Problem with Graphics 2D scale and manual scale on multilayer. please help!
public void paintComponent(Graphics g){
Graphics2D g2d = (Graphics2D) g;
if(image != null){
g2d.scale(scaleFactor,scaleFactor);
g2d.setComposite(AlphaComposite.getInstance (AlphaComposite.SRC_OVER, 1.0f));
g2d.drawImage(image,0,0,null);
}else{
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f));
g2d.setColor(Color.WHITE);
g2d.fillRect(0,0,getWidth(),getHeight());
}
g2d.setComposite(AlphaComposite.getInstance (AlphaComposite.SRC_OVER, FLOAT_ALPHA));
g2d.drawImage(overlapLayer,0,0,null);
}
Basically i have 2 layers - one background that has an image and one is the one transparent on top of it. The problem is this - the background layer I want to use the Graphics 2D to autoscale the size BUT the layer on top of it I want only the SIZE INCREASE but not the scaling - I have a manual scaling mechanism for the foreground. The reason for the manual scaling is if i dont have the background on (image == null) then I am not going to be able to autoscale much.
Is there anything I can do to change the size of both layers, use the graphics 2D to scale the bottom layer and use my own scaling for the top layer or I HAVE TO stick to one scaling mechanism?
Thanks!
[1293 byte] By [
shaselaia] at [2007-11-27 7:34:22]
# 1
Unsolicited suggestion: If you are always going to have an alpha value of 1.0f for the
background you can eliminate the setComposite call.
About your question: I can think of three ways to do the multiple scaling:
1 — reset the graphics transform after each use
if(image != null){
g2d.scale(scaleFactor,scaleFactor);
g2d.drawImage(image,0,0,null);
// Reset scale to 1.0
g2d.scale(1.0/scaleFactor, 1.0/scaleFactor);
}else{
g2d.setColor(Color.WHITE);
g2d.fillRect(0,0,getWidth(),getHeight());
}
g2d.setComposite(AlphaComposite.getInstance (AlphaComposite.SRC_OVER, FLOAT_ALPHA));
g2d.drawImage(overlapLayer,0,0,null);
2 — use a copy of the graphics context and dispose it after use
if(image != null){
Graphics2D copy = (Graphics2D)g.create();
copy.scale(scaleFactor,scaleFactor);
copy.drawImage(image,0,0,null);
copy.dispose();
// Carry on with g2d
3 — use AffineTransform
if(image != null){
double x = // sometimes a translation
double y = // is needed sometimes not
AffineTransform at = AffineTransform.getTranslateInstance(x, y);
at.scale(scaleFactor,scaleFactor);
g2d.drawRenderedImage(image,at);
}else{
g2d.setColor(Color.WHITE);
g2d.fillRect(0,0,getWidth(),getHeight());
}
x = // as needed to locate
y = // scaled ovelay image
at.setToTranslation(x, y);
at.scale(...
g2d.setComposite(AlphaComposite.getInstance (AlphaComposite.SRC_OVER, FLOAT_ALPHA));
g2d.drawRenderedImage(overlapLayer,at);
Using a RenderingHint value of INTERPOLATION_BICUBIC often helps in scaling ops.
