The color picker displayed horizontally

[Mage111]

why is the color picker displayed horizontally?
I want the HEX will be under the color picker, what I'm doing wrong?

maybe the reason is that the picker is displayed on the screen and not on the alert window?

Thank you for any help!!

`  child: ColorPicker(
        portraitOnly: true,
        pickerColor: selectedColor,
        onColorChanged: (Color color) {
          selectedColor = color;
          if (widget.onColorChanged != null) {
            widget.onColorChanged!(selectedColor);
          }
        },
          pickerAreaHeightPercent: 0.7,
          enableAlpha: true,
          displayThumbColor: true,
          paletteType: PaletteType.hsv,
          pickerAreaBorderRadius: const BorderRadius.only(
                                  topLeft: Radius.circular(2.0),
                                  topRight: Radius.circular(2.0),
                                ),
      ),

`**