how to acces the RGB array.

Natural_Bugger

hi,

i found this code: lQGraphicsView_QGraphicsScenet
It compiles and works using QT 5.9, i believe.

What enables me to access the RGB array to insert a custom one.
Qimage?

i want to create something that's looks like an oscilloscope.
i really want to access the RGB array.

i haven't done much "visual" QT for a while.

SGaist

Hi,

Qwt provides a nice oscilloscope example that might be of interest.

It would also help if you could explain what you want to do with the RGB values.

Natural_Bugger

Well, actually in the end, i want to make a mcp4921 dac move to create ADSR profiles.
linear, exponentiation, logarithmic.

this guy, who is making the "Jeany" teensy 4.1 polyphonic synthesizer gave me this, after i asked how the envelope code create these logarithmic/exponential curves.

Rolf Degen:
    if (I <= 3) {
            tft.drawLine(xplot1,40,xplot1 + xplot1_decay,yplot2_sustain,ST7735_RED);
            } else {
            for (i = 0; i <= I; i++) {
                result = (exp(k*i/I) - exp(0)) / (exp(k) - exp(0));
                int value = float(result * (46 - (SUSvalue / 2.8f)));
                tft.drawLine(xplot1 + i2, 40 + value2, xplot1 + i, 40 + value, ST7735_RED);
                i2 = i;
                value2 = value;
            }
       }

i would like to simulate that, pixel based.

SGaist

You can draw on a QImage with that equation.

Otherwise, the underlying buffer is accessible as well as each pixels.

Natural_Bugger

@Natural_Bugger said in how to acces the RGB array.:

result = (exp(k*i/I) - exp(0)) / (exp(k) - exp(0));

i don't know what "k" or "I" is.
i have done some reading, it returns the Euler number, that's all i know, some weird number if you try it online euler calculator/c++ compiler and enter 1, 2.

i only have the code from the above example.
How to add a "QImage" via code, what is the indentifierof the buffer?

it's my first project in ages.

SGaist

You might want to ask him a reference for the equations used.

To access the raw data: QImage::bits.

If you really don't remember how to create an object like QImage then I would suggest to first check the C++ basics.

Natural_Bugger

didn't get a response from him.

console coding, openGL isn't a big deal, haven't done much on QT "visual" lately.

want to learn how to create logarithmic, experiential curves in a binary method.
having a array of 12 bit values (mcp4921), time vs amplitude.

the Akai MPC devices have this as well in their envelopes.