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Comments, clarification about io.WantCaptureMouse, io.WantCaptureKeyboard flags timing and NewFrame(). (#1262)

This commit is contained in:
omar 2017-08-05 19:15:03 +08:00
parent 95f2706d1c
commit d762f1dbfb

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@ -141,8 +141,9 @@
SwapBuffers();
}
- You can read back 'io.WantCaptureMouse', 'io.WantCaptureKeybord' etc. flags from the IO structure to tell how ImGui intends to use your
inputs and to know if you should share them or hide them from the rest of your application. Read the FAQ below for more information.
- When calling NewFrame(), the 'io.WantCaptureMouse'/'io.WantCaptureKeyboard'/'io.WantTextInput' flags are updated.
They tell you if ImGui intends to use your inputs. So for example, if 'io.WantCaptureMouse' is set you would typically want to hide
mouse inputs from the rest of your application. Read the FAQ below for more information about those flags.
API BREAKING CHANGES
@ -397,11 +398,13 @@
e.g. when displaying a list of objects, using indices or pointers as ID will preserve the node open/closed state differently. experiment and see what makes more sense!
Q: How can I tell when ImGui wants my mouse/keyboard inputs and when I can pass them to my application?
A: You can read the 'io.WantCaptureXXX' flags in the ImGuiIO structure. Preferably read them after calling ImGui::NewFrame() to avoid those flags lagging by one frame, but either should be fine.
When 'io.WantCaptureMouse' or 'io.WantCaptureKeyboard' flags are set you may want to discard/hide the inputs from the rest of your application.
When 'io.WantInputsCharacters' is set to may want to notify your OS to popup an on-screen keyboard, if available.
ImGui is tracking dragging and widget activity that may occur outside the boundary of a window, so 'io.WantCaptureMouse' is a more accurate and complete than testing for ImGui::IsMouseHoveringAnyWindow().
(Advanced note: text input releases focus on Return 'KeyDown', so the following Return 'KeyUp' event that your application receive will typically have 'io.WantcaptureKeyboard=false'.
A: You can read the 'io.WantCaptureMouse'/'io.WantCaptureKeyboard'/'ioWantTextInput' flags from the ImGuiIO structure.
- When 'io.WantCaptureMouse' or 'io.WantCaptureKeyboard' flags are set you may want to discard/hide the inputs from the rest of your application.
- When 'io.WantTextInput' is set to may want to notify your OS to popup an on-screen keyboard, if available (e.g. on a mobile phone, or console without a keyboard).
Preferably read the flags after calling ImGui::NewFrame() to avoid them lagging by one frame. But reading those flags before calling NewFrame() is also generally ok,
as the bool toggles fairly rarely and you don't generally expect to interact with either ImGui or your application during the same frame when that transition occurs.
ImGui is tracking dragging and widget activity that may occur outside the boundary of a window, so 'io.WantCaptureMouse' is more accurate and correct than checking if a window is hovered.
(Advanced note: text input releases focus on Return 'KeyDown', so the following Return 'KeyUp' event that your application receive will typically have 'io.WantCaptureKeyboard=false'.
Depending on your application logic it may or not be inconvenient. You might want to track which key-downs were for ImGui (e.g. with an array of bool) and filter out the corresponding key-ups.)
Q: How can I load a different font than the default? (default is an embedded version of ProggyClean.ttf, rendered at size 13)