WIP - Fonts: avoid both ImTextureRef being set simultaneously.

Author: ocornut

imgui.h

@@ -3520,7 +3520,7 @@ struct IMGUI_API ImTextureData
     unsigned char*      GetPixelsAt(int x, int y)   { IM_ASSERT(Pixels != NULL); return Pixels + (x + y * Width) * BytesPerPixel; }
     int                 GetSizeInBytes() const      { return Width * Height * BytesPerPixel; }
     int                 GetPitch() const            { return Width * BytesPerPixel; }
-    ImTextureRef        GetTexRef()                 { ImTextureRef tex_ref; tex_ref._TexData = this; tex_ref._TexID = TexID; return tex_ref; } // FIXME-TEXREF
+    ImTextureRef        GetTexRef()                 { ImTextureRef tex_ref; tex_ref._TexData = this; tex_ref._TexID = ImTextureID_Invalid; return tex_ref; }
     ImTextureID         GetTexID() const            { return TexID; }
     void                SetTexID(ImTextureID tex_id){ TexID = tex_id; } // Called by the Renderer backend after creating or destroying the texture. Never modify TexID directly!
 };
@@ -3852,11 +3852,12 @@ struct ImFont
 // We added an indirection to avoid patching ImDrawCmd after texture updates but this could be a solution too.
 inline ImTextureID ImTextureRef::GetTexID() const
 {
+    IM_ASSERT(!(_TexData != NULL && _TexID != ImTextureID_Invalid));
     return _TexData ? _TexData->TexID : _TexID;
 }
 inline ImTextureID ImDrawCmd::GetTexID() const
 {
-    ImTextureID tex_id = TexRef._TexData ? TexRef._TexData->TexID : TexRef._TexID;
+    ImTextureID tex_id = TexRef.GetTexID();
     IM_ASSERT((TexRef._TexData == NULL || tex_id != ImTextureID_Invalid) && "ImDrawCmd is referring to ImTextureData that wasn't uploaded to graphics system. Backend must call ImTextureData::SetTexID()!");
     return tex_id;
 }

imgui_draw.cpp

@@ -2617,7 +2617,6 @@ ImFontAtlas::ImFontAtlas()
     TexMaxWidth = 8192;
     TexMaxHeight = 8192;
     RendererHasTextures = false; // Assumed false by default, as apps can call e.g Atlas::Build() after backend init and before ImGui can update.
-    TexRef._TexData = NULL;// this;
     TexNextUniqueID = 1;
     FontNextUniqueID = 1;
     Builder = NULL;
@@ -3885,9 +3884,8 @@ static void ImFontAtlasBuildSetTexture(ImFontAtlas* atlas, ImTextureData* tex)
     atlas->TexData = tex;
     atlas->TexUvScale = ImVec2(1.0f / tex->Width, 1.0f / tex->Height);
     atlas->TexRef._TexData = tex;
-    //atlas->TexID._TexID = tex->TexID; // <-- We intentionally don't do that and leave it 0, to allow late upload.
-    ImTextureRef new_tex_ref = atlas->TexRef;
-    ImFontAtlasUpdateDrawListsTextures(atlas, old_tex_ref, new_tex_ref);
+    //atlas->TexRef._TexID = tex->TexID; // <-- We intentionally don't do that. It would be misleading and betray promise that both fields aren't set.
+    ImFontAtlasUpdateDrawListsTextures(atlas, old_tex_ref, atlas->TexRef);
 }
 
 // Create a new texture, discard previous one