Re: [PATCH 4/6] dwrite: Use font fallback when mapping characters

[Nikolay Sivov]

On 05/23/2018 09:07 PM, Lucian Poston wrote:
> - /**
> -
> * This is a rough hack. We search the system font collection because
> -
> * the system fontfallback, which would have been searched above, is not
> -
> * fully implemented as it isn't populated with any system fonts. Once
> -
> * implemented, the block below can be removed.
> -
> * */
> - if (!*mapped_length) {
> -
>    IDWriteFontFamily *family;
> -
>    IDWriteFont *font;
> -
>    UINT32 i, count = IDWriteFontCollection_GetFontFamilyCount((IDWriteFontCollection *)fallback->systemcollection);
> -
>    for (i = 0; i < count; i++) {
> -
>        hr = IDWriteFontCollection_GetFontFamily((IDWriteFontCollection *)fallback->systemcollection, i, &family);
> -
>        if (FAILED(hr)) {
> -
>            ERR("Failed to get font family.\n");
> -
>            continue;
>         }
> -
> -
>        hr = IDWriteFontFamily_GetFirstMatchingFont(family, weight, stretch, style, &font);
> -
>        IDWriteFontFamily_Release(family);
> -
>        if (FAILED(hr)) {
> -
>            continue;
> -
>        }
> -
> -
>        hr = fallback_map_characters(font, text, length, mapped_length);
> -
>        if (SUCCEEDED(hr) && mapped_length > 0) {
> -
>            *ret_font = font;
> -
>            break;
> -
>        }
> -
> -
>        IDWriteFont_Release(font);
>     }

This block will pick arbitrary font, depending on fonts user has 
installed, and can change if user installs more or removes some.
That doesn't sound like a good idea to me, and your comment already 
hints at that.