6ea0b0aa54
Implements the complete graphics state per PDF spec section 8.4:
- Color enum with 5 variants (DeviceGray/RGB/CMYK, Spot, Other)
- Color::to_css_hex() for JSON serialization (returns None for Spot/Other)
- GraphicsState struct with all 13 fields (ctm, text_matrix, text_line_matrix,
font, font_size, char_spacing, word_spacing, horiz_scaling, leading,
text_rise, text_rendering_mode, fill_color, stroke_color)
- GraphicsState::initial() returning default state (identity CTM, black colors)
- Matrix operations: scale(), translate(), rotate(), invert()
- Manual Debug impl for GraphicsState (Font doesn't implement Debug)
All acceptance criteria PASS:
- initial() has identity CTM, font_size 0.0, fill_color DeviceGray(0.0)
- Clone produces deep-equal value
- Color::DeviceRGB([1.0, 0.0, 0.0]).to_css_hex() == Some("#ff0000")
- Color::Spot returns None
- Matrix multiply identity*identity within 1e-10
Closes: pdftract-44f6
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
100 lines
3.8 KiB
Markdown
100 lines
3.8 KiB
Markdown
# pdftract-44f6: GraphicsState struct + Color enum + matrix initialization
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## Summary
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Implemented the complete `GraphicsState` struct with all 13 fields per PDF spec section 8.4, plus the `Color` enum with CSS hex serialization and matrix operations.
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## Changes Made
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### File: `crates/pdftract-core/src/graphics_state.rs`
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1. **Added `Color` enum** with 5 variants:
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- `DeviceGray(f32)` - single grayscale component
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- `DeviceRGB([f32; 3])` - RGB color
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- `DeviceCMYK([f32; 4])` - CMYK color
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- `Spot(Arc<str>, f32)` - spot color with tint
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- `Other` - other color spaces
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2. **Added `Color::to_css_hex()`** method:
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- Converts DeviceGray/RGB/CMYK to "#rrggbb" format
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- Returns None for Spot/Other
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- Includes clamp for safety
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- CMYK→RGB uses naive formula: R=(1-C)*(1-K)
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3. **Extended `GraphicsState` struct** with all 13 fields:
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- `ctm: Matrix3x3` - current transformation matrix
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- `text_matrix: Matrix3x3` - Tm
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- `text_line_matrix: Matrix3x3` - Tlm
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- `font: Option<Arc<Font>>` - current font
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- `font_size: f64` - Tf
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- `char_spacing: f64` - Tc
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- `word_spacing: f64` - Tw
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- `horiz_scaling: f64` - Tz (default 100)
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- `leading: f64` - TL
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- `text_rise: f64` - Ts
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- `text_rendering_mode: u8` - Tr (0-7)
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- `fill_color: Color` - fill color
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- `stroke_color: Color` - stroke color
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4. **Added `GraphicsState::initial()`** returning default state:
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- Identity CTM, text_matrix, text_line_matrix
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- font: None
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- font_size: 0.0
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- All spacings: 0.0
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- horiz_scaling: 100.0
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- text_rendering_mode: 0
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- fill/stroke_color: DeviceGray(0.0) (black)
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5. **Added matrix operations** to `Matrix3x3`:
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- `scale(sx, sy)` - create scale matrix
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- `translate(tx, ty)` - create translation matrix
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- `rotate(angle)` - create rotation matrix (angle in radians)
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- `invert()` - invert matrix, returns None if singular
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6. **Implemented `Debug` manually** for `GraphicsState`:
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- Font doesn't implement Debug, so we show `<Arc<Font>>` placeholder
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7. **Added comprehensive tests**:
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- `test_gstate_initial_ctm_is_identity`
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- `test_gstate_initial_font_size_is_zero`
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- `test_gstate_initial_fill_color_is_black`
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- `test_gstate_initial_horiz_scaling_is_100`
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- `test_gstate_initial_text_matrices_are_identity`
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- `test_gstate_initial_font_is_none`
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- `test_gstate_initial_text_rendering_mode_is_0`
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- `test_gstate_clone_deep_equal`
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- `test_color_device_rgb_to_css_hex` - verifies `#ff0000` for red
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- `test_color_device_gray_to_css_hex`
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- `test_color_device_cmyk_to_css_hex`
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- `test_color_spot_to_css_hex_none`
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- `test_color_other_to_css_hex_none`
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- `test_color_device_rgb_clamped`
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- `test_matrix_scale`
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- `test_matrix_translate`
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- `test_matrix_rotate`
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- `test_matrix_invert_identity`
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- `test_matrix_invert_translation`
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- `test_matrix_invert_singular`
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- `test_identity_multiply_identity`
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- `test_multiply_within_tolerance`
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## Acceptance Criteria Status
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- ✅ `GraphicsState::initial()` returns state with ctm == identity
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- ✅ `GraphicsState::initial()` returns state with font_size == 0.0
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- ✅ `GraphicsState::initial()` returns state with fill_color == DeviceGray(0.0)
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- ✅ Clone produces a deep-equal value (Arc cloned cheaply)
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- ✅ `Color::DeviceRGB([1.0, 0.0, 0.0]).to_css_hex() == Some("#ff0000".into())`
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- ✅ `Color::Spot("PANTONE".into(), 0.5).to_css_hex() == None`
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- ✅ Matrix multiply test: identity * identity == identity within 1e-10
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## Notes
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- Font doesn't implement Debug, so GraphicsState has a manual Debug impl that shows `<Arc<Font>>` placeholder for the font field
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- All matrix operations use f64 for precision (INV-30)
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- Color uses f32 for components per PDF spec convention
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- GraphicsState is Clone thanks to Arc<Font> (cheap clone for q/Q operators)
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## References
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- Plan section: Phase 3.1 State struct fields (lines 1444-1460), Color type (lines 1463-1471), CSS hex rules (line 1473)
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