<Swing Dev> Fake-Opaque Swing Components

[Kirill Grouchnikov]

Shannon,

My intent was that the component will paint pixels that don't really belong to it visually. While it will work for most of the application that have grid-like layouts, it will result in incorrect clipping of layout that use overlapping components. The same would apply for animating the layout changes where controls would slide from place to place - even if it happens for a fraction of second.

And as far as i can tell from the rendering pipeline, a non-opaque component does not cause the entire parent to be repainted - only the relevant portion of the parent. While it still results in more repaints (especially if the parent itself is non-opaque), it shouldn't be that big of a problem.

Thanks
Kirill


----- Original Message ----
From: Shannon Hickey <Shannon.Hickey at Sun.COM>
To: Kirill Grouchnikov <kirillcool at yahoo.com>
Cc: swing-dev at openjdk.java.net
Sent: Monday, November 12, 2007 12:36:54 PM
Subject: Re: <Swing Dev> Fake-Opaque Swing Components


Hi Kirill,

Kirill Grouchnikov wrote:
> Hi, Jasper
> 
> Wouldn't that conflict with the optimizations made in the rendering 
> pipeline? The component is still declared as opaque, but does not 
> effectively paint all the pixels in its bounds.

Jasper's proposal WILL paint all pixels in its bounds. It simply 
mentions painting the outer edges in the parent background color.


 > So, potentially you can
> have overlapping components (by design or during layout transitions) 
> which will be cut off in that area around the visual painting of the 
> components. In addition, this approach (as well as the existing one) 
> doesn't address watermarking functionality.
> 
> The issues with the performance can be addressed by repainting only
 the 
> relevant area (such as caret does when it's blinking).

Of course. Swing already tries to constrain the areas that it repaints.
 
What Jasper refers to is the performance hit we'll take (although it's 
not quantified how much...Jasper?) by forcing painting to start at a 
higher level.

Thanks!
Shannon

> 
> Thanks
> Kirill
> 
> ----- Original Message ----
> From: Jasper Potts <Jasper.Potts at Sun.COM>
> To: swing-dev at openjdk.java.net
> Sent: Monday, November 12, 2007 10:53:41 AM
> Subject: <Swing Dev> Fake-Opaque Swing Components
> 
> I have a problem with Nimbus that is common with other modern look
 and 
> feels which we need to fix. The problem is how do setBackgound() and 
> setForeground() map to how the component looks.
> Because of the some components having rounded corners and all
 components 
> having 2px spacing for painting the focus glow. You end up with this 
> background area around the component (in red above). The area is not 
> really of color Component.getBackgound() as that has another meaning 
> which is the background of the actual component content such as the
 text 
> field background(in green above).   
> 
> The obvious solution to the problem is to make the component
 non-opaque. 
> Which means the red area would be transparent. The issue with this is
 it 
> the performance for opaque components is much worse so for components
 
> like a text field which needs to be very responsive as you type this 
> could be a issue.
> 
> *P**roposed Solution*
> So the proposed solution is for the component to be opaque and the
 outer 
> background area to be painted as before but be the parent components 
> getBackgound() color. This seems the right answer but means a change
 at 
> a low level. So what I propose is adding a UIManager property to turn
 
> this on and changing the ComponentUI.update() method from:
> 
> public abstract class ComponentUI {
> ...
>   public void update(Graphics g, JComponent c) {
> if (c.isOpaque()) {
>     g.setColor(c.getBackground());
>     g.fillRect(0, 0, c.getWidth(),c.getHeight());
> }
> paint(g, c);
>   }
> ...
> }
> 
> to:
> 
> public abstract class ComponentUI {
> ...
>   public void update(Graphics g, JComponent c) {
> if (c.isOpaque()) {
>             if
 (UIManager.getBoolean("Opaque.useParentBackgroundColor") && 
>                 c.getParent() != null){
>                 g.setColor(c.getParent().getBackground());
>             } else {
>             g.setColor(c.getBackground());
>             }
>     g.fillRect(0, 0, c.getWidth(),c.getHeight());
> }
> paint(g, c);
>   }
> ...
> }
> 
> I am open for better suggestions for the UIManager key name but that
 is 
> the basic idea.
> 
> *So what do you think??????*
> 
> Thanks
> 
> Jasper
> 
> 

-- 
Shannon Hickey
shannon.hickey at sun.com
Swing Team - Sun Microsystems, Inc.
http://java.sun.com/javase/technologies/desktop





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