将blob图像数据加载到QPixmap中 [英] Load blob image data into QPixmap

问题描述

我正在使用PyQt4为前端GUI编写程序，该程序访问后端数据库（可以是MySQL或SQLite）。我需要在数据库中存储一些图像数据，下面是我用来将图像文件（JPEG格式）导入数据库中的blob数据字段的Python代码：

I am writing a program using PyQt4 for front-end GUI and this program accesses a back-end database (which can be either MySQL or SQLite). I need to store some image data in the database and below is the Python code I use to import image files (in JPEG format) to a blob data field in the database:

def dump_image(imgfile):
    i = open(imgfile, 'rb')
    i.seek(0)
    w = i.read()
    i.close()
    return cPickle.dumps(w,1)

blob = dump_image(imgfile)
hex_str = blob.encode('hex') 
# x"%s"%hex_str will be the string inserted into the SQL command

这部分工作正常。我的问题是如何从PyQt4中存储在数据库中的图像数据创建QPixmap对象。我目前的方法涉及以下步骤：

This part works fine. My question is about how to create a QPixmap object from the image data stored in the database in PyQt4. My current approach involves the following steps:

（1）数据库中的Hex str - cPickle& StringIO - > PIL图像对象

(1) Hex str in database -- cPickle&StringIO --> PIL Image Object

def load_image(s):
    o = cPickle.loads(s)
    c = StringIO.StringIO()
    c.write(o)
    c.seek(0)
    im = Image.open(c)
    return im

（2）PIL图像对象 - >临时图像文件

(2) PIL Image Object -->Temporary image file

（3）临时图像文件 - > QPixmap

(3) Temporary image file --> QPixmap

这种方法也可以。但如果我不必编写/读取临时图像文件会更好，这可能会减慢程序对用户交互的响应速度。我想我可以直接使用 QPixmap :: loadFromData（）从存储在数据库中的blob数据加载，并希望有人在这里向我展示如何使用此函数的示例。

This approach also works fine. But it would be better if I don't have to write/read temporary image files which may slow down the program response to user interactions. I guess I could use QPixmap::loadFromData() to directly load from the blob data stored in the database and hope someone here could show me an example on how to use this function.

TIA，

Bing

推荐答案

您可以使用QImage.fromData静态方法从字符串加载图像然后将其转换为像素图：

You can use the QImage.fromData static method to load an image from a string and then convert it to a pixmap:

 image_data = get_image_data_from_blob()
 qimg = QtGui.QImage.fromData(image_data)
 pixmap = QtGui.QPixmap.fromImage(qimg)

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