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Home » Community » Newbie corner » Display transparent paper
Display transparent paper [message #58049] Sat, 29 January 2022 20:38 Go to next message
Silvan is currently offline  Silvan
Messages: 56
Registered: December 2014
Location: Trento (IT)
Member
There is a simple way to draw text on a display with transparent background?
And to set font size?

Thanks

[Updated on: Sat, 29 January 2022 20:39]

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Re: Display transparent paper [message #58050 is a reply to message #58049] Sun, 30 January 2022 00:09 Go to previous messageGo to next message
Lance is currently offline  Lance
Messages: 536
Registered: March 2007
Contributor
If I want to change the background to something I specify, I just
draw.DrawRect(arect, acolor);

without this, the text will be drawn on whatever the current background is. Is this the transparent background you meant? So do nothing, you get a transparent background.

As for font.
Draw::DrawText(int x, int y, const String& text, Font font = StdFont(),...)

Just specify the font you intended there.

HTH,
Lance
Re: Display transparent paper [message #58051 is a reply to message #58049] Sun, 30 January 2022 09:34 Go to previous messageGo to next message
Silvan is currently offline  Silvan
Messages: 56
Registered: December 2014
Location: Trento (IT)
Member
Thak you, I specify better my question-
I want to use the alignment capacity of Display and I use this:

Display::Paint(Draww,Rectrc,AttrText(sometext).Center(),Red, White,0);

White is the paper color, but I want to write on the existing background (transparent).

I finally used something like this:

Size size = GetTextSize(sometext, font);
Draw::.DrawText((sz.cx-size.cx)/2, (sz.cy-size.cy)/2, sometext, font, Red);

I'm wandering if there exist I direct way to use Display.

Bye
Silvano
Re: Display transparent paper [message #58052 is a reply to message #58051] Sun, 30 January 2022 18:14 Go to previous messageGo to next message
Lance is currently offline  Lance
Messages: 536
Registered: March 2007
Contributor
Silvan:

Dig a little into Upp source code, I find something like this
void Display::PaintBackground(Draw& w, const Rect& r, const Value& q,
                              Color ink, Color paper, dword style) const
{
	if(IsType<AttrText>(q)) {
		const AttrText& t = ValueTo<AttrText>(q);
		if(!IsNull(t.paper))
			paper = t.paper;
		if(!IsNull(t.normalpaper) && !(style & (CURSOR|SELECT|READONLY)))
			paper = t.normalpaper;
	}
	w.DrawRect(r, paper);
}

void Display::Paint(Draw& w, const Rect& r, const Value& q, Color ink, Color paper, dword style) const
{
	PaintBackground(w, r, q, ink, paper, style);
	Single<StdDisplayClass>().Paint0(w, r, q, ink, paper, style);
}


Do you want to try set both paper for AttrText and the Paint parameter to Null and see if you get what you want. Obviously when you set the paper color of AttrText to Null, then the paper color of passed in parameter to funciton Display::Paint will be used. I am not quite sure if set it to Null will make a do nothing DrawRect. I think its the only reasonable result, but before actually test it, I cannot really tell for sure.

HTH,
Lance
Re: Display transparent paper [message #58053 is a reply to message #58052] Sun, 30 January 2022 18:20 Go to previous messageGo to next message
Lance is currently offline  Lance
Messages: 536
Registered: March 2007
Contributor
Yes, it should work as you wanted.

Test code
#include <CtrlLib/CtrlLib.h>
using namespace Upp;

struct App:TopWindow
{
	void Paint(Draw& w)override
	{
		w.DrawRect(GetSize(), Cyan());
//		w.DrawRect(GetSize()/2, SColorPaper());
		w.DrawRect(GetSize()/2, Null); // Do nothing, transparant background achieved.
	}
};

GUI_APP_MAIN
{
	App().Run();
}
Re: Display transparent paper [message #58054 is a reply to message #58049] Sun, 30 January 2022 19:15 Go to previous messageGo to next message
Silvan is currently offline  Silvan
Messages: 56
Registered: December 2014
Location: Trento (IT)
Member
Yes it works. Thank you

Display::Paint(aDraw,aRect,AttrText(sometext).Center().SetFo nt(Arial(40)),Red,Null,0);

The answer is to set to Null the paper color.

Ps:
I have to declare the Display object, but I read somewhere that it is static.
How can I use it directly without declaraction?

Like this:

Single<StdDisplayClass>().Paint(w, r, q, ink, paper, style); // don't compile

Re: Display transparent paper [message #58055 is a reply to message #58054] Sun, 30 January 2022 23:17 Go to previous messageGo to next message
Lance is currently offline  Lance
Messages: 536
Registered: March 2007
Contributor
Please take a look at <Reference/ArrayCtrl>

In particular:
ArrayCtrlExample::ArrayCtrlExample()
{
        ...
	array.AddColumn("with display").SetDisplay(Single<MyDisplay>());
        ...
}
Re: Display transparent paper [message #58056 is a reply to message #58055] Sun, 30 January 2022 23:23 Go to previous messageGo to next message
Lance is currently offline  Lance
Messages: 536
Registered: March 2007
Contributor
I have a feeling my answer is not what you're looking. However you can investigate ArrayCtrl code that uses
Display* display;

to standardize painting work. Adapt it to your particular situation.

Or you can upload a minimal test package, not necessarily compile-able. Explain in comments what you intend to achieve.
Re: Display transparent paper [message #58057 is a reply to message #58049] Mon, 31 January 2022 12:20 Go to previous messageGo to next message
Silvan is currently offline  Silvan
Messages: 56
Registered: December 2014
Location: Trento (IT)
Member
Thank you.

I refer to the content of the last paragraph of that page:
https://www.ultimatepp.org/src$Draw$Display_en-us.html

It says:
"Standard Displays are implemented as "functional globals" - functions returning constant reference to single global Display instance."

So I suppose it is possible to use StdDisplay without declaration, like me and you did.


Re: Display transparent paper [message #58058 is a reply to message #58057] Mon, 31 January 2022 17:47 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1096
Registered: August 2007
Senior Contributor
Hello Silvan,

#include <CtrlLib/CtrlLib.h>

using namespace Upp;

struct MyApp : TopWindow {
	MyApp()
	{
		Sizeable().Zoomable().CenterScreen().SetRect(0, 0, 640, 480);
	}
	
	void Paint(Draw& w) override
	{
		Size sz = GetSize();
		w.DrawRect(sz, Red());
		StdCenterDisplay().Paint(w, sz, "Centered", White, Null, 0L);  // <-- There are ready-made displays which you can use in-place (they are functional globals)
	}

};

GUI_APP_MAIN
{
	MyApp().Run();
}



You can also create your own Display objects. See uppsrc/Draw/Display.cpp for details.


Best regards,
Oblivion


[Updated on: Mon, 31 January 2022 17:54]

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Re: Display transparent paper [message #58059 is a reply to message #58049] Mon, 31 January 2022 18:46 Go to previous message
Silvan is currently offline  Silvan
Messages: 56
Registered: December 2014
Location: Trento (IT)
Member
Thank you!
yes, simple and direct!

Best Regards
Silvano
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