AsyncResponses.h

#include "esp_camera.h"
#include <Arduino.h>
#include "ESPAsyncWebServer.h"

typedef struct {
        camera_fb_t * fb;
        size_t index;
} camera_frame_t;

#define PART_BOUNDARY "123456789000000000000987654321"
static const char* STREAM_CONTENT_TYPE = "multipart/x-mixed-replace;boundary=" PART_BOUNDARY;
static const char* STREAM_BOUNDARY = "\r\n--" PART_BOUNDARY "\r\n";
static const char* STREAM_PART = "Content-Type: %s\r\nContent-Length: %u\r\n\r\n";

static const char * JPG_CONTENT_TYPE = "image/jpeg";
static const char * BMP_CONTENT_TYPE = "image/x-windows-bmp";

class AsyncBufferResponse: public AsyncAbstractResponse {
    private:
        uint8_t * _buf;
        size_t _len;
        size_t _index;
    public:
        AsyncBufferResponse(uint8_t * buf, size_t len, const char * contentType){
            _buf = buf;
            _len = len;
            _callback = nullptr;
            _code = 200;
            _contentLength = _len;
            _contentType = contentType;
            _index = 0;
        }
        ~AsyncBufferResponse(){
            if(_buf != nullptr){
                free(_buf);
            }
        }
        bool _sourceValid() const { return _buf != nullptr; }
        virtual size_t _fillBuffer(uint8_t *buf, size_t maxLen) override{
            size_t ret = _content(buf, maxLen, _index);
            if(ret != RESPONSE_TRY_AGAIN){
                _index += ret;
            }
            return ret;
        }
        size_t _content(uint8_t *buffer, size_t maxLen, size_t index){
            memcpy(buffer, _buf+index, maxLen);
            if((index+maxLen) == _len){
                free(_buf);
                _buf = nullptr;
            }
            return maxLen;
        }
};

class AsyncFrameResponse: public AsyncAbstractResponse {
    private:
        camera_fb_t * fb;
        size_t _index;
    public:
        AsyncFrameResponse(camera_fb_t * frame, const char * contentType){
            _callback = nullptr;
            _code = 200;
            _contentLength = frame->len;
            _contentType = contentType;
            _index = 0;
            fb = frame;
        }
        ~AsyncFrameResponse(){
            if(fb != nullptr){
                esp_camera_fb_return(fb);
            }
        }
        bool _sourceValid() const { return fb != nullptr; }
        virtual size_t _fillBuffer(uint8_t *buf, size_t maxLen) override{
            size_t ret = _content(buf, maxLen, _index);
            if(ret != RESPONSE_TRY_AGAIN){
                _index += ret;
            }
            return ret;
        }
        size_t _content(uint8_t *buffer, size_t maxLen, size_t index){
            memcpy(buffer, fb->buf+index, maxLen);
            if((index+maxLen) == fb->len){
                esp_camera_fb_return(fb);
                fb = nullptr;
            }
            return maxLen;
        }
};

class AsyncJpegStreamResponse: public AsyncAbstractResponse {
    private:
        camera_frame_t _frame;
        size_t _index;
        size_t _jpg_buf_len;
        uint8_t * _jpg_buf;
        uint64_t lastAsyncRequest;
    public:
        AsyncJpegStreamResponse(){
            _callback = nullptr;
            _code = 200;
            _contentLength = 0;
            _contentType = STREAM_CONTENT_TYPE;
            _sendContentLength = false;
            _chunked = true;
            _index = 0;
            _jpg_buf_len = 0;
            _jpg_buf = NULL;
            lastAsyncRequest = 0;
            memset(&_frame, 0, sizeof(camera_frame_t));
        }
        ~AsyncJpegStreamResponse(){
            if(_frame.fb){
                if(_frame.fb->format != PIXFORMAT_JPEG){
                    free(_jpg_buf);
                }
                esp_camera_fb_return(_frame.fb);
            }
        }
        bool _sourceValid() const {
            return true;
        }
        virtual size_t _fillBuffer(uint8_t *buf, size_t maxLen) override {
            size_t ret = _content(buf, maxLen, _index);
            if(ret != RESPONSE_TRY_AGAIN){
                _index += ret;
            }
            return ret;
        }
        size_t _content(uint8_t *buffer, size_t maxLen, size_t index){
            if(!_frame.fb || _frame.index == _jpg_buf_len){
                if(index && _frame.fb){
                    uint64_t end = (uint64_t)micros();
                    int fp = (end - lastAsyncRequest) / 1000;
                    log_printf("Size: %uKB, Time: %ums (%.1ffps)\n", _jpg_buf_len/1024, fp);
                    lastAsyncRequest = end;
                    if(_frame.fb->format != PIXFORMAT_JPEG){
                        free(_jpg_buf);
                    }
                    esp_camera_fb_return(_frame.fb);
                    _frame.fb = NULL;
                    _jpg_buf_len = 0;
                    _jpg_buf = NULL;
                }
                if(maxLen < (strlen(STREAM_BOUNDARY) + strlen(STREAM_PART) + strlen(JPG_CONTENT_TYPE) + 8)){
                    //log_w("Not enough space for headers");
                    return RESPONSE_TRY_AGAIN;
                }
                //get frame
                _frame.index = 0;

                _frame.fb = esp_camera_fb_get();
                if (_frame.fb == NULL) {
                    log_e("Camera frame failed");
                    return 0;
                }

                if(_frame.fb->format != PIXFORMAT_JPEG){
                    unsigned long st = millis();
                    bool jpeg_converted = frame2jpg(_frame.fb, 80, &_jpg_buf, &_jpg_buf_len);
                    if(!jpeg_converted){
                        log_e("JPEG compression failed");
                        esp_camera_fb_return(_frame.fb);
                        _frame.fb = NULL;
                        _jpg_buf_len = 0;
                        _jpg_buf = NULL;
                        return 0;
                    }
                    log_i("JPEG: %lums, %uB", millis() - st, _jpg_buf_len);
                } else {
                    _jpg_buf_len = _frame.fb->len;
                    _jpg_buf = _frame.fb->buf;
                }

                //send boundary
                size_t blen = 0;
                if(index){
                    blen = strlen(STREAM_BOUNDARY);
                    memcpy(buffer, STREAM_BOUNDARY, blen);
                    buffer += blen;
                }
                //send header
                size_t hlen = sprintf((char *)buffer, STREAM_PART, JPG_CONTENT_TYPE, _jpg_buf_len);
                buffer += hlen;
                //send frame
                hlen = maxLen - hlen - blen;
                if(hlen > _jpg_buf_len){
                    maxLen -= hlen - _jpg_buf_len;
                    hlen = _jpg_buf_len;
                }
                memcpy(buffer, _jpg_buf, hlen);
                _frame.index += hlen;
                return maxLen;
            }

            size_t available = _jpg_buf_len - _frame.index;
            if(maxLen > available){
                maxLen = available;
            }
            memcpy(buffer, _jpg_buf+_frame.index, maxLen);
            _frame.index += maxLen;

            return maxLen;
        }
};