Show window only when mouse is over?

[sonoro1234]

Hi,

How could I show a window (used as transport control) only when mouse is over it?

Thanks, victor bombi

[ocornut]

I don't understand the question. Please clarify and explain the context.

[sonoro1234]

Having a transparent window that gets drawed only when mouse is over it I have tried

ig.PushStyleVar(imgui.ImGuiStyleVar_Alpha,0)
if ig.Begin("Transport",nil,imgui.ImGuiWindowFlags_NoTitleBar + imgui.ImGuiWindowFlags_NoResize) then
        if ig.IsWindowHovered(imgui.ImGuiHoveredFlags_RectOnly) then
            ig.PushStyleVar(imgui.ImGuiStyleVar_Alpha,1)
        end

But window mouse over is not detected with alpha==0

[sonoro1234]

alpha == 0.0001 works!! and it is almost invisible. Still I would like the window to be visible and not only the items inside when style alpha changes.

[ocornut]

As you just found out, Alpha==0.0 clips elements at a higher-level. So Alpha = 0.0001 will work for what you aim to do.

Still I would like the window to be visible and not only the items inside when style alpha changes.

Sorry I don't understand this sentence either.

[sonoro1234]

In the solution I tryed when alpha changes to 1 ( on mouse over ) it is applied only to the items that follow, but the window background remains transparent.

Beasides, when opening a popup window from transport window, IsWindowHovered returns false and window dissappears. I even disappears when doing mouse click on any item of this window.

[ocornut]

the window background remains transparent.

The window background is drawn by Begin(). Here you are querying IsWindowHovered() after Begin. You'll probably need to track state in your application to remember which window is hovered and apply that Alpha before Begin.

(This is because there's no way to use IsWindowHovered() on a different window than the current at the moment)

I have no idea what "transport window" mean. Please provide code and screenshots (as explained here). It's hard to understand your use case right now, and I can't be spending time to guess what you want in order to help you.

Popups inhibit inputs behind them. Check the flags for IsWindowHovered().

[sonoro1234]

when doing click on any item of this window IsWindowHovered returns false and window dissappears.

function transport:draw()

        local height = ig.GetItemsLineHeightWithSpacing() + ig.GetStyle().WindowPadding.y*2
        ig.SetNextWindowPos(ig.ImVec2(0, ig.GetIO().DisplaySize.y - height),0);
        ig.SetNextWindowSize(ig.ImVec2(ig.GetIO().DisplaySize.x,height),0);

        local numpops = 1
        ig.PushStyleVar(imgui.ImGuiStyleVar_Alpha,0.0001)

        if ig.Begin("Transport",nil,imgui.ImGuiWindowFlags_NoTitleBar + imgui.ImGuiWindowFlags_NoResize) then
            if ig.IsWindowHovered(imgui.ImGuiHoveredFlags_RectOnly) then
                ig.PushStyleVar(imgui.ImGuiStyleVar_Alpha,1)
                numpops=2
            end

            if ig.Button(play_but_text) then 
                transport.play()
            end

            ig.SameLine()
            ig.Text("(%05.1f FPS)", ig.GetIO().Framerate)

            ig.SameLine()
            if ig.Button("next") then 
                GL.timeprovider:set_time(GL.globaltime[0] + 1/GL.fps)
            end
            ig.SameLine()
            if ig.Button("prev") then 
                GL.timeprovider:set_time(GL.globaltime[0] - 1/GL.fps)
            end
            ig.SameLine()

            if ig.Button("save") then  save_image_browser.open() end
            save_image_browser.draw()
            ig.SameLine()

            if ig.Button("tools") then imgui.igOpenPopup("toolbox") end
            ToolBox(GL):draw()
            ig.SameLine()

            ig.PushItemWidth(-1)
            if ig.SliderFloat("", GL.globaltime, 0, GL.timeprovider.totdur, "%.3f", 1.0) then
                GL.timeprovider:set_time(GL.globaltime[0])
            end
            ig.PopItemWidth()
        end

        ig.End()
        ig.PopStyleVar(numpops)
    end

Thanks for your patience victor

[ocornut]

According to this section of the Demo window, it should work with RectOnly:

(you can try the demo)

RectOnly is a shortcut: ImGuiHoveredFlags_RectOnly = ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_AllowWhenOverlapped,

Make sure your value for ImGuiHoveredFlags_RectOnly is the correct value that C++ imgui expects. Those define values change from time to time, if you have a language wrapper it should be using values from imgui.h.

(This is == 104 in current imgui.. maybe your back-end copied from values instead of reading them from imgui.h?)

[sonoro1234]

I am using cimgui.h for imgui 1.53 and the value is 52. (4 + 16 + 32)

[ocornut]

It is == 52 with in imgui 1.53 you are right. Does that area of the Demo works correctly with your version? Click "Item" and check the value next to "AllowWhenBlockedByActiveItem".

PS: ( Actually, the ImGuiHoveredFlags_AllowWhenOverlapped flag is not supported by IsWindowHovered() and therefore ImGuiHoveredFlags_RectOnly isn't either:

bool ImGui::IsWindowHovered(ImGuiHoveredFlags flags)
{
    IM_ASSERT((flags & ImGuiHoveredFlags_AllowWhenOverlapped) == 0);   // Flags not supported by this function
    ImGuiContext& g = *GImGui;

This shouldn't concern you here, but you should maybe only use ImGuiHoveredFlags_AllowWhenBlockedByActiveItem, depending on how you want this to work. )

[sonoro1234]

Demo works ok. I found error in cimgui implementation!! Thanks

[ocornut]

Nice. Please report issue or a PR to the cimgui repo ideally :)