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add fallible font methods to FontCollection #63

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add fallible font methods to FontCollection #63

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64 changes: 45 additions & 19 deletions src/font_collection.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ use winapi::shared::minwindef::{BOOL, FALSE, TRUE};
use winapi::shared::winerror::S_OK;
use winapi::um::dwrite::IDWriteFontCollectionLoader;
use winapi::um::dwrite::{IDWriteFont, IDWriteFontCollection, IDWriteFontFamily};
use winapi::um::winnt::HRESULT;
use wio::com::ComPtr;

use super::{DWriteFactory, Font, FontDescriptor, FontFace, FontFamily};
Expand Down Expand Up @@ -108,62 +109,87 @@ impl FontCollection {
unsafe { (*self.native.get()).GetFontFamilyCount() }
}

#[deprecated(note = "Use `font_family` instead.")]
pub fn get_font_family(&self, index: u32) -> FontFamily {
self.font_family(index).unwrap()
}

pub fn font_family(&self, index: u32) -> Result<FontFamily, HRESULT> {
let mut family: *mut IDWriteFontFamily = ptr::null_mut();
unsafe {
let mut family: *mut IDWriteFontFamily = ptr::null_mut();
let hr = (*self.native.get()).GetFontFamily(index, &mut family);
assert!(hr == 0);
FontFamily::take(ComPtr::from_raw(family))
if hr != S_OK {
return Err(hr);
}
Ok(FontFamily::take(ComPtr::from_raw(family)))
}
}

// Find a font matching the given font descriptor in this
// font collection.
#[deprecated(note = "Use `font_from_descriptor` instead.")]
pub fn get_font_from_descriptor(&self, desc: &FontDescriptor) -> Option<Font> {
if let Some(family) = self.get_font_family_by_name(&desc.family_name) {
let font = family.get_first_matching_font(desc.weight, desc.stretch, desc.style);
self.font_from_descriptor(desc).unwrap()
}

// Find a font matching the given font descriptor in this font collection.
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Suggested change
// Find a font matching the given font descriptor in this font collection.
/// Find a font matching the given font descriptor in this font collection.

pub fn font_from_descriptor(&self, desc: &FontDescriptor) -> Result<Option<Font>, HRESULT> {
if let Some(family) = self.font_family_by_name(&desc.family_name)? {
let font = family.first_matching_font(desc.weight, desc.stretch, desc.style)?;
// Exact matches only here
if font.weight() == desc.weight
&& font.stretch() == desc.stretch
&& font.style() == desc.style
{
return Some(font);
return Ok(Some(font));
}
}

None
Ok(None)
}

#[deprecated(note = "Use `font_from_face` instead.")]
pub fn get_font_from_face(&self, face: &FontFace) -> Option<Font> {
self.font_from_face(face).ok()
}

pub fn font_from_face(&self, face: &FontFace) -> Result<Font, HRESULT> {
let mut font: *mut IDWriteFont = ptr::null_mut();
unsafe {
let mut font: *mut IDWriteFont = ptr::null_mut();
let hr = (*self.native.get()).GetFontFromFontFace(face.as_ptr(), &mut font);
if hr != 0 {
return None;
if hr != S_OK {
return Err(hr);
}
Some(Font::take(ComPtr::from_raw(font)))
Ok(Font::take(ComPtr::from_raw(font)))
}
}

#[deprecated(note = "Use `font_family_by_name` instead.")]
pub fn get_font_family_by_name(&self, family_name: &str) -> Option<FontFamily> {
self.font_family_by_name(family_name).unwrap()
}

pub fn font_family_by_name(&self, family_name: &str) -> Result<Option<FontFamily>, HRESULT> {
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@acarl005 acarl005 Feb 25, 2025 •
edited
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Note that we have a Result<Option<FontFamily>, HRESULT> instead of just a Result<FontFamily, HRESULT>. I think this makes sense, as there may be no font family with the given name, so Ok(None) is returned to designate that the name doesn't exist, and no errors occurred.

An alternative I considered was creating a new error enum, e.g.

enum GetError {
    Win32Error(HRESULT),
    NotFound
}

And we could return Result<FontFamily, GetError> instead.

let mut index: u32 = 0;
let mut exists: BOOL = FALSE;
unsafe {
let mut index: u32 = 0;
let mut exists: BOOL = FALSE;
let hr = (*self.native.get()).FindFamilyName(
family_name.to_wide_null().as_ptr(),
&mut index,
&mut exists,
);
assert!(hr == 0);
if hr != S_OK {
return Err(hr);
}
if exists == FALSE {
return None;
return Ok(None);
}

let mut family: *mut IDWriteFontFamily = ptr::null_mut();
let hr = (*self.native.get()).GetFontFamily(index, &mut family);
assert!(hr == 0);
if hr != S_OK {
return Err(hr);
}

Some(FontFamily::take(ComPtr::from_raw(family)))
Ok(Some(FontFamily::take(ComPtr::from_raw(family))))
}
}
}