如何制作图像并在下一页显示

Question

下午好，我使用 Python 和 Kivy 编写了一个简单的相机程序，但我就是无法拍摄。您需要拍摄“ScreenThree”的快照（将其保存在手机内存中）并将生成的图像显示在“ScreenFour”上。

我使用 kivy.uix.camera 来显示相机，使用 kivymd 和 kv 来创建界面。 android.permissions:INTERNET,CAMERA,WRITE_EXTERNAL_STORAGE,READ_EXTERNAL_STORAGE

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.camera import Camera
from kivymd.theming import ThemeManager

import time

Builder.load_string("""
#:import MDFillRoundFlatButton kivymd.button.MDFillRoundFlatButton
#:import MDIconButton kivymd.button.MDIconButton
<ScreenOne@Screen>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        MDFillRoundFlatButton:
            color: [1,1,1,1]
            text: "Перейти к созданию фото"
            pos_hint: {'center_x':.50, 'center_y':.50}
            on_press:
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_two'

<ScreenTwo@Screen>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        MDFillRoundFlatButton:
            color: [1,1,1,1]
            text: "Выбрать фон"
            pos_hint: {'center_x':.50, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_three'
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_one'

<ScreenThree@Screen>:
    id: entry
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Camera:
            id: camera
            index: 0
            resolution: (1280,720)
            play: True  
        MDFillRoundFlatButton:
            text: "take photo"
            pos_hint: {'center_x': 0.50, 'center_y': .10}
            on_press:
                root.capture()   #TAKE PHOTO
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_four'    
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_two'

<ScreenFour@Screen>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
# HERE I NEED TO DISPLAY THE IMAGE
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_three'
""")


class ScreenOne(Screen):
    pass


class ScreenTwo(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Blue'
    main_widget = None

class ScreenThree(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Blue'
    main_widget = None

    def capture(self):
        camera = self.ids['camera']
        timestr = time.strftime("%Y%m%d_%H%M%S")
        photo = camera.export_to_png("IMG_{}.png".format(timestr))
        print("Captured")



class ScreenFour(Screen):
    pass


screen_manager = ScreenManager()


screen_manager.add_widget(ScreenOne(name="screen_one"))
screen_manager.add_widget(ScreenTwo(name="screen_two"))
screen_manager.add_widget(ScreenThree(name="screen_three"))
screen_manager.add_widget(ScreenFour(name="screen_four"))


class Interface(App):

    def build(self):
        return screen_manager

sample_app = Interface()
sample_app.run()

请告诉我，如何修改代码来完成任务。

错误

Take photo White screen

04-08 21:15:19.925   796 13801 E mm-camera: <STATS_AF ><ERROR> 959: af_spd_detect_process: ERROR! SPOT_LIGHT_FLAG =0!!! :AEC_grid = 256, BG_grid = 3072, ave luma = 0
04-08 21:15:19.933   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b332278c0
04-08 21:15:19.949   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b332278c0
04-08 21:15:19.959   796 13801 E mm-camera: <STATS_AF ><ERROR> 959: af_spd_detect_process: ERROR! SPOT_LIGHT_FLAG =0!!! :AEC_grid = 256, BG_grid = 3072, ave luma = 0
04-08 21:15:19.966   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b332278c0
04-08 21:15:19.983   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b332278c0
04-08 21:15:19.992   796 13801 E mm-camera: <STATS_AF ><ERROR> 959: af_spd_detect_process: ERROR! SPOT_LIGHT_FLAG =0!!! :AEC_grid = 256, BG_grid = 3072, ave luma = 0
04-08 21:15:19.999   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b332278c0

错误2

04-09 08:27:25.140   796  6243 E mm-camera: <STATS_AF ><ERROR> 959: af_spd_detect_process: ERROR! SPOT_LIGHT_FLAG =0!!! :AEC_grid = 256, BG_grid = 3072, ave luma = 0
04-09 08:27:25.146   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b32a54420
04-09 08:27:25.146  6164  6198 I python  : Captured
04-09 08:27:25.147  6164  6198 I python  : [ERROR  ] [Image       ] Error reading file IMG_20190409_082724.png
04-09 08:27:25.162   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b32a54420
04-09 08:27:25.175   796  6243 E mm-camera: <STATS_AF ><ERROR> 959: af_spd_detect_process: ERROR! SPOT_LIGHT_FLAG =0!!! :AEC_grid = 256, BG_grid = 3072, ave luma = 0
04-09 08:27:25.179   835   902 W SurfaceFlinger: EventThread: dropping event (7673796e) for connection 0x7b32a54420

Answer 1

访问照片

使用以下方法引用照片：

class ScreenFour(Screen):

    def on_pre_enter(self, *args):
        self.ids.img.source = self.manager.ids.entry.photo

解决方案

注意

<class-name@widget>: 

这是dynamic class。使用动态类时，无需在 Python 脚本中定义类。

kv 文件

• 通过删除所有@Screen，将所有动态类更改为类规则。
• 添加类规则，<ScreenManagement>:
• 将所有屏幕实例化为类规则的子级，<ScreenManagement>:
• 添加id: entry下实例化的孩子，ScreenThree：
• 实例化，Image: 作为类规则FloatLayout: 的子级，<ScreenFour>:
• 在实例化子项下添加id: img，Image:

片段

#:import MDIconButton kivymd.button.MDIconButton

<ScreenManagement>:
    ScreenOne:
        name: "screen_one"
    ScreenTwo:
        name: "screen_two"
    ScreenThree:
        id: entry
        name: "screen_three"
    ScreenFour:
        name: "screen_four"
...

<ScreenFour>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size

    FloatLayout:
        Image:
            id: img

Py 文件

• 添加导入语句，from os.path import dirname
• 添加导入语句，from kivy.properties import StringProperty
• 添加class ScreenManagement()
• 删除所有对screen_manager 的引用
• 声明类属性，photo = StringProperty('')在class ScreenThree()下
• 初始化类属性，self.photo = f"{dirname(__file__)}/IMG_{time.strftime('%Y%m%d_%H%M%S')}.png"
• 实现方法on_pre_enter()显示照片。

片段

from os.path import dirname
from kivy.properties import StringProperty
...
class ScreenThree(Screen):
    photo = StringProperty('')

    def capture(self):
        camera = self.ids['camera']
        self.photo = f"{dirname(__file__)}/IMG_{time.strftime('%Y%m%d_%H%M%S')}.png"
        camera.export_to_png(self.photo)
        print("Captured")


class ScreenFour(Screen):

    def on_pre_enter(self, *args):
        self.ids.img.source = self.manager.ids.entry.photo


class ScreenManagement(ScreenManager):
    pass


class Interface(App):

    def build(self):
        return ScreenManagement()

示例

main.py

from os.path import dirname
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.theming import ThemeManager
from kivy.properties import StringProperty

import time

Builder.load_string("""
#:import MDFillRoundFlatButton kivymd.button.MDFillRoundFlatButton
#:import MDIconButton kivymd.button.MDIconButton

<ScreenManagement>:
    ScreenOne:
        name: "screen_one"
    ScreenTwo:
        name: "screen_two"
    ScreenThree:
        name: "screen_three"
        id: entry
    ScreenFour:
        name: "screen_four"

<ScreenOne>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        MDFillRoundFlatButton:
            color: [1,1,1,1]
            text: "Перейти к созданию фото"
            pos_hint: {'center_x':.50, 'center_y':.50}
            on_press:
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_two'

<ScreenTwo>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        MDFillRoundFlatButton:
            color: [1,1,1,1]
            text: "Выбрать фон"
            pos_hint: {'center_x':.50, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_three'
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_one'

<ScreenThree>:
    id: entry
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Camera:
            id: camera
            index: 0
            resolution: (1280,720)
            play: True  
        MDFillRoundFlatButton:
            text: "take photo"
            pos_hint: {'center_x': 0.50, 'center_y': .10}
            on_press:
                root.capture()   #TAKE PHOTO
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_four'    
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_two'

<ScreenFour>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Image:
            id: img

        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_three'
""")


class ScreenOne(Screen):
    pass


class ScreenTwo(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Blue'
    main_widget = None


class ScreenThree(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Blue'
    main_widget = None
    photo = StringProperty('')

    def capture(self):
        camera = self.ids['camera']
        self.photo = f"{dirname(__file__)}/IMG_{time.strftime('%Y%m%d_%H%M%S')}.png"
        camera.export_to_png(self.photo)
        print("Captured")


class ScreenFour(Screen):

    def on_pre_enter(self, *args):
        self.ids.img.source = self.manager.ids.entry.photo


class ScreenManagement(ScreenManager):
    pass


class Interface(App):

    def build(self):
        return ScreenManagement()


sample_app = Interface()
sample_app.run()

输出

Answer 2

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.camera import Camera
from kivymd.theming import ThemeManager

import time

filename = ''
screenfour = ''

Builder.load_string("""
#:import MDFillRoundFlatButton kivymd.button.MDFillRoundFlatButton
#:import MDIconButton kivymd.button.MDIconButton
<ScreenOne@Screen>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        MDFillRoundFlatButton:
            color: [1,1,1,1]
            text: "Перейти к созданию фото"
            pos_hint: {'center_x':.50, 'center_y':.50}
            on_press:
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_two'

<ScreenTwo@Screen>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        MDFillRoundFlatButton:
            color: [1,1,1,1]
            text: "Выбрать фон"
            pos_hint: {'center_x':.50, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_three'
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_one'

<ScreenThree@Screen>:
    id: entry
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Camera:
            id: camera
            index: 0
            resolution: (1280,720)
            play: True
        MDFillRoundFlatButton:
            text: "take photo"
            pos_hint: {'center_x': 0.50, 'center_y': .10}
            on_press:
                root.capture()   #TAKE PHOTO
                root.manager.transition.direction = 'up'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_four'
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_two'

<ScreenFour@Screen>:
    canvas:
        Color:
            rgb: [.30,.50,.99]
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Image:
            size: root.width, root.height
            source: ''
            id: imageWid
        MDIconButton:
            icon: 'chevron-double-right'
            pos_hint: {'center_x':.95, 'center_y':.10}
            on_press:
                root.manager.transition.direction = 'down'
                root.manager.transition.duration = 1
                root.manager.current = 'screen_three'
""")


class ScreenOne(Screen):
    pass


class ScreenTwo(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Blue'
    main_widget = None

class ScreenThree(Screen):
    theme_cls = ThemeManager()
    theme_cls.primary_palette = 'Blue'
    main_widget = None

    def capture(self):
        camera = self.ids['camera']
        timestr = time.strftime("%Y%m%d_%H%M%S")
        photo = camera.export_to_png("IMG_{}.png".format(timestr))
        global filename, screenfour
        filename = "IMG_{}.png".format(timestr)
        print("Captured")
        screenfour.update()

class ScreenFour(Screen):
    def __init__(self, **kwargs):
        super(ScreenFour, self).__init__(**kwargs)
        global screenfour
        screenfour = self

    def update(self, *args):
        global filename
        imageWidget = self.ids['imageWid']
        imageWidget.source = filename

screen_manager = ScreenManager()

screen_manager.add_widget(ScreenOne(name="screen_one"))
screen_manager.add_widget(ScreenTwo(name="screen_two"))
screen_manager.add_widget(ScreenThree(name="screen_three"))
screen_manager.add_widget(ScreenFour(name="screen_four"))

class Interface(App):

    def build(self):
        return screen_manager

sample_app = Interface()
sample_app.run()

您将创建一个global 变量来保存图片的文件名，然后在您的screenfour Screen 中创建一个Image 小部件，您将在其中将图像小部件的源更新为您拍摄的图片的文件名。如有任何问题，请随时与我联系