swf: Introduce `GradientFilterFlags`

swf/src/read.rs

@@ -2122,23 +2122,14 @@ impl<'a> Reader<'a> {
                 ratio: self.read_u8()?,
             });
         }
-        let blur_x = self.read_fixed16()?;
-        let blur_y = self.read_fixed16()?;
-        let angle = self.read_fixed16()?;
-        let distance = self.read_fixed16()?;
-        let strength = self.read_fixed8()?;
-        let flags = self.read_u8()?;
         Ok(GradientFilter {
             colors: gradient_records,
-            blur_x,
-            blur_y,
-            angle,
-            distance,
-            strength,
-            is_inner: flags & 0b1000_0000 != 0,
-            is_knockout: flags & 0b0100_0000 != 0,
-            is_on_top: flags & 0b0001_0000 != 0,
-            num_passes: flags & 0b0000_1111,
+            blur_x: self.read_fixed16()?,
+            blur_y: self.read_fixed16()?,
+            angle: self.read_fixed16()?,
+            distance: self.read_fixed16()?,
+            strength: self.read_fixed8()?,
+            flags: GradientFilterFlags::from_bits_truncate(self.read_u8()?),
         })
     }
 

swf/src/test_data.rs

@@ -2133,10 +2133,10 @@ pub fn tag_tests() -> Vec<TagTestData> {
                         angle: Fixed16::from_f64(0.7853851318359375),
                         distance: Fixed16::from_f32(5.0),
                         strength: Fixed8::ONE,
-                        is_inner: true,
-                        is_knockout: true,
-                        is_on_top: false,
-                        num_passes: 3,
+                        flags: GradientFilterFlags::INNER_SHADOW
+                            | GradientFilterFlags::KNOCKOUT
+                            | GradientFilterFlags::COMPOSITE_SOURCE
+                            | GradientFilterFlags::from_passes(3),
                     })),
                     Filter::GradientGlowFilter(Box::new(GradientFilter {
                         colors: vec![
@@ -2164,10 +2164,9 @@ pub fn tag_tests() -> Vec<TagTestData> {
                         angle: Fixed16::from_f64(0.174530029296875),
                         distance: Fixed16::from_f32(5.0),
                         strength: Fixed8::from_f64(0.19921875),
-                        is_inner: false,
-                        is_knockout: false,
-                        is_on_top: true,
-                        num_passes: 1,
+                        flags: GradientFilterFlags::COMPOSITE_SOURCE
+                            | GradientFilterFlags::ON_TOP
+                            | GradientFilterFlags::from_passes(1),
                     })),
                     Filter::BlurFilter(Box::new(BlurFilter {
                         blur_x: Fixed16::from_f32(30.0),

swf/src/types.rs

@@ -32,7 +32,7 @@ pub use convolution_filter::ConvolutionFilter;
 pub use drop_shadow_filter::{DropShadowFilter, DropShadowFilterFlags};
 pub use fixed::{Fixed16, Fixed8};
 pub use glow_filter::{GlowFilter, GlowFilterFlags};
-pub use gradient_filter::GradientFilter;
+pub use gradient_filter::{GradientFilter, GradientFilterFlags};
 pub use matrix::Matrix;
 pub use point::Point;
 pub use rectangle::Rectangle;

swf/src/types/gradient_filter.rs

@@ -1,4 +1,5 @@
 use crate::{Fixed16, Fixed8, GradientRecord};
+use bitflags::bitflags;
 
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct GradientFilter {
@@ -8,8 +9,46 @@ pub struct GradientFilter {
     pub angle: Fixed16,
     pub distance: Fixed16,
     pub strength: Fixed8,
-    pub is_inner: bool,
-    pub is_knockout: bool,
-    pub is_on_top: bool,
-    pub num_passes: u8,
+    pub flags: GradientFilterFlags,
+}
+
+impl GradientFilter {
+    #[inline]
+    pub fn is_inner(&self) -> bool {
+        self.flags.contains(GradientFilterFlags::INNER_SHADOW)
+    }
+
+    #[inline]
+    pub fn is_knockout(&self) -> bool {
+        self.flags.contains(GradientFilterFlags::KNOCKOUT)
+    }
+
+    #[inline]
+    pub fn is_on_top(&self) -> bool {
+        self.flags.contains(GradientFilterFlags::ON_TOP)
+    }
+
+    #[inline]
+    pub fn num_passes(&self) -> u8 {
+        (self.flags & GradientFilterFlags::PASSES).bits()
+    }
+}
+
+bitflags! {
+    pub struct GradientFilterFlags: u8 {
+        const INNER_SHADOW     = 1 << 7;
+        const KNOCKOUT         = 1 << 6;
+        const COMPOSITE_SOURCE = 1 << 5;
+        const ON_TOP           = 1 << 4;
+        const PASSES           = 0b1111;
+    }
+}
+
+impl GradientFilterFlags {
+    #[inline]
+    pub fn from_passes(num_passes: u8) -> Self {
+        let flags = Self::from_bits_truncate(num_passes);
+        debug_assert_eq!(flags & Self::PASSES, flags);
+        flags
+    }
 }

swf/src/write.rs

@@ -1817,12 +1817,7 @@ impl<W: Write> Writer<W> {
         self.write_fixed16(filter.angle)?;
         self.write_fixed16(filter.distance)?;
         self.write_fixed8(filter.strength)?;
-        let mut bits = self.bits();
-        bits.write_bit(filter.is_inner)?;
-        bits.write_bit(filter.is_knockout)?;
-        bits.write_bit(true)?;
-        bits.write_bit(filter.is_on_top)?;
-        bits.write_ubits(4, filter.num_passes.into())?;
+        self.write_u8(filter.flags.bits())?;
         Ok(())
     }