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FAQ update, removed redundant block in imgui.cpp
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@ -36,12 +36,13 @@ HOW TO UPDATE?
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Breaking Changes:
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- Removed unncessary ID (first arg) of ImFontAtlas::AddCustomRectRegular() function. Please
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- Removed unnecessary ID (first arg) of ImFontAtlas::AddCustomRectRegular() function. Please
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note that this is a Beta api and will likely be reworked to support multi-monitor multi-DPI.
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- Renamed OpenPopupOnItemClick() to OpenPopupContextItem(). Kept inline redirection function (will obsolete).
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- Removed BeginPopupContextWindow(const char*, int mouse_button, bool also_over_items) in favor
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of BeginPopupContextWindow(const char*, ImGuiPopupFlags flags) with ImGuiPopupFlags_NoOverItems.
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- Removed CalcItemRectClosestPoint() entry point which was made obsolete and asserting in December 2017.
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Kept inline redirection function (will obsolete).
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- Removed obsoleted CalcItemRectClosestPoint() entry point (has been asserting since December 2017).
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Other Changes:
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13
docs/FAQ.md
13
docs/FAQ.md
@ -23,7 +23,7 @@ or view this file with any Markdown viewer.
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| [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) |
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| [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) |
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| **Q&A: Usage** |
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| **[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)** |
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| **[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)** |
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| [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)|
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| [How can I use my own math types instead of ImVec2/ImVec4?](#q-how-can-i-use-my-own-math-types-instead-of-imvec2imvec4) |
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| [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) |
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@ -173,7 +173,9 @@ Refer to rendering back-ends in the [examples/](https://github.com/ocornut/imgui
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# Q&A: Usage
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### 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?
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### Q: How can I have widgets with an empty label?
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### Q: How can I have multiple widgets with the same label?
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### Q: Why are multiple widgets reacting when I interact with one?
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A primer on labels and the ID Stack...
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@ -295,11 +297,12 @@ if (TreeNode("node")) // <-- this function call will do a PushID() for you (unl
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TreePop();
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}
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```
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- When working with trees, ID are used to preserve the open/close state of each tree node.
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When working with trees, ID are used to preserve the open/close state of each tree node.
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Depending on your use cases you may want to use strings, indices or pointers as ID.
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e.g. when following a single pointer that may change over time, using a static string as ID
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- e.g. when following a single pointer that may change over time, using a static string as ID
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will preserve your node open/closed state when the targeted object change.
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e.g. when displaying a list of objects, using indices or pointers as ID will preserve the
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- e.g. when displaying a list of objects, using indices or pointers as ID will preserve the
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node open/closed state differently. See what makes more sense in your situation!
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##### [Return to Index](#index)
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126
imgui.cpp
126
imgui.cpp
@ -601,7 +601,10 @@ CODE
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FREQUENTLY ASKED QUESTIONS (FAQ)
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================================
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Read all answers online: https://www.dearimgui.org/faq, or in docs/FAQ.md (with a Markdown viewer)
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Read all answers online:
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https://www.dearimgui.org/faq or https://github.com/ocornut/imgui/blob/master/docs/FAQ.md (same url)
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Read all answers locally (with a text editor or ideally a Markdown viewer):
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docs/FAQ.md
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Some answers are copied down here to facilitate searching in code.
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Q&A: Basics
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@ -645,125 +648,10 @@ CODE
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Q&A: Usage
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----------
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Q: Why are multiple widgets reacting when I interact with a single one?
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Q: How can I have multiple widgets with the same label or with an empty label?
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A: A primer on labels and the ID Stack...
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Dear ImGui internally need to uniquely identify UI elements.
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Elements that are typically not clickable (such as calls to the Text functions) don't need an ID.
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Interactive widgets (such as calls to Button buttons) need a unique ID.
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Unique ID are used internally to track active widgets and occasionally associate state to widgets.
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Unique ID are implicitly built from the hash of multiple elements that identify the "path" to the UI element.
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- Unique ID are often derived from a string label:
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Button("OK"); // Label = "OK", ID = hash of (..., "OK")
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Button("Cancel"); // Label = "Cancel", ID = hash of (..., "Cancel")
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- ID are uniquely scoped within windows, tree nodes, etc. which all pushes to the ID stack. Having
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two buttons labeled "OK" in different windows or different tree locations is fine.
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We used "..." above to signify whatever was already pushed to the ID stack previously:
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Begin("MyWindow");
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Button("OK"); // Label = "OK", ID = hash of ("MyWindow", "OK")
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End();
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Begin("MyOtherWindow");
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Button("OK"); // Label = "OK", ID = hash of ("MyOtherWindow", "OK")
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End();
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- If you have a same ID twice in the same location, you'll have a conflict:
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Button("OK");
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Button("OK"); // ID collision! Interacting with either button will trigger the first one.
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Fear not! this is easy to solve and there are many ways to solve it!
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- Solving ID conflict in a simple/local context:
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When passing a label you can optionally specify extra ID information within string itself.
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Use "##" to pass a complement to the ID that won't be visible to the end-user.
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This helps solving the simple collision cases when you know e.g. at compilation time which items
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are going to be created:
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Begin("MyWindow");
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Button("Play"); // Label = "Play", ID = hash of ("MyWindow", "Play")
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Button("Play##foo1"); // Label = "Play", ID = hash of ("MyWindow", "Play##foo1") // Different from above
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Button("Play##foo2"); // Label = "Play", ID = hash of ("MyWindow", "Play##foo2") // Different from above
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End();
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- If you want to completely hide the label, but still need an ID:
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Checkbox("##On", &b); // Label = "", ID = hash of (..., "##On") // No visible label, just a checkbox!
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- Occasionally/rarely you might want change a label while preserving a constant ID. This allows
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you to animate labels. For example you may want to include varying information in a window title bar,
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but windows are uniquely identified by their ID. Use "###" to pass a label that isn't part of ID:
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Button("Hello###ID"); // Label = "Hello", ID = hash of (..., "###ID")
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Button("World###ID"); // Label = "World", ID = hash of (..., "###ID") // Same as above, even though the label looks different
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sprintf(buf, "My game (%f FPS)###MyGame", fps);
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Begin(buf); // Variable title, ID = hash of "MyGame"
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- Solving ID conflict in a more general manner:
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Use PushID() / PopID() to create scopes and manipulate the ID stack, as to avoid ID conflicts
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within the same window. This is the most convenient way of distinguishing ID when iterating and
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creating many UI elements programmatically.
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You can push a pointer, a string or an integer value into the ID stack.
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Remember that ID are formed from the concatenation of _everything_ pushed into the ID stack.
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At each level of the stack we store the seed used for items at this level of the ID stack.
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Begin("Window");
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for (int i = 0; i < 100; i++)
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{
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PushID(i); // Push i to the id tack
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Button("Click"); // Label = "Click", ID = hash of ("Window", i, "Click")
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PopID();
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}
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for (int i = 0; i < 100; i++)
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{
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MyObject* obj = Objects[i];
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PushID(obj);
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Button("Click"); // Label = "Click", ID = hash of ("Window", obj pointer, "Click")
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PopID();
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}
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for (int i = 0; i < 100; i++)
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{
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MyObject* obj = Objects[i];
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PushID(obj->Name);
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Button("Click"); // Label = "Click", ID = hash of ("Window", obj->Name, "Click")
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PopID();
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}
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End();
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- You can stack multiple prefixes into the ID stack:
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Button("Click"); // Label = "Click", ID = hash of (..., "Click")
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PushID("node");
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Button("Click"); // Label = "Click", ID = hash of (..., "node", "Click")
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PushID(my_ptr);
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Button("Click"); // Label = "Click", ID = hash of (..., "node", my_ptr, "Click")
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PopID();
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PopID();
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- Tree nodes implicitly creates a scope for you by calling PushID().
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Button("Click"); // Label = "Click", ID = hash of (..., "Click")
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if (TreeNode("node")) // <-- this function call will do a PushID() for you (unless instructed not to, with a special flag)
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{
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Button("Click"); // Label = "Click", ID = hash of (..., "node", "Click")
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TreePop();
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}
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- When working with trees, ID are used to preserve the open/close state of each tree node.
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Depending on your use cases you may want to use strings, indices or pointers as ID.
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e.g. when following a single pointer that may change over time, using a static string as ID
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will preserve your node open/closed state when the targeted object change.
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e.g. when displaying a list of objects, using indices or pointers as ID will preserve the
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node open/closed state differently. See what makes more sense in your situation!
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Q: How can I have widgets with an empty label?
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Q: How can I have multiple widgets with the same label?
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Q: Why are multiple widgets reacting when I interact with one?
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Q: How can I display an image? What is ImTextureID, how does it works?
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>> See https://www.dearimgui.org/faq and https://github.com/ocornut/imgui/wiki/Image-Loading-and-Displaying-Examples
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Q: How can I use my own math types instead of ImVec2/ImVec4?
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Q: How can I interact with standard C++ types (such as std::string and std::vector)?
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Q: How can I display custom shapes? (using low-level ImDrawList API)
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