Single Dialog :

If you only need to display one file dialog at a time, use ImGuiFileDialog's singleton pattern to avoid explicitly declaring an object:

ImGuiFileDialog::Instance()->method_of_your_choice();

Multiple Dialogs :

If you need to have multiple file dialogs open at once, declare each dialog explicity:

ImGuiFileDialog instance_a;
instance_a.method_of_your_choice();
ImGuiFileDialog instance_b;
instance_b.method_of_your_choice();

void drawGui()
{ 
  // open Dialog Simple
  if (ImGui::Button("Open File Dialog"))
    ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose File", ".cpp,.h,.hpp", ".");

  // display
  if (ImGuiFileDialog::Instance()->Display("ChooseFileDlgKey")) 
  {
    // action if OK
    if (ImGuiFileDialog::Instance()->IsOk())
    {
      std::string filePathName = ImGuiFileDialog::Instance()->GetFilePathName();
      std::string filePath = ImGuiFileDialog::Instance()->GetCurrentPath();
      // action
    }
    
    // close
    ImGuiFileDialog::Instance()->Close();
  }
}

you have now a flag for open modal dialog :

ImGuiFileDialogFlags_Modal

you can use it like that :

ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose File", ".cpp,.h,.hpp", 
	".", 1, nullptr, ImGuiFileDialogFlags_Modal);

To have a directory chooser, set the file extension filter to nullptr:

ImGuiFileDialog::Instance()->OpenDialog("ChooseDirDlgKey", "Choose a Directory", nullptr, ".");

In this mode you can select any directory with one click and open a directory with a double-click.

The signature of the custom pane callback is:

for C++ :

void(const char *vFilter, IGFDUserDatas vUserDatas, bool *vCantContinue)

for C :

void(const char *vFilter, void* vUserDatas, bool *vCantContinue)

Example :

static bool canValidateDialog = false;
inline void InfosPane(cosnt char *vFilter, IGFDUserDatas vUserDatas, bool *vCantContinue) // if vCantContinue is false, the user cant validate the dialog
{
    ImGui::TextColored(ImVec4(0, 1, 1, 1), "Infos Pane");
    ImGui::Text("Selected Filter : %s", vFilter.c_str());
    if (vUserDatas)
        ImGui::Text("UserDatas : %s", vUserDatas);
    ImGui::Checkbox("if not checked you cant validate the dialog", &canValidateDialog);
    if (vCantContinue)
        *vCantContinue = canValidateDialog;
}

void drawGui()
{
  // open Dialog with Pane
  if (ImGui::Button("Open File Dialog with a custom pane"))
    ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose File", ".cpp,.h,.hpp",
            ".", "", std::bind(&InfosPane, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3), 350, 1, UserDatas("InfosPane"));

  // display and action if ok
  if (ImGuiFileDialog::Instance()->Display("ChooseFileDlgKey")) 
  {
    if (ImGuiFileDialog::Instance()->IsOk())
    {
        std::string filePathName = ImGuiFileDialog::Instance()->GetFilePathName();
        std::string filePath = ImGuiFileDialog::Instance()->GetCurrentPath();
        std::string filter = ImGuiFileDialog::Instance()->GetCurrentFilter();
        // here convert from string because a string was passed as a userDatas, but it can be what you want
        std::string userDatas;
        if (ImGuiFileDialog::Instance()->GetUserDatas())
            userDatas = std::string((const char*)ImGuiFileDialog::Instance()->GetUserDatas()); 
        auto selection = ImGuiFileDialog::Instance()->GetSelection(); // multiselection

        // action
    }
    // close
    ImGuiFileDialog::Instance()->Close();
  }
}

You can define style for files/dirs/links in many ways :

the style can be colors, icons and fonts

the general form is :

ImGuiFileDialog::Instance()->SetFileStyle(styleType, criteria, color, icon, font);

styleType can be thoses :

IGFD_FileStyleByTypeFile				// define style for all files
IGFD_FileStyleByTypeDir					// define style for all dir
IGFD_FileStyleByTypeLink				// define style for all link
IGFD_FileStyleByExtention				// define style by extention, for files or links
IGFD_FileStyleByFullName				// define style for particular file/dir/link full name (filename + extention)
IGFD_FileStyleByContainedInFullName		// define style for file/dir/link when criteria is contained in full name

ImGuiFileDialog accepts icon font macros as well as text tags for file types.

ImGuIFontStudio is useful here. I wrote it to make it easy to create custom icon sets for use with Dear ImGui.

It is inspired by IconFontCppHeaders, which can also be used with ImGuiFileDialog.

you can also use a regex for the filtering. the regex must be betwwen the ( and ) for be recognized as a regex

samples :

// define style by file extention and Add an icon for .png files 
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".png", ImVec4(0.0f, 1.0f, 1.0f, 0.9f), ICON_IGFD_FILE_PIC, font1);
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".gif", ImVec4(0.0f, 1.0f, 0.5f, 0.9f), "[GIF]");

// define style for all directories
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeDir, "", ImVec4(0.5f, 1.0f, 0.9f, 0.9f), ICON_IGFD_FOLDER);
// can be for a specific directory
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeDir, ".git", ImVec4(0.5f, 1.0f, 0.9f, 0.9f), ICON_IGFD_FOLDER);

// define style for all files
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeFile, "", ImVec4(0.5f, 1.0f, 0.9f, 0.9f), ICON_IGFD_FILE);
// can be for a specific file
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeFile, ".git", ImVec4(0.5f, 1.0f, 0.9f, 0.9f), ICON_IGFD_FILE);

// define style for all links
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeLink, "", ImVec4(0.5f, 1.0f, 0.9f, 0.9f));
// can be for a specific link
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeLink, "Readme.md", ImVec4(0.5f, 1.0f, 0.9f, 0.9f));

// define style for any files/dirs/links by fullname
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByFullName, "doc", ImVec4(0.9f, 0.2f, 0.0f, 0.9f), ICON_IGFD_FILE_PIC);

// define style by file who are containing this string
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByContainedInFullName, ".git", ImVec4(0.9f, 0.2f, 0.0f, 0.9f), ICON_IGFD_BOOKMARK);

all of theses can be miwed with IGFD_FileStyleByTypeDir / IGFD_FileStyleByTypeFile / IGFD_FileStyleByTypeLink
like theses by ex :
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeDir | IGFD_FileStyleByContainedInFullName, ".git", ImVec4(0.9f, 0.2f, 0.0f, 0.9f), ICON_IGFD_BOOKMARK);
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeFile | IGFD_FileStyleByFullName, "cmake", ImVec4(0.5f, 0.8f, 0.5f, 0.9f), ICON_IGFD_SAVE);

// for all these,s you can use a regex
// ex for color files like Custom*.h
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByFullName, "(Custom.+[.]h)", ImVec4(0.0f, 1.0f, 1.0f, 0.9f), ICON_IGFD_FILE_PIC, font1);

this sample code of master/main.cpp produce the picture above :

ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByFullName, "(Custom.+[.]h)", ImVec4(1.0f, 1.0f, 0.0f, 0.9f));
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".cpp", ImVec4(1.0f, 1.0f, 0.0f, 0.9f));
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".h", ImVec4(0.0f, 1.0f, 0.0f, 0.9f));
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".hpp", ImVec4(0.0f, 0.0f, 1.0f, 0.9f));
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".md", ImVec4(1.0f, 0.0f, 1.0f, 0.9f));
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".png", ImVec4(0.0f, 1.0f, 1.0f, 0.9f), ICON_IGFD_FILE_PIC); // add an icon for the filter type
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByExtention, ".gif", ImVec4(0.0f, 1.0f, 0.5f, 0.9f), "[GIF]"); // add an text for a filter type
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeDir, nullptr, ImVec4(0.5f, 1.0f, 0.9f, 0.9f), ICON_IGFD_FOLDER); // for all dirs
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeFile, "CMakeLists.txt", ImVec4(0.1f, 0.5f, 0.5f, 0.9f), ICON_IGFD_ADD);
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByFullName, "doc", ImVec4(0.9f, 0.2f, 0.0f, 0.9f), ICON_IGFD_FILE_PIC);
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeDir | IGFD_FileStyleByContainedInFullName, ".git", ImVec4(0.9f, 0.2f, 0.0f, 0.9f), ICON_IGFD_BOOKMARK);
ImGuiFileDialog::Instance()->SetFileStyle(IGFD_FileStyleByTypeFile | IGFD_FileStyleByContainedInFullName, ".git", ImVec4(0.5f, 0.8f, 0.5f, 0.9f), ICON_IGFD_SAVE);

You can define a custom filter name that corresponds to a group of filters using this syntax:

You can also use a regex for the filtering. the regex must be betwwen the ( and ) for be recognized as a regex

custom_name1{filter1,filter2,filter3,(regex0),(regex1)},custom_name2{filter1,filter2,(regex0)},filter1

When you select custom_name1, filters 1 to 3 will be applied. The characters { and } are reserved. Don't use them for filter names.

this code :

const char *filters = "Source files (*.cpp *.h *.hpp){.cpp,.h,.hpp},Image files (*.png *.gif *.jpg *.jpeg){.png,.gif,.jpg,.jpeg},.md";
ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", ICON_IMFDLG_FOLDER_OPEN " Choose a File", filters, ".");

will produce :

You can define in OpenDialog call the count file you want to select :

• 0 => infinite
• 1 => one file only (default)
• n => n files only

See the define at the end of these funcs after path.

ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose File", ".*,.cpp,.h,.hpp", ".");
ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose 1 File", ".*,.cpp,.h,.hpp", ".", 1);
ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose 5 File", ".*,.cpp,.h,.hpp", ".", 5);
ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose many File", ".*,.cpp,.h,.hpp", ".", 0);
ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey", "Choose File", ".png,.jpg",
   ".", "", std::bind(&InfosPane, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3), 350, 1, "SaveFile"); // 1 file

You can set the minimum and/or maximum size of the dialog:

ImVec2 maxSize = ImVec2((float)display_w, (float)display_h);  // The full display area
ImVec2 minSize = maxSize * 0.5f;  // Half the display area
ImGuiFileDialog::Instance()->Display("ChooseFileDlgKey", ImGuiWindowFlags_NoCollapse, minSize, maxSize);

Dear ImGui just released an improved table API. If your downloaded version of Dear ImGui includes the beta version of table support (included for some time now) you can enable table support by uncommenting #define USE_IMGUI_TABLES in you custom config file (CustomImGuiFileDialogConfig.h)

If your version of Dear ImGui has finalized tables support, it will be enabled by default.

You can activate this feature by uncommenting #define USE_EXPLORATION_BY_KEYS in your custom config file (CustomImGuiFileDialogConfig.h)

You can also uncomment the next lines to define navigation keys:

• IGFD_KEY_UP => Up key for explore to the top
• IGFD_KEY_DOWN => Down key for explore to the bottom
• IGFD_KEY_ENTER => Enter key for open directory
• IGFD_KEY_BACKSPACE => BackSpace for comming back to the last directory

You can also jump to a point in the file list by pressing the corresponding key of the first filename character.

As you see the current item is flashed by default for 1 second. You can define the flashing lifetime with the function

ImGuiFileDialog::Instance()->SetFlashingAttenuationInSeconds(1.0f);

You can create/edit/call path bookmarks and load/save them.

Activate this feature by uncommenting: #define USE_BOOKMARK in your custom config file (CustomImGuiFileDialogConfig.h)

More customization options:

#define bookmarkPaneWith 150.0f => width of the bookmark pane
#define IMGUI_TOGGLE_BUTTON ToggleButton => customize the Toggled button (button stamp must be : (const char* label, bool *toggle)
#define bookmarksButtonString "Bookmark" => the text in the toggle button
#define bookmarksButtonHelpString "Bookmark" => the helper text when mouse over the button
#define addBookmarkButtonString "+" => the button for add a bookmark
#define removeBookmarkButtonString "-" => the button for remove the selected bookmark

• You can select each bookmark to edit the displayed name corresponding to a path
• Double-click on the label to apply the bookmark

You can also serialize/deserialize bookmarks (for example to load/save from/to a file):

Load => ImGuiFileDialog::Instance()->DeserializeBookmarks(bookmarString);
Save => std::string bookmarkString = ImGuiFileDialog::Instance()->SerializeBookmarks();

you can also add/remove bookmark by code :

and in this case, you can also avoid serialization of code based bookmark

Add => ImGuiFileDialog::Instance()->AddBookmark(bookmark_name, bookmark_path);
Remove => ImGuiFileDialog::Instance()->RemoveBookmark(bookmark_name);

// true for prevent serialization of code based bookmarks
Save => std::string bookmarkString = ImGuiFileDialog::Instance()->SerializeBookmarks(true);

(please see example code for details)

Right clicking on any path element button allows the user to manually edit the path from that portion of the tree. Pressing the completion key (GLFW uses enter by default) validates the new path. Pressing the cancel key (GLFW usesescape by default) cancels the manual entry and restores the original path.

Here's the manual entry operation in action:

If you want avoid overwriting files after selection, ImGuiFileDialog can show a dialog to confirm or cancel the operation.

To do so, define the flag ImGuiFileDialogFlags_ConfirmOverwrite in your call to OpenDialog/OpenModal.

By default this flag is not set since there is no pre-defined way to define if a dialog will be for Open or Save behavior. (by design! :) )

Example code For Standard Dialog :

ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey",
    ICON_IGFD_SAVE " Choose a File", filters,
    ".", "", 1, nullptr, ImGuiFileDialogFlags_ConfirmOverwrite);

Example code For Modal Dialog :

ImGuiFileDialog::Instance()->OpenDialog("ChooseFileDlgKey",
    ICON_IGFD_SAVE " Choose a File", filters,
    ".", "", 1, nullptr, ImGuiFileDialogFlags_Modal | ImGuiFileDialogFlags_ConfirmOverwrite);

This dialog will only verify the file in the file field, not with GetSelection().

The confirmation dialog will be a non-movable modal (input blocking) dialog displayed in the middle of the current ImGuiFileDialog window.

As usual, you can customize the dialog in your custom config file (CustomImGuiFileDialogConfig.h in this example)

Uncomment these line for customization options:

//#define OverWriteDialogTitleString "The file Already Exist !"
//#define OverWriteDialogMessageString "Would you like to OverWrite it ?"
//#define OverWriteDialogConfirmButtonString "Confirm"
//#define OverWriteDialogCancelButtonString "Cancel"

See the result :

ImGuiFileDialog uses the same code internally for Open and Save dialogs. To distinguish between them access the various data return functions depending on what the dialog is doing.

When selecting an existing file (for example, a Load or Open dialog), use

std::map<std::string, std::string> GetSelection(); // Returns selection via a map<FileName, FilePathName>
UserDatas GetUserDatas();                          // Get user data provided by the Open dialog

To selecting a new file (for example, a Save As... dialog), use:

std::string GetFilePathName();                     // Returns the content of the selection field with current file extension and current path
std::string GetCurrentFileName();                  // Returns the content of the selection field with current file extension but no path
std::string GetCurrentPath();                      // Returns current path only
std::string GetCurrentFilter();                    // The file extension

You can now, display thumbnails of pictures.

The file resize use stb/image so the following files extentions are supported :

• .png (tested sucessfully)
• .bmp (tested sucessfully)
• .tga (tested sucessfully)
• .jpg (tested sucessfully)
• .jpeg (tested sucessfully)
• .gif (tested sucessfully_ but not animation just first frame)
• .psd (not tested)
• .pic (not tested)
• .ppm (not tested)
• .pgm (not tested)

Corresponding to your backend (ex : OpenGl) you need to define two callbacks :

• the first is a callback who will be called by ImGuiFileDialog for create the backend texture
• the second is a callback who will be called by ImGuiFileDialog for destroy the backend texture

After that you need to call the function who is responsible to create / destroy the textures. this function must be called in your GPU Rendering zone for avoid destroying of used texture. if you do that at the same place of your imgui code, some backend can crash your app, by ex with vulkan.

To Clarify :

This feature is spliited in two zones :

• CPU Zone : for load/destroy picture file
• GPU Zone : for load/destroy gpu textures. This modern behavior for avoid destroying of used texture, was needed for vulkan.

This feature was Successfully tested on my side with Opengl and Vulkan. But im sure is perfectly compatible with other modern apis like DirectX and Metal

ex, for opengl :

// Create thumbnails texture
ImGuiFileDialog::Instance()->SetCreateThumbnailCallback([](IGFD_Thumbnail_Info *vThumbnail_Info) -> void
{
	if (vThumbnail_Info && 
		vThumbnail_Info->isReadyToUpload && 
		vThumbnail_Info->textureFileDatas)
	{
		GLuint textureId = 0;
		glGenTextures(1, &textureId);
		vThumbnail_Info->textureID = (void*)textureId;

		glBindTexture(GL_TEXTURE_2D, textureId);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,
			(GLsizei)vThumbnail_Info->textureWidth, (GLsizei)vThumbnail_Info->textureHeight, 
			0, GL_RGBA, GL_UNSIGNED_BYTE, vThumbnail_Info->textureFileDatas);
		glFinish();
		glBindTexture(GL_TEXTURE_2D, 0);

		delete[] vThumbnail_Info->textureFileDatas;
		vThumbnail_Info->textureFileDatas = nullptr;

		vThumbnail_Info->isReadyToUpload = false;
		vThumbnail_Info->isReadyToDisplay = true;
	}
});

// Destroy thumbnails texture
ImGuiFileDialog::Instance()->SetDestroyThumbnailCallback([](IGFD_Thumbnail_Info* vThumbnail_Info)
{
	if (vThumbnail_Info)
	{
		GLuint texID = (GLuint)vThumbnail_Info->textureID;
		glDeleteTextures(1, &texID);
		glFinish();
	}
});

// GPU Rendering Zone // To call for Create/ Destroy Textures
ImGuiFileDialog::Instance()->ManageGPUThumbnails();

The dialog can be embedded in another user frame than the standard or modal dialog

You have to create a variable of type ImGuiFileDialog. (if you are suing the singleton, you will not have the possibility to open other dialog)

ex :

ImGuiFileDialog fileDialog;

// open dialog; in this case, Bookmark, directory creation are disabled with, and also the file input field is readonly.
// btw you can od what you want
fileDialog.OpenDialog("embedded", "Select File", ".*", "", -1, nullptr, 
	ImGuiFileDialogFlags_NoDialog | 
	ImGuiFileDialogFlags_DisableBookmarkMode | 
	ImGuiFileDialogFlags_DisableCreateDirectoryButton | 
	ImGuiFileDialogFlags_ReadOnlyFileNameField);
// then display, here 
// to note, when embedded the ImVec2(0,0) (MinSize) do nothing, only the ImVec2(0,350) (MaxSize) can size the dialog frame 
fileDialog.Display("embedded", ImGuiWindowFlags_NoCollapse, ImVec2(0,0), ImVec2(0,350)))

the result :

you have a separator between two directories in the path composer when you click on it you can explore a list of parrallels directories of this point

this feature is disabled by default you can enable it with the compiler flag : #define USE_QUICK_PATH_SELECT

you can also customize the spacing between path button's with and without this mode you can do that by define the compiler flag : #define CUSTOM_PATH_SPACING 2 if undefined the spacing is defined by the imgui theme

you can use this flag 'ImGuiFileDialogFlags_CaseInsensitiveExtention' when you call the open functions

by ex :
if the flag ImGuiFileDialogFlags_CaseInsensitiveExtention is used
with filters like .jpg or .Jpg or .JPG
all files with extentions by ex : .jpg and .JPG will be displayed

Customize ImGuiFileDialog :

You can customize many aspects of ImGuiFileDialog by overriding ImGuiFileDialogConfig.h.

To enable your customizations, define the preprocessor directive CUSTOM_IMGUIFILEDIALOG_CONFIG with the path of your custom config file. This path must be relative to the directory where you put the ImGuiFileDialog module.

This operation is demonstrated in CustomImGuiFileDialog.h in the example project to:

• Have a custom icon font instead of labels for buttons or message titles
• Customize the button text (the button call signature must be the same, by the way! :)

The custom icon font used in the example code (CustomFont.cpp and CustomFont.h) was made with ImGuiFontStudio, which I wrote. :)

ImGuiFontStudio uses ImGuiFileDialog! Check it out.

You can specify :

• the width of "ok" and "cancel" buttons, by the set the defines "okButtonWidth" and "cancelButtonWidth"
• the alignement of the button group (left, right, middle, etc..) by set the define "okCancelButtonAlignement"
• if you want to have the ok button on the left and cancel button on the right or inverted by set the define "invertOkAndCancelButtons"

just see theses defines in the config file

//Validation buttons
//#define okButtonString " OK"
//#define okButtonWidth 0.0f
//#define cancelButtonString " Cancel"
//#define cancelButtonWidth 0.0f
//alignement [0:1], 0.0 is left, 0.5 middle, 1.0 right, and other ratios
//#define okCancelButtonAlignement 0.0f
//#define invertOkAndCancelButtons false

with Alignement 0.0 => left

with Alignement 1.0 => right

with Alignement 0.5 => middle

ok and cancel buttons inverted (cancel on the left and ok on the right)

you can use a regex for filtering and file coloring

for have a filter recognized as a regex, you must have it between a ( and a )

this one will filter files who start by the word "Common" and finish by ".h"

ex : "(Custom.+[.]h)" 

use cases :

• Simple filter :

OpenDialog("toto", "Choose File", "(Custom.+[.]h)");

• Collections filter : for this one the filter is between "{" and "}", so you can use the "(" and ")" outside

OpenDialog("toto", "Choose File", "Source files (*.cpp *.h *.hpp){(Custom.+[.]h),.h,.hpp},);

• file coloring : this one will colorized all files who start by the word "Common" and finish by ".h"

SetFileStyle(IGFD_FileStyleByFullName, "(Custom.+[.]h)", ImVec4(1.0f, 1.0f, 0.0f, 0.9f));

• with this feature you can by ex filter and colorize render frame pictures who have ext like .000, .001, .002, etc..

OpenDialog("toto", "Choose File", "([.][0-9]{3})");
SetFileStyle(IGFD_FileStyleByFullName, "([.][0-9]{3})", ImVec4(1.0f, 1.0f, 0.0f, 0.9f));

the C Api

this api was sucessfully tested with CImGui

A C API is available let you include ImGuiFileDialog in your C project. btw, ImGuiFileDialog depend of ImGui and dirent (for windows)

Sample code with cimgui :

// create ImGuiFileDialog
ImGuiFileDialog *cfileDialog = IGFD_Create();

// open dialog
if (igButton("Open File", buttonSize))
{
	IGFD_OpenDialog(cfiledialog,
		"filedlg",                              // dialog key (make it possible to have different treatment reagrding the dialog key
		"Open a File",                          // dialog title
		"c files(*.c *.h){.c,.h}",              // dialog filter syntax : simple => .h,.c,.pp, etc and collections : text1{filter0,filter1,filter2}, text2{filter0,filter1,filter2}, etc..
		".",                                    // base directory for files scan
		"",                                     // base filename
		0,                                      // a fucntion for display a right pane if you want
		0.0f,                                   // base width of the pane
		0,                                      // count selection : 0 infinite, 1 one file (default), n (n files)
		"User data !",                          // some user datas
		ImGuiFileDialogFlags_ConfirmOverwrite); // ImGuiFileDialogFlags
}

ImGuiIO* ioptr = igGetIO();
ImVec2 maxSize;
maxSize.x = ioptr->DisplaySize.x * 0.8f;
maxSize.y = ioptr->DisplaySize.y * 0.8f;
ImVec2 minSize;
minSize.x = maxSize.x * 0.25f;
minSize.y = maxSize.y * 0.25f;

// display dialog
if (IGFD_DisplayDialog(cfiledialog, "filedlg", ImGuiWindowFlags_NoCollapse, minSize, maxSize))
{
	if (IGFD_IsOk(cfiledialog)) // result ok
	{
		char* cfilePathName = IGFD_GetFilePathName(cfiledialog);
		printf("GetFilePathName : %s\n", cfilePathName);
		char* cfilePath = IGFD_GetCurrentPath(cfiledialog);
		printf("GetCurrentPath : %s\n", cfilePath);
		char* cfilter = IGFD_GetCurrentFilter(cfiledialog);
		printf("GetCurrentFilter : %s\n", cfilter);
		// here convert from string because a string was passed as a userDatas, but it can be what you want
		void* cdatas = IGFD_GetUserDatas(cfiledialog);
		if (cdatas)
			printf("GetUserDatas : %s\n", (const char*)cdatas);
		struct IGFD_Selection csel = IGFD_GetSelection(cfiledialog); // multi selection
		printf("Selection :\n");
		for (int i = 0; i < (int)csel.count; i++)
		{
			printf("(%i) FileName %s => path %s\n", i, csel.table[i].fileName, csel.table[i].filePathName);
		}
		// action

		// destroy
		if (cfilePathName) free(cfilePathName);
		if (cfilePath) free(cfilePath);
		if (cfilter) free(cfilter);

		IGFD_Selection_DestroyContent(&csel);
	}
	IGFD_CloseDialog(cfiledialog);
}

// destroy ImGuiFileDialog
IGFD_Destroy(cfiledialog);

The sample app is [here in master branch]((https://github.com/aiekick/ImGuiFileDialog/tree/master)

You need to use cMake. For the 3 Os (Win, Linux, MacOs), the cMake usage is exactly the same,

Choose a build directory. (called here my_build_directory for instance) and
Choose a Build Mode : "Release" / "MinSizeRel" / "RelWithDebInfo" / "Debug" (called here BuildMode for instance)
Run cMake in console : (the first for generate cmake build files, the second for build the binary)

cmake -B my_build_directory -DCMAKE_BUILD_TYPE=BuildMode cmake --build my_build_directory --config BuildMode

Some cMake version need Build mode define via the directive CMAKE_BUILD_TYPE or via --Config when we launch the build. This is why i put the boths possibilities

By the way you need before, to make sure, you have needed dependencies.

On Windows :

You need to have the opengl library installed

On Linux :

You need many lib : (X11, xrandr, xinerama, xcursor, mesa)

If you are on debian you can run :

sudo apt-get update sudo apt-get install libgl1-mesa-dev libx11-dev libxi-dev libxrandr-dev libxinerama-dev libxcursor-dev

On MacOs :

you need many lib : opengl and cocoa framework