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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use std::cell::UnsafeCell;
use std::ptr::null_mut;
use winapi::um::dwrite_2::{IDWriteFactory2, IDWriteFontFallback};
use wio::com::ComPtr;
use super::*;
pub struct FontFallback {
native: UnsafeCell<ComPtr<IDWriteFontFallback>>,
}
pub struct FallbackResult {
/// Length of mapped substring, in utf-16 code units.
pub mapped_length: usize,
/// The font that should be used to render the substring.
pub mapped_font: Option<Font>,
/// The scale factor to apply.
pub scale: f32,
}
impl FontFallback {
pub fn get_system_fallback() -> Option<FontFallback> {
unsafe {
let factory = ComPtr::from_raw(DWriteFactory());
let factory2: Option<ComPtr<IDWriteFactory2>> = factory.cast().ok();
std::mem::forget(factory);
let factory2 = factory2?;
let mut native = null_mut();
let hr = factory2.GetSystemFontFallback(&mut native);
assert_eq!(hr, 0);
Some(Self::take(ComPtr::from_raw(native)))
}
}
pub fn take(native: ComPtr<IDWriteFontFallback>) -> FontFallback {
FontFallback {
native: UnsafeCell::new(native),
}
}
// TODO: I'm following crate conventions for unsafe, but it's bullshit
pub unsafe fn as_ptr(&self) -> *mut IDWriteFontFallback {
(*self.native.get()).as_raw()
}
// TODO: map_characters (main function)
pub fn map_characters(
&self,
text_analysis_source: &TextAnalysisSource,
text_position: u32,
text_length: u32,
base_font: &FontCollection,
base_family: Option<&str>,
base_weight: FontWeight,
base_style: FontStyle,
base_stretch: FontStretch,
) -> FallbackResult {
unsafe {
let mut font = null_mut();
let mut mapped_length = 0;
let mut scale = 0.0;
let hr = (*self.as_ptr()).MapCharacters(
text_analysis_source.as_ptr(),
text_position,
text_length,
base_font.as_ptr(),
base_family
.map(|s| s.to_wide_null().as_mut_ptr())
.unwrap_or(null_mut()),
base_weight.t(),
base_style.t(),
base_stretch.t(),
&mut mapped_length,
&mut font,
&mut scale,
);
assert_eq!(hr, 0);
let mapped_font = if font.is_null() {
None
} else {
Some(Font::take(ComPtr::from_raw(font)))
};
FallbackResult {
mapped_length: mapped_length as usize,
mapped_font,
scale,
}
}
}
}
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