Thank you. libgphoto2 depends on other dylb. Compilation seems to be a task
Regards Anand On Tue, 17 Sept, 2024, 6:18 am Ole Aamot, <o...@gnu.org> wrote: > Implement libgphoto2 Camera Driver for iPad USB > > Implementing a camera driver using `libgphoto2` and `libusb` for iPadOS is > complex, particularly due to iOS's restrictions on direct USB access. > However, I can guide you through writing code that integrates `libgphoto2` > and `libusb` in a general way, while recognizing the unique hurdles on > iPadOS. > > Here’s an example that assumes you're able to compile `libusb` and > `libgphoto2` for iOS. This example sets up a simple app that uses a camera > connected via USB. Keep in mind that on iPad, actual USB access will likely > be limited unless you have the proper entitlements from Apple. > > ### 1. **Cross-Compiling `libgphoto2` and `libusb`** > > First, you need to cross-compile `libgphoto2` and `libusb` for iPad. This > process involves setting up a toolchain and using CMake to build the > libraries as static libraries for ARM architecture. Here’s a guide for that > process: > > ```bash > # Install dependencies (on macOS) > brew install automake libtool cmake > > # Clone libgphoto2 > git clone https://github.com/gphoto/libgphoto2.git > cd libgphoto2 > > # Build for iOS (ensure you have an iOS toolchain configured) > ./autogen.sh > ./configure --host=arm-apple-darwin > make > ``` > > ### 2. **Basic iOS App Setup (Swift + Objective-C)** > > In Xcode, create a new iOS project in Swift, then add the compiled static > libraries for `libgphoto2` and `libusb`. > > ### 3. **Bridging Header for `libgphoto2` in Swift** > > Since `libgphoto2` is a C library, you will need to create a bridging > header to use it within a Swift-based iOS project. > > **Create `gphoto2_bridge.h` (Objective-C bridging header):** > > ```objective-c > // gphoto2_bridge.h > #import <Foundation/Foundation.h> > > #ifdef __cplusplus > extern "C" { > #endif > > #include <gphoto2/gphoto2.h> > > int detect_camera(GPContext *context); > > #ifdef __cplusplus > } > #endif > ``` > > **Create `gphoto2_bridge.c` (C code that interacts with libgphoto2):** > > ```c > #include "gphoto2_bridge.h" > > int detect_camera(GPContext *context) { > int ret; > Camera *camera; > GPPortInfoList *portinfolist = NULL; > CameraAbilitiesList *abilities = NULL; > > ret = gp_camera_new(&camera); > if (ret < GP_OK) return ret; > > ret = gp_abilities_list_new(&abilities); > if (ret < GP_OK) return ret; > > ret = gp_port_info_list_new(&portinfolist); > if (ret < GP_OK) return ret; > > ret = gp_abilities_list_load(abilities, context); > if (ret < GP_OK) return ret; > > ret = gp_port_info_list_load(portinfolist); > if (ret < GP_OK) return ret; > > return GP_OK; > } > ``` > > ### 4. **Swift Code (ViewController.swift)** > > This Swift code will interact with the `libgphoto2` library via the > bridging header. > > ```swift > import UIKit > > class ViewController: UIViewController { > > override func viewDidLoad() { > super.viewDidLoad() > > // Call the C function to detect the camera > detectCamera() > } > > func detectCamera() { > // Create the GPContext > let context = createGPContext() > > // Call the detect_camera function from the C library > let result = detect_camera(context) > if result == 0 { > print("Camera detected successfully!") > } else { > print("Failed to detect camera.") > } > } > > // GPContext is a placeholder for actual libgphoto2 context management > func createGPContext() -> OpaquePointer? { > let context: OpaquePointer? = nil > // You'd need to properly initialize the context here > return context > } > } > ``` > > ### 5. **Handling USB Access (libusb)** > > You would similarly add a bridging header and interact with `libusb`. > However, due to iOS restrictions, `libusb` is likely to require > entitlements to access USB devices directly. > > **Create `usb_bridge.h` (bridging header for libusb):** > > ```objective-c > #import <Foundation/Foundation.h> > > #ifdef __cplusplus > extern "C" { > #endif > > #include <libusb-1.0/libusb.h> > > int initialize_usb(); > > #ifdef __cplusplus > } > #endif > ``` > > **Create `usb_bridge.c`:** > > ```c > #include "usb_bridge.h" > > int initialize_usb() { > libusb_context *ctx = NULL; > int r = libusb_init(&ctx); > if (r < 0) { > return r; > } > > // Find connected USB devices > libusb_device **devs; > ssize_t cnt = libusb_get_device_list(ctx, &devs); > if (cnt < 0) return (int)cnt; > > libusb_free_device_list(devs, 1); > libusb_exit(ctx); > return 0; > } > ``` > > ### 6. **Swift Code for USB Initialization** > > ```swift > func initializeUSB() { > let result = initialize_usb() > if result == 0 { > print("USB initialized successfully.") > } else { > print("Failed to initialize USB.") > } > } > ``` > > ### 7. **Handle iOS Permissions and Testing** > > Given iOS’s restrictions on USB access, you’ll need to consider using > Apple’s `ExternalAccessory` framework for official USB hardware access. > Alternatively, if the camera supports wireless (e.g., Wi-Fi), you can > communicate over the network to avoid USB restrictions altogether. > > Testing on an actual device will be critical because the iOS Simulator > does not support USB or accessory connections. > > ### 8. **Next Steps and Entitlements** > > - **Request Entitlements**: To access USB devices, you will likely need to > join Apple's MFi (Made for iPhone/iPad) program and request the necessary > entitlements. > - **Test and Debug**: Testing on actual hardware will help you understand > how the app behaves when communicating with a camera via USB. > > Would you like assistance with any specific part of the code, or do you > need further guidance on handling USB in iOS? > > Sincerely, > > > Ole Aamot > > o...@aamot.org > > www.aamot.org > > +47-4173-2002 > > > > On Mon, Sep 16, 2024 at 7:28 AM Anand Walvekar < > anand.walve...@onemorehustle.com> wrote: > >> Thank you Ole for your time. >> >> ChatGPT seems to be more descriptive to you 😊 >> >> I have been trying to recompile the libgphoto2 and its dependencies with >> clang and linking with iOS framework. Clang treats warning as errors and it >> needs source code changes. Also libgphoto2 loads dylb from system path >> which also needs to be taken into account. >> >> Over it's not straightforward. >> >> Thank you >> Anand >> >> >> >> On Mon, 16 Sept, 2024, 3:37 am Ole Aamot, <o...@gnu.org> wrote: >> >>> ChatGPT gave this answer: >>> >>> To implement a **libgphoto2** camera driver for an iPad over USB, you >>> would need to address several layers of challenges including hardware >>> support, communication protocols, and OS-level restrictions. Here's a >>> high-level approach to guide the development: >>> >>> ### Steps to Implement libgphoto2 Camera Driver for iPad USB >>> >>> #### 1. **Understand the iPad USB Accessory Framework** >>> - Apple provides the **External Accessory framework** to communicate >>> with external hardware. However, it's quite restrictive and typically meant >>> for licensed manufacturers. >>> - iOS and iPadOS don't natively support generic USB drivers like on >>> Linux or Windows, so the challenge is creating a bridge for libgphoto2 to >>> access the camera hardware over USB. >>> - Check if the camera can be accessed via a **Camera Connection Kit** >>> or Lightning-to-USB adapter and whether it's recognized as a USB accessory. >>> >>> #### 2. **Develop a Custom iOS App** >>> - You would likely need to create a custom iOS application using >>> **Swift** or **Objective-C** to interface with the camera. >>> - Investigate the **USBDevice** API (for iOS 16+) if available, which >>> offers more flexibility in accessing USB devices directly on iOS/iPadOS. >>> - Use the **USB Accessory Mode** for detecting connected devices. >>> >>> #### 3. **Compile libgphoto2 for iOS** >>> - Libgphoto2 is built for POSIX systems, so you’ll need to >>> cross-compile it for iOS using tools like **Xcode** or **CMake** with >>> specific target flags for ARM architecture. >>> - It may require modifications to libgphoto2 code to interact with >>> iOS's unique environment and APIs. >>> - Remove or adapt dependencies in libgphoto2 that might not be >>> supported by iOS (such as certain POSIX libraries). >>> >>> #### 4. **USB Communication Bridge** >>> - Libgphoto2 communicates with cameras using PTP (Picture Transfer >>> Protocol) or proprietary protocols over USB. >>> - Implement a communication bridge between libgphoto2 and iOS's USB >>> interface. This may involve writing code to mimic Linux's USB driver >>> behavior within the iOS app. >>> - The **libusb** library might also need to be ported or modified for >>> iOS to enable USB communication, since it is widely used by libgphoto2. >>> >>> #### 5. **Sandboxing and Permissions** >>> - iOS has strict sandboxing. Ensure that your app requests the >>> necessary permissions to communicate with USB devices and interact with >>> external hardware. >>> - Add necessary entitlements in the **Info.plist** file, like >>> `com.apple.external-accessory` or `com.apple.developer.usb`. >>> >>> #### 6. **Testing with Different Cameras** >>> - Libgphoto2 supports a wide range of cameras, so you'll need to test >>> with specific camera models. >>> - Ensure that the camera can be recognized by the app, and you can >>> trigger functions like capturing images, downloading files, or controlling >>> camera settings. >>> >>> #### 7. **Distributing the App** >>> - If the app is for personal use, you can sideload it to your iPad >>> using Xcode and a developer account. >>> - If the goal is broader distribution, you would need to ensure >>> compliance with Apple's guidelines, especially for apps interacting with >>> external hardware. >>> >>> ### Challenges >>> - **Apple's closed ecosystem**: iOS is not designed to be an open >>> system like Linux, so you will face challenges accessing hardware. >>> - **Licensing**: If this driver is to be distributed, you may need >>> Apple's MFi (Made for iPhone/iPad) certification for USB accessory >>> communication. >>> >>> ### Summary >>> This task involves cross-compiling libgphoto2 for iOS, interfacing with >>> iPad USB APIs, and overcoming OS-level restrictions. Starting with Apple’s >>> USBDevice APIs and building a custom iOS app to bridge libgphoto2’s >>> functionality is the best approach. You will likely need to experiment with >>> lower-level hardware protocols and iOS permissions to make it work >>> effectively. >>> >>> Sincerely, >>> >>> >>> Ole Aamot >>> >>> o...@aamot.org >>> >>> www.aamot.org >>> >>> +47-4173-2002 >>> >>> >>> >>> On Tue, Sep 10, 2024 at 9:11 AM Marcus Meissner <mar...@jet.franken.de> >>> wrote: >>> >>>> Hi, >>>> >>>> On Sun, Sep 08, 2024 at 07:21:03PM +0530, Anand Walvekar wrote: >>>> > Hi Team >>>> > Hope you are doing well. >>>> > >>>> > I need your help to integrate libgphoto2 in iPad application. Could >>>> you >>>> > please share me few links which I can try it out. >>>> > >>>> > Thank you >>>> > Anand >>>> >>>> This likely means the iPad as USB Host for cameras? >>>> >>>> I am not familar with either iPad or if iPad USB-Host is even possible, >>>> perhaps someone else knows it :/ >>>> >>>> Ciao, Marcus >>>> >>>> >>>> _______________________________________________ >>>> Gphoto-devel mailing list >>>> Gphoto-devel@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/gphoto-devel >>>> >>>
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