FreeType库是一个完全免费(开源)的、高质量的且可移植的字体引擎,它提供统一的接口来访问多种字体格式文件,包括TrueType, OpenType, Type1, CID, CFF, Windows FON/FNT, X11 PCF等。在做图像展示的时候,可以写入中文文字,效果还是很好。
在之前安装库时基本都是直接切换到python3.6环境下直接pip install XXX,在安装freetype直接pip install freetype
不可以了,查了半天又是编译又是官网下载的,太麻烦,不推荐。
(1)正确的安装方法:
注意:一定要加上 -py
pip install freetype-py
(2)常用调用方法
已经封装好了一个文件,可直接保存后调用。
import freetype
import copy
class put_chinese_text(object):
def __init__(self, ttf):
self._face = freetype.Face(ttf)
def draw_text(self, image, pos, text, text_size, text_color):
'''
draw chinese(or not) text with ttf
:param image: image(numpy.ndarray) to draw text
:param pos: where to draw text
:param text: the context, for chinese should be unicode type
:param text_size: text size
:param text_color:text color
:return: image
'''
self._face.set_char_size(text_size * 64)
metrics = self._face.size
ascender = metrics.ascender / 64.0
# descender = metrics.descender/64.0
# height = metrics.height/64.0
# linegap = height - ascender + descender
ypos = int(ascender)
text = text
img = self.draw_string(image, pos[0], pos[1] + ypos, text, text_color)
return img
def draw_string(self, img, x_pos, y_pos, text, color):
'''
draw string
:param x_pos: text x-postion on img
:param y_pos: text y-postion on img
:param text: text (unicode)
:param color: text color
:return: image
'''
prev_char = 0
pen = freetype.Vector()
pen.x = x_pos << 6 # div 64
pen.y = y_pos << 6
hscale = 1.0
matrix = freetype.Matrix(int(hscale) * 0x10000, int(0.2 * 0x10000), \
int(0.0 * 0x10000), int(1.1 * 0x10000))
cur_pen = freetype.Vector()
pen_translate = freetype.Vector()
image = copy.deepcopy(img)
for cur_char in text:
self._face.set_transform(matrix, pen_translate)
self._face.load_char(cur_char)
kerning = self._face.get_kerning(prev_char, cur_char)
pen.x += kerning.x
slot = self._face.glyph
bitmap = slot.bitmap
cur_pen.x = pen.x
cur_pen.y = pen.y - slot.bitmap_top * 64
self.draw_ft_bitmap(image, bitmap, cur_pen, color)
pen.x += slot.advance.x
prev_char = cur_char
return image
def draw_ft_bitmap(self, img, bitmap, pen, color):
'''
draw each char
:param bitmap: bitmap
:param pen: pen
:param color: pen color e.g.(0,0,255) - red
:return: image
'''
x_pos = pen.x >> 6
y_pos = pen.y >> 6
cols = bitmap.width
rows = bitmap.rows
glyph_pixels = bitmap.buffer
for row in range(rows):
for col in range(cols):
if glyph_pixels[row * cols + col] != 0:
try:
img[y_pos + row][x_pos + col][0] = color[0]
img[y_pos + row][x_pos + col][1] = color[1]
img[y_pos + row][x_pos + col][2] = color[2]
except:
continue
if __name__ == '__main__':
# just for test
import cv2
line = '毛不易'
img = cv2.imread('./aa.jpg')
color_ = (0, 255, 0) # Green
pos = (3, 3)
text_size = 24
ft = put_chinese_text('yahei.ttf')
image = ft.draw_text(img, pos, line, text_size, color_)
cv2.imshow('ss', image)
cv2.waitKey(0)
总结
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