Kivy: export_to_png() with an arbitrary scale - export

Question

Is there a way to export a widget to png with an arbitrary scale in Kivy?
As far as I understand, now by default the scale of an exported image is 1:1 relative to size of widget that I see on the screen.
But what if I want to export to 1:10 (and get an image 10 times larger)?
Interested in any ideas how this can be done.

Answer 1

I don't know a straight forward method to do the same, but you can fork export_to_png method of Widget class
Here is a working example:
from kivy.uix.widget import Widget
from kivy.base import runTouchApp
from kivy.lang import Builder
from kivy.graphics import (Canvas, Translate, Fbo, ClearColor,
ClearBuffers, Scale)
kv='''
BoxLayout:
orientation: 'vertical'
MyWidget:
id: wgt
BoxLayout:
size_hint_y: .1
orientation: 'horizontal'
Label:
text: 'enter scale:'
TextInput:
id: txtinpt
text: '2.5'
Button:
text: 'Export with new scale'
on_release: wgt.export_scaled_png('kvwgt.png', image_scale=float(txtinpt.text))
<MyWidget>:
canvas:
PushMatrix:
Color:
rgba: (0, 0, 1, .75)
Ellipse:
pos: (self.x + self.width // 5, self.y + self.height // 5)
size: (self.width * 3 // 5, self.height * 3 // 5)
Color:
rgba: (1, 0, 0, .5)
Rectangle:
pos: (self.x + self.width // 4, self.y + self.height // 4)
size: (self.width // 2, self.height // 2)
Rotate:
origin:
self.center
angle:
45
Button:
text: 'useless child widget\\njust for demonstration'
center: root.center
size: (root.width // 2, root.height // 8)
canvas:
PopMatrix:
'''
class MyWidget(Widget):
def export_scaled_png(self, filename, image_scale=1):
re_size = (self.width * image_scale,
self.height * image_scale)
if self.parent is not None:
canvas_parent_index = self.parent.canvas.indexof(self.canvas)
if canvas_parent_index > -1:
self.parent.canvas.remove(self.canvas)
fbo = Fbo(size=re_size, with_stencilbuffer=True)
with fbo:
ClearColor(0, 0, 0, 0)
ClearBuffers()
Scale(image_scale, -image_scale, image_scale)
Translate(-self.x, -self.y - self.height, 0)
fbo.add(self.canvas)
fbo.draw()
fbo.texture.save(filename, flipped=False)
fbo.remove(self.canvas)
if self.parent is not None and canvas_parent_index > -1:
self.parent.canvas.insert(canvas_parent_index, self.canvas)
runTouchApp(Builder.load_string(kv))
Note re_size variable, which in turn passes to Fbo constructor.
And the "Scale(image_scale, -image_scale, image_scale)" instruction inside export_scaled_png method.