Allow more fine grained control over style overrides

Add tons of ASS_OVERRIDE_ flags, which control whether certain ASS_Style
fields are copied when doing selective style overrides with
ass_set_selective_style_override_enabled().

This comes with some cleanup. It should be fully backwards-compatible.

1 files changed, 69 insertions, 28 deletions

diff --git a/libass/ass_render.c b/libass/ass_render.c
index 3e54710..b03fc30 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -139,6 +139,7 @@ ASS_Renderer *ass_renderer_init(ASS_Library *library)
     priv->text_info.lines = calloc(MAX_LINES_INITIAL, sizeof(LineInfo));
 
     priv->settings.font_size_coeff = 1.;
+    priv->settings.selective_style_overrides = ASS_OVERRIDE_BIT_SELECTIVE_FONT_SCALE;
 
     priv->shaper = ass_shaper_new(0);
     ass_shaper_info(library);
@@ -750,55 +751,95 @@ static ASS_Style *handle_selective_style_overrides(ASS_Renderer *render_priv,
                                                    ASS_Style *rstyle)
 {
     // The script style is the one the event was declared with.
-    // The rstyle is either NULL, or the style used with a \r tag.
     ASS_Style *script = render_priv->track->styles +
                         render_priv->state.event->Style;
+    // The user style was set with ass_set_selective_style_override().
+    ASS_Style *user = &render_priv->user_override_style;
     ASS_Style *new = &render_priv->state.override_style_temp_storage;
     int explicit = event_is_positioned(render_priv->state.event->Text);
     int requested = render_priv->settings.selective_style_overrides;
     double scale;
 
+    user->Name = "OverrideStyle"; // name insignificant
+
+    // Either the event's style, or the style forced with a \r tag.
     if (!rstyle)
         rstyle = script;
 
-    render_priv->state.style = script;
-    render_priv->state.overrides = ASS_OVERRIDE_BIT_FONT_SIZE; // odd default
-
-    if (explicit && (requested & ASS_OVERRIDE_BIT_FONT_SIZE))
-        render_priv->state.overrides &= ~(unsigned)ASS_OVERRIDE_BIT_FONT_SIZE;
-
-    if (!explicit && (requested & ASS_OVERRIDE_BIT_STYLE))
-        render_priv->state.overrides |= ASS_OVERRIDE_BIT_STYLE;
-
-    if (!(render_priv->state.overrides & ASS_OVERRIDE_BIT_STYLE))
-        return rstyle;
-
     // Create a new style that contains a mix of the original style and
     // user_style (the user's override style). Copy only fields from the
     // script's style that are deemed necessary.
-    *new = render_priv->user_override_style;
+    *new = *rstyle;
+
+    render_priv->state.apply_font_scale =
+        !explicit || !(requested & ASS_OVERRIDE_BIT_SELECTIVE_FONT_SCALE);
 
-    new->Bold = rstyle->Bold;
-    new->StrikeOut = rstyle->StrikeOut;
-    new->Underline = rstyle->Underline;
-    new->Angle = rstyle->Angle;
+    // On positioned events, do not apply most overrides.
+    if (explicit)
+        requested = 0;
 
-    new->MarginL = rstyle->MarginL;
-    new->MarginR = rstyle->MarginR;
-    new->MarginV = rstyle->MarginV;
-    new->Alignment = rstyle->Alignment;
-    new->Encoding = rstyle->Encoding;
+    if (requested & ASS_OVERRIDE_BIT_STYLE)
+        requested |= ASS_OVERRIDE_BIT_FONT_NAME |
+                     ASS_OVERRIDE_BIT_FONT_SIZE_FIELDS |
+                     ASS_OVERRIDE_BIT_COLORS |
+                     ASS_OVERRIDE_BIT_BORDER |
+                     ASS_OVERRIDE_BIT_ATTRIBUTES;
+
+    // Copies fields even not covered by any of the other bits.
+    if (requested & ASS_OVERRIDE_FULL_STYLE)
+        *new = *user;
 
     // The user style is supposed to be independent of the script resolution.
     // Treat the user style's values as if they were specified for a script with
     // PlayResY=288, and rescale the values to the current script.
     scale = render_priv->track->PlayResY / 288.0;
-    new->FontSize *= scale;
-    new->Spacing *= scale;
-    new->Outline *= scale;
-    new->Shadow *= scale;
+
+    if (requested & ASS_OVERRIDE_BIT_FONT_SIZE_FIELDS) {
+        new->FontSize = user->FontSize * scale;
+        new->Spacing = user->Spacing * scale;
+        new->ScaleX = user->ScaleX;
+        new->ScaleY = user->ScaleY;
+    }
+
+    if (requested & ASS_OVERRIDE_BIT_FONT_NAME) {
+        new->FontName = user->FontName;
+        new->treat_fontname_as_pattern = user->treat_fontname_as_pattern;
+    }
+
+    if (requested & ASS_OVERRIDE_BIT_COLORS) {
+        new->PrimaryColour = user->PrimaryColour;
+        new->SecondaryColour = user->SecondaryColour;
+        new->OutlineColour = user->OutlineColour;
+        new->BackColour = user->BackColour;
+    }
+
+    if (requested & ASS_OVERRIDE_BIT_ATTRIBUTES) {
+        new->Bold = user->Bold;
+        new->Italic = user->Italic;
+        new->Underline = user->Underline;
+        new->StrikeOut = user->StrikeOut;
+    }
+
+    if (requested & ASS_OVERRIDE_BIT_BORDER) {
+        new->BorderStyle = user->BorderStyle;
+        new->Outline = user->Outline * scale;
+        new->Shadow = user->Shadow * scale;
+    }
+
+    if (requested & ASS_OVERRIDE_BIT_ALIGNMENT)
+        new->Alignment = user->Alignment;
+
+    if (requested & ASS_OVERRIDE_BIT_MARGINS) {
+        new->MarginL = user->MarginL;
+        new->MarginR = user->MarginR;
+        new->MarginV = user->MarginV;
+    }
+
+    if (!new->FontName)
+        new->FontName = rstyle->FontName;
 
     render_priv->state.style = new;
+    render_priv->state.overrides = requested;
 
     return new;
 }
@@ -823,7 +864,7 @@ static void init_font_scale(ASS_Renderer *render_priv)
     if (!settings_priv->storage_height)
         render_priv->blur_scale = render_priv->border_scale;
 
-    if (render_priv->state.overrides & ASS_OVERRIDE_BIT_FONT_SIZE) {
+    if (render_priv->state.apply_font_scale) {
         render_priv->font_scale *= settings_priv->font_size_coeff;
         render_priv->border_scale *= settings_priv->font_size_coeff;
         render_priv->blur_scale *= settings_priv->font_size_coeff;