一、什么是Android GestureDetector?
Android GestureDetector是一种功能强大的类,它可以识别各种手势,例如单击、双击、向上滑动、向下滑动、旋转等。Android GestureDetector库是在Android系统中可用的一个专用类,具有高度的可定制性和灵活性。
在Python中,使用Android Kivy库可以轻松访问Android GestureDetector库,以实现手势识别和识别响应。
二、如何使用Android GestureDetector?
要实现手势识别,我们需要使用Android Kivy库中的GestureListener类。该类继承自Android GestureDetector类,提供了一个简化的界面,以便我们可以更轻松地捕获各种手势。
以下是GestureListener类的基本用法示例:
from kivy.uix.widget import Widget from kivy.properties import ObjectProperty from kivy.app import App from kivy.gesture import Gesture, GestureDatabase, GestureNode from kivy.uix.label import Label from kivy.graphics import Color, Line class GestureDraw(Widget): gesture = ObjectProperty(None) label = ObjectProperty(None) gesture_db = GestureDatabase() def on_touch_down(self, touch): if not self.collide_point(*touch.pos): return self.gesture = Gesture() self.gesture.add_stroke([touch.pos]) self.label.text = '[b]Started[/b]\n%s' % self.gesture.strk_len() return True def on_touch_move(self, touch): if not self.collide_point(*touch.pos): return self.gesture.add_stroke([touch.pos]) self.label.text = '[b]Drawing[/b]\n%s' % self.gesture.strk_len() def on_touch_up(self,touch): if not self.collide_point(*touch.pos): return if not self.gesture.normalize(): self.label.text = '[color=ff0000]Too short[/color]' self.gesture = None return True if len(self.gesture.nodes) < 2: self.label.text = '[color=ff0000]Too few\n nodes[/color]' self.gesture = None return True self.gesture_db.add_gesture(self.gesture.name, self.gesture) self.label.text = '[b]Saved Gesture[/b]' def on_double_tap(self): self.clear_widgets() self.__init__() self.add_widget(Label(text='+[b] Gesture\nLibrary[/b]\n%d Gestures' % len(self.gesture_db.gestures), font_size=30, markup = True, pos_hint = {'center_x':0.5, 'center_y':0.6})) for name in self.gesture_db.list_gestures(): data = self.gesture_db.get_gesture(name) scale = min(self.width / data['width'], self.height / data['height']) trans_x = (self.width - data['width'] * scale) / 2. trans_y = (self.height - data['height'] * scale) / 2. for stroke in data['strokes']: points = [(x * scale + trans_x, self.height - (y * scale + trans_y)) for x, y in stroke] with self.canvas: GestureDraw.color_255() Line(points=points) @staticmethod def color_255(color=[1.0, 0.0, 0.0, 1]): Color(*[x * 255 for x in color])
在上述代码中,我们定义了一个名为GestureDraw的小部件,该小部件可以捕获手势,并将其添加到手势数据库中。在屏幕上,我们可以向GestureDraw小部件绘制多个手势,然后您可以双击来查看手势库,并将其转换为相应的动作。
三、如何实现手势响应?
要使用从手势库中检索到的手势来响应手势,您可以使用GestureDetector类。以下是GestureDetector类的基本示例:
from kivy.uix.widget import Widget from kivy.properties import ObjectProperty from kivy.app import App from kivy.gesture import Gesture, GestureDatabase, GestureNode from kivy.uix.label import Label from kivy.graphics import Color, Line from kivy.core.window import Window from kivy.uix.button import Button from kivy.uix.floatlayout import FloatLayout class GestureDraw(Widget): gesture = ObjectProperty(None) label = ObjectProperty(None) gesture_db = GestureDatabase() def on_touch_down(self, touch): if not self.collide_point(*touch.pos): return self.gesture = Gesture() self.gesture.add_stroke([touch.pos]) self.label.text = '[b]Started[/b]\n%s' % self.gesture.strk_len() return True def on_touch_move(self, touch): if not self.collide_point(*touch.pos): return self.gesture.add_stroke([touch.pos]) self.label.text = '[b]Drawing[/b]\n%s' % self.gesture.strk_len() def on_touch_up(self,touch): if not self.collide_point(*touch.pos): return if not self.gesture.normalize(): self.label.text = '[color=ff0000]Too short[/color]' self.gesture = None return True if len(self.gesture.nodes) < 2: self.label.text = '[color=ff0000]Too few\n nodes[/color]' self.gesture = None return True self.gesture_db.add_gesture(self.gesture.name, self.gesture) self.label.text = '[b]Saved Gesture[/b]' def on_double_tap(self): self.clear_widgets() self.__init__() self.add_widget(Label(text='+[b] Gesture\nLibrary[/b]\n%d Gestures' % len(self.gesture_db.gestures), font_size=30, markup = True, pos_hint = {'center_x':0.5, 'center_y':0.6})) for name in self.gesture_db.list_gestures(): data = self.gesture_db.get_gesture(name) scale = min(self.width / data['width'], self.height / data['height']) trans_x = (self.width - data['width'] * scale) / 2. trans_y = (self.height - data['height'] * scale) / 2. for stroke in data['strokes']: points = [(x * scale + trans_x, self.height - (y * scale + trans_y)) for x, y in stroke] with self.canvas: GestureDraw.color_255() Line(points=points) @staticmethod def color_255(color=[1.0, 0.0, 0.0, 1]): Color(*[x * 255 for x in color]) class MyFlaotLayout(FloatLayout): def __init__(self, **kwargs): super(MyFlaotLayout, self).__init__(**kwargs) self.button1 = Button(text='按钮1', size_hint=(None, None), pos_hint={'x':0.1,'y':0.1}, size=(100, 50)) self.button1.bind(on_release=self.callback) self.add_widget(self.button1) self.button2 = Button(text='按钮2', size_hint=(None, None), pos_hint={'x':0.9,'y':0.1}, size=(100, 50)) self.button2.bind(on_release=self.callback) self.add_widget(self.button2) def callback(self, instance): if instance.text == '按钮1': self.add_widget(Label(text='Button1 clicked!', pos_hint={'center_x':0.5, 'center_y':0.5})) if instance.text == '按钮2': self.add_widget(Label(text='Button2 clicked!', pos_hint={'center_x':0.5, 'center_y':0.5})) for child in self.children: child.pos_hint = {'center_x': 0.5, 'center_y': 0.4} class GestureApp(App): def build(self): layout = MyFlaotLayout() gd = GestureDraw() layout.add_widget(gd) gd.bind(on_double_tap=gd.on_double_tap) label = Label(text='Click & Drag to draw gesture\nDouble-Click to Testing', markup=True, size_hint_y=None, height=50, pos_hint={'center_x': 0.5, 'center_y': 0}) gd.label = label layout.add_widget(label) return layout if __name__ == '__main__': GestureApp().run()
此示例中,我们创建了一个名为MyFlaotLayout的小部件,它包含两个按钮和一个可以响应手势的GestureDraw小部件。当点击按钮时,会在屏幕上显示一个文本标签,告诉您已点击哪个按钮。如果您双击GestureDraw小部件,则会在控制台输出” Gesture Detected”消息。
四、总结
本文主要介绍了如何使用Python语言的Android GestureDetector库实现手势识别。首先,我们介绍了Android GestureDetector是什么以及如何使用,并提供了一个使用GestureListener类的基本示例。然后,我们讨论了如何使用从手势库中检索到的手势来响应手势,并提供了一个使用GestureDetector类的基本示例。最后,在一个综合示例中,我们演示了如何将GestureDraw小部件与其他小部件集成在同一布局内,并在响应手势时进行相应的操作。
代码示例:
请参考以上所有代码部分。