Bitmap with mask/transparency

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Hi,


I'm trying to use a bitmap arrow in my indicator but the background of my arrow hide the prices candle and the back color :

Is there any way to make white as transparent ?


Thank you for your help,

Ghen.

 
ghendar:

Hi,


I'm trying to use a bitmap arrow in my indicator but the background of my arrow hide the prices candle and the back color :

Is there any way to make white as transparent ?


Thank you for your help,

Ghen.


You need to use an image editor to make the background transparent.

 
nicholishen:

You need to use an image editor to make the background transparent.


Thank you for your help Nicholishen. Unfortunately that doesn't work. I remove background with eraser tool of Corel paint shop pro but it's alaways white on MT4.


Maybe I have to save the file in a specific format and with specific options  ? for now I save it into standard BMP file...

Any solutions ?

Thanks,

Ghen

 
ghendar:

Thank you for your help Nicholishen. Unfortunately that doesn't work. I remove background with eraser tool of Corel paint shop pro but it's alaways white on MT4.


Maybe I have to save the file in a specific format and with specific options  ? for now I save it into standard BMP file...

Any solutions ?

Thanks,

Ghen


You can follow this guide -- or the easier way would be creating separate bmp images with background colors to match the chart background.

#include <ChartObjects\ChartObjectsBmpControls.mqh>
void OnStart()
{
   CChartObjectBitmap label;
   label.Create(0,"bmp",0,Time[100],Low[100]);
   label.Background(true);
   while(!IsStopped())
   {
      color bck = (color)ChartGetInteger(0,CHART_COLOR_BACKGROUND);
      if(bck == clrWhite)
         label.BmpFile("arrow_white.bmp");
      else
         label.BmpFile("arrow_black.bmp");
      ChartRedraw();
      Sleep(500);
   }
}
 
ghendar:

Hi,


I'm trying to use a bitmap arrow in my indicator but the background of my arrow hide the prices candle and the back color :

Is there any way to make white as transparent ?


Thank you for your help,

Ghen.

You can replace your white background with a transparent one "on the fly".

//--- resources
#resource "\\Images\\your_picture.bmp" as bitmap MyPicture[]
...

ulong pattern=(ulong(clrWhite)<<8)+255;

...
int size=ArraySize(MyPicture);
for(int i=0;i<size;i++)
  {
   if(MyPicture[i]==pattern)
     {
      MyPicture[i]=0;
     }
  }
...
 
Alain Verleyen:

You can replace your white background with a transparent one "on the fly".


That's cool... didn't know that. Thanks for sharing!

 
Alain Verleyen:

You can replace your white background with a transparent one "on the fly".


Hi,


It seems to be interesting but MQL4 doesn't want to compile this syntax (only available for MQL5) :

#resource "\\Images\\your_picture.bmp" as bitmap MyPicture[]


Maybe could you provide the good code for MQL4 ?

If I understand the aim is to have a variable of Bitmap type.... but is it possible on MT4 ?


Thanks !

Ghen.

 
ghendar:

Hi,


It seems to be interesting but MQL4 doesn't want to compile this syntax (only available for MQL5) :


Maybe could you provide the good code for MQL4 ?

If I understand the aim is to have a variable of Bitmap type.... but is it possible on MT4 ?


Thanks !

Ghen.

Use the link provided by Nicholishen.

 
Alain Verleyen:

Use the link provided by Nicholishen.


Hi,


I see the link and read carefully. But Canvas class seems to be usable for MQL5 only.

I'm right ?

Regards,

Ghen.

 
ghendar:

Hi,


I see the link and read carefully. But Canvas class seems to be usable for MQL5 only.

I'm right ?

Regards,

Ghen.

No, you are not right. Canvas is working well with mql4 too.

 

I know this subject is very old, but I may have some simpler tip for that, which would help me a lot if it was here, when I first found this thread.

Save your transparent arrow as transparent PNG, then use the free XnView tool to convert it to 32-bit BMP (that is RGB + alpha channel).

I have found transparent BMP exported in Corel and some other software not usable with MQL, while XNView 32-bit BMP exports always work.


Also the image has to be included as a resource for some reason. Transparency stops working if you change the path to load it from the disk instead. Example where transparency works:

#resource "\\Images\\trader2.bmp"
[...]
string path_to_bar_graphics = "::Images\\trader2.bmp";
BitmapLabelCreate([...]);

And here it won't:

string path_to_bar_graphics = "\\Images\\trader2.bmp";
BitmapLabelCreate([...]);
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