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Java Forum / GUI / July 2004Scale Question (Graphics2D)
Hi, I use a JPanel as a Canvas to draw some shapes. The Panel is embedded in an JScrollPane. When I scale the canvas ( i do this in the paint() - method by using scale() method) my drawing zoomes like i want it. But the drawing is bigger than the visible area. The problem is, that no scrolling bars appear. I thought, a JScrollPane enables them if the client in the viewport becomes bigger than the visible area?! Where's my error? And second problem: I recognize the shapes when I click on them using mousePressed method. If I don't scale the drawing everything works fine, but when i scale it an then click in a shape, it's not recognized. It seems as if i should "scale" the mouse coordinates too, but how to do?! best regards Andreas > When I scale the canvas ( i do this in the paint() - method by using scale() > method) my drawing zoomes like i want it. But the drawing is bigger than > the visible area. The problem is, that no scrolling bars appear. I thought, > a JScrollPane enables them if the client in the viewport becomes bigger than > the visible area?! Where's my error? You also need to resize the JPanel. Java has no problems drawing outside the bounds of a component, and scaling (and other transforms) in Java2D only affects the Shape drawn. "Tor Iver Wilhelmsen" <tor.iver.wilhelmsen@broadpark.no> schrieb : > You also need to resize the JPanel. Java has no problems drawing > outside the bounds of a component, and scaling (and other transforms) > in Java2D only affects the Shape drawn. I already tried this, but no success... maybe another problem? I'll give you code... Canvas canvas = new Canvas(); JScrollPane canvasScroll = new JScrollPane(canvas); mainWindow.getContentPane().add(BorderLayout.CENTER,canvasScroll); class Canvas extends JPaenl{ public Canvas(){ setSize(10000,1000); // <- I think this should be enough to show scroll bars ?! } } > setSize(10000,1000); // <- I think this should be enough to show > scroll bars ?! Except when using layout managers - including the very custom one in JScrollPane - they will resize as they see fit. As another poster pointed out, there are other methods in Swing to set the min, max and preferred sizes. > Hi, > [quoted text clipped - 5 lines] > a JScrollPane enables them if the client in the viewport becomes bigger than > the visible area?! Where's my error? the problem is, that you scale Graphics, canvas size is unchanged. > And second problem: I recognize the shapes when I click on them using > mousePressed method. If I don't scale the drawing everything works fine, but > when > i scale it an then click in a shape, it's not recognized. It seems as if i > should "scale" the mouse coordinates too, but how to do?! the question is what you should scale? you could a) apply scale to all your shapes, or b) scale graphics, change size of canvas, put glassPane over canvas and scale mouse events (I didn't tested it)  SignatureAndrei Kouznetsov http://uio.dev.java.net Unified I/O for Java http://reader.imagero.com Java image reader > I thought, >a JScrollPane enables them if the client in the viewport becomes bigger than >the visible area?! Where's my error? What does getSize say? You probably have not implemented getMinimumSize getMaximumSize getPreferredSize. SignatureCanadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. >i scale it an then click in a shape, it's not recognized. It seems as if i >should "scale" the mouse coordinates too, but how to do?! And Dale thinks this is where we should START the poor newbies! see http://mindprod.com/jgloss/affinetransform.html#MOUSE SignatureCanadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. "Roedy Green" <look-on@mindprod.com.invalid> schrieb: > And Dale thinks this is where we should START the poor newbies! > see http://mindprod.com/jgloss/affinetransform.html#MOUSE And this works really very fine, thanks a lot :-) > I use a JPanel as a Canvas to draw some shapes. The Panel is embedded in an > JScrollPane. [quoted text clipped - 3 lines] > a JScrollPane enables them if the client in the viewport becomes bigger than > the visible area?! Where's my error? The scale method only affects the results of the paint operation. What you want to do is change the result of getPreferredSize, and then call revalidate() on the component. That should be done at whatever point you make the change that will cause the scale factor to increase. Incidentally, you should be overriding paintComponent to draw on a JPanel, not paint. And then, unless you intend to overwrite every pixel of the contents, you should start the whole process with a call to super.paintComponent as well. > And second problem: I recognize the shapes when I click on them using > mousePressed method. If I don't scale the drawing everything works fine, but > when > i scale it an then click in a shape, it's not recognized. It seems as if i > should "scale" the mouse coordinates too, but how to do?! You can scale the mouse coordinates by multiplying the x coordinate by the horizontal scale factor, and the y coordinate by the vertical scale factor. These scale factors are the values you pass into the Graphics2D.scale method. If you start doing more complex transformations than just scaling, then you ought to save the AffineTransform object that represents your transformations. Then whenever you need to do a transformation, use one of the appropriate transform methods on that AffineTransform object. At the beginning of paintComponent, you can call g2d.setTransform to reuse the same AffineTransform for painting as well. Signaturewww.designacourse.com The Easiest Way to Train Anyone... Anywhere. Chris Smith - Lead Software Developer/Technical Trainer MindIQ Corporation "Chris Smith" <cdsmith@twu.net> schrieb: > The scale method only affects the results of the paint operation. What > you want to do is change the result of getPreferredSize, and then call > revalidate() on the component. That should be done at whatever point > you make the change that will cause the scale factor to increase. Ah ok, when I use setPrefferedSize it works... Free MagazinesGet these publications absolutely FREE for up to 12 months. 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