servo: Add a PNG graphics sink

Source-Repo: https://github.com/servo/servo
Source-Revision: 572d505037caa703ef9752ebea96e607e55fe791

servo/src/servo/gfx/pngsink.rs

@@ -0,0 +1,122 @@
+#[doc = "
+A graphics sink that renders to PNG format buffers
+
+Each time the renderer renders a frame the bufsink will output a
+`[u8]` containing the frame in PNG format.
+"];
+
+export msg, pngsink;
+
+import azure::cairo;
+import azure_bg = azure::bindgen;
+import azure::AzDrawTargetRef;
+import cairo_bg = cairo::bindgen;
+
+enum msg {
+    begin_drawing(chan<AzDrawTargetRef>),
+    draw(chan<AzDrawTargetRef>, AzDrawTargetRef),
+    exit
+}
+
+impl pngsink of renderer::sink for chan<msg> {
+    fn begin_drawing(next_dt: chan<AzDrawTargetRef>) {
+        self.send(begin_drawing(next_dt))
+    }
+    fn draw(next_dt: chan<AzDrawTargetRef>, draw_me: AzDrawTargetRef) {
+        self.send(draw(next_dt, draw_me))
+    }
+}
+
+fn pngsink(output: chan<[u8]>) -> chan<msg> {
+    task::spawn_listener::<msg> { |po|
+
+        let cairo_surf = cairo_bg::cairo_image_surface_create(
+            cairo::CAIRO_FORMAT_ARGB32, 800 as libc::c_int, 600 as libc::c_int
+            );
+        assert cairo_surf.is_not_null();
+
+        let draw_target = azure_bg::AzCreateDrawTargetForCairoSurface(cairo_surf);
+        assert draw_target.is_not_null();
+
+        loop {
+            alt po.recv() {
+              begin_drawing(sender) {
+                sender.send(draw_target);
+              }
+              draw(sender, dt) {
+                do_draw(sender, dt, output, cairo_surf);
+              }
+              exit { break }
+            }
+        }
+
+        azure_bg::AzReleaseDrawTarget(draw_target);
+        cairo_bg::cairo_surface_destroy(cairo_surf);
+    }
+}
+
+fn do_draw(sender: chan<AzDrawTargetRef>,
+           dt: AzDrawTargetRef,
+           output: comm::chan<[u8]>,
+           cairo_surf: *cairo::cairo_surface_t) {
+
+    import libc::*;
+
+    listen {|data_ch|
+
+        crust fn write_fn(closure: *c_void,
+                          data: *c_uchar,
+                          len: c_uint)
+
+            -> cairo::cairo_status_t unsafe {
+
+            let p: *chan<[u8]> = unsafe::reinterpret_cast(closure);
+            let data_ch = *p;
+
+            // Convert from *c_uchar to *u8
+            let data = unsafe::reinterpret_cast(data);
+            let len = len as uint;
+            // Copy to a vector
+            let data = vec::unsafe::from_buf(data, len);
+            data_ch.send(data);
+
+            ret cairo::CAIRO_STATUS_SUCCESS;
+        }
+
+        let closure = ptr::addr_of(data_ch);
+
+        unsafe {
+            cairo_bg::cairo_surface_write_to_png_stream(
+                cairo_surf, write_fn, unsafe::reinterpret_cast(closure));
+        }
+
+        // Collect the entire image into a single vector
+        let mut result = [];
+        while data_ch.peek() {
+            result += data_ch.recv();
+        }
+
+        // Send the PNG image away
+        output.send(result);
+    }
+    // Send the next draw target to the renderer
+    sender.send(dt);
+}
+
+#[test]
+fn sanity_check() {
+
+    listen {|ch|
+
+        let sink = pngsink(ch);
+        let renderer = renderer::renderer(sink);
+
+        let dlist = [];
+        renderer.send(renderer::render(dlist));
+        listen {|resp|
+            renderer.send(renderer::exit(resp));
+            resp.recv();
+        }
+        sink.send(exit)
+    }
+}

servo/src/servo/servo.rc

@@ -19,6 +19,7 @@ mod gfx {
     mod geom;
     mod surface;
     mod renderer;
+    mod pngsink;
 }
 
 mod image {