From f98bb033ff14f39188f2bcafe11099c10920cb80 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Mon, 8 Jun 2020 02:53:37 +1000
Subject: [PATCH] HostDisplay: Add an interface for setting software cursor

---
 src/core/host_display.cpp | 60 +++++++++++++++++++++++++++++++++++++++
 src/core/host_display.h   | 19 +++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/src/core/host_display.cpp b/src/core/host_display.cpp
index 67df4e63f..07dd1ce32 100644
--- a/src/core/host_display.cpp
+++ b/src/core/host_display.cpp
@@ -1,6 +1,7 @@
 #include "host_display.h"
 #include "common/log.h"
 #include "common/string_util.h"
+#include "stb_image.h"
 #include "stb_image_resize.h"
 #include "stb_image_write.h"
 #include <cmath>
@@ -18,6 +19,50 @@ void HostDisplay::WindowResized(s32 new_window_width, s32 new_window_height)
   m_window_height = new_window_height;
 }
 
+void HostDisplay::SetSoftwareCursor(std::unique_ptr<HostDisplayTexture> texture, float scale /*= 1.0f*/)
+{
+  m_cursor_texture = std::move(texture);
+  m_cursor_texture_scale = scale;
+}
+
+bool HostDisplay::SetSoftwareCursor(const void* pixels, u32 width, u32 height, u32 stride, float scale /*= 1.0f*/)
+{
+  std::unique_ptr<HostDisplayTexture> tex = CreateTexture(width, height, pixels, stride, false);
+  if (!tex)
+    return false;
+
+  SetSoftwareCursor(std::move(tex), scale);
+  return true;
+}
+
+bool HostDisplay::SetSoftwareCursor(const char* path, float scale /*= 1.0f*/)
+{
+  int width, height, file_channels;
+  u8* pixel_data = stbi_load(path, &width, &height, &file_channels, 4);
+  if (!pixel_data)
+  {
+    const char* error_reason = stbi_failure_reason();
+    Log_ErrorPrintf("Failed to load image from '%s': %s", path, error_reason ? error_reason : "unknown error");
+    return false;
+  }
+
+  std::unique_ptr<HostDisplayTexture> tex = CreateTexture(static_cast<u32>(width), static_cast<u32>(height), pixel_data,
+                                                          sizeof(u32) * static_cast<u32>(width), false);
+  stbi_image_free(pixel_data);
+  if (!tex)
+    return false;
+
+  Log_InfoPrintf("Loaded %dx%d image from '%s' for software cursor", width, height, path);
+  SetSoftwareCursor(std::move(tex), scale);
+  return true;
+}
+
+void HostDisplay::ClearSoftwareCursor()
+{
+  m_cursor_texture.reset();
+  m_cursor_texture_scale = 1.0f;
+}
+
 void HostDisplay::CalculateDrawRect(s32 window_width, s32 window_height, s32* out_left, s32* out_top, s32* out_width,
                                     s32* out_height, s32* out_left_padding, s32* out_top_padding, float* out_scale,
                                     float* out_y_scale) const
@@ -88,6 +133,21 @@ std::tuple<s32, s32, s32, s32> HostDisplay::CalculateDrawRect(s32 window_width,
   return std::make_tuple(left + left_padding, top + top_padding + top_margin, width, height);
 }
 
+std::tuple<s32, s32, s32, s32> HostDisplay::CalculateSoftwareCursorDrawRect() const
+{
+  const u32 cursor_extents_x =
+    static_cast<u32>(static_cast<float>(m_cursor_texture->GetWidth()) * m_cursor_texture_scale * 0.5f);
+  const u32 cursor_extents_y =
+    static_cast<u32>(static_cast<float>(m_cursor_texture->GetHeight()) * m_cursor_texture_scale * 0.5f);
+
+  const s32 out_left = m_mouse_position_x - cursor_extents_x;
+  const s32 out_top = m_mouse_position_y - cursor_extents_y;
+  const s32 out_width = cursor_extents_x * 2u;
+  const s32 out_height = cursor_extents_y * 2u;
+
+  return std::tie(out_left, out_top, out_width, out_height);
+}
+
 std::tuple<s32, s32> HostDisplay::ConvertWindowCoordinatesToDisplayCoordinates(s32 window_x, s32 window_y,
                                                                                s32 window_width, s32 window_height,
                                                                                s32 top_margin) const
diff --git a/src/core/host_display.h b/src/core/host_display.h
index dee65c20c..687469d01 100644
--- a/src/core/host_display.h
+++ b/src/core/host_display.h
@@ -106,6 +106,18 @@ public:
   void SetDisplayTopMargin(s32 height) { m_display_top_margin = height; }
   void SetDisplayIntegerScaling(bool enabled) { m_display_integer_scaling = enabled; }
 
+  /// Sets the software cursor to the specified texture. Ownership of the texture is transferred.
+  void SetSoftwareCursor(std::unique_ptr<HostDisplayTexture> texture, float scale = 1.0f);
+
+  /// Sets the software cursor to the specified image.
+  bool SetSoftwareCursor(const void* pixels, u32 width, u32 height, u32 stride, float scale = 1.0f);
+
+  /// Sets the software cursor to the specified path (png image).
+  bool SetSoftwareCursor(const char* path, float scale = 1.0f);
+
+  /// Disables the software cursor.
+  void ClearSoftwareCursor();
+
   /// Helper function for computing the draw rectangle in a larger window.
   std::tuple<s32, s32, s32, s32> CalculateDrawRect(s32 window_width, s32 window_height, s32 top_margin) const;
 
@@ -125,10 +137,14 @@ public:
                                    bool clear_alpha = true);
 
 protected:
+  ALWAYS_INLINE bool HasSoftwareCursor() const { return static_cast<bool>(m_cursor_texture); }
+
   void CalculateDrawRect(s32 window_width, s32 window_height, s32* out_left, s32* out_top, s32* out_width,
                          s32* out_height, s32* out_left_padding, s32* out_top_padding, float* out_scale,
                          float* out_y_scale) const;
 
+  std::tuple<s32, s32, s32, s32> CalculateSoftwareCursorDrawRect() const;
+
   s32 m_window_width = 0;
   s32 m_window_height = 0;
 
@@ -153,6 +169,9 @@ protected:
 
   s32 m_display_top_margin = 0;
 
+  std::unique_ptr<HostDisplayTexture> m_cursor_texture;
+  float m_cursor_texture_scale = 1.0f;
+
   bool m_display_linear_filtering = false;
   bool m_display_changed = false;
   bool m_display_integer_scaling = false;