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| 1 | +//! Annotation canvas with layered surfaces. |
| 2 | +//! |
| 3 | +//! The canvas manages three layers: |
| 4 | +//! 1. Background: Original screenshot (immutable) |
| 5 | +//! 2. Annotations: Committed drawings |
| 6 | +//! 3. Preview: Current tool preview (uncommitted) |
| 7 | + |
| 8 | +use anyhow::{Context, Result}; |
| 9 | +use gartk_core::Size; |
| 10 | +use gartk_render::Surface; |
| 11 | + |
| 12 | +/// Annotation canvas with layered rendering. |
| 13 | +pub struct AnnotationCanvas { |
| 14 | + /// Original screenshot (immutable background). |
| 15 | + background: Surface, |
| 16 | + /// Committed annotations layer. |
| 17 | + annotations: Surface, |
| 18 | + /// Live preview of current tool. |
| 19 | + preview: Surface, |
| 20 | + /// Composited output for display. |
| 21 | + composite: Surface, |
| 22 | + /// Canvas dimensions. |
| 23 | + size: Size, |
| 24 | +} |
| 25 | + |
| 26 | +impl AnnotationCanvas { |
| 27 | + /// Create a new annotation canvas from image data. |
| 28 | + /// |
| 29 | + /// # Arguments |
| 30 | + /// * `image_data` - RGBA pixel data |
| 31 | + /// * `width` - Image width in pixels |
| 32 | + /// * `height` - Image height in pixels |
| 33 | + pub fn new(image_data: &[u8], width: u32, height: u32) -> Result<Self> { |
| 34 | + let size = Size::new(width, height); |
| 35 | + |
| 36 | + // Create background surface from image data |
| 37 | + let background = Surface::from_rgba(image_data, width, height) |
| 38 | + .context("Failed to create background surface")?; |
| 39 | + |
| 40 | + // Create transparent annotation layer |
| 41 | + let annotations = Surface::new(width, height) |
| 42 | + .context("Failed to create annotation surface")?; |
| 43 | + |
| 44 | + // Create transparent preview layer |
| 45 | + let preview = Surface::new(width, height) |
| 46 | + .context("Failed to create preview surface")?; |
| 47 | + |
| 48 | + // Create composite surface for display |
| 49 | + let composite = Surface::new(width, height) |
| 50 | + .context("Failed to create composite surface")?; |
| 51 | + |
| 52 | + Ok(Self { |
| 53 | + background, |
| 54 | + annotations, |
| 55 | + preview, |
| 56 | + composite, |
| 57 | + size, |
| 58 | + }) |
| 59 | + } |
| 60 | + |
| 61 | + /// Get canvas dimensions. |
| 62 | + pub fn size(&self) -> Size { |
| 63 | + self.size |
| 64 | + } |
| 65 | + |
| 66 | + /// Get width. |
| 67 | + pub fn width(&self) -> u32 { |
| 68 | + self.size.width |
| 69 | + } |
| 70 | + |
| 71 | + /// Get height. |
| 72 | + pub fn height(&self) -> u32 { |
| 73 | + self.size.height |
| 74 | + } |
| 75 | + |
| 76 | + /// Get the annotations surface for drawing. |
| 77 | + pub fn annotations_surface(&self) -> &Surface { |
| 78 | + &self.annotations |
| 79 | + } |
| 80 | + |
| 81 | + /// Get the preview surface for drawing. |
| 82 | + pub fn preview_surface(&self) -> &Surface { |
| 83 | + &self.preview |
| 84 | + } |
| 85 | + |
| 86 | + /// Get the composite surface for display. |
| 87 | + pub fn composite_surface(&self) -> &Surface { |
| 88 | + &self.composite |
| 89 | + } |
| 90 | + |
| 91 | + /// Get mutable reference to composite surface. |
| 92 | + pub fn composite_surface_mut(&mut self) -> &mut Surface { |
| 93 | + &mut self.composite |
| 94 | + } |
| 95 | + |
| 96 | + /// Clear the preview layer. |
| 97 | + pub fn clear_preview(&self) -> Result<()> { |
| 98 | + let ctx = self.preview.context()?; |
| 99 | + ctx.set_operator(cairo::Operator::Clear); |
| 100 | + ctx.paint()?; |
| 101 | + ctx.set_operator(cairo::Operator::Over); |
| 102 | + Ok(()) |
| 103 | + } |
| 104 | + |
| 105 | + /// Commit preview to annotations layer. |
| 106 | + pub fn commit_preview(&self) -> Result<()> { |
| 107 | + // Paint preview onto annotations |
| 108 | + let ctx = self.annotations.context()?; |
| 109 | + ctx.set_source_surface(self.preview.cairo_surface(), 0.0, 0.0)?; |
| 110 | + ctx.paint()?; |
| 111 | + |
| 112 | + // Clear preview |
| 113 | + self.clear_preview()?; |
| 114 | + |
| 115 | + Ok(()) |
| 116 | + } |
| 117 | + |
| 118 | + /// Render all layers to composite surface. |
| 119 | + pub fn render(&self) -> Result<()> { |
| 120 | + let ctx = self.composite.context()?; |
| 121 | + |
| 122 | + // Clear composite |
| 123 | + ctx.set_operator(cairo::Operator::Source); |
| 124 | + |
| 125 | + // Draw background |
| 126 | + ctx.set_source_surface(self.background.cairo_surface(), 0.0, 0.0)?; |
| 127 | + ctx.paint()?; |
| 128 | + |
| 129 | + // Draw annotations with alpha blending |
| 130 | + ctx.set_operator(cairo::Operator::Over); |
| 131 | + ctx.set_source_surface(self.annotations.cairo_surface(), 0.0, 0.0)?; |
| 132 | + ctx.paint()?; |
| 133 | + |
| 134 | + // Draw preview |
| 135 | + ctx.set_source_surface(self.preview.cairo_surface(), 0.0, 0.0)?; |
| 136 | + ctx.paint()?; |
| 137 | + |
| 138 | + Ok(()) |
| 139 | + } |
| 140 | + |
| 141 | + /// Export the final composited image as RGBA data. |
| 142 | + pub fn export(&mut self) -> Result<Vec<u8>> { |
| 143 | + // Render final composite |
| 144 | + self.render()?; |
| 145 | + |
| 146 | + // Get pixel data from composite surface |
| 147 | + self.composite |
| 148 | + .to_rgba() |
| 149 | + .context("Failed to export canvas data") |
| 150 | + } |
| 151 | + |
| 152 | + /// Get a snapshot of the annotations layer for undo. |
| 153 | + pub fn snapshot_annotations(&mut self) -> Result<Vec<u8>> { |
| 154 | + self.annotations |
| 155 | + .to_rgba() |
| 156 | + .context("Failed to snapshot annotations") |
| 157 | + } |
| 158 | + |
| 159 | + /// Restore annotations layer from snapshot. |
| 160 | + pub fn restore_annotations(&self, data: &[u8]) -> Result<()> { |
| 161 | + let ctx = self.annotations.context()?; |
| 162 | + |
| 163 | + // Clear current annotations |
| 164 | + ctx.set_operator(cairo::Operator::Clear); |
| 165 | + ctx.paint()?; |
| 166 | + |
| 167 | + // Create temporary surface from snapshot data |
| 168 | + let temp = Surface::from_rgba(data, self.size.width, self.size.height)?; |
| 169 | + |
| 170 | + // Paint snapshot onto annotations |
| 171 | + ctx.set_operator(cairo::Operator::Source); |
| 172 | + ctx.set_source_surface(temp.cairo_surface(), 0.0, 0.0)?; |
| 173 | + ctx.paint()?; |
| 174 | + |
| 175 | + ctx.set_operator(cairo::Operator::Over); |
| 176 | + Ok(()) |
| 177 | + } |
| 178 | +} |