【精华推荐】使用Moblin进行应用程序开发——Clutter之Event
上次的Demo太简单了，仅仅在窗口中铺了一堆图片，用户只能看，却不能动。这次我们要给之前的Demo增加一个功能：支持鼠标拖动。
这次我们会接触到clutter的事件机制。Actor可以接受输入的事件，比如键盘按键、鼠标移动等事件，并且可以通过回调函数对事件进行处理。由于这一套机制是通过glib的signal来实现的，因此熟悉glib和gtk编程的用户对此肯定是相当的熟悉。但是与gtk相比，clutter还是有一点不太相同的地方，就是除了Stage之外，所有的Actor默认不接受事件。如果需要让某个Actor接受事件，程序员需要通过clutter_actor_set_reactive()函数手动的将Actor设为reactive，也就是说能够接受事件。我猜想这样的设计是为了减少事件处理时寻找事件源所花费的时间。
下图是从clutter参考手册中截下来的，每一个有“？”标记的地方用户都可以插入有关的事件处理的代码。
（这里应该有一张图片，但是我们这里不支持，大家可以直接看原文：http://software.intel.com/zh-cn/blogs/2009/04/20/moblinclutterevent/）
好了，下面是这次demo的源代码。
#!/usr/bin/python
import sys
import os
import random
import clutter
STAGE_WIDTH=1024
STAGE_HEIGHT=768
Dragging = False
DraggingPhoto = None
class Photo:
'''Photo class'''
border_width = 10
def __init__(self, path, stage):
self.stage = stage
self.path = path
self.x = 0
self.y = 0
self.degree = 0
self.drag_start_x = 0
self.drag_start_y = 0
self.pic = clutter.Texture()
self.pic.set_from_file(path)
self.width = self.pic.get_width()+2*Photo.border_width
self.height = self.pic.get_height()+2*Photo.border_width
self.frame = clutter.Rectangle()
self.frame.set_color(clutter.Color(0xff, 0xff, 0xff, 0xff))
self.frame.set_position(self.x, self.y)
self.frame.set_size(self.width, self.height)
self.group = clutter.Group()
self.group.add(self.frame)
self.group.add(self.pic)
self.pic.set_position(Photo.border_width, Photo.border_width)
self.stage.add(self.group)
self.group.set_reactive(True)
self.group.connect("button-press-event", self.on_button_press)
self.group.connect("button-release-event", self.on_button_release)
self.group.connect("motion-event", self.on_motion)
def set_random_position(self):
stage_width = self.stage.get_width()
stage_height = self.stage.get_height()
left = random.randint(0, stage_width)
top = random.randint(0, stage_height)
degree = random.randint(0, 360)
while left+self.width > stage_width:
left = random.randint(0, stage_width)
while top+self.height > stage_height:
top = random.randint(0, stage_height)
self.set_position(left, top, degree)
def set_position(self, x, y, degree):
self.x = x
self.y = y
self.degree = degree
self.group.set_position(x, y)
self.group.set_rotation(clutter.Z_AXIS, degree, (x+self.width)/2, (y+self.width)/2, 0)
def on_button_press(self, actor, event):
global Dragging, DraggingPhoto
if event.button == 1 and Dragging == False:
Dragging = True
DraggingPhoto = self
self.drag_start_x = event.x
self.drag_start_y = event.y
self.group.raise_top()
return True
def on_motion(self, actor, event):
global Dragging, DraggingPhoto
if event.modifier_state & clutter.BUTTON1_MASK and Dragging == True and DraggingPhoto == self:
dist_x = event.x - self.drag_start_x
dist_y = event.y - self.drag_start_y
self.group.move_by(dist_x, dist_y)
self.drag_start_x = event.x
self.drag_start_y = event.y
return True
def on_button_release(self, actor, event):
global Dragging, DraggingPhoto
if event.button == 1
Dragging = False
DraggingPhoto = None
return True
def main(args):
if len(args) < 2:
print "The number of arguments is less than 2!"
return -1
path=args[1]
if not os.path.exists(path):
print path, "doesn't exist!"
return -1
stage = clutter.Stage()
stage.set_size(STAGE_WIDTH, STAGE_HEIGHT)
stage.set_color(clutter.Color(0x00, 0x00, 0x00, 0x00))
stage.connect("destroy", clutter.main_quit)
if not path.endswith(os.sep):
path+=os.sep
filelist = os.listdir(path)
for item in filelist:
pic=Photo(path+item, stage)
pic.set_random_position()
stage.show_all()
clutter.main()
if __name__ == '__main__':
main(sys.argv)
基本思路：当鼠标点击某张照片时将照片移至顶部。使用全局变量Dragging来控制进入与退出拖拽模式。DraggingPhoto这个变量的引入有些不得已，可能是我的鼠标扫描速率太低，拖拽时常有指针飞出Photo区域的现象，于是多加了这个变量进行控制。
在Moblin中文站里面还有很多这样比较好的技术文章，欢迎大家来阅读。技术文章版块链接：http://moblin.csdn.net/c_channelrecomm/more
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很不错,学习中!!!!
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很不错,学习中!!!!
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learning
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def set_random_position(self):
stage_width = self.stage.get_width()
stage_height = self.stage.get_height()
left = random.randint(0, stage_width)
top = random.randint(0, stage_height)
degree = random.randint(0, 360)
while left+self.width > stage_width:
left = random.randint(0, stage_width)
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dddd
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的
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该回复于2009-05-13 10:39:00被版主删除
