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Is there a "Graphics.clearRect()" method? [SOLVED]

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smallfly

Post subject: Is there a "Graphics.clearRect()" method? [SOLVED]

Posted: Tue Jun 05, 2012 9:48 pm

Joined: Sat Feb 19, 2011 2:59 pm
Posts: 52

Hello together,

I need a function that clears only part of an image. With graphics.clear() I can clear the whole image. But I only want to clear a rectangular region of an image.

A method like graphics.clearRect(x, y, width, height) would be perfect. But there is no function like that (?)

If there is really no method like that, how can I achieve my wish to clear a rect area?

fillRect() with color(0, 0, 0, 0) does not help since it has absolutely no effect. how can i change the draw mode so that the fillRect color is not added but replaces the underlying colors which are only in buffer at these positions?

Thanks for your help!
smallfly

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http://www.p1sim.org - Economy/Logistics simulaton based on Java and Slick2D

Last edited by smallfly on Sat Jun 09, 2012 11:15 am, edited 1 time in total.

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davedes

Post subject: Re: Is there a "Graphics.clearRect()" method?

Posted: Tue Jun 05, 2012 10:28 pm

Slick Zombie

Joined: Sat Jan 27, 2007 7:10 pm
Posts: 1467

Option A:

Code:

      g.setDrawMode(Graphics.MODE_COLOR_MULTIPLY);
      g.setColor(new Color(0f,0f,0f,0f));
      g.fillRect(50, 50, 100, 100);
      g.setDrawMode(Graphics.MODE_NORMAL);

Option B:
(I just tested it and it seems bugged -- the y value is flipped.)

Code:

      g.setClip(50, 50, 100, 100);

      // not always necessary since this is the default background/clear color
      g.setBackground(new Color(0f, 0f, 0f, 0f));
      g.clear();
      g.clearClip();

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smallfly

Post subject: Re: Is there a "Graphics.clearRect()" method?

Posted: Wed Jun 06, 2012 7:58 am

Joined: Sat Feb 19, 2011 2:59 pm
Posts: 52

aaaah. of course: MODE_COLOR_MULTIPLY. stupid me. i saw this draw mode but i ignored it, since i looked for something like OVERWRITE. but yeah: 0 * color = 0

thank you very much

_________________
http://www.p1sim.org - Economy/Logistics simulaton based on Java and Slick2D

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