update Dear ImGui to 1.92.0, part 2

TODO:
- testing
- testing
- testing
- additional testing
- extra testing

and of course:
- testing

extern/imgui_software_renderer/imgui_sw.cpp

@@ -17,7 +17,6 @@
 struct ImGui_ImplSW_Data
 {
     SDL_Window*  Window;
-    SWTexture*   FontTexture;
 
     ImGui_ImplSW_Data() { memset((void*)this, 0, sizeof(*this)); }
 };
@@ -537,7 +536,7 @@ static void paint_draw_cmd(const PaintTarget &target,
   const ImDrawCmd &pcmd,
   const ImVec2& white_uv)
 {
-  const SWTexture* texture = (const SWTexture*)(pcmd.TextureId);
+  const SWTexture* texture = (const SWTexture*)(pcmd.GetTexID());
   IM_ASSERT(texture);
 
   for (unsigned int i = 0; i + 3 <= pcmd.ElemCount;) {
@@ -647,7 +646,7 @@ static void paint_imgui(uint32_t *pixels, ImDrawData *drawData, int fb_width, in
 
 bool ImGui_ImplSW_Init(SDL_Window* win) {
   ImGuiIO& io = ImGui::GetIO();
-  ImGuiIO& platform_io = ImGui::GetPlatformIO();
+  ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
   IM_ASSERT(io.BackendRendererUserData == nullptr);
 
   if (SDL_HasWindowSurface(win)==SDL_FALSE) {
@@ -677,17 +676,22 @@ void ImGui_ImplSW_Shutdown() {
   IM_DELETE(bd);
 }
 
-bool ImGui_ImplSW_NewFrame() {
+void ImGui_ImplSW_NewFrame() {
   ImGui_ImplSW_Data* bd = ImGui_ImplSW_GetBackendData();
   IM_ASSERT(bd != nullptr);
-
-  return true;
 }
 
 void ImGui_ImplSW_RenderDrawData(ImDrawData* draw_data) {
   ImGui_ImplSW_Data* bd = ImGui_ImplSW_GetBackendData();
   IM_ASSERT(bd != nullptr);
 
+  // update textures if needed
+  if (draw_data->Textures!=NULL) {
+    for (ImTextureData* i: *draw_data->Textures) {
+      if (i->Status!=ImTextureStatus_OK) ImGui_ImplSW_UpdateTexture(i);
+    }
+  }
+
   SDL_Surface* surf = SDL_GetWindowSurface(bd->Window);
   if (!surf) return;
 
@@ -704,38 +708,84 @@ void ImGui_ImplSW_RenderDrawData(ImDrawData* draw_data) {
 
 /// CREATE OBJECTS
 
-bool ImGui_ImplSW_CreateFontsTexture() {
-  ImGuiIO &io = ImGui::GetIO();
-  ImGui_ImplSW_Data* bd = ImGui_ImplSW_GetBackendData();
-
-  // Load default font (embedded in code):
-  uint8_t *tex_data;
-  int font_width, font_height;
-  io.Fonts->GetTexDataAsAlpha8(&tex_data, &font_width, &font_height);
-  SWTexture* texture = new SWTexture((uint32_t*)tex_data,font_width,font_height,true);
-  io.Fonts->SetTexID((ImTextureID)texture);
-  bd->FontTexture = texture;
-
-  return true;
-}
-
-void ImGui_ImplSW_DestroyFontsTexture() {
-  ImGuiIO& io = ImGui::GetIO();
-  ImGui_ImplSW_Data* bd = ImGui_ImplSW_GetBackendData();
-  if (bd->FontTexture)
-  {
-      delete bd->FontTexture;
-      io.Fonts->SetTexID(0);
-      bd->FontTexture = 0;
-  }
-}
-
 bool ImGui_ImplSW_CreateDeviceObjects() {
   return true;
 }
 
 void ImGui_ImplSW_DestroyDeviceObjects() {
-  ImGui_ImplSW_DestroyFontsTexture();
+}
+
+void ImGui_ImplSW_UpdateTexture(ImTextureData* tex) {
+  if (tex->Status==ImTextureStatus_WantCreate) {
+    SWTexture* t=new SWTexture(tex->Width,tex->Height,tex->Format==ImTextureFormat_Alpha8);
+    memcpy(t->pixels,tex->GetPixels(),tex->GetSizeInBytes());
+
+    tex->SetTexID((ImTextureID)t);
+    tex->SetStatus(ImTextureStatus_OK);
+  } else if (tex->Status==ImTextureStatus_WantUpdates) {
+    SWTexture* t=(SWTexture*)tex->GetTexID();
+
+    // we don't support format changes (this should not happen)
+    assert(t->isAlpha==(tex->Format==ImTextureFormat_Alpha8));
+
+    if (t->width!=tex->Width || t->height!=tex->Height) {
+      // width/height changed; recreate texture
+      SWTexture* newTex=new SWTexture(tex->Width,tex->Height,tex->Format==ImTextureFormat_Alpha8);
+
+      // copy previous texture to new one
+      int i_y=0;
+      int i_y1=0;
+      if (t->isAlpha) {
+        for (int i=0; i<t->height; i++) {
+          unsigned char* dataOld=(unsigned char*)t->pixels;
+          unsigned char* dataNew=(unsigned char*)newTex->pixels;
+          memcpy(&dataNew[i_y1],&dataOld[i_y],t->width);
+          i_y1+=newTex->width;
+          i_y+=t->width;
+        }
+      } else {
+        for (int i=0; i<t->height; i++) {
+          uint32_t* dataOld=t->pixels;
+          uint32_t* dataNew=newTex->pixels;
+          memcpy(&dataNew[i_y1],&dataOld[i_y],t->width*sizeof(uint32_t));
+          i_y1+=newTex->width;
+          i_y+=t->width;
+        }
+      }
+
+      // delete previous texture and change texture ID
+      tex->SetTexID((ImTextureID)newTex);
+      delete t;
+      t=newTex;
+    }
+
+    // update region
+    if (t->isAlpha) {
+      unsigned char* data=(unsigned char*)t->pixels;
+      int i_y=t->width*tex->UpdateRect.y;
+      for (int i=tex->UpdateRect.y; i<tex->UpdateRect.y+tex->UpdateRect.w; i++) {
+        memcpy(&data[i_y],tex->GetPixelsAt(tex->UpdateRect.x,i),tex->UpdateRect.w);
+        i_y+=t->width;
+      }
+    } else {
+      uint32_t* data=t->pixels;
+      int i_y=t->width*tex->UpdateRect.y;
+      for (int i=tex->UpdateRect.y; i<tex->UpdateRect.y+tex->UpdateRect.w; i++) {
+        memcpy(&data[i_y],tex->GetPixelsAt(tex->UpdateRect.x,i),tex->UpdateRect.w*sizeof(uint32_t));
+        i_y+=t->width;
+      }
+    }
+
+    tex->SetStatus(ImTextureStatus_OK);
+  } else if (tex->Status==ImTextureStatus_WantDestroy && tex->UnusedFrames>0) {
+    SWTexture* t=(SWTexture*)tex->GetTexID();
+    delete t;
+
+    tex->SetTexID(ImTextureID_Invalid);
+    tex->SetStatus(ImTextureStatus_Destroyed);
+  } else {
+    // ????????
+  }
 }
 
 #endif // #ifndef IMGUI_DISABLE