B4R Question uint8_t - some questions

hatzisn · Jan 9, 2025

Here is a line of code in C++.

C++:

uint8_t *jpeg_buf = (uint8_t*) pic->buf;

the pic is an ESP32CAM image of type camera_fb_t so I suppose the buf is the buffer of the image taken.

The question is what is the jpeg_buf? Is it a conversion of all the buf[ii] to uint8_t? So jpeg_buf is an array of uint8_t numbers or am I wrong?
If it is an array of uint8_t numbers, how can I convert it to a B4R byte array?

hatzisn · Jan 9, 2025

The pic is an ESP32CAM image of type camera_fb_t which of course is not a type but a structure with the following definition:

C++:

  typedef struct {
    uint8_t *buf;
    size_t len;
    uint32_t width;
    uint32_t height;
    pixformat_t format;
} camera_fb_t;

I have managed to copy the data successfully to an in line c byte array.
Is there any way to copy with B4R byte converter this inline c byte array to a new B4R byte array?

C++:

  byte imageData[pic->len];
  // Copy the image data from the camera frame buffer to the byte array
  memcpy(imageData, pic->buf, pic->len);

peacemaker · Jan 10, 2025

Maybe something like https://www.b4x.com/android/forum/threads/pass-user-defined-type-to-inline-c.127133/post-800646 ?

candide · Jan 10, 2025

to create an ArrayByte for B4R, you can try like this example:

B4X:

    ArrayByte* B4RTEST1::testArrayByte(byte a, byte b)
    {
       byte* raw = rcs->testArrayByte(a, b);
       uint16_t len = 2; //or raw.size() or fixe value depending of the arduino part
       ArrayByte* arr = CreateStackMemoryObject(ArrayByte);
       arr->data=raw;
       arr->length=len;
       return arr;
    };

B4R Question uint8_t - some questions

hatzisn

Expert

hatzisn

Expert

peacemaker

Expert

candide

Active Member

Similar Threads

B4R Question uint8_t - some questions

hatzisn

Expert

hatzisn

Expert

peacemaker

Expert

candide

Active Member

Similar Threads

Privacy & Transparency

Privacy & Transparency