Fixed GetScrollMaxX(), GetScrollMaxY(). Tweak demo to display more data. Using functions in Begin(). (#1271)

imgui.cpp

@@ -4205,7 +4205,10 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
         }
         window->Scroll = ImMax(window->Scroll, ImVec2(0.0f, 0.0f));
         if (!window->Collapsed && !window->SkipItems)
-            window->Scroll = ImMin(window->Scroll, ImMax(ImVec2(0.0f, 0.0f), window->SizeContents - window->SizeFull + window->ScrollbarSizes));
+        {
+            window->Scroll.x = ImMin(window->Scroll.x, GetScrollMaxX());
+            window->Scroll.y = ImMin(window->Scroll.y, GetScrollMaxY());
+        }
 
         // Modal window darkens what is behind them
         if ((flags & ImGuiWindowFlags_Modal) != 0 && window == GetFrontMostModalRootWindow())
@@ -5267,13 +5270,13 @@ float ImGui::GetScrollY()
 float ImGui::GetScrollMaxX()
 {
     ImGuiWindow* window = GetCurrentWindowRead();
-    return window->SizeContents.x - window->SizeFull.x - window->ScrollbarSizes.x;
+    return ImMax(0.0f, window->SizeContents.x - (window->SizeFull.x - window->ScrollbarSizes.x));
 }
 
 float ImGui::GetScrollMaxY()
 {
     ImGuiWindow* window = GetCurrentWindowRead();
-    return window->SizeContents.y - window->SizeFull.y - window->ScrollbarSizes.y;
+    return ImMax(0.0f, window->SizeContents.y - (window->SizeFull.y - window->ScrollbarSizes.y));
 }
 
 void ImGui::SetScrollX(float scroll_x)

imgui_demo.cpp

@@ -1097,9 +1097,9 @@ void ImGui::ShowTestWindow(bool* p_open)
             static int track_line = 50, scroll_to_px = 200;
             ImGui::Checkbox("Track", &track);
             ImGui::PushItemWidth(100);
-            ImGui::SameLine(130); track |= ImGui::DragInt("##line", &track_line, 0.25f, 0, 99, "Line %.0f");
-            bool scroll_to = ImGui::Button("Scroll To");
-            ImGui::SameLine(130); scroll_to |= ImGui::DragInt("##pos_y", &scroll_to_px, 1.00f, 0, 9999, "y = %.0f px");
+            ImGui::SameLine(130); track |= ImGui::DragInt("##line", &track_line, 0.25f, 0, 99, "Line = %.0f");
+            bool scroll_to = ImGui::Button("Scroll To Pos");
+            ImGui::SameLine(130); scroll_to |= ImGui::DragInt("##pos_y", &scroll_to_px, 1.00f, 0, 9999, "Y = %.0f px");
             ImGui::PopItemWidth();
             if (scroll_to) track = false;
 
@@ -1123,7 +1123,9 @@ void ImGui::ShowTestWindow(bool* p_open)
                         ImGui::Text("Line %d", line);
                     }
                 }
+                float scroll_y = ImGui::GetScrollY(), scroll_max_y = ImGui::GetScrollMaxY();
                 ImGui::EndChild();
+                ImGui::Text("%.0f/%0.f", scroll_y, scroll_max_y);
                 ImGui::EndGroup();
             }
             ImGui::TreePop();
@@ -1158,12 +1160,14 @@ void ImGui::ShowTestWindow(bool* p_open)
                     ImGui::PopID();
                 }
             }
+            float scroll_x = ImGui::GetScrollX(), scroll_max_x = ImGui::GetScrollMaxX();
             ImGui::EndChild();
             ImGui::PopStyleVar(2);
             float scroll_x_delta = 0.0f;
-            ImGui::SmallButton("<<"); if (ImGui::IsItemActive()) scroll_x_delta = -ImGui::GetIO().DeltaTime * 1000.0f;
-            ImGui::SameLine(); ImGui::Text("Scroll from code"); ImGui::SameLine();
-            ImGui::SmallButton(">>"); if (ImGui::IsItemActive()) scroll_x_delta = +ImGui::GetIO().DeltaTime * 1000.0f;
+            ImGui::SmallButton("<<"); if (ImGui::IsItemActive()) scroll_x_delta = -ImGui::GetIO().DeltaTime * 1000.0f; ImGui::SameLine(); 
+            ImGui::Text("Scroll from code"); ImGui::SameLine();
+            ImGui::SmallButton(">>"); if (ImGui::IsItemActive()) scroll_x_delta = +ImGui::GetIO().DeltaTime * 1000.0f; ImGui::SameLine(); 
+            ImGui::Text("%.0f/%.0f", scroll_x, scroll_max_x);
             if (scroll_x_delta != 0.0f)
             {
                 ImGui::BeginChild("scrolling"); // Demonstrate a trick: you can use Begin to set yourself in the context of another window (here we are already out of your child window)