lib/browser/awtUtilities/ScrollCanvas.java

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/browser/awtUtilities/ScrollCanvas.java	Wed Aug 06 00:06:47 1997 +0200
@@ -0,0 +1,169 @@
+/***************************************************************************
+  Title:      awtUtilities/ScrollCanvas.java
+  ID:         $Id$
+  Author:     Stefan Berghofer, TU Muenchen
+  Copyright   1997  TU Muenchen
+
+  This class contains defines a window with scrollbars, which is not
+  supported by the 1.0.2 version of the JDK. To use this class, simply
+  derive your own class from it and overwrite the paintCanvas method.
+  When a repaint event occurs, ScrollCanvas automatically calls the
+  paintCanvas method. The user doesn't have to take care of transposing
+  mouse or graphics coordinates.
+  Note: In later versions of the JDK, a ScrollPane class will be provided,
+  which can be used instead.
+***************************************************************************/
+
+package awtUtilities;
+
+import java.awt.*;
+
+class DummyCanvas extends Canvas {
+	ScrollCanvas parent;
+
+	public DummyCanvas(ScrollCanvas p) {
+		parent=p;
+	}
+
+	public void paint(Graphics g) {
+		parent.paint(g);
+	}
+
+	public void update(Graphics g) {
+		parent.update(g);
+	}
+}
+
+public class ScrollCanvas extends Panel
+{
+	Scrollbar scrollv,scrollh;
+	Canvas can;
+	Image img=null;
+	int offset_x=0,offset_y=0;
+	int size_x=100,size_y=100;
+	int old_x=0,old_y=0;
+
+	public boolean handleEvent(Event evt)
+	{
+		evt.x+=offset_x;
+		evt.y+=offset_y;
+		if (evt.target instanceof Scrollbar)
+		{
+			offset_x=scrollh.getValue();
+			offset_y=scrollv.getValue();
+			Graphics g=can.getGraphics();
+			if (old_x!=size_x || old_y!=size_y)
+				update(g);
+			else {
+				g.translate(-offset_x,-offset_y);
+				g.drawImage(img,0,0,this);
+			}
+			return true;
+		}
+		else return super.handleEvent(evt);
+	}
+
+	public void adjust_scrollbars()
+	{
+		int viewport_v=can.size().height;
+		int viewport_h=can.size().width;
+		int value_v=scrollv.getValue();
+		int value_h=scrollh.getValue();
+
+		scrollv.setValues(value_v,viewport_v,0,size_y-viewport_v);
+		scrollh.setValues(value_h,viewport_h,0,size_x-viewport_h);
+		scrollv.setLineIncrement(viewport_v/20);
+		scrollv.setPageIncrement(viewport_v);
+		scrollh.setLineIncrement(viewport_h/20);
+		scrollh.setPageIncrement(viewport_h);
+		offset_x=scrollh.getValue();
+		offset_y=scrollv.getValue();
+	}
+
+	public void set_size(int x,int y)
+	{
+		size_x=x;size_y=y;
+		adjust_scrollbars();
+	}
+
+	public void focus_to(int x,int y) {
+		offset_x=Math.min(scrollh.getMaximum(),Math.max(0,x-can.size().width/2));
+		offset_y=Math.min(scrollv.getMaximum(),Math.max(0,y-can.size().height/2));
+
+		scrollh.setValue(offset_x);
+		scrollv.setValue(offset_y);
+		Graphics g=can.getGraphics();
+		if (old_x!=size_x || old_y!=size_y)
+			update(g);
+		else {
+			g.translate(-offset_x,-offset_y);
+			g.drawImage(img,0,0,this);
+		}
+	}		
+
+	public void update(Graphics g) {
+		g=can.getGraphics();
+		int viewport_v=can.size().height;
+		int viewport_h=can.size().width;
+		int img_x=Math.max(viewport_h,size_x+1);
+		int img_y=Math.max(viewport_v,size_y+1);
+
+		old_x=size_x;old_y=size_y;
+		img=createImage(img_x,img_y);
+		Graphics g2=img.getGraphics();
+		g2.setColor(Color.lightGray);
+		g2.fillRect(0,0,img_x,img_y);
+		g2.setColor(Color.black);
+		paintCanvas(g2);
+		adjust_scrollbars();
+		g.translate(-offset_x,-offset_y);
+		g.drawImage(img,0,0,this);
+	}
+
+	public void paint(Graphics g)
+	{
+		if (img!=null && old_x==size_x && old_y==size_y) {
+			g=can.getGraphics();
+			adjust_scrollbars();
+			g.translate(-offset_x,-offset_y);
+			g.drawImage(img,0,0,this);
+		} else update(g);
+	}
+
+	public Graphics getGraphics() {
+		Graphics g=can.getGraphics();
+
+		g.translate(-offset_x,-offset_y);
+		return g;
+	}	
+
+	public void paintCanvas(Graphics g)
+	{}
+
+	public ScrollCanvas()
+	{
+		can=new DummyCanvas(this);
+		GridBagLayout gridbag = new GridBagLayout();
+		GridBagConstraints c = new GridBagConstraints();
+		scrollv=new Scrollbar(Scrollbar.VERTICAL);
+		scrollh=new Scrollbar(Scrollbar.HORIZONTAL);
+
+		setLayout(gridbag);
+		c.weightx = 1.0;
+		c.weighty = 1.0;
+		c.gridwidth=1;
+		c.fill = GridBagConstraints.BOTH;
+		gridbag.setConstraints(can,c);
+		add(can);
+		c.weightx=0;
+		c.weighty=0;
+		c.gridwidth = GridBagConstraints.REMAINDER;
+		c.fill = GridBagConstraints.VERTICAL;
+		gridbag.setConstraints(scrollv,c);
+		add(scrollv);
+		c.gridwidth = 1;
+		c.fill = GridBagConstraints.HORIZONTAL;
+		gridbag.setConstraints(scrollh,c);
+		add(scrollh);
+	}
+}