I'm trying to write a fun project for myself, which is a screenshot tool written in Python. I've run into an issue with one part of this, which is that I want to draw a rectangle on the screen, get the coordinates, then take a screenshot of this region. I have this working for the most part, but when the window underneath the selection updates, it breaks the drawing of the rectangle.
Here is a video displaying the issue: https://gfycat.com/EmotionalThankfulFlycatcher
I've tried reading the Xlib documentation to see if there's a way I can comfortably handle this, but wasn't able to find anything. Another alternative I could try would be to take a screenshot of the entire screen, and then take a selection of that instead of taking a region of the live desktop.
Is there anyway I can handle this, without going the route of taking a screenshot of the entire desktop and cropping that?
import sys
from Xlib import X, display, Xutil, xobject, Xcursorfont
class xselect:
def __init__(self):
# X display
self.d = display.Display()
# Screen
self.screen = self.d.screen()
# Draw on the root window (desktop surface)
self.window = self.screen.root
def select_region(self):
# Set cursor to crosshair
font = self.d.open_font('cursor')
cursor = font.create_glyph_cursor(font, Xcursorfont.crosshair,
Xcursorfont.crosshair+1,
(65535, 65535, 65535), (0, 0, 0))
self.window.grab_pointer(1, X.PointerMotionMask|X.ButtonReleaseMask|X.ButtonPressMask,
X.GrabModeAsync, X.GrabModeAsync, X.NONE, cursor, X.CurrentTime)
colormap = self.screen.default_colormap
color = colormap.alloc_color(0, 0, 0)
# Xor it because we'll draw with X.GXxor function
xor_color = color.pixel ^ 0xffffff
self.gc = self.window.create_gc(
line_width = 1,
line_style = X.LineSolid,
fill_style = X.FillOpaqueStippled,
fill_rule = X.WindingRule,
cap_style = X.CapButt,
join_style = X.JoinMiter,
foreground = xor_color,
background = self.screen.black_pixel,
function = X.GXxor,
graphics_exposures = False,
subwindow_mode = X.IncludeInferiors,
)
done = False
started = False
start = dict(x=0, y=0)
end = dict(x=0, y=0)
last = None
while not done:
e = self.d.next_event()
# Window has been destroyed, quit
if e.type == X.DestroyNotify:
sys.exit(0)
# Mouse button press
elif e.type == X.ButtonPress:
# Left mouse button?
if e.detail == 1:
start = dict(x=e.root_x, y=e.root_y)
started = True
# Right mouse button?
elif e.detail == 3:
sys.exit(0)
# Mouse button release
elif e.type == X.ButtonRelease:
end = dict(x=e.root_x, y=e.root_y)
if last:
self.draw_rectangle(start, last)
done = True
pass
# Mouse movement
elif e.type == X.MotionNotify and started:
if last:
self.draw_rectangle(start, last)
last = None
last = dict(x=e.root_x, y=e.root_y)
self.draw_rectangle(start, last)
pass
# Keyboard key
elif e.type == X.KeyPress:
sys.exit(0)
elif e.type == X.EnterNotify:
print(' EnterNotify')
self.d.ungrab_pointer(0)
self.d.flush()
coords = self.get_coords(start, end)
if coords['width'] <= 1 or coords['height'] <= 1:
sys.exit(0)
else:
return coords
def get_coords(self, start, end):
safe_start = dict(x=0, y=0)
safe_end = dict(x=0, y=0)
if start['x'] > end['x']:
safe_start['x'] = end['x']
safe_end['x'] = start['x']
else:
safe_start['x'] = start['x']
safe_end['x'] = end['x']
if start['y'] > end['y']:
safe_start['y'] = end['y']
safe_end['y'] = start['y']
else:
safe_start['y'] = start['y']
safe_end['y'] = end['y']
return {
'start': {
'x': safe_start['x'],
'y': safe_start['y'],
},
'end': {
'x': safe_end['x'],
'y': safe_end['y'],
},
'width' : safe_end['x'] - safe_start['x'],
'height': safe_end['y'] - safe_start['y'],
}
def draw_rectangle(self, start, end):
coords = self.get_coords(start, end)
self.window.rectangle(
self.gc,
coords['start']['x'],
coords['start']['y'],
coords['end']['x'] - coords['start']['x'],
coords['end']['y'] - coords['start']['y']
)
