ImDrawList's PushClipRect not inherited by child window about imgui

[ocornut]

Oh actually the reason is that you used draw_list->PushClipRect(), this has no effect on GUI logic only draw list rendering.
It's a bit ill-defined what it would do in this case, I am not entirely sure would more correct to inherent ImDrawList's ClipRect in the child window.

If you instead use ImGui::PushClipRect() it does what you expect:

ImGui::PushStyleColor(ImGuiCol_WindowBg, IM_COL32(255, 0, 0, 255));
ImGui::Begin("Main Window");

ImDrawList* draw_list = ImGui::GetWindowDrawList();
ImVec2 min = { 5 + ImGui::GetWindowPos().x, 5 + ImGui::GetWindowPos().y };
ImVec2 max = { min.x + 100, min.y + 100 };
ImGui::PushClipRect(min, max, true);
ImGui::PushStyleColor(ImGuiCol_ChildBg, IM_COL32(0, 255, 0, 200));
if (ImGui::BeginChild("Child Window 1", { 300,200 }, true) == true)
{
    ImVec2 p = ImGui::GetCursorScreenPos();
    ImGui::Text("abcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\n");
    ImGui::SetCursorScreenPos(p);

    ImGui::PushStyleColor(ImGuiCol_ChildBg, IM_COL32(0, 0, 255, 200));
    ImGui::BeginChild("Child Window 2", ImVec2(300, 200), ImGuiChildFlags_Border);
    ImGui::Text("abcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\n");
    ImGui::PopStyleColor();

    ImGui::EndChild();
}
ImGui::PopStyleColor();
ImGui::EndChild();
ImGui::PopClipRect();

ImGui::End();
ImGui::PopStyleColor();

[ocornut]

The screenshot shows that the first child window was cropped correctly, but the second child window is not cropped the same way as the first. Is that how it should be?

Actually, only the background of the first child window is cropped correctly, because as an optimized it is drawn in the drawlist of the parent window. In the following modified repro you can see the text in first child goes out.

ImGui::PushStyleColor(ImGuiCol_WindowBg, IM_COL32(255, 0, 0, 255));
ImGui::Begin("Main Window");

ImDrawList* draw_list = ImGui::GetWindowDrawList();
ImVec2 min = { 5 + ImGui::GetWindowPos().x, 5 + ImGui::GetWindowPos().y };
ImVec2 max = { min.x + 100, min.y + 100 };
draw_list->PushClipRect(min, max);
ImGui::PushStyleColor(ImGuiCol_ChildBg, IM_COL32(0, 255, 0, 200));
if (ImGui::BeginChild("Child Window 1", { 300,200 }, true) == true)
{
    ImVec2 p = ImGui::GetCursorScreenPos();
    ImGui::Text("abcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\n");
    ImGui::SetCursorScreenPos(p);

    ImGui::PushStyleColor(ImGuiCol_ChildBg, IM_COL32(0, 0, 255, 200));
    ImGui::BeginChild("Child Window 2", ImVec2(300, 200), ImGuiChildFlags_Border);
    ImGui::Text("abcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\n");
    ImGui::PopStyleColor();

    ImGui::EndChild();
}
ImGui::PopStyleColor();
draw_list->PopClipRect();

ImGui::EndChild();

ImGui::End();
ImGui::PopStyleColor();

[ElectroidDes]

Thank you very much, it worked.