Fixed ImDrawList::AddRect() which used to render a rectangle 1 px too large on each axis., fixed Image(), ImageButton() as well (#457)

imgui.cpp

@@ -148,6 +148,7 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2015/12/27 (1.48) - fixed ImDrawList::AddRect() which used to render a rectangle 1 px too large on each axis.
  - 2015/12/04 (1.47) - renamed Color() helpers to ValueColor() - dangerously named, rarely used and probably to be made obsolete.
  - 2015/08/29 (1.45) - with the addition of horizontal scrollbar we made various fixes to inconsistencies with dealing with cursor position.
                        GetCursorPos()/SetCursorPos() functions now include the scrolled amount. It shouldn't affect the majority of users, but take note that SetCursorPosX(100.0f) puts you at +100 from the starting x position which may include scrolling, not at +100 from the window left side.
@@ -2665,8 +2666,8 @@ void ImGui::RenderFrame(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, bool border,
     window->DrawList->AddRectFilled(p_min, p_max, fill_col, rounding);
     if (border && (window->Flags & ImGuiWindowFlags_ShowBorders))
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max, GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max-ImVec2(1,1), GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
     }
 }
 
@@ -3982,8 +3983,8 @@ bool ImGui::Begin(const char* name, bool* p_opened, const ImVec2& size_on_first_
             // Borders
             if (flags & ImGuiWindowFlags_ShowBorders)
             {
-                window->DrawList->AddRect(window->Pos+ImVec2(1,1), window->Pos+window->Size, GetColorU32(ImGuiCol_BorderShadow), window_rounding);
-                window->DrawList->AddRect(window->Pos, window->Pos+window->Size-ImVec2(1,1), GetColorU32(ImGuiCol_Border), window_rounding);
+                window->DrawList->AddRect(window->Pos+ImVec2(1,1), window->Pos+window->Size+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), window_rounding);
+                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding);
                 if (!(flags & ImGuiWindowFlags_NoTitleBar))
                     window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,0), title_bar_rect.GetBR()-ImVec2(1,0), GetColorU32(ImGuiCol_Border));
             }

imgui.h

@@ -1113,8 +1113,8 @@ struct ImDrawList
 
     // Primitives
     IMGUI_API void  AddLine(const ImVec2& a, const ImVec2& b, ImU32 col, float thickness = 1.0f);
-    IMGUI_API void  AddRect(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners = 0x0F);
-    IMGUI_API void  AddRectFilled(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners = 0x0F);
+    IMGUI_API void  AddRect(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners = 0x0F);        // a: upper-left, b: lower-right
+    IMGUI_API void  AddRectFilled(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners = 0x0F);  // a: upper-left, b: lower-right
     IMGUI_API void  AddRectFilledMultiColor(const ImVec2& a, const ImVec2& b, ImU32 col_upr_left, ImU32 col_upr_right, ImU32 col_bot_right, ImU32 col_bot_left);
     IMGUI_API void  AddTriangleFilled(const ImVec2& a, const ImVec2& b, const ImVec2& c, ImU32 col);
     IMGUI_API void  AddCircle(const ImVec2& centre, float radius, ImU32 col, int num_segments = 12);

imgui_draw.cpp

@@ -771,11 +771,12 @@ void ImDrawList::AddLine(const ImVec2& a, const ImVec2& b, ImU32 col, float thic
     PathStroke(col, false, thickness);
 }
 
+// a: upper-left, b: lower-right. we don't render 1 px sized rectangles properly.
 void ImDrawList::AddRect(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding, int rounding_corners)
 {
     if ((col >> 24) == 0)
         return;
-    PathRect(a + ImVec2(0.5f,0.5f), b + ImVec2(0.5f,0.5f), rounding, rounding_corners);
+    PathRect(a + ImVec2(0.5f,0.5f), b - ImVec2(0.5f,0.5f), rounding, rounding_corners);
     PathStroke(col, true);
 }