Moves ownership of the scan and line buffers out of the BufferingScanTarget.

Outputs/OpenGL/ScanTarget.cpp

@@ -79,6 +79,9 @@ ScanTarget::ScanTarget(GLuint target_framebuffer, float output_gamma) :
 	unprocessed_line_texture_(LineBufferWidth, LineBufferHeight, UnprocessedLineBufferTextureUnit, GL_NEAREST, false),
 	full_display_rectangle_(-1.0f, -1.0f, 2.0f, 2.0f) {
 
+	set_scan_buffer(scan_buffer_.data(), scan_buffer_.size());
+	set_line_buffer(line_buffer_.data(), line_metadata_buffer_.data(), line_buffer_.size());
+
 	// Allocate space for the scans and lines.
 	allocate_buffer(scan_buffer_, scan_buffer_name_, scan_vertex_array_);
 	allocate_buffer(line_buffer_, line_buffer_name_, line_vertex_array_);
@@ -253,7 +256,7 @@ void ScanTarget::update(int, int output_height) {
 					1 + area.end.write_area_y - area.start.write_area_y,
 					formatForDepth(write_area_data_size()),
 					GL_UNSIGNED_BYTE,
-					&write_area_texture_[size_t(TextureAddress(0, area.start.write_area_y)) * write_area_data_size()]);
+					&write_area_texture_[size_t(area.start.write_area_y * WriteAreaWidth) * write_area_data_size()]);
 			} else {
 				// The circular buffer wrapped around; submit the data from the read pointer to the end of
 				// the buffer and from the start of the buffer to the submit pointer.
@@ -264,7 +267,7 @@ void ScanTarget::update(int, int output_height) {
 					WriteAreaHeight - area.start.write_area_y,
 					formatForDepth(write_area_data_size()),
 					GL_UNSIGNED_BYTE,
-					&write_area_texture_[size_t(TextureAddress(0, area.start.write_area_y)) * write_area_data_size()]);
+					&write_area_texture_[size_t(area.start.write_area_y * WriteAreaWidth) * write_area_data_size()]);
 				test_gl(glTexSubImage2D,
 					GL_TEXTURE_2D, 0,
 					0, 0,

Outputs/OpenGL/ScanTarget.hpp

@@ -51,6 +51,9 @@ class ScanTarget: public Outputs::Display::BufferingScanTarget {
 		void update(int output_width, int output_height);
 
 	private:
+		static constexpr int LineBufferWidth = 2048;
+		static constexpr int LineBufferHeight = 2048;
+
 #ifndef NDEBUG
 		struct OpenGLVersionDumper {
 			OpenGLVersionDumper() {
@@ -146,8 +149,11 @@ class ScanTarget: public Outputs::Display::BufferingScanTarget {
 		*/
 		bool is_soft_display_type();
 
-		// Storage for the write area.
+		// Storage for the various buffers.
 		std::vector<uint8_t> write_area_texture_;
+		std::array<Scan, 16384> scan_buffer_;
+		std::array<Line, LineBufferHeight> line_buffer_;
+		std::array<LineMetadata, LineBufferHeight> line_metadata_buffer_;
 };
 
 }

Outputs/ScanTargets/BufferingScanTarget.cpp

@@ -14,6 +14,7 @@
 #define TextureAddressGetY(v)	uint16_t((v) >> 11)
 #define TextureAddressGetX(v)	uint16_t((v) & 0x7ff)
 #define TextureSub(a, b)		(((a) - (b)) & 0x3fffff)
+#define TextureAddress(x, y)	(((y) << 11) | (x))
 
 using namespace Outputs::Display;
 
@@ -162,7 +163,7 @@ void BufferingScanTarget::announce(Event event, bool is_visible, const Outputs::
 			}
 
 			// Attempt to allocate a new line; note allocation failure if necessary.
-			const auto next_line = uint16_t((write_pointers_.line + 1) % LineBufferHeight);
+			const auto next_line = uint16_t((write_pointers_.line + 1) % line_buffer_size_);
 			if(next_line == read_pointers.line) {
 				allocation_has_failed_ = true;
 				active_line_ = nullptr;
@@ -229,7 +230,7 @@ Outputs::Display::ScanTarget::Scan *BufferingScanTarget::begin_scan() {
 	const auto read_pointers = read_pointers_.load();
 
 	// Advance the pointer.
-	const auto next_write_pointer = decltype(write_pointers_.scan_buffer)((write_pointers_.scan_buffer + 1) % scan_buffer_.size());
+	const auto next_write_pointer = decltype(write_pointers_.scan_buffer)((write_pointers_.scan_buffer + 1) % scan_buffer_size_);
 
 	// Check whether that's too many.
 	if(next_write_pointer == read_pointers.scan_buffer) {
@@ -298,3 +299,14 @@ void BufferingScanTarget::perform(const std::function<void(void)> &function) {
 	function();
 	is_updating_.clear(std::memory_order_release);
 }
+
+void BufferingScanTarget::set_scan_buffer(Scan *buffer, size_t size) {
+	scan_buffer_ = buffer;
+	scan_buffer_size_ = size;
+}
+
+void BufferingScanTarget::set_line_buffer(Line *line_buffer, LineMetadata *metadata_buffer, size_t size) {
+	line_buffer_ = line_buffer;
+	line_metadata_buffer_ = metadata_buffer;
+	line_buffer_size_ = size;
+}

Outputs/ScanTargets/BufferingScanTarget.hpp

@@ -18,8 +18,6 @@
 #include <mutex>
 #include <vector>
 
-#define TextureAddress(x, y)	(((y) << 11) | (x))
-
 namespace Outputs {
 namespace Display {
 
@@ -45,9 +43,6 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
 		static constexpr int WriteAreaWidth = 2048;
 		static constexpr int WriteAreaHeight = 2048;
 
-		static constexpr int LineBufferWidth = 2048;
-		static constexpr int LineBufferHeight = 2048;
-
 		BufferingScanTarget();
 
 		// This is included because it's assumed that scan targets will want to expose one.
@@ -93,22 +88,23 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
 			bool previous_frame_was_complete;
 		};
 
+		/// Sets the area of memory to use as a scan buffer.
+		void set_scan_buffer(Scan *buffer, size_t size);
+
+		/// Sets the area of memory to use as line and line metadata buffers.
+		void set_line_buffer(Line *line_buffer, LineMetadata *metadata_buffer, size_t size);
+
 		// These are safe to read only within a `perform` block.
 		// TODO: can I do better than that?
 		Modals modals_;
 		bool modals_are_dirty_ = false;
 
-		/// Maintains a buffer of the most recent scans.
+		/// Sets a new base address for the texture.
-		// TODO: have the owner supply buffers and sizes.
+		/// When called this will flush all existing data and load up the
-		// That'll allow owners to place this in shared video memory if possible.
+		/// new data size.
-		std::array<Scan, 16384> scan_buffer_;
-		std::array<Line, LineBufferHeight> line_buffer_;
-		std::array<LineMetadata, LineBufferHeight> line_metadata_buffer_;
-
-		// Used by subclasses to set a new base address for the texture.
-		// When called this will flush all existing data and load up the
-		// new data size.
 		void set_write_area(uint8_t *base);
+
+		/// @returns The number of bytes per input sample, as per the latest modals.
 		size_t write_area_data_size() const;
 
 		/// Defines a segment of data now ready for output, consisting of start and endpoints for:
@@ -130,9 +126,12 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
 
 			Endpoint start, end;
 		};
-		void perform(const std::function<void(const OutputArea &)> &);
+		/// Performs @c action ensuring that no other @c perform actions, or any
-		void perform(const std::function<void(void)> &);
+		/// change to modals, occurs simultaneously.
+		void perform(const std::function<void(void)> &action);
 
+		/// Acts as per void(void) @c perform but also dequeues all latest available video output.
+		void perform(const std::function<void(const OutputArea &)> &);
 
 	private:
 		// ScanTarget overrides.
@@ -205,6 +204,15 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
 
 		/// A pointer to the next thing that should be provided to the caller for data.
 		PointerSet write_pointers_;
+
+		// The owner-supplied scan buffer and size.
+		Scan *scan_buffer_ = nullptr;
+		size_t scan_buffer_size_ = 0;
+
+		// The owner-supplied line buffer and size.
+		Line *line_buffer_ = nullptr;
+		LineMetadata *line_metadata_buffer_ = nullptr;
+		size_t line_buffer_size_ = 0;
 };