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)
Recently I'm learning skia library(google open source 2d engine,be used on Android and chromium,etc.),Now I want to use it on windows instead of GDI+ dont support clip area with antialias,during it, I find a problem about pixel.
up is set antialias,down is not set antialias
the main code is:
paint.setStrokeWidth(1);
paint.setStyle(SkPaint::kStroke_Style);
paint.setAntiAlias(true);
canvas.drawRect(skrect,paint); //draw up rect
skrect.fTop += 110;
skrect.fBottom += 110;
paint.setAntiAlias(false);
canvas.drawRect(skrect, paint); //draw down rect
As you see,the same rect,if I not set Antialias,the boundary pixel is 1(I set strock width is 1),but if I set Antialias, the boundary pixel is 2,and it become a bit light,although I set color is black.
I dont konw why,anyone can tell me?
thk,
now,maybe I konw.
the skia library canvas should be like Html5`s canvas ,Canvas every line have an infinite thin "line", the width of the line from the center line to stretch,so if we draw a 1px line,in fact,it will fill two of 0.5 pixel point,but the display device dont allow it do that,so it will fill 2 pixel point,and set it color more light to differentiate real 2 pixels .
I will search more material to prove it.
This happens because OpenGL assumes that each pixel is centered at [0.5; 0.5]. The rasterizer have to draw indeed two pixels and interpolate the alpha. Read more here
If you would like to draw sharp 1px lines with antialiasing turned on just offset coordinates of a line or other figure with 0.5f.
For example a point at [10; 10] should have coordinates [10.5; 10.5] and so on
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'm using vtkTexturedActor2D and vtkImageMapper to display a 2D image. I can use
actor.GetPositionCoordinate().SetCoordinateSystemToNormalizedDisplay();
actor.this.Actor.SetPosition(0.5, 0.9);
to place the image in the center of the window, but it's not center-aligned. The corner of the image is placed in the center. How can I center-align the image so that the center of the image is at the center of the window?
I had this same problem.
This seems to solve it:
float height, width;
this->d_actor->GetPositionCoordinate()->SetCoordinateSystemToNormalizedViewport();
this->d_actor->GetPositionCoordinate()->SetViewport(this); // Without this was getting weird results
height = this->d_actor->GetHeight();
width = this->d_actor->GetWidth();
this->d_actor->GetPositionCoordinate()->SetValue(.5 - width/2.0, .5 - height/2.0);
When using the JavaFX 2.0 scatter chart the plotted dots are graphed with the top left corner of the dot touching the point rather than the center of the dot on the point. So rather than it looking like it is plotting at the point (1, 1) it looks more like it's at (1.1, 0.9). Does anyone know how to fix this?
There is a bug in a way ScatterChart draws shifting plotted dots.
Until fix as a workaround you can override dots style class. To perform that add new file "style.css" to the same package with your main class and next content:
.chart-symbol { /* solid circle */
-fx-background-color: #f9d900;
-fx-background-radius: 5px;
-fx-translate-x: -4px;
-fx-translate-y: -4px;
}
In the code where your main scene is created add next line:
scene.getStylesheets().add("style.css");