I'm using PyQTGraph along with PyQT5, and I've added a GraphicsLayoutWidget, with mouse events to add markers.
canvas_ruler = pg.GraphicsLayoutWidget()
formLayout.addWidget(self.canvas_ruler)
plot_ruler = canvas_ruler.addPlot(name="Ruler")
plot_ruler.hideAxis('left')
canvas_ruler.scene().sigMouseMoved.connect(self.mouseMoved)
canvas_ruler.scene().sigMouseClicked.connect(self.mouseClicked)
plot_ruler.setMouseEnabled(x=True, y=False)
What I would like to add, are 2 buttons, to zoom in and zoom out, currently the mouse wheel event, does zooming in/out. But I want to disable that and add 2 buttons for it. I probably should:
setMouseEnabled(x=False, y=False)
But I don't know how to trigger the zoom using code, I couldn't find it's APIs, like sigMouseMoved.connect.
The nearest native thing pyqtgraph does that approaches this (AFAIK) is the zoom with the mouse wheel feature. The MouseWheelEvent() function in ViewBox achives this with a call to the ViewBox function scaleBy().
You can see the source for all inputs and more detail but the main one is s (scale) and center (center around which to zoom). Leave center as None to zoom around the center of the plot.
Pass a tuple of x and y zoom scales to the function to zoom, < 1 for in and > 1 for out. e.g.:
def handle_plot_zoom_buttons(self, in_or_out):
"""
see ViewBox.scaleBy()
pyqtgraph wheel zoom is s = ~0.75
"""
s = 0.9
zoom = (s, s) if in_or_out == "in" else (1/s, 1/s)
self.plot.vb.scaleBy(zoom)
Related
I'm bringing this question from Altair's github. (https://github.com/altair-viz/altair/issues/2456) Is there a way to get the Scale on Y-axis in the bottom chart to respond to the selection brush? I'd like to be able to pan around the top chart with a selection and see the zoomed-in results in the bottom chart. If I uncomment the alt.Y, then both the X and Y axes show Years and it's messed up. Is there a way to pass just an X or Y value in the 'brush' maybe? Thank you very much!
brush = alt.selection_interval(init={'x':[1950, 1970], 'y':[1500000, 2500000]}, encodings=['x', 'y'])
base = alt.Chart().mark_line().encode(
x=alt.X('Year:Q', title=None),
y='Deaths:Q',
color='Entity:N'
)
alt.vconcat(
base.add_selection(brush).encode().properties(height=150, width=150),
base.encode(
alt.X('Year:Q', scale=alt.Scale(domain=brush)),
#alt.Y('Deaths:Q', scale=alt.Scale(domain=brush)) # (un)commenting this line makes it work/fail only along the x-axis
).properties(
height=500, width=500
),
data='https://vega.github.io/vega-datasets/data/disasters.csv'
)
Yes, see Open the Chart in the Vega Editor
It filters the data of the 2nd chart using a filter transform on the brush param.
I am a non-developer product manager for an application built in both Android and iOS. We have a bar graph in iOS that provides text for the content of the graph. It displays Totals for each bar, and percentages for each segment of each bar.
In Android, using AndroidPlot (so I understand) we just display the bars with different color segments and no percent totals or totals. I am told by the developer that we can't show more.
I would display the images here, but stackoverflow tells me I don't have enough reputation points to do this. I have created a link to my dropbox with the images https://www.dropbox.com/sh/2uocm5bn79rerbe/AAB7s9QEEYIRIgXhKbUAaOyDa
Is it possible to use AndroidPlot to emulate this iOS chart or at least represent to same information to the end user?
Your developer is more or less correct but you have options. Androidplot's BarRenderer by default provides only an optional label at the top of each bar, which in your iOS images is occupied by the "available", "new", "used" and "rent" label. That label appears to be unused in your Android screenshot so one option would be to utilize those labels do display your totals.
As far as exactly matching the iOS implementation with Androidplot, the missing piece is the ability to add additional labels horizontally and vertically along the side of each bar. You can extend BarRenderer to do this by overriding it's onRender(...) method. Here's a link for your developer that shows where in the code he'll want to modify onRender(...).
I'd suggest these modifications to add the vertical labels:
Invoke Canvas.save(Canvas.ALL_SAVE_FLAG) to store the default orientation of the Canvas.
Use Canvas.translate(leftX, bottom) to center on the bottom left point of the bar
Rotate the Canvas 90 degrees using Canvas.rotate(90) to enable vertical text drawing
Draw whatever text is needed along the side of the plot; 0,0 now corresponds to the bottom left corner of the bar so start there when invoking canvas.drawText(x,y).
Invoke Canvas.restore() to restore the canvas' original orientation.
After implementing the above, adding horizontal "%" labels should be self evident but if you run into trouble feel free to ask more questions along the way.
UPDATE:
Here's a very basic implementation of the above. First the drawVerticalText method:
/**
*
* #param canvas
* #param paint paint used to draw the text
* #param text the text to be drawn
* #param x x-coord of where the text should be drawn
* #param y y-coord of where the text should be drawn
*/
protected void drawVerticalText(Canvas canvas, Paint paint, String text, float x, float y) {
// record the state of the canvas before the draw:
canvas.save(Canvas.ALL_SAVE_FLAG);
// center the canvas on our drawing coords:
canvas.translate(x, y);
// rotate into the desired "vertical" orientation:
canvas.rotate(-90);
// draw the text; note that we are drawing at 0, 0 and *not* x, y.
canvas.drawText(text, 0, 0, paint);
// restore the canvas state:
canvas.restore();
}
All that's left is to invoke this method where necessary. In your case it should be done once per BarGroup and should maintain a consistent position on the y axis. I added the following code to the STACKED case in BarRenderer.onRender(...), immediately above the break:
// needed some paint to draw with so I'll just create it here for now:
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(PixelUtils.spToPix(20));
drawVerticalText(
canvas,
paint,
"test",
barGroup.leftX,
basePositionY - PixelUtils.dpToPix(50)); // offset so the text doesnt intersect with the origin
Here's a screenshot of the result...sorry it's so huge:
Personally, I don't care for the fixed y-position of these vertical labels and would prefer them to float along the upper part of the bars. To accomplish this I modify my invocation of drawVerticalText(...) to look like this:
// needed some paint to draw with so I'll just create it here for now:
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(PixelUtils.spToPix(20));
// right-justify the text so it doesnt extend beyond the top of the bar
paint.setTextAlign(Paint.Align.RIGHT);
drawVerticalText(
canvas,
paint,
"test",
barGroup.leftX,
bottom);
Which produces this result:
Does anyone know how to trigger zoom in/out with Raphaël-ZPD by clicking on a button?
If take a look to the code of Raphael-ZPD you would see that all the zooming and panning are made by using svg matrices. In the particular case of zooming, it first draw a reference point where the mouse is, and calculates the zoom direction relative to that point, using the delta of the mouse wheel to apply the amount of zoom.
Now, if you want to use a button, you would have to decide the delta on your code, and you could maybe use the center of the screen as the relative point to calculate the direction of zooming.
For starters you could just use the svg scale property, something like this could be ok if you are using Raphael ZPD:
paper = Raphael('container',600, 600);
paper.ZPD({ zoom: true, pan: true, drag: false });
scale = 1;
var zoomin = document.getElementById('in')
var zoomout = document.getElementById('out')
zoomin.onclick = function(){
scale *= 1.2
paper.canvas.setAttribute("transform", "scale("+scale+")")
}
zoomout.onclick = function(){
scale *= 0.8
paper.canvas.setAttribute("transform", "scale("+scale+")")
}
Here is Fiddle with a working example
I reccomend to add some translate calculating the center of the screen, so the zoom doesn't go to corner. But think all this could point you in the right direction.
I have a project where i have to create a 4 way split screen using pygame. On this screen i have to draw the same image on each of the screen just have different view of the image. I just can not figure out how to create this 4 way split screen using pygame.
I need my screen to be divided like above so i can draw my points onto each section.
I have been looking around and I can not find anything like this so any help would be great
thanks
In addition to the surface you have that gets rendered to the display, likely called something like screen, you should create another surface which all of the "action" gets drawn to. You can then use a Rect object for each quadrant of the screen which will represent the "camera" (assuming each quadrant doesn't necessarily need to show exactly the same image). When you draw back to screen, you use each camera Rect object to select a portion of the game space to draw to a specific quadrant.
# canvas will be a surface that captures the entirety of the "action"
canvas = pygame.Surface((800, 600))
# the following are your "camera" objects
# right now they are taking up discrete and even portions of the canvas,
# but the idea is that they can move and possibly cover overlapping sections
# of the canvas
p1_camera = pygame.Rect(0,0,400,300)
p2_camera = pygame.Rect(400,0,400,300)
p3_camera = pygame.Rect(0,300,400,300)
p4_camera = pygame.Rect(400,300,400,300)
On each update, you would then use these "camera" objects to blit various portions of the canvas back to the screen surface.
# draw player 1's view to the top left corner
screen.blit(canvas, (0,0), p1_camera)
# player 2's view is in the top right corner
screen.blit(canvas, (400, 0), p2_camera)
# player 3's view is in the bottom left corner
screen.blit(canvas, (0, 300), p3_camera)
# player 4's view is in the bottom right corner
screen.blit(canvas, (400, 300), p4_camera)
# then you update the display
# this can be done with either display.flip() or display.update(), the
# uses of each are beyond this question
display.flip()
There is no functions to split screen. But you can draw 4 views directly on screen or you can draw on 4 surfaces (pygame.Surface) and than blit surfaces on screen.
Since you were looking for a way to split the screen in to 4 sections and draw some points on to them I'd suggest creating 4 subsurface surfaces of the original "canvas" image for convenience.
These surfaces would act as your player(split screen) canvasses which can easily be modified.
This will enable the usage of normalized coordinates for player specific drawing purposes.
Assuming you have a screen surface set up
# Image(Surface) which will be refrenced
canvas = pygame.Surface((800, 600))
# Camera rectangles for sections of the canvas
p1_camera = pygame.Rect(0,0,400,300)
p2_camera = pygame.Rect(400,0,400,300)
p3_camera = pygame.Rect(0,300,400,300)
p4_camera = pygame.Rect(400,300,400,300)
# subsurfaces of canvas
# Note that subx needs refreshing when px_camera changes.
sub1 = canvas.subsurface(p1_camera)
sub2 = canvas.subsurface(p2_camera)
sub3 = canvas.subsurface(p3_camera)
sub4 = canvas.subsurface(p4_camera)
Now drawing on any of of the subsurfaces with these normalized coordinates
# Drawing a line on each split "screen"
pygame.draw.line(sub2, (255,255,255), (0,0), (0,300), 10)
pygame.draw.line(sub4, (255,255,255), (0,0), (0,300), 10)
pygame.draw.line(sub3, (255,255,255), (0,0), (400,0), 10)
pygame.draw.line(sub4, (255,255,255), (0,0), (400,0), 10)
# draw player 1's view to the top left corner
screen.blit(sub1, (0,0))
# player 2's view is in the top right corner
screen.blit(sub2, (400, 0))
# player 3's view is in the bottom left corner
screen.blit(sub3, (0, 300))
# player 4's view is in the bottom right corner
screen.blit(sub4, (400, 300))
# Update the screen
pygame.display.update()
Note that modifications to the subsurface pixels will affect the canvas as well. I'd recommend reading the full documentation on subsurfaces.
I have a zoomable QGraphicsView with scene that contains hundreds (and even thousands) of datapoints. The points are represented by QGraphicsEllipseItems and collected into a QGraphicsItemGroup. When the view is zoomed in to I want datapoints to stay at a constant size (i.e., the distances between neigbouring points increase but the sizes stay the same). Right now I achieve this by running this code every time the user zooms in:
#get all the QGraphicsEllipseItems that make up the QGraphicsItemGroup
children = graphics_item_group.childItems()
for c in children:
#base_size_x and base_size_y are the sizes of the
#untrasformed ellipse (on the scene) when zoom factor is 1
#New width and height are obtained from the original sizes and
#the new zoom factors (h_scale, v_scale)
new_width = base_size_x/h_scale
new_height = base_size_y/v_scale
#The top-left corner of the new rectangle for the item has to be recalculated
#when scaling in order to keep the center at a constant position
#For this, the center of the item has to be stored first
old_center_x = c.rect().center().x()
old_center_y = c.rect().center().y()
#New coordinates of the rectangle top left point are calculated
new_topleft_x = old_center_x - new_width/2.
new_topleft_y = old_center_y - new_height/2.
#Finally a new rectangle is set for the ellipse
c.setRect(new_topleft_x, new_topleft_y, new_width, new_height)
This code works. The problem is that it is quite slow (without the compensatory scaling zooming in/out works very smoothly). I tried turning off antialiasing for the view but it makes things look pretty ugly. Is there anything else that I can do to make the processing/redrawing faster?
In the constructor of the QGraphicsItem:
setFlag(ItemIgnoresTransformations);
When you zoom, the item will remain the same size, and you won't have to manually scale it.