Merge pull request #1513 from ramox81/codex/image-transparency

Raster images: draw opaque when transparency is off; TRANSPARENCY command

src/scene/model/image_model.rs

@@ -94,6 +94,9 @@ pub struct ImageModel {
     /// Magnified pixels stay square (raster images); otherwise they blend
     /// (PDF pages, OLE pictures).
     pub pixelated: bool,
+    /// Pixel alpha applies. A raster image whose transparency is off draws
+    /// every pixel opaque in its stored colour.
+    pub use_alpha: bool,
 }
 
 impl ImageModel {
@@ -165,6 +168,9 @@ impl ImageModel {
             draw_depth: 0.0,
             verts,
             pixelated: true,
+            use_alpha: img
+                .flags
+                .contains(codec::entities::ImageDisplayFlags::TRANSPARENCY_ON),
         })
     }
 }
@@ -274,6 +280,7 @@ impl ImageModel {
             draw_depth: 0.0,
             verts,
             pixelated: false,
+            use_alpha: true,
         })
     }
 }
@@ -355,6 +362,7 @@ impl ImageModel {
             draw_depth: 0.0,
             verts,
             pixelated: false,
+            use_alpha: true,
         })
     }
 }

src/scene/pipeline/image_gpu.rs

@@ -79,7 +79,9 @@ struct ImageParams {
     /// Signed draw-order depth (-1,1); applied as a clip-z bias in the shader
     /// so the raster orders against other entity types. 0.0 = neutral.
     draw_depth: f32,
-    _pad: [f32; 2],
+    /// 1.0 when pixel alpha applies, 0.0 when pixels draw opaque.
+    use_alpha: f32,
+    _pad: f32,
 } // 16 bytes
 
 // ── Per-image GPU handle ──────────────────────────────────────────────────
@@ -196,7 +198,8 @@ impl ImageGpu {
         let params = ImageParams {
             opacity: model.opacity.clamp(0.0, 1.0),
             draw_depth: 0.0,
-            _pad: [0.0; 2],
+            use_alpha: if model.use_alpha { 1.0 } else { 0.0 },
+            _pad: 0.0,
         };
         let params_buf = Arc::new(super::gpu_upload::upload_buffer(
             device,