add plugin camera desktop

plugins/camera_desktop/linux/camera_texture.h

@@ -0,0 +1,30 @@
+#ifndef CAMERA_TEXTURE_H_
+#define CAMERA_TEXTURE_H_
+
+#include <flutter_linux/flutter_linux.h>
+
+G_BEGIN_DECLS
+
+#define CAMERA_TEXTURE_TYPE (camera_texture_get_type())
+G_DECLARE_FINAL_TYPE(CameraTexture, camera_texture, CAMERA, TEXTURE,
+                     FlPixelBufferTexture)
+
+// Creates a new CameraTexture instance.
+CameraTexture* camera_texture_new(void);
+
+// Updates the texture with new RGBA frame data.
+// |data| must point to tightly-packed RGBA pixels (stride == width * 4).
+// |width| and |height| are the frame dimensions.
+// This is called from the GStreamer streaming thread; it writes to the
+// internal write buffer and swaps it into the ready slot.
+void camera_texture_update(CameraTexture* self,
+                           const uint8_t* data,
+                           uint32_t width,
+                           uint32_t height);
+
+// Returns the FlTexture base pointer (for registrar calls).
+FlTexture* camera_texture_as_fl_texture(CameraTexture* self);
+
+G_END_DECLS
+
+#endif  // CAMERA_TEXTURE_H_