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FAQ update, removed redundant block in imgui.cpp

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docking
omar 5 years ago
parent fed80b9537
commit 45a7cf47ab
3 changed files with 19 additions and 127 deletions
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5
docs/CHANGELOG.txt
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@ -36,12 +36,13 @@ HOW TO UPDATE?
Breaking Changes:
- Removed unncessary ID (first arg) of ImFontAtlas::AddCustomRectRegular() function. Please
- Removed unnecessary ID (first arg) of ImFontAtlas::AddCustomRectRegular() function. Please
note that this is a Beta api and will likely be reworked to support multi-monitor multi-DPI.
- Renamed OpenPopupOnItemClick() to OpenPopupContextItem(). Kept inline redirection function (will obsolete).
- Removed BeginPopupContextWindow(const char*, int mouse_button, bool also_over_items) in favor
of BeginPopupContextWindow(const char*, ImGuiPopupFlags flags) with ImGuiPopupFlags_NoOverItems.
- Removed CalcItemRectClosestPoint() entry point which was made obsolete and asserting in December 2017.
Kept inline redirection function (will obsolete).
- Removed obsoleted CalcItemRectClosestPoint() entry point (has been asserting since December 2017).
Other Changes:

13
docs/FAQ.md
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@ -23,7 +23,7 @@ or view this file with any Markdown viewer.
| [I integrated Dear ImGui in my engine and some elements are clipping or disappearing when I move windows around..](#q-i-integrated-dear-imgui-in-my-engine-and-some-elements-are-clipping-or-disappearing-when-i-move-windows-around) |
| [I integrated Dear ImGui in my engine and some elements are displaying outside their expected windows boundaries..](#q-i-integrated-dear-imgui-in-my-engine-and-some-elements-are-displaying-outside-their-expected-windows-boundaries) |
| **Q&A: Usage** |
| **[Why are multiple widgets reacting when I interact with a single one?<br>How can I have multiple widgets with the same label or with an empty label?](#q-why-are-multiple-widgets-reacting-when-i-interact-with-a-single-one-q-how-can-i-have-multiple-widgets-with-the-same-label-or-with-an-empty-label)** |
| **[How can I have widgets with an empty label?<br>How can I have multiple widgets with the same label?<br>Why are multiple widgets reacting when I interact with one?](#q-how-can-i-have-widgets-with-an-empty-label)** |
| [How can I display an image? What is ImTextureID, how does it work?](#q-how-can-i-display-an-image-what-is-imtextureid-how-does-it-work)|
| [How can I use my own math types instead of ImVec2/ImVec4?](#q-how-can-i-use-my-own-math-types-instead-of-imvec2imvec4) |
| [How can I interact with standard C++ types (such as std::string and std::vector)?](#q-how-can-i-interact-with-standard-c-types-such-as-stdstring-and-stdvector) |
@ -173,7 +173,9 @@ Refer to rendering back-ends in the [examples/](https://github.com/ocornut/imgui
# Q&A: Usage
### Q: Why are multiple widgets reacting when I interact with a single one? <br>Q: How can I have multiple widgets with the same label or with an empty label?
### Q: How can I have widgets with an empty label?
### Q: How can I have multiple widgets with the same label?
### Q: Why are multiple widgets reacting when I interact with one?
A primer on labels and the ID Stack...
@ -295,11 +297,12 @@ if (TreeNode("node")) // <-- this function call will do a PushID() for you (unl
TreePop();
}
```
- When working with trees, ID are used to preserve the open/close state of each tree node.
When working with trees, ID are used to preserve the open/close state of each tree node.
Depending on your use cases you may want to use strings, indices or pointers as ID.
e.g. when following a single pointer that may change over time, using a static string as ID
- e.g. when following a single pointer that may change over time, using a static string as ID
will preserve your node open/closed state when the targeted object change.
e.g. when displaying a list of objects, using indices or pointers as ID will preserve the
- e.g. when displaying a list of objects, using indices or pointers as ID will preserve the
node open/closed state differently. See what makes more sense in your situation!
##### [Return to Index](#index)

126
imgui.cpp
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@ -601,7 +601,10 @@ CODE
FREQUENTLY ASKED QUESTIONS (FAQ)
================================
Read all answers online: https://www.dearimgui.org/faq, or in docs/FAQ.md (with a Markdown viewer)
Read all answers online:
https://www.dearimgui.org/faq or https://github.com/ocornut/imgui/blob/master/docs/FAQ.md (same url)
Read all answers locally (with a text editor or ideally a Markdown viewer):
docs/FAQ.md
Some answers are copied down here to facilitate searching in code.
Q&A: Basics
@ -645,125 +648,10 @@ CODE
Q&A: Usage
----------
Q: Why are multiple widgets reacting when I interact with a single one?
Q: How can I have multiple widgets with the same label or with an empty label?
A: A primer on labels and the ID Stack...
Dear ImGui internally need to uniquely identify UI elements.
Elements that are typically not clickable (such as calls to the Text functions) don't need an ID.
Interactive widgets (such as calls to Button buttons) need a unique ID.
Unique ID are used internally to track active widgets and occasionally associate state to widgets.
Unique ID are implicitly built from the hash of multiple elements that identify the "path" to the UI element.
- Unique ID are often derived from a string label:
Button("OK"); // Label = "OK", ID = hash of (..., "OK")
Button("Cancel"); // Label = "Cancel", ID = hash of (..., "Cancel")
- ID are uniquely scoped within windows, tree nodes, etc. which all pushes to the ID stack. Having
two buttons labeled "OK" in different windows or different tree locations is fine.
We used "..." above to signify whatever was already pushed to the ID stack previously:
Begin("MyWindow");
Button("OK"); // Label = "OK", ID = hash of ("MyWindow", "OK")
End();
Begin("MyOtherWindow");
Button("OK"); // Label = "OK", ID = hash of ("MyOtherWindow", "OK")
End();
- If you have a same ID twice in the same location, you'll have a conflict:
Button("OK");
Button("OK"); // ID collision! Interacting with either button will trigger the first one.
Fear not! this is easy to solve and there are many ways to solve it!
- Solving ID conflict in a simple/local context:
When passing a label you can optionally specify extra ID information within string itself.
Use "##" to pass a complement to the ID that won't be visible to the end-user.
This helps solving the simple collision cases when you know e.g. at compilation time which items
are going to be created:
Begin("MyWindow");
Button("Play"); // Label = "Play", ID = hash of ("MyWindow", "Play")
Button("Play##foo1"); // Label = "Play", ID = hash of ("MyWindow", "Play##foo1") // Different from above
Button("Play##foo2"); // Label = "Play", ID = hash of ("MyWindow", "Play##foo2") // Different from above
End();
- If you want to completely hide the label, but still need an ID:
Checkbox("##On", &b); // Label = "", ID = hash of (..., "##On") // No visible label, just a checkbox!
- Occasionally/rarely you might want change a label while preserving a constant ID. This allows
you to animate labels. For example you may want to include varying information in a window title bar,
but windows are uniquely identified by their ID. Use "###" to pass a label that isn't part of ID:
Button("Hello###ID"); // Label = "Hello", ID = hash of (..., "###ID")
Button("World###ID"); // Label = "World", ID = hash of (..., "###ID") // Same as above, even though the label looks different
sprintf(buf, "My game (%f FPS)###MyGame", fps);
Begin(buf); // Variable title, ID = hash of "MyGame"
- Solving ID conflict in a more general manner:
Use PushID() / PopID() to create scopes and manipulate the ID stack, as to avoid ID conflicts
within the same window. This is the most convenient way of distinguishing ID when iterating and
creating many UI elements programmatically.
You can push a pointer, a string or an integer value into the ID stack.
Remember that ID are formed from the concatenation of _everything_ pushed into the ID stack.
At each level of the stack we store the seed used for items at this level of the ID stack.
Begin("Window");
for (int i = 0; i < 100; i++)
{
PushID(i); // Push i to the id tack
Button("Click"); // Label = "Click", ID = hash of ("Window", i, "Click")
PopID();
}
for (int i = 0; i < 100; i++)
{
MyObject* obj = Objects[i];
PushID(obj);
Button("Click"); // Label = "Click", ID = hash of ("Window", obj pointer, "Click")
PopID();
}
for (int i = 0; i < 100; i++)
{
MyObject* obj = Objects[i];
PushID(obj->Name);
Button("Click"); // Label = "Click", ID = hash of ("Window", obj->Name, "Click")
PopID();
}
End();
- You can stack multiple prefixes into the ID stack:
Button("Click"); // Label = "Click", ID = hash of (..., "Click")
PushID("node");
Button("Click"); // Label = "Click", ID = hash of (..., "node", "Click")
PushID(my_ptr);
Button("Click"); // Label = "Click", ID = hash of (..., "node", my_ptr, "Click")
PopID();
PopID();
- Tree nodes implicitly creates a scope for you by calling PushID().
Button("Click"); // Label = "Click", ID = hash of (..., "Click")
if (TreeNode("node")) // <-- this function call will do a PushID() for you (unless instructed not to, with a special flag)
{
Button("Click"); // Label = "Click", ID = hash of (..., "node", "Click")
TreePop();
}
- When working with trees, ID are used to preserve the open/close state of each tree node.
Depending on your use cases you may want to use strings, indices or pointers as ID.
e.g. when following a single pointer that may change over time, using a static string as ID
will preserve your node open/closed state when the targeted object change.
e.g. when displaying a list of objects, using indices or pointers as ID will preserve the
node open/closed state differently. See what makes more sense in your situation!
Q: How can I have widgets with an empty label?
Q: How can I have multiple widgets with the same label?
Q: Why are multiple widgets reacting when I interact with one?
Q: How can I display an image? What is ImTextureID, how does it works?
>> See https://www.dearimgui.org/faq and https://github.com/ocornut/imgui/wiki/Image-Loading-and-Displaying-Examples
Q: How can I use my own math types instead of ImVec2/ImVec4?
Q: How can I interact with standard C++ types (such as std::string and std::vector)?
Q: How can I display custom shapes? (using low-level ImDrawList API)

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