python3.6环境下安装freetype库和基本使用方法(推荐)

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