OP的回答，从问题中删除：
这是我的解决方案：
基本思想是：
- 捕获 xlim_changed 或 ylim_changed 事件
- 根据图像大小和所需的像素数计算所需的步幅
- Draw
https://github.com/flailingsquirrel/cmake_scipy_ctypes_example/blob/master/src/python/FastImshow.py https://github.com/flailingsquirrel/cmake_scipy_ctypes_example/blob/master/src/python/FastImshow.py
#!/usr/bin/env python
'''
Fast Plotter for Large Images - Resamples Images to a target resolution on each zoom.
Example::
sz = (10000,20000) # rows, cols
buf = np.arange(sz[0]*sz[1]).reshape(sz)
extent = (100,150,1000,2000)
fig = plt.figure()
ax = fig.add_subplot(111)
im = FastImshow(buf,extent,ax)
im.show()
plt.show()
'''
import numpy as np
import matplotlib.pyplot as plt
class FastImshow:
'''
Fast plotter for large image buffers
Example::
sz = (10000,20000) # rows, cols
buf = np.arange(sz[0]*sz[1]).reshape(sz)
extent = (100,150,1000,2000)
fig = plt.figure()
ax = fig.add_subplot(111)
im = FastImshow(buf,extent,ax)
im.show()
plt.show()
'''
def __init__(self,buf,ax,extent=None,tgt_res=512):
'''
[in] img buffer
[in] extent
[in] axis to plot on
[in] tgt_res(default=512) : target resolution
'''
self.buf = buf
self.sz = self.buf.shape
self.tgt_res = tgt_res
self.ax = ax
# Members required to account for mapping extent to buf coordinates
if extent:
self.extent = extent
else:
self.extent = [ 0, self.sz[1], 0, self.sz[0] ]
self.startx = self.extent[0]
self.starty = self.extent[2]
self.dx = self.sz[1] / (self.extent[1] - self.startx ) # extent dx
self.dy = self.sz[0] / (self.extent[3] - self.starty ) # extent dy
# end __init__
def get_strides( self,xstart=0, xend=-1, ystart=0, yend=-1, tgt_res=512 ):
'''
Get sampling strides for a given bounding region. If none is provided,
use the full buffer size
'''
# size = (rows,columns)
if xend == -1:
xend = self.sz[1]
if yend == -1:
yend = self.sz[0]
if (xend-xstart) <= self.tgt_res:
stridex = 1
else:
stridex = max(int((xend - xstart) / self.tgt_res),1)
if (yend-ystart) <= self.tgt_res:
stridey = 1
else:
stridey = max(int((yend - ystart) / self.tgt_res),1)
return stridex,stridey
# end get_strides
def ax_update(self, ax):
'''
Event handler for re-plotting on zoom
- gets bounds in img extent coordinates
- converts to buffer coordinates
- calculates appropriate strides
- sets new data in the axis
'''
ax.set_autoscale_on(False) # Otherwise, infinite loop
# Get the range for the new area
xstart, ystart, xdelta, ydelta = ax.viewLim.bounds
xend = xstart + xdelta
yend = ystart + ydelta
xbin_start = int(self.dx * ( xstart - self.startx ))
xbin_end = int(self.dx * ( xend - self.startx ))
ybin_start = int(self.dy * ( ystart - self.starty ))
ybin_end = int(self.dy * ( yend - self.starty ))
# Update the image object with our new data and extent
im = ax.images[-1]
stridex,stridey = self.get_strides( xbin_start,xbin_end,ybin_start,ybin_end)
im.set_data( self.buf[ybin_start:ybin_end:stridey,xbin_start:xbin_end:stridex] )
im.set_extent((xstart, xend, ystart, yend))
ax.figure.canvas.draw_idle()
# end ax_update
def show(self):
'''
Initial plotter for buffer
'''
stridex, stridey = self.get_strides()
self.ax.imshow( buf[::stridex,::stridey],extent=self.extent,origin='lower',aspect='auto' )
self.ax.figure.canvas.draw_idle()
self.ax.callbacks.connect('xlim_changed', self.ax_update)
self.ax.callbacks.connect('ylim_changed', self.ax_update)
# end show
# end ImgDisplay
if __name__=="__main__":
sz = (10000,20000) # rows, cols
buf = np.arange(sz[0]*sz[1]).reshape(sz)
extent = (100,150,1000,2000)
fig = plt.figure()
ax = fig.add_subplot(111)
im = FastImshow(buf,ax,extent=extent,tgt_res=1024)
im.show()
plt.show()
