/* * File: ViewportScroller.java * * 5/29/96 Larry Barowski * */ package EDU.auburn.VGJ.gui; import java.awt.Image; import java.awt.Canvas; import java.awt.Rectangle; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Color; import java.awt.Event; import java.awt.Point; /** * A ViewportScroller is a window used to scroll a window through a * larger area of content. The content is shown as a white rectangle, with * the window being represented by a black rectangle outline within it. A * SCROLL event is sent when the user drags the "window" with the mouse. *

Here is the source. * *@author Larry Barowski **/ public class ViewportScroller extends Canvas { /** * Event indicating the scroller has been moved. **/ public static int SCROLL = 38773; public static int DONE = 38774; private int width_ = -1, height_ = -1; private double portWidth_, portHeight_; private double contentWidth_, contentHeight_; private double offsetX_, offsetY_; private Rectangle portRect_; private Rectangle contentRect_; private int preferredW_, preferredH_; private Color color_; private boolean mousedown_ = false; private int dragOffsetX_, dragOffsetY_; private DragFix dragFix_; private Image backImage_ = null; public synchronized void paint(Graphics graphics) { graphics.dispose(); paintOver(); } public ViewportScroller(int width, int height, double contentw, double contenth, double portw, double porth, double offsx, double offsy) { dragFix_ = new DragFix(this); preferredW_ = width; preferredH_ = height; contentWidth_ = contentw; contentHeight_ = contenth; portWidth_ = portw; portHeight_ = porth; offsetX_ = offsx; offsetY_ = offsy; contentRect_ = new Rectangle(); portRect_ = new Rectangle(); color_ = Color.white; } public void setPortSize(double width, double height) { if(portWidth_ == width && portHeight_ == height) return; portWidth_ = width; portHeight_ = height; recompute_(); repaint(); } public void setContentSize(double width, double height) { if(contentWidth_ == width && contentHeight_ == height) return; contentWidth_ = width; contentHeight_ = height; recompute_(); repaint(); } public void setOffset(double x, double y) { if((int)offsetX_ == (int)x && (int)offsetY_ == (int)y) return; offsetX_ = x; offsetY_ = y; recompute_(); paintOver(); } double getOffsetX() { return offsetX_; } double getOffsetY() { return offsetY_; } void setTheColor(Color new_color) { color_ = new_color; } // this will give the initial size public Dimension preferredSize() { return new Dimension(preferredW_, preferredH_); } public synchronized void paintOver() { Dimension winsize = size(); if(winsize.width != width_ || winsize.height != height_) { width_ = winsize.width; height_ = winsize.height; recompute_(); backImage_ = null; } if(backImage_ == null) { backImage_ = createImage(width_, height_); } Graphics graphics = backImage_.getGraphics(); graphics.setColor(getBackground()); graphics.fillRect(0, 0, width_, height_); graphics.setColor(color_); graphics.fillRect(contentRect_.x, contentRect_.y, contentRect_.width, contentRect_.height); graphics.setColor(Color.black); graphics.setPaintMode(); graphics.drawRect(contentRect_.x, contentRect_.y, contentRect_.width, contentRect_.height); graphics.dispose(); Graphics screen = getGraphics(); screen.drawImage(backImage_, 0, 0, null); screen.drawRect(portRect_.x, portRect_.y, portRect_.width, portRect_.height); screen.dispose(); } private void recompute_() { double d_width = (double)width_ - 1.0; double d_height = (double)height_ - 1.0; if(d_width * contentHeight_ > d_height * contentWidth_) // Canvas is proportionally wider than content. { contentRect_.y = 0; contentRect_.height = (int)d_height; contentRect_.width = (int)(d_height * contentWidth_ / contentHeight_); contentRect_.x = (int)((d_width - contentRect_.width) / 2.0); } else // Canvas is proportional with or proportionally taller thatn // content. { contentRect_.x = 0; contentRect_.width = (int)d_width; contentRect_.height = (int)(d_width * contentHeight_ / contentWidth_); contentRect_.y = (int)((d_height - contentRect_.height) / 2.0); } double scale_ratio = ((double)contentRect_.width) / contentWidth_; portRect_.x = contentRect_.x + (int)(offsetX_ * scale_ratio); portRect_.y = contentRect_.y + (int)(offsetY_ * scale_ratio); portRect_.width = (int)(portWidth_ * scale_ratio) + 1; portRect_.height = (int)(portHeight_ * scale_ratio) + 1; if(portRect_.x < contentRect_.x) portRect_.x = contentRect_.x; if(portRect_.y < contentRect_.y) portRect_.y = contentRect_.y; if(portRect_.x + portRect_.width > contentRect_.x + contentRect_.width) portRect_.x = contentRect_.x + contentRect_.width - portRect_.width; if(portRect_.y + portRect_.height > contentRect_.y + contentRect_.height) portRect_.y = contentRect_.y + contentRect_.height - portRect_.height; } public boolean mouseDown(Event e, int x, int y) { if(mousedown_) return true; mousedown_ = true; dragOffsetX_ = x - portRect_.x + contentRect_.x; dragOffsetY_ = y - portRect_.y + contentRect_.y; return true; } public boolean mouseDrag(Event e, int x, int y) { if(!mousedown_) return true; if(x < dragOffsetX_) x = dragOffsetX_; if(x - dragOffsetX_ + portRect_.width > contentRect_.width) x = contentRect_.width + dragOffsetX_ - portRect_.width; if(y < dragOffsetY_) y = dragOffsetY_; if(y - dragOffsetY_ + portRect_.height > contentRect_.height) y = contentRect_.height + dragOffsetY_ - portRect_.height; Graphics graphics = getGraphics(); getGraphics().drawImage(backImage_, 0, 0, null); portRect_.x = x - dragOffsetX_ + contentRect_.x; portRect_.y = y - dragOffsetY_ + contentRect_.y; graphics.drawRect(portRect_.x, portRect_.y, portRect_.width, portRect_.height); graphics.dispose(); double scale_ratio = contentWidth_ / (double)(contentRect_.width); offsetX_ = (double)(portRect_.x - contentRect_.x) * scale_ratio + 0.5; offsetY_ = (double)(portRect_.y - contentRect_.y) * scale_ratio + 0.5; // Post an event indicating a scroll. getParent().postEvent(new Event((Object)this, SCROLL, (Object)this)); return true; } public boolean mouseUp(Event e, int x, int y) { mousedown_ = false; paintOver(); // Post an event indicating we are done scrolling. getParent().postEvent(new Event((Object)this, DONE, (Object)this)); return true; } public boolean handleEvent(Event e) { if(e.id == DragFix.QUEUED) { super.handleEvent((Event)e.arg); getParent().postEvent((Event)e.arg); return true; } dragFix_.queueEvent(e); return true; } public synchronized void removeNotify() { dragFix_.killThread(); super.removeNotify(); } }