AI Display Client API

Overview

The AI Display Client API provides an interface for communicating with the ai_display_service display service. It enables high-performance framebuffer submission and display control through shared memory and Unix Socket.

Key Features

Dual buffer slot design: Supports main application and overlay layer
Zero-copy transfer: Framebuffer transfer based on shared memory
Reliable communication: Unix Socket command channel
Multi-client support: Focus request for display priority management

Architecture

┌─────────────────┐     ┌─────────────────────┐
│  Client App     │     │  ai_display_service │
│                 │     │                     │
│  ┌───────────┐  │     │  ┌───────────┐      │
│  │framebuffer│◄─┼─SHM─┼─►│framebuffer│      │
│  └───────────┘  │     │  └───────────┘      │
│       │         │     │        ▲            │
│       ▼         │     │        │            │
│  ┌───────────┐  │     │  ┌─────┴─────┐      │
│  │  commit   │──┼─UDS─┼─►│  Refresh  │      │
│  └───────────┘  │     │  └───────────┘      │
└─────────────────┘     └─────────────────────┘

API Reference

Core Functions

Function	Description
`ai_display_init()`	Initialize client, return handle
`ai_display_connect()`	Connect to display service
`ai_display_disconnect()`	Disconnect (reconnectable)
`ai_display_get_framebuffer()`	Get main framebuffer pointer (Slot 0)
`ai_display_get_framebuffer_slot()`	Get specified slot framebuffer pointer
`ai_display_commit_frame()`	Commit frame update to screen
`ai_display_request_focus()`	Request display focus
`ai_display_cleanup()`	Cleanup resources

Helper Functions

Function	Description
`ai_display_is_connected()`	Check connection status
`ai_display_get_error_string()`	Get error description string

Error Codes

Error Code	Value	Description
`AI_DISPLAY_SUCCESS`	0	Success
`AI_DISPLAY_ERROR_INIT`	-1	Initialization failed
`AI_DISPLAY_ERROR_CONNECT`	-2	Connection failed
`AI_DISPLAY_ERROR_SHM`	-3	Shared memory operation failed
`AI_DISPLAY_ERROR_SOCKET`	-4	Socket operation failed
`AI_DISPLAY_ERROR_SEND`	-5	Send failed
`AI_DISPLAY_ERROR_PARAM`	-6	Invalid parameter
`AI_DISPLAY_ERROR_NOT_READY`	-7	Client not ready

Usage Example

Basic Usage

#include "ai_display.h"
#include <string.h>

int main() {
    // 1. Initialize client
    ai_display_client_t *client = ai_display_init();
    if (!client) {
        printf("Initialization failed\n");
        return -1;
    }

    // 2. Connect to service
    int ret = ai_display_connect(client);
    if (ret != AI_DISPLAY_SUCCESS) {
        printf("Connection failed: %s\n", ai_display_get_error_string(ret));
        ai_display_cleanup(client);
        return -1;
    }

    // 3. Get framebuffer
    uint8_t *framebuffer = ai_display_get_framebuffer(client);
    if (!framebuffer) {
        printf("Failed to get framebuffer\n");
        ai_display_cleanup(client);
        return -1;
    }

    // 4. Write frame data (example: fill with black)
    memset(framebuffer, 0, AI_DISPLAY_FRAME_SIZE);

    // 5. Commit frame
    ret = ai_display_commit_frame(client, 0, 0, 0, AI_DISPLAY_WIDTH, AI_DISPLAY_HEIGHT);
    if (ret != AI_DISPLAY_SUCCESS) {
        printf("Commit failed: %s\n", ai_display_get_error_string(ret));
    }

    // 6. Cleanup
    ai_display_cleanup(client);
    return 0;
}

Using Overlay Slot

// Get overlay framebuffer (Slot 1)
uint8_t *overlay = ai_display_get_framebuffer_slot(client, 1);
if (overlay) {
    // Draw overlay content...

    // Commit overlay frame
    ai_display_commit_frame(client, 1, 0, 0, AI_DISPLAY_WIDTH, AI_DISPLAY_HEIGHT);
}

Request Display Focus

// Request foreground display in multi-client scenario
int ret = ai_display_request_focus(client);
if (ret == AI_DISPLAY_SUCCESS) {
    printf("Display focus acquired\n");
}

Build and Link

# Compile
gcc -I/path/to/ai_glass_sdk/include -c your_app.c -o your_app.o

# Link (static library)
gcc your_app.o -L/path/to/ai_glass_sdk/lib -lai_glass_sdk -lrt -o your_app

# Link (shared library)
gcc your_app.o -L/path/to/ai_glass_sdk/lib -lai_glass_sdk -lrt -o your_app

Notes

Service must be running first: ai_display_service must be started before calling ai_display_connect()
Thread safety: A single client handle should not be used concurrently across multiple threads
Framebuffer format: Uses 4BPP format, size is AI_DISPLAY_FRAME_SIZE bytes
Resource cleanup: Always call ai_display_cleanup() when done to release resources

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