Draw composite rectangles/positions

[simsam8]

Hi,

I want to add the functionality to plot positions in my program like the image shows below. Currently I draw two independent rects using the add_rect function. The goal is to have it be all in one rect object, being able to adjust the take profit line and stop loss independently. Something similar as to tradingview's (image 2), but without the textboxes.

I am thinking of two approaches,

1. Using pyqtgraph's ROI
2. Create two rects with add_rect and sychronize them with events.

Thanks in advance.

[highfestiva]

They are very similar, although the pyqtgraph one might contain more features.

[simsam8]

I figured out a solution. Instead of creating two rectangles/ROIs, I instead extended the ROI class from pyqtgraph. It takes a given ratio, and depending on what type of position it is, it paints the tp and sl accordingly.

class FinPosition(pg.ROI):
    def __init__(self, ax, brush_tp, position_type, brush_sl, ratio=.5, *args, **kwargs):
        self.ax = ax
        self.brush_tp = brush_tp
        self.brush_sl = brush_sl
        self.position_type = position_type

        if position_type == "long":
            ratio=1-ratio
        self.ratio = ratio

        super().__init__(*args, **kwargs)

        center = [0.5, ratio]

        dy = -self.size()[1]*self.ratio
        self.translate(0, dy, False)
            
        if self.resizable:
            self.addScaleHandle([1, 0.5], [0, 0.5])
            self.addScaleHandle([0, 1], [0, center[1]])
            self.addScaleHandle([0, 0], [0, center[1]])
        
    def paint(self, p, *args):
        r = QtCore.QRectF(0, 0, self.state['size'][0], self.state['size'][1]).normalized()
        if self.position_type == "long":
            first_brush = self.brush_sl
            second_brush = self.brush_tp
        elif self.position_type == "short":
            first_brush = self.brush_tp
            second_brush = self.brush_sl
        else:
            raise Exception(f"{self.position_type}: is not a valid position type. Must be 'long' or 'short'")
            
        p.setPen(self.currentPen)
        p.setBrush(first_brush)

        p.translate(r.left(), r.top())
        p.scale(r.width(), r.height())

        p.scale(1, self.ratio)
        p.drawRect(0, 0, 1, 1)

        p.drawLine(0,1,1,1)

        p.setBrush(second_brush)
        p.translate(0, 1)
        p.scale(1,(1-self.ratio)/self.ratio)

        p.drawRect(0, 0, 1, 1)

    def addScaleHandle(self, *args, **kwargs):
        if self.resizable:
            self.handleSize = 15
            self.handlePen = pg.mkPen("blue")
            super().addScaleHandle(*args, **kwargs)

I also created a function to add positions, similary to the add_rect function.

def add_position(p0, p1, position_type, ratio=.5, interactive=False, ax=None):
    ax = fplt._create_plot(ax=ax, maximize=False)
    x_pts = fplt._pdtime2index(ax, pd.Series([p0[0], p1[0]]))
    ix = ax.vb.yscale.invxform
    y0,y1 = sorted([p0[1], p1[1]])
    pos  = (x_pts[0], ix(y0))
    size = (x_pts[1]-pos[0], ix(y1)-ix(y0))
    tp_color = fplt.candle_bull_color+"80"
    sl_color = fplt.candle_bear_color+"80"
    brush_tp = pg.mkBrush(tp_color)
    brush_sl = pg.mkBrush(sl_color)
    rect = FinPosition(ax=ax, ratio=ratio, position_type=position_type, brush_tp=brush_tp, brush_sl=brush_sl, pos=pos, size=size, movable=interactive, resizable=interactive, rotatable=False)
    rect.setZValue(0)
    if interactive:
        ax.vb.rois.append(rect)
    rect.ax = ax
    ax.addItem(rect)
    return rect

[simsam8]

I could create a pull request with this as well. I think the ability to create positions could be a nice feature to have. What do you think @highfestiva?

[highfestiva]

Glad you were able to get to what you wanted! However, I think this is too specialized for a plotting library, but thank you anyway!

[simsam8]

No worries. Thanks for the help. Your library is great!

[kumarangp]

@simsam8 can you please provide full working code to draw rectangle you explained above.