle with a `pixmap` pattern.
pub fn draw_pixmap(
&mut self,
x: i32,
y: i32,
pixmap: PixmapRef,
paint: &PixmapPaint,
transform: Transform,
mask: Option<&Mask>,
) {
let rect = pixmap.size().to_int_rect(x, y).to_rect();
// TODO: SkSpriteBlitter
// TODO: partially clipped
// TODO: clipped out
// Translate pattern as well as bounds.
let patt_transform = Transform::from_translate(x as f32, y as f32);
let paint = Paint {
shader: Pattern::new(
pixmap,
SpreadMode::Pad, // Pad, otherwise we will get weird borders overlap.
paint.quality,
paint.opacity,
patt_transform,
),
blend_mode: paint.blend_mode,
anti_alias: false, // Skia doesn't use it too.
force_hq_pipeline: false, // Pattern will use hq anyway.
};
self.fill_rect(rect, &paint, transform, mask);
}
/// Applies a masks.
///
/// When a `Mask` is passed to drawing methods, it will be used to mask-out
/// content we're about to draw.
/// This method masks-out an already drawn content.
/// It's not as fast, but can be useful when a mask is not available during drawing.
///
/// This method is similar to filling the whole pixmap with an another,
/// mask-like pixmap using the `DestinationOut` blend mode.
///
/// `Mask` must have the same size as `Pixmap`. No transform or offset are allowed.
pub fn apply_mask(&mut self, mask: &Mask) {
if self.size() != mask.size() {
log::warn!("Pixmap and Mask are expected to have the same size");
return;
}
// Just a dummy.
let pixmap_src = PixmapRef::from_bytes(&[0, 0, 0, 0], 1, 1).unwrap();
let mut p = RasterPipelineBuilder::new();
p.push(pipeline::Stage::LoadMaskU8);
p.push(pipeline::Stage::LoadDestination);
p.push(pipeline::Stage::DestinationIn);
p.push(pipeline::Stage::Store);
let mut p = p.compile();
let rect = self.size().to_screen_int_rect(0, 0);
p.run(
&rect,
pipeline::AAMaskCtx::default(),
mask.as_submask().mask_ctx(),
pixmap_src,
&mut self.as_subpixmap(),
);
}
}
fn treat_as_hairline(paint: &Paint, stroke: &Stroke, mut ts: Transform) -> Option<f32> {
fn fast_len(p: Point) -> f32 {
let mut x = p.x.abs();
let mut y = p.y.abs();
if x < y {
core::mem::swap(&mut x, &mut y);
}
x + y.half()
}
debug_assert!(stroke.width >= 0.0);
if stroke.width == 0.0 {
return Some(1.0);
}
if !paint.anti_alias {
return None;
}
// We don't care about translate.
ts.tx = 0.0;
ts.ty = 0.0;
// We need to try to fake a thick-stroke with a modulated hairline.
let mut points = [
Point::from_xy(stroke.width, 0.0),
Point::from_xy(0.0, stroke.width),
];
ts.map_points(&mut points);
let len0 = fast_len(points[0]);
let len1 = fast_len(points[1]);
if len0 <= 1.0 && len1 <= 1.0 {
return Some(len0.ave(len1));
}
None
}
/// Sometimes in the drawing pipeline, we have to perform math on path coordinates, even after
/// the path is in device-coordinates. Tessellation and clipping are two examples. Usually this
/// is pretty modest, but it can involve subtracting/adding coordinates, or multiplying by
/// small constants (e.g. 2,3,4). To try to preflight issues where these optionations could turn
/// finite path values into infinities (or NaNs), we allow the upper drawing code to reject
/// the path if its bounds (in device coordinates) is too close to max float.
pub(crate) fn is_too_big_for_math(path: &Path) -> bool {
// This value is just a guess. smaller is safer, but we don't want to reject largish paths
// that we don't have to.
const SCALE_DOWN_TO_ALLOW_FOR_SMALL_MULTIPLIES: f32 = 0.25;
const MAX: f32 = SCALAR_MAX * SCALE_DOWN_TO_ALLOW_FOR_SMALL_MULTIPLIES;
let b = path.bounds();
// use ! expression so we return true if bounds contains NaN
!(b.left() >= -MAX && b.top() >= -MAX && b.right() <= MAX && b.bottom() <= MAX)
}
/// Splits the target pixmap into a list of tiles.
///
/// Skia/tiny-skia uses a lot of fixed-point math during path rendering.
/// Probably more for precision than performance.
/// And our fixed-point types are limited by 8192 and 32768.
/// Which means that we cannot render a path larger than 8192 onto a pixmap.
/// When pixmap is smaller than 8192, the path will be automatically clipped anyway,
/// but for large pixmaps we have to render in tiles.
pub(crate) struct DrawTiler {
image_width: u32,
image_height: u32,
x_offset: u32,
y_offset: u32,
finished: bool,
}
impl DrawTiler {
// 8K is 1 too big, since 8K << supersample == 32768 which is too big for Fixed.
const MAX_DIMENSIONS: u32 = 8192 - 1;
fn required(image_width: u32, image_height: u32) -> bool {
image_width > Self::MAX_DIMENSIONS || image_height > Self::MAX_DIMENSIONS
}
pub(crate) fn new(image_width: u32, image_height: u32) -> Option<Self> {
if Self::required(image_width, image_height) {
Some(DrawTiler {
image_width,
image_height,
x_offset: 0,
y_offset: 0,
finished: false,
})
} else {
None
}
}
}
impl Iterator for DrawTiler {
type Item = ScreenIntRect;
fn next(&mut self) -> Option<Self::Item> {
if self.finished {
return None;
}
// TODO: iterate only over tiles that actually affected by the shape
if self.x_offset < self.image_width && self.y_offset < self.image_height {
let h = if self.y_offset < self.image_height {
(self.image_height - self.y_offset).min(Self::MAX_DIMENSIONS)
} else {
self.image_height
};
let r = ScreenIntRect::from_xywh(
self.x_offset,
self.y_offset,
(self.image_width - self.x_offset).min(Self::MAX_DIMENSIONS),
h,
);
self.x_offset += Self::MAX_DIMENSIONS;
if self.x_offset >= self.image_width {
self.x_offset = 0;
self.y_offset += Self::MAX_DIMENSIONS;
}
return r;
}
None
}
}
#[cfg(test)]
mod tests {
use super::*;
const MAX_DIM: u32 = DrawTiler::MAX_DIMENSIONS;
#[test]
fn skip() {
assert!(DrawTiler::new(100, 500).is_none());
}
#[test]
fn horizontal() {
let mut iter = DrawTiler::new(10000, 500).unwrap();
assert_eq!(iter.next(), ScreenIntRect::from_xywh(0, 0, MAX_DIM, 500));
assert_eq!(
iter.next(),
ScreenIntRect::from_xywh(MAX_DIM, 0, 10000 - MAX_DIM, 500)
);
assert_eq!(iter.next(), None);
}
#[test]
fn vertical() {
let mut iter = DrawTiler::new(500, 10000).unwrap();
assert_eq!(iter.next(), ScreenIntRect::from_xywh(0, 0, 500, MAX_DIM));
assert_eq!(
iter.next(),
ScreenIntRect::from_xywh(0, MAX_DIM, 500, 10000 - MAX_DIM)
);
assert_eq!(iter.next(), None);
}
#[test]
fn rect() {
let mut iter = DrawTiler::new(10000, 10000).unwrap();
// Row 1
assert_eq!(
iter.next(),
ScreenIntRect::from_xywh(0, 0, MAX_DIM, MAX_DIM)
);
assert_eq!(
iter.next(),
ScreenIntRect::from_xywh(MAX_DIM, 0, 10000 - MAX_DIM, MAX_DIM)
);
// Row 2
assert_eq!(
iter.next(),
ScreenIntRect::from_xywh(0, MAX_DIM, MAX_DIM, 10000 - MAX_DIM)
);
assert_eq!(
iter.next(),
ScreenIntRect::from_xywh(MAX_DIM, MAX_DIM, 10000 - MAX_DIM, 10000 - MAX_DIM)
);
assert_eq!(iter.next(), None);
}
}