WPF TextBox和PasswordBox添加水印

本文实例为大家分享textbox和passwordbox加水印的方法，供大家参考，具体内容如下

textbox加水印

textbox加水印，需要一个visualbrush和触发器验证text是否为空，在空的时候设置背景的brush就可以实现水印效果。

<textbox name="txtboxname" width="120" height="23">
      <textbox.resources>
        <visualbrush x:key="helpbrush" tilemode="none" opacity="0.3" stretch="none" alignmentx="left">
          <visualbrush.visual>
            <textblock fontstyle="italic" text="水印效果"/>
          </visualbrush.visual>
        </visualbrush>
      </textbox.resources>
      <textbox.style>
        <style targettype="textbox">
          <setter property="height" value="23"/>
          <setter property="horizontalalignment" value="left"/>
          <setter property="verticalalignment" value="top"/>
          <style.triggers>
            <trigger property="text" value="{x:null}">
              <setter property="background" value="{staticresource helpbrush}"/>
            </trigger>
            <trigger property="text" value="">
              <setter property="background" value="{staticresource helpbrush}"/>
            </trigger>
          </style.triggers>
        </style>
      </textbox.style>
    </textbox>

passwordbox加水印

passwordbox加水印，需要添加判断输入非空的依赖属性，因为passwordbox本身没有这个属性。

通过一个passwordlength函数判断密码框的长度是不是0，如果是0则显示背景水印，否则就隐藏。

属性部分代码，cs文件

public class passwordboxmonitor : dependencyobject
  {
    public static bool getismonitoring(dependencyobject obj)
    {
      return (bool)obj.getvalue(ismonitoringproperty);
    }

    public static void setismonitoring(dependencyobject obj, bool value)
    {
      obj.setvalue(ismonitoringproperty, value);
    }

    public static readonly dependencyproperty ismonitoringproperty =
      dependencyproperty.registerattached("ismonitoring", typeof(bool), typeof(passwordboxmonitor), new uipropertymetadata(false, onismonitoringchanged));



    public static int getpasswordlength(dependencyobject obj)
    {
      return (int)obj.getvalue(passwordlengthproperty);
    }

    public static void setpasswordlength(dependencyobject obj, int value)
    {
      obj.setvalue(passwordlengthproperty, value);
    }

    public static readonly dependencyproperty passwordlengthproperty =
      dependencyproperty.registerattached("passwordlength", typeof(int), typeof(passwordboxmonitor), new uipropertymetadata(0));

    private static void onismonitoringchanged(dependencyobject d, dependencypropertychangedeventargs e)
    {
      var pb = d as passwordbox;
      if (pb == null)
      {
        return;
      }
      if ((bool)e.newvalue)
      {
        pb.passwordchanged += passwordchanged;
      }
      else
      {
        pb.passwordchanged -= passwordchanged;
      }
    }

    static void passwordchanged(object sender, routedeventargs e)
    {
      var pb = sender as passwordbox;
      if (pb == null)
      {
        return;
      }
      setpasswordlength(pb, pb.password.length);
    }
  }

xmal代码

<passwordbox name="pb" width="120" verticalalignment="bottom" height="35">
      <passwordbox.style>
        <style targettype="passwordbox">
          <setter property="height" value="23"/>
          <setter property="horizontalalignment" value="left"/>
          <setter property="verticalalignment" value="top"/>
          <setter property="local:passwordboxmonitor.ismonitoring" value="true"/>
          <setter property="template">
            <setter.value>
              <controltemplate targettype="{x:type passwordbox}">
                <border name="bd" background="{templatebinding background}" borderthickness="{templatebinding borderthickness}" borderbrush="{templatebinding borderbrush}" snapstodevicepixels="true">
                  <grid>
                    <scrollviewer x:name="part_contenthost" snapstodevicepixels="{templatebinding snapstodevicepixels}"/>
                    <stackpanel orientation="horizontal" visibility="collapsed" name="mystackpanel">
                      <textblock horizontalalignment="left" verticalalignment="center" foreground="lightgray" text="水印效果"/>
                    </stackpanel>
                  </grid>
                </border>
                <controltemplate.triggers>
                  <trigger property="isenabled" value="false">
                    <setter property="visibility" targetname="mystackpanel" value="collapsed"/>
                  </trigger>
                  <trigger property="local:passwordboxmonitor.passwordlength" value="0">
                    <setter property="visibility" targetname="mystackpanel" value="visible"/>
                  </trigger>
                </controltemplate.triggers>
              </controltemplate>
            </setter.value>
          </setter>
        </style>
      </passwordbox.style>
    </passwordbox>

效果图

2016-09-07 新增内容

将textblock暴露出来，做一个可以修改水印的textbox控件

<textbox x:class="oraclecodegenerator.watermarktextbox"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
       xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
       xmlns:local="clr-namespace:oraclecodegenerator"
       mc:ignorable="d" 
       d:designheight="300" d:designwidth="300" name="tb">
  <textbox.resources>
    <visualbrush x:key="helpbrush" tilemode="none" opacity="0.3" stretch="none" alignmentx="left">
      <visualbrush.visual>
        <textblock text="{binding tbtext,elementname=tb}" fontstyle="italic"/>
      </visualbrush.visual>
    </visualbrush>
  </textbox.resources>
  <textbox.style>
    <style targettype="textbox">
      <setter property="height" value="23"/>
      <setter property="horizontalalignment" value="left"/>
      <setter property="verticalalignment" value="top"/>
      <style.triggers>
        <trigger property="text" value="{x:null}">
          <setter property="background" value="{staticresource helpbrush}"/>
        </trigger>
        <trigger property="text" value="">
          <setter property="background" value="{staticresource helpbrush}"/>
        </trigger>
      </style.triggers>
    </style>
  </textbox.style>
</textbox>

public partial class watermarktextbox : textbox
  {
    public watermarktextbox()
    {
      initializecomponent();
    }

    private string tbtext;

    public string tbtext
    {
      get
      {
        return tbtext;
      }

      set
      {
        tbtext = value;
      }
    }
  }

调用只有一句话

<local:watermarktextbox width="150" tbtext="我是水印"/>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。