Adding generic immediate mode drawing API and migrating microprofile.

Future changes will move elemental-forms and imgui to the common API as
well.

src/xenia/ui/immediate_drawer.h

@@ -0,0 +1,109 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2015 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_UI_IMMEDIATE_DRAWER_H_
+#define XENIA_UI_IMMEDIATE_DRAWER_H_
+
+#include <memory>
+
+namespace xe {
+namespace ui {
+
+class GraphicsContext;
+
+// Describes the filter applied when sampling textures.
+enum class ImmediateTextureFilter {
+  kNearest,
+  kLinear,
+};
+
+// Simple texture compatible with the immediate renderer.
+class ImmediateTexture {
+ public:
+  virtual ~ImmediateTexture() = default;
+
+  // Texture width, in pixels.
+  uint32_t width;
+  // Texture height, in pixels.
+  uint32_t height;
+  // Internal handle. Can be passed with the ImmediateDrawBatch.
+  uintptr_t handle;
+
+ protected:
+  ImmediateTexture(uint32_t width, uint32_t height)
+      : width(width), height(height) {}
+};
+
+// Describes the primitive type used by a draw call.
+enum class ImmediatePrimitiveType {
+  kLines,
+  kTriangles,
+};
+
+// Simple vertex used by the immediate mode drawer.
+struct ImmediateVertex {
+  float x, y;
+  float u, v;
+  uint32_t color;
+};
+
+// All parameters required to draw an immediate-mode batch of vertices.
+struct ImmediateDrawBatch {
+  // Primitive type the vertices/indices represent.
+  ImmediatePrimitiveType primitive_type = ImmediatePrimitiveType::kTriangles;
+
+  // Vertices to draw.
+  const ImmediateVertex* vertices = nullptr;
+  int vertex_count = 0;
+
+  // Optional index buffer indices.
+  const uint16_t* indices = nullptr;
+  int index_count = 0;
+
+  // Texture used when drawing, or nullptr if color only.
+  // This is most commonly the handle of an ImmediateTexture.
+  uintptr_t texture_handle = 0;
+
+  // True to enable scissoring using the region defined by scissor_rect.
+  bool scissor = false;
+  // Scissoring region in framebuffer pixels as (x, y, w, h).
+  int scissor_rect[4] = {0};
+};
+
+class ImmediateDrawer {
+ public:
+  virtual ~ImmediateDrawer() = default;
+
+  // Creates a new texture with the given attributes and optionally updates
+  // initial data.
+  virtual std::unique_ptr<ImmediateTexture> CreateTexture(
+      uint32_t width, uint32_t height, ImmediateTextureFilter filter,
+      bool repeat, const uint8_t* data = nullptr) = 0;
+  // Uploads data to the given texture, replacing the current contents.
+  virtual void UpdateTexture(ImmediateTexture* texture,
+                             const uint8_t* data) = 0;
+
+  // Begins drawing in immediate mode using the given projection matrix.
+  virtual void Begin(int render_target_width, int render_target_height) = 0;
+  // Issues an immediate mode draw batch.
+  virtual void Draw(const ImmediateDrawBatch& batch) = 0;
+  // Ends drawing in immediate mode and flushes contents.
+  virtual void End() = 0;
+
+ protected:
+  ImmediateDrawer(GraphicsContext* graphics_context)
+      : graphics_context_(graphics_context) {}
+
+  GraphicsContext* graphics_context_ = nullptr;
+};
+
+}  // namespace ui
+}  // namespace xe
+
+#endif  // XENIA_UI_IMMEDIATE_DRAWER_H_