From fd394e1e95474bb658c48086ac7edf0719aa7c7e Mon Sep 17 00:00:00 2001 From: omar Date: Sun, 20 Aug 2017 16:39:11 +0800 Subject: [PATCH] Scrollbar: Comments. Fixed potential div-by-zero error which I can repro now, so added an assert to notify us if it's actually ever useful or not. --- imgui.cpp | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/imgui.cpp b/imgui.cpp index c3721cdf..ab4ad2b8 100644 --- a/imgui.cpp +++ b/imgui.cpp @@ -4490,15 +4490,17 @@ static void Scrollbar(ImGuiWindow* window, bool horizontal) window->DrawList->AddRectFilled(bb.Min, bb.Max, ImGui::GetColorU32(ImGuiCol_ScrollbarBg), window_rounding, window_rounding_corners); bb.Reduce(ImVec2(ImClamp((float)(int)((bb.Max.x - bb.Min.x - 2.0f) * 0.5f), 0.0f, 3.0f), ImClamp((float)(int)((bb.Max.y - bb.Min.y - 2.0f) * 0.5f), 0.0f, 3.0f))); - // V denote the main axis of the scrollbar + // V denote the main, longer axis of the scrollbar (= height for a vertical scrollbar) float scrollbar_size_v = horizontal ? bb.GetWidth() : bb.GetHeight(); float scroll_v = horizontal ? window->Scroll.x : window->Scroll.y; float win_size_avail_v = (horizontal ? window->SizeFull.x : window->SizeFull.y) - other_scrollbar_size_w; float win_size_contents_v = horizontal ? window->SizeContents.x : window->SizeContents.y; - // The grabbable box size generally represent the amount visible (vs the total scrollable amount) + // Calculate the height of our grabbable box. It generally represent the amount visible (vs the total scrollable amount) // But we maintain a minimum size in pixel to allow for the user to still aim inside. - const float grab_h_pixels = ImMin(ImMax(scrollbar_size_v * ImSaturate(win_size_avail_v / ImMax(win_size_contents_v, win_size_avail_v)), style.GrabMinSize), scrollbar_size_v); + IM_ASSERT(ImMax(win_size_contents_v, win_size_avail_v) > 0.0f); // Adding this assert to check if the ImMax(XXX,1.0f) is still needed. PLEASE CONTACT ME if this triggers. + const float win_size_v = ImMax(ImMax(win_size_contents_v, win_size_avail_v), 1.0f); + const float grab_h_pixels = ImClamp(scrollbar_size_v * (win_size_avail_v / win_size_v), style.GrabMinSize, scrollbar_size_v); const float grab_h_norm = grab_h_pixels / scrollbar_size_v; // Handle input right away. None of the code of Begin() is relying on scrolling position before calling Scrollbar().