今天来分享一个比较常用的系统api的小功能。
我们在编写好了ea之后，有时候想要通过点击图表上的按钮或者图片后，能够打开指定的网页，网页就显示本EA的详细使用方法，甚至可以看到介绍视频，这样，更利于用户对这个ea的了解。
编写这个ea的时候，首先是创建要给按钮，这个非常简单，使用MQL语言参考里面自带的函数即可。
创建按钮的函数如下：
bool ButtonCreate(const long chart_ID=0, // chart's ID
const string name="Button", // button name
const int sub_window=0, // subwindow index
const int x=0, // X coordinate
const int y=0, // Y coordinate
const int width=50, // button width
const int height=18, // button height
const ENUM_BASE_CORNER corner=CORNER_LEFT_UPPER, // chart corner for anchoring
const string text="Button", // text
const string font="Arial", // font
const int font_size=10, // font size
const color clr=clrBlack, // text color
const color back_clr=C'236,233,216', // background color
const color border_clr=clrNONE, // border color
const bool state=false, // pressed/released
const bool back=false, // in the background
const bool selection=false, // highlight to move
const bool hidden=true, // hidden in the object list
const long z_order=0) // priority for mouse click
{
//--- reset the error value
ResetLastError();
//--- create the button
if(!ObjectCreate(chart_ID,name,OBJ_BUTTON,sub_window,0,0))
{
Print(__FUNCTION__,
": failed to create the button! Error code = ",GetLastError());
return(false);
}
//--- set button coordinates
ObjectSetInteger(chart_ID,name,OBJPROP_XDISTANCE,x);
ObjectSetInteger(chart_ID,name,OBJPROP_YDISTANCE,y);
//--- set button size
ObjectSetInteger(chart_ID,name,OBJPROP_XSIZE,width);
ObjectSetInteger(chart_ID,name,OBJPROP_YSIZE,height);
//--- set the chart's corner, relative to which point coordinates are defined
ObjectSetInteger(chart_ID,name,OBJPROP_CORNER,corner);
//--- set the text
ObjectSetString(chart_ID,name,OBJPROP_TEXT,text);
//--- set text font
ObjectSetString(chart_ID,name,OBJPROP_FONT,font);
//--- set font size
ObjectSetInteger(chart_ID,name,OBJPROP_FONTSIZE,font_size);
//--- set text color
ObjectSetInteger(chart_ID,name,OBJPROP_COLOR,clr);
//--- set background color
ObjectSetInteger(chart_ID,name,OBJPROP_BGCOLOR,back_clr);
//--- set border color
ObjectSetInteger(chart_ID,name,OBJPROP_BORDER_COLOR,border_clr);
//--- display in the foreground (false) or background (true)
ObjectSetInteger(chart_ID,name,OBJPROP_BACK,back);
//--- set button state
ObjectSetInteger(chart_ID,name,OBJPROP_STATE,state);
//--- enable (true) or disable (false) the mode of moving the button by mouse
ObjectSetInteger(chart_ID,name,OBJPROP_SELECTABLE,selection);
ObjectSetInteger(chart_ID,name,OBJPROP_SELECTED,selection);
//--- hide (true) or display (false) graphical object name in the object list
ObjectSetInteger(chart_ID,name,OBJPROP_HIDDEN,hidden);
//--- set the priority for receiving the event of a mouse click in the chart
ObjectSetInteger(chart_ID,name,OBJPROP_ZORDER,z_order);
//--- successful execution
return(true);
}
//+------------------------------------------------------------------+
这个函数加入到默认的空的EA程序里面之后，然后在初始化函数中引用他，即可创建了按钮。
int OnInit()
{
//---
ButtonCreate(0,"Button",0,5,20,100,30,0,"打开网页");
//---
return(INIT_SUCCEEDED);
}下面就是访问网络需要用的核心模块了，我们使用windows自带的shell32.dll，这个dll中有一个函数ShellExecuteW 可以实现这个功能。
#import "shell32.dll"
int ShellExecuteW(int hwnd,string Operation,string
File,string Parameters,string Directory,int ShowCmd);
#import这个函数有6个参数，我们只需要用到前面三个，需要了解更多的可以去查阅windows的相关编程手册。
然后，在图表的按钮点击事件里面引用这个函数即可，看如下例子代码：
void OnChartEvent(const int id,
const long &lparam,
const double &dparam,
const string &sparam)
{
//---
if(id==CHARTEVENT_OBJECT_CLICK || sparam=="Button")
{
ShellExecuteW(0,"Open","http://www.forexmt4.cn","","",0);
}
}核心部分已经全部解释完毕。
使用这个功能的时候，需要勾选“允许导入动态链接库”，因为使用的dll文件是windows系统自带的，所以我们不需要单独提供shell32.dll文件。
完整代码如下：
//+------------------------------------------------------------------+
//| 点击按钮打开网页.mq4 |
//| 漆学军 |
//| http://www.forexmt4.cn |
//+------------------------------------------------------------------+
#property copyright "漆学军"
#property link "http://www.forexmt4.cn"
#property version "1.00"
#property strict
#import "shell32.dll"
int ShellExecuteW(int hwnd,string Operation,string
File,string Parameters,string Directory,int ShowCmd);
#import
//+------------------------------------------------------------------+
//| Expert initialization function |
//+------------------------------------------------------------------+
int OnInit()
{
//---
ButtonCreate(0,"Button",0,5,20,100,30,0,"打开网页");
//---
return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Expert deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
//---
ObjectDelete(0,"Button");
}
//+------------------------------------------------------------------+
//| Expert tick function |
//+------------------------------------------------------------------+
void OnTick()
{
//---
}
//+------------------------------------------------------------------+
//| ChartEvent function |
//+------------------------------------------------------------------+
void OnChartEvent(const int id,
const long &lparam,
const double &dparam,
const string &sparam)
{
//---
if(id==CHARTEVENT_OBJECT_CLICK || sparam=="Button")
{
ShellExecuteW(0,"Open","http://www.forexmt4.cn","","",0);
}
}
//+------------------------------------------------------------------+
bool ButtonCreate(const long chart_ID=0, // chart's ID
const string name="Button", // button name
const int sub_window=0, // subwindow index
const int x=0, // X coordinate
const int y=0, // Y coordinate
const int width=50, // button width
const int height=18, // button height
const ENUM_BASE_CORNER corner=CORNER_LEFT_UPPER, // chart corner for anchoring
const string text="Button", // text
const string font="Arial", // font
const int font_size=10, // font size
const color clr=clrBlack, // text color
const color back_clr=C'236,233,216', // background color
const color border_clr=clrNONE, // border color
const bool state=false, // pressed/released
const bool back=false, // in the background
const bool selection=false, // highlight to move
const bool hidden=true, // hidden in the object list
const long z_order=0) // priority for mouse click
{
//--- reset the error value
ResetLastError();
//--- create the button
if(!ObjectCreate(chart_ID,name,OBJ_BUTTON,sub_window,0,0))
{
Print(__FUNCTION__,
": failed to create the button! Error code = ",GetLastError());
return(false);
}
//--- set button coordinates
ObjectSetInteger(chart_ID,name,OBJPROP_XDISTANCE,x);
ObjectSetInteger(chart_ID,name,OBJPROP_YDISTANCE,y);
//--- set button size
ObjectSetInteger(chart_ID,name,OBJPROP_XSIZE,width);
ObjectSetInteger(chart_ID,name,OBJPROP_YSIZE,height);
//--- set the chart's corner, relative to which point coordinates are defined
ObjectSetInteger(chart_ID,name,OBJPROP_CORNER,corner);
//--- set the text
ObjectSetString(chart_ID,name,OBJPROP_TEXT,text);
//--- set text font
ObjectSetString(chart_ID,name,OBJPROP_FONT,font);
//--- set font size
ObjectSetInteger(chart_ID,name,OBJPROP_FONTSIZE,font_size);
//--- set text color
ObjectSetInteger(chart_ID,name,OBJPROP_COLOR,clr);
//--- set background color
ObjectSetInteger(chart_ID,name,OBJPROP_BGCOLOR,back_clr);
//--- set border color
ObjectSetInteger(chart_ID,name,OBJPROP_BORDER_COLOR,border_clr);
//--- display in the foreground (false) or background (true)
ObjectSetInteger(chart_ID,name,OBJPROP_BACK,back);
//--- set button state
ObjectSetInteger(chart_ID,name,OBJPROP_STATE,state);
//--- enable (true) or disable (false) the mode of moving the button by mouse
ObjectSetInteger(chart_ID,name,OBJPROP_SELECTABLE,selection);
ObjectSetInteger(chart_ID,name,OBJPROP_SELECTED,selection);
//--- hide (true) or display (false) graphical object name in the object list
ObjectSetInteger(chart_ID,name,OBJPROP_HIDDEN,hidden);
//--- set the priority for receiving the event of a mouse click in the chart
ObjectSetInteger(chart_ID,name,OBJPROP_ZORDER,z_order);
//--- successful execution
return(true);
}
//+------------------------------------------------------------------+
代码经过测试，正确可用。
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