add challenge 3: Add watermark for png pictures

Author: zhiwehu

003_Add_text_watermark_on_pictures.md

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+# Add text watermark on pictures
+
+## Requirements
+
+1. Run the code in console using command line.
+2. It'll ask you what's the text you want to add as watermark, and the text size, transparency and position. Please use 20, 50% and bottom right as the default values.
+3. It'll add the text watermark on every png pictures in the 'images' dirtionary of the current path, and save these pictures into 'watermark' dirtionary.
+
+## What will we practice in this project?
+
+- for loop
+- input text
+- if conditions
+- functions
+- tuple
+- Open/save files
+- Image RGBA conception
+- os package
+- PIL package (need to install by `pip install pillow`)
+
+## A reference code
+
+```python
+import os
+
+from PIL import Image, ImageDraw, ImageFont
+
+
+def get_position(image_width, image_height, text_width, text_height, position_id=9, margin=10):
+    '''
+    Get the position of the text by the position_id
+    1: top left, 2: top center, 3: top right
+    4: middle left, 5: middle center, 6: middle right
+    7: bottom left, 8: bottom center, 9: bottom right
+    :param image_width: image width
+    :param image_height: image height
+    :param text_width: text width
+    :param text_height: text height
+    :param position_id: position_id
+    :param margin: the text position margin value to the image
+    :return: text position tuple
+    '''
+    margin = 10
+    if position_id == 1:
+        return (margin, margin)
+    elif position_id == 2:
+        return (image_width // 2 - text_width // 2, margin)
+    elif position_id == 3:
+        return (image_width - text_width - margin, margin)
+    elif position_id == 4:
+        return (margin, image_height // 2 - text_height // 2)
+    elif position_id == 5:
+        return (image_width // 2 - text_width // 2, image_height // 2 - text_height // 2)
+    elif position_id == 6:
+        return (image_width - text_width - margin, image_height // 2 - text_height // 2)
+    elif position_id == 7:
+        return (margin, image_height - text_height - margin)
+    elif position_id == 8:
+        return (image_width // 2 - text_width // 2, image_height - text_height - margin)
+    elif position_id == 9:
+        return (image_width - text_width - margin, image_height - text_height - margin)
+
+
+def add_watermark(filename, text, font_name='Roboto-Italic.ttf', font_size=20, font_opacity=50, position_id=9):
+    '''
+    Add watermark function
+    :param filename: origin image filename
+    :param text: watermark text
+    :param font_name: Roboto-Italic.ttf, you can use your font, please make sure your program can find it
+    :param font_size: font size, default is 20
+    :param font_opacity: font opacity, default is 50
+    :param position_id: position id, defalut is 9 (bottom right)
+    :return: 
+    '''
+    # get an image
+    with Image.open(filename).convert("RGBA") as base:
+        # make a blank image for the text, initialized to transparent text color
+        txt = Image.new("RGBA", base.size, (255, 255, 255, 0))
+
+        # get a font
+        fnt = ImageFont.truetype(font_name, font_size)
+        # get a drawing context
+        d = ImageDraw.Draw(txt)
+        # get the text widht and height
+        text_width, text_height = d.textsize(text, font=fnt)
+        # get the text position of the image
+        pos = get_position(base.size[0], base.size[1], text_width, text_height, position_id=position_id)
+        # draw text with opacity
+        d.text(pos, text, font=fnt, fill=(255, 255, 255, 256 * font_opacity // 100))
+        out = Image.alpha_composite(base, txt)
+
+        # save the image file
+        out_filename = 'watermark/{}'.format(os.path.basename(filename))
+        if not os.path.exists('watermark'):
+            os.makedirs('watermark')
+        out.save(out_filename, 'PNG')
+
+
+if __name__ == '__main__':
+    text = input('Please input a watermark text: ').strip()
+    font_size = int(input('Please input the font size: [20]') or '20')
+    font_opacity = int(input('Please input the font opacity: [50]') or '50')
+    # 1: top left, 2: top center, 3: top right
+    # 4: middle left, 5: middle center, 6: middle right
+    # 7: bottom left, 8: bottom center, 9: bottom right
+    position_id = int(input('Please input the position: [9]') or '9')
+
+    for f in os.listdir('images'):
+        if f.endswith('.png'):
+            filename = 'images/{}'.format(f)
+            print('add watermark for {}'.format(filename))
+            add_watermark(filename=filename, text=text, font_size=font_size, font_opacity=font_opacity,
+                          position_id=position_id)
+
+```
+
+## Run the demo
+
+- make sure you have a `image` dirtionary and put some `png` files in this dirtionary
+- use `pip install requirements.txt` to install packages
+- run it in console
+
+```shell
+python 3.py
+```
+
+- it'll add watermark on every picture in `images` dirtionary and save them to `watermark` dirtionary.
+
+![](images/challenge_3_1.png)
+
+![](images/challenge_3_2.png)
+
+![](images/challenge_3_3.png)
+
+![](images/challenge_3_4.png)
+
+![](images/challenge_3_5.png)
+
+# 给图片增加文字水印
+
+## 项目需求
+
+1. 在命令行窗口运行；
+2. 程序运行时，会提示输入水印的文字，以及水印文字大小，透明度和位置，文字大小默认值为20，透明度默认为50%，位置默认为右下角。使用数字1-9分别代表左上、中上、右上、中左、正中、中右、下左、下中、下右；
+3. 程序会给当前目录下的images目录中所有png文件增加水印，并保存到watermark目录中。
+
+## Python编程知识点
+
+- for循环
+- 用户输入字符串
+- 条件判断
+- 自定义函数
+- 元组
+- 打开、保存图片文件
+- 图片RGBA概念
+- os模块
+- PIL 模块 (需要使用`pip install pillow`安装)
+
+## 参考代码
+
+```python
+import os
+
+from PIL import Image, ImageDraw, ImageFont
+
+
+def get_position(image_width, image_height, text_width, text_height, position_id=9, margin=10):
+    '''
+    获取文字位置，position_id
+    1: 左上, 2: 中上, 3: 右上
+    4: 中左, 5: 正中, 6: 中右
+    7: 左下, 8: 下中, 9: 右下
+    :param image_width: 图片宽度
+    :param image_height: 图片高度
+    :param text_width: 文字宽度
+    :param text_height: 文字高度
+    :param position_id: 位置ID，1-9，默认是9（右下）
+    :param margin: 边距值，默认为10px
+    :return: 文字位置的(x, y)元组
+    '''
+    margin = 10
+    if position_id == 1:
+        return (margin, margin)
+    elif position_id == 2:
+        return (image_width // 2 - text_width // 2, margin)
+    elif position_id == 3:
+        return (image_width - text_width - margin, margin)
+    elif position_id == 4:
+        return (margin, image_height // 2 - text_height // 2)
+    elif position_id == 5:
+        return (image_width // 2 - text_width // 2, image_height // 2 - text_height // 2)
+    elif position_id == 6:
+        return (image_width - text_width - margin, image_height // 2 - text_height // 2)
+    elif position_id == 7:
+        return (margin, image_height - text_height - margin)
+    elif position_id == 8:
+        return (image_width // 2 - text_width // 2, image_height - text_height - margin)
+    elif position_id == 9:
+        return (image_width - text_width - margin, image_height - text_height - margin)
+
+
+def add_watermark(filename, text, font_name='Roboto-Italic.ttf', font_size=20, font_opacity=50, position_id=9):
+    '''
+    增加水印
+    :param filename: 要加水印的文件(dir/file.png)
+    :param text: 水印文字
+    :param font_name: 默认为Roboto-Italic.ttf字体
+                      你也可以使用自己的字体，确保代码能够找到这个字体文件（在当前目录或者系统字体目录中）
+    :param font_size: 字体大小，默认值为20px
+    :param font_opacity: 透明度，默认为50%
+    :param position_id: 位置ID，1-9，默认是9（右下）
+    :return: 
+    '''
+    # 打开原图片文件
+    with Image.open(filename).convert("RGBA") as base:
+        # 创建一个新的透明画面，大小和原图片一样
+        txt = Image.new("RGBA", base.size, (255, 255, 255, 0))
+        # 使用指定的字体
+        fnt = ImageFont.truetype(font_name, font_size)
+        # 准备“画”文字
+        d = ImageDraw.Draw(txt)
+        # 得到文字的宽度和高度
+        text_width, text_height = d.textsize(text, font=fnt)
+        # 得到文字的位置
+        pos = get_position(base.size[0], base.size[1], text_width, text_height, position_id=position_id)
+        # 将文字“画”到画布上
+        d.text(pos, text, font=fnt, fill=(255, 255, 255, 256 * font_opacity // 100))
+        # 将画布和原图片合并
+        out = Image.alpha_composite(base, txt)
+
+        # 保存图片文件
+        out_filename = 'watermark/{}'.format(os.path.basename(filename))
+        if not os.path.exists('watermark'):
+            os.makedirs('watermark')
+        out.save(out_filename, 'PNG')
+
+
+if __name__ == '__main__':
+    text = input('请输入水印文字: ').strip()
+    font_size = int(input('请输入文字大小: [20]') or '20')
+    font_opacity = int(input('请输入文字透明度: [50]') or '50')
+    # 1: 左上, 2: 中上, 3: 右上
+    # 4: 中左, 5: 正中, 6: 中右
+    # 7: 左下, 8: 下中, 9: 右下
+    position_id = int(input('请输入水印位置: [9]') or '9')
+
+    for f in os.listdir('images'):
+        if f.endswith('.png'):
+            filename = 'images/{}'.format(f)
+            print('给{}增加水印'.format(filename))
+            add_watermark(filename=filename, text=text, font_size=font_size, font_opacity=font_opacity,
+                          position_id=position_id)
+
+
+```
+
+## 运行测试
+
+- 将需要加水印的图片放到当前目录的`images`目录中
+- 使用 `pip install requirements.txt`来安装工具包
+- 运行
+
+```shell
+python 3.py
+```
+
+- 程序会将`images`目录中所有png图片增加水印并保存到`watermark`目录中
+
+![](images/challenge_3_1.png)
+
+![](images/challenge_3_2.png)
+
+![](images/challenge_3_3.png)
+
+![](images/challenge_3_4.png)
+
+![](images/challenge_3_5.png)
+
+> 注意，如果要增加汉字水印，请使用一个汉字字体

code/3/3.py

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+import os
+
+from PIL import Image, ImageDraw, ImageFont
+
+
+def get_position(image_width, image_height, text_width, text_height, position_id=9, margin=10):
+    '''
+    Get the position of the text by the position_id
+    1: top left, 2: top center, 3: top right
+    4: middle left, 5: middle center, 6: middle right
+    7: bottom left, 8: bottom center, 9: bottom right
+    :param image_width: image width
+    :param image_height: image height
+    :param text_width: text width
+    :param text_height: text height
+    :param position_id: position_id
+    :param margin: the text position margin value to the image
+    :return: text position tuple
+    '''
+    margin = 10
+    if position_id == 1:
+        return (margin, margin)
+    elif position_id == 2:
+        return (image_width // 2 - text_width // 2, margin)
+    elif position_id == 3:
+        return (image_width - text_width - margin, margin)
+    elif position_id == 4:
+        return (margin, image_height // 2 - text_height // 2)
+    elif position_id == 5:
+        return (image_width // 2 - text_width // 2, image_height // 2 - text_height // 2)
+    elif position_id == 6:
+        return (image_width - text_width - margin, image_height // 2 - text_height // 2)
+    elif position_id == 7:
+        return (margin, image_height - text_height - margin)
+    elif position_id == 8:
+        return (image_width // 2 - text_width // 2, image_height - text_height - margin)
+    elif position_id == 9:
+        return (image_width - text_width - margin, image_height - text_height - margin)
+
+
+def add_watermark(filename, text, font_name='Roboto-Italic.ttf', font_size=20, font_opacity=50, position_id=9):
+    '''
+    Add watermark function
+    :param filename: origin image filename
+    :param text: watermark text
+    :param font_name: Roboto-Italic.ttf, you can use your font, please make sure your program can find it
+    :param font_size: font size, default is 20
+    :param font_opacity: font opacity, default is 50
+    :param position_id: position id, defalut is 9 (bottom right)
+    :return:
+    '''
+    # get an image
+    with Image.open(filename).convert("RGBA") as base:
+        # make a blank image for the text, initialized to transparent text color
+        txt = Image.new("RGBA", base.size, (255, 255, 255, 0))
+
+        # get a font
+        fnt = ImageFont.truetype(font_name, font_size)
+        # get a drawing context
+        d = ImageDraw.Draw(txt)
+        # get the text widht and height
+        text_width, text_height = d.textsize(text, font=fnt)
+        # get the text position of the image
+        pos = get_position(base.size[0], base.size[1], text_width, text_height, position_id=position_id)
+        # draw text with opacity
+        d.text(pos, text, font=fnt, fill=(255, 255, 255, 256 * font_opacity // 100))
+        out = Image.alpha_composite(base, txt)
+
+        # save the image file
+        out_filename = 'watermark/{}'.format(os.path.basename(filename))
+        if not os.path.exists('watermark'):
+            os.makedirs('watermark')
+        out.save(out_filename, 'PNG')
+
+
+if __name__ == '__main__':
+    text = input('Please input a watermark text: ').strip()
+    font_size = int(input('Please input the font size: [20]') or '20')
+    font_opacity = int(input('Please input the font opacity: [50]') or '50')
+    # 1: top left, 2: top center, 3: top right
+    # 4: middle left, 5: middle center, 6: middle right
+    # 7: bottom left, 8: bottom center, 9: bottom right
+    position_id = int(input('Please input the position: [9]') or '9')
+
+    for f in os.listdir('images'):
+        if f.endswith('.png'):
+            filename = 'images/{}'.format(f)
+            print('add watermark for {}'.format(filename))
+            add_watermark(filename=filename, text=text, font_size=font_size, font_opacity=font_opacity,
+                          position_id=position_id)

code/3/images/1.png

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+pillow