[WPF 学习] 10.触发器

一、属性触发器
要改变的属性值不能再控件里面设置初始值，否则不能触发，如下例的width

     <rectangle height="100"  fill="black"  name="r1" rendertransformorigin="0.5,0.5">
            <rectangle.rendertransform>
                <rotatetransform></rotatetransform>
            </rectangle.rendertransform>
            <rectangle.style>
                <style targettype="rectangle">
                    <setter property="width" value="100"></setter>
                    <style.triggers>
                        <trigger property="fill" value="black">
                            <trigger.enteractions>
                                <beginstoryboard>
                                    <storyboard repeatbehavior="forever" >
                                        <doubleanimation storyboard.targetproperty="height" from="100" to="200" duration="0:0:1"></doubleanimation>
                                        <doubleanimation storyboard.targetproperty="(rectangle.rendertransform).(rotatetransform.angle)" from="0" to="360" duration="0:0:1"></doubleanimation>
                                    </storyboard>
                                </beginstoryboard>
                            </trigger.enteractions>
                            <setter property="width" value="200"></setter>
                        </trigger>
                    </style.triggers>
                </style>
            </rectangle.style>
        </rectangle>

二、数据触发器
相比对属性触发器而言，他可以绑定其他控件的属性或者viewmodel里面的属性

        <rectangle  width="200" name="r2" fill="green" rendertransformorigin="0.5,0.5">
            <rectangle.rendertransform >
                <rotatetransform x:name="r2rt" angle="0"></rotatetransform>
            </rectangle.rendertransform>
            <rectangle.style>
                <style targettype="rectangle">
                    <setter property="height" value="100"></setter>
                    <style.triggers>
                        <datatrigger binding="{binding elementname=r1,path=fill}" value="black">
                            <setter property="height" value="200"></setter>
                            <datatrigger.enteractions>
                                <beginstoryboard>
                                    <storyboard repeatbehavior="forever" >
                                        <doubleanimation storyboard.targetproperty="(rectangle.rendertransform).(rotatetransform.angle)" from="0" to="360" duration="0:0:1"></doubleanimation>
                                    </storyboard>
                                </beginstoryboard>
                            </datatrigger.enteractions>
                        </datatrigger>
                    </style.triggers>
                </style>
            </rectangle.style>

        </rectangle>

三、事件触发器

1. 只能触发故事板（不知道是否正确）
2. 分为控件触发器和样式触发器（这两个名字自己取的，也不知道有没有官方说法）
   控件触发器( storyboard.targetname似乎专为它服务)

     <rectangle width="200" height="200" name="r3" rendertransformorigin="0.5,0.5" fill="yellow">
            <rectangle.rendertransform>
                <rotatetransform x:name="r3rt"></rotatetransform>
            </rectangle.rendertransform>
            
            <rectangle.triggers>
                <eventtrigger routedevent="mouse.mouseenter">
                    <beginstoryboard>
                        <storyboard>
                            <doubleanimation storyboard.targetname="r2rt" storyboard.targetproperty="angle" from="0" to="360" repeatbehavior="forever" duration="0:0:1"></doubleanimation>
                            <doubleanimation storyboard.targetname="r3rt" storyboard.targetproperty="angle" from="0" to="360" repeatbehavior="forever" duration="0:0:1"></doubleanimation>
                        </storyboard>
                    </beginstoryboard>
                </eventtrigger>
            </rectangle.triggers>
        </rectangle>

样式触发器

        <rectangle width="200" height="200" name="r4" rendertransformorigin="0.5,0.5" fill="yellow">
            <rectangle.rendertransform>
                <rotatetransform x:name="r4rt"></rotatetransform>
            </rectangle.rendertransform>
            <rectangle.style>
                <style targettype="rectangle">
                    <style.triggers>
                        <eventtrigger routedevent="mouse.mouseenter">
                            <eventtrigger.actions>
                                <beginstoryboard>
                                    <storyboard>
                                        <doubleanimation storyboard.targetproperty="(rectangle.rendertransform).(rotatetransform.angle)" from="0" to="360" repeatbehavior="forever" duration="0:0:1"></doubleanimation>
                                    </storyboard>
                                </beginstoryboard>
                            </eventtrigger.actions>
                        </eventtrigger>
                    </style.triggers>
                </style>
            </rectangle.style>
        </rectangle>